Maryland Supreme Court Opinion on Federal Preemption of State Law Claims
Summary
The Maryland Supreme Court affirmed the dismissal of state common law tort claims filed by local governments against 26 oil and gas companies. The Court held that federal law displaces and preempts these state law claims related to damages from greenhouse gas emissions.
What changed
The Maryland Supreme Court, in a consolidated opinion involving cases from Baltimore City and Anne Arundel County, has ruled that state common law tort claims brought by local governments against 26 multinational oil and gas companies are preempted by federal law. The local governments sought to recover damages for alleged harm caused by greenhouse gas emissions, asserting claims such as public nuisance, private nuisance, trespass, and negligent/strict liability failure to warn. The Court affirmed the lower courts' decisions to dismiss these claims.
This ruling has significant implications for entities facing similar climate change-related litigation at the state level. Compliance officers should note that claims based on state tort law for damages attributed to greenhouse gas emissions may be subject to federal preemption. While this decision specifically addresses Maryland law, it could set a precedent for how such cases are handled in other jurisdictions, potentially limiting the avenues for state and local governments to seek damages from fossil fuel companies through common law actions.
What to do next
- Review legal counsel regarding potential impact on ongoing or future climate change litigation
- Assess exposure to federal preemption challenges for state law claims in environmental litigation
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March 24, 2026 Get Citation Alerts Download PDF Add Note
Mayor & City Cncl. Of Balt. V. B.P. P.L.C.
Court of Appeals of Maryland
- Citations: None known
- Docket Number: 11/25
Judges: Booth
Combined Opinion
Mayor & City Council of Baltimore v. B.P. P.L.C., et al.; Anne Arundel County, Maryland
v. B.P. P.L.C., et al; City of Annapolis v. B.P. P.L.C., et al., No. 11, September Term, 2025,
Opinion by Booth, J.
FEDERAL DISPLACEMENT/PREEMPTION OF STATE LAW CLAIMS
The Supreme Court of Maryland considered three consolidated cases—one case filed in
the Circuit Court for Baltimore City and two cases filed in the Circuit Court for Anne
Arundel County. In these cases, the Mayor and Council of Baltimore City (“Baltimore”),
Anne Arundel County, and the City of Annapolis, (collectively, the “local governments”)
filed state common law tort claims against 26 multinational oil and gas companies to
recover damages caused by global greenhouse gas emissions. Specifically, the local
governments asserted five causes of action against the Defendants, all arising under
Maryland law: (1) public nuisance; (2) private nuisance; (3) trespass; (4) negligent failure
to warn; and (5) strict liability failure to warn.
The local governments argued that the Defendants, individually and collectively, are
responsible for extracting, processing, producing, promoting, and marketing fossil fuel
products, the normal and intended use of which has led to the emission of a substantial
percentage of the total volume of greenhouse gases released into the atmosphere for over
50 years. The local governments contend that the Defendants deceived consumers and the
public about the dangers associated with their fossil fuel products when they knew of a
direct link between their products and climate change threats, causing sea levels to rise, as
well as other physical and environmental impacts, resulting in inundation, destruction,
and/or other interference with the local governments’ property and citizenry.
The Circuit Court for Baltimore City and the Circuit Court for Anne Arundel County
granted the Defendants’ motions to dismiss. After an appeal to the Appellate Court of
Maryland, in which the cases were consolidated, this Court issued a bypass writ of
certiorari to determine whether Maryland local governments may bring the state common
law tort claims against the 26 companies to recover damages caused by global greenhouse
gas emissions.
The Supreme Court of Maryland affirmed the judgments of the lower courts dismissing the
complaints. The Court held that the local governments’ state law claims are displaced and
preempted by federal law. The Court determined that the local governments, through their
state law claims, are attempting to regulate air emissions. The Court explained that, for
over a century, the United States Supreme Court has held that cases involving regulations
of interstate pollution arise under federal law. Under the United States Supreme Court’s
jurisprudence, any state law claims are displaced by federal common law. Moreover, as
the United States Supreme Court held in American Electric Power Co., Inc. v. Connecticut,
564 U.S. 410 (2011), the Clean Air Act, 42 U.S.C. § 7401, et seq. (1970), displaces
applicable federal common law. Applying the preemption framework adopted by the
United States Supreme Court in International Paper Company v. Ouellette, 479 U.S. 481
(1987), the Supreme Court of Maryland held that the Clean Air Act does not authorize the
broad state law claims under its saving clause. Finally, the Supreme Court of Maryland
held that federal common law would not extend to apply to the local governments’ claims
that regulate international conduct. The United States Supreme Court has made it clear
that the political branches, not the Judiciary, have the responsibility and institutional
capacity to weigh foreign policy concerns.
The Supreme Court further held that, even if the local governments’ state law claims were
not displaced or preempted by federal law, the local governments failed to state legally
cognizable claims under state law for public nuisance, private nuisance, trespass, and
negligent and strict liability failure to warn.
PUBLIC NUISANCE
The Supreme Court held that the local governments failed to state a claim for public
nuisance under Maryland law. As this Court explained in Express Scripts, Inc. v. Anne
Arundel County, Maryland, ___ Md. _____ (filed March 23, 2026), Maryland has not
expanded the public nuisance doctrine beyond the traditional historical principles
embodied in the common law—namely, that a public nuisance action was not regarded as
a tort but was instead a public action by a government entity to pursue criminal
prosecutions or seek injunctive relief to abate harmful conduct. Additionally, this Court
has never recognized a government entity’s ability to recover damages for public nuisance.
Moreover, assuming without deciding that there is a public right to be free from adverse
effects of climate change, the Court stated that it nonetheless declines to expand
Maryland’s common law of public nuisance to govern the conduct alleged in the local
governments’ complaints given the extensive federal statutory and regulatory framework
that governs the highly complex conduct of regulating air emissions.
PRIVATE NUISANCE
The Supreme Court held that the local governments failed to state a claim for private
nuisance because that tort requires that the plaintiff establish an injury to property that is
different in kind from that suffered by the public generally. Here, the injuries alleged by
the local governments are not unique or different from any injuries suffered by the public
generally.
TRESPASS
The Court held that the local governments’ trespass claim exceeds the bounds of the tort
established in this Court’s case law, which holds that when an adjacent property is invaded
by an inanimate or intangible object, the defendant must have some connection or control
over that object for a trespass action to lie. The Court agreed with the Circuit Court for
Baltimore City that the link between the Defendants’ activities and the harms alleged by
the local governments, which are caused by human activities around the world, are far too
attenuated to constitute the Defendants’ connection or control over the rainfall and storms
that invaded the local governments’ property.
STRICT LIABILITY/NEGLIGENCE ARISING FROM FAILURE TO WARN
The Court held that the local governments failed to state claims for strict liability and
negligent failure to warn. The Court determined that the duty the local governments seek
to impose is a duty to warn the entire human race of the effects of climate change. The
Court stated that finding such a duty would stretch Maryland tort law beyond manageable
bounds.
Circuit Court for Baltimore City
Case No.: 24-C-18-004219
IN THE SUPREME COURT
Circuit Court for Anne Arundel County
Case No.: C-02-CV-21-000250
OF MARYLAND
Circuit Court for Anne Arundel County
Case No.: C-02-CV-21-000565 No. 11
September Term, 2025
Argued: October 6, 2025
MAYOR & CITY COUNCIL OF BALTIMORE
v.
B.P. P.L.C., et al.
ANNE ARUNDEL COUNTY, MARYLAND
v.
B.P. P.L.C., et al.
CITY OF ANNAPOLIS
v.
B.P. P.L.C., et al.
Fader, C.J.,
Watts,
Booth,
Gould,
Eaves,
Killough,
Battaglia, Lynne A.
(Senior Justice, Specially Assigned)
JJ.
Opinion by Booth, J.
Fader, C.J., concurs.
Gould, J., concurs.
Watts, J., concurs and dissents.
Pursuant to the Maryland Uniform Electronic Legal Killough, J., concurs and dissents.
Materials Act (§§ 10-1601 et seq. of the State
Government Article) this document is authentic.
2026.03.24 Filed: March 24, 2026
13:47:24 -04'00'
Gregory Hilton, Clerk
The question presented in this case is whether Maryland local governments may
bring state common law tort claims against 26 multinational oil and gas companies to
recover damages caused by global greenhouse gas emissions. We hold that they may not.
For the reasons set forth more fully herein, we determine that state common law has
never applied to the conduct alleged by the local governments. We determine that the local
governments, through their various state law claims, are seeking to regulate air emissions
beyond their jurisdictional boundaries. For over a century, the United States Supreme
Court has held that cases involving regulation of interstate pollution arise under federal
law. Under the United States Supreme Court’s jurisprudence, we conclude that any state
law claims are displaced by federal common law. Moreover, as the United States Supreme
Court held in American Electric Power Co., Inc. v. Connecticut, 564 U.S. 410 (2011), the
Clean Air Act, 42 U.S.C. § 7401, et seq. (1970), displaces applicable federal common law.
Applying the preemption framework adopted by the Supreme Court in International Paper
Company v. Ouellette, 479 U.S. 481 (1987), we hold that that the Clean Air Act does not
authorize the broad state law claims under its saving clause. Additionally, to the extent
that the local governments seek recovery for harms caused by foreign emissions, foreign
policy concerns would foreclose a federal common law action targeting emissions
emanating from beyond our borders.
Finally, we hold that, even if the local governments’ state law claims were not
displaced or preempted by federal law, they fail to state claims under Maryland law for
public and private nuisance, strict liability and negligent failure to warn, and trespass. We
discuss the legal deficiencies pertaining to each of these state law claims below.
This appeal comprises three consolidated cases—one filed in the Circuit Court for
Baltimore City and two filed in the Circuit Court for Anne Arundel County. These cases
took an extended detour through the federal courts arising from the oil and gas companies’
unsuccessful attempts at removal. We briefly recount the circuitous route that brought
these cases to this Court.
I
Procedural History
A. Baltimore City Case
1. Complaint
In July 2018, the Mayor and City Council of Baltimore (“Baltimore”) filed suit
against 26 major oil and gas companies (“the Defendants”) 1 in the Circuit Court for
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Baltimore City. Baltimore asserts that the Defendants substantially contributed to
greenhouse gas pollution, global warming, and climate change by extracting, producing,
promoting, refining, marketing, distributing, and selling fossil fuel products (i.e., coal, oil,
and natural gas). Baltimore contends that the Defendants deceived consumers and the
1
The Defendants consist of BP entities (BP P.L.C.; BP America, Inc.; and BP
Products North America Inc.); Crown Central entities (Crown Central Petroleum
Corporation; Crown Central LLC; and Crown Central New Holdings LLC); Chevron
entities (Chevron Corp. and Chevron U.S.A. Inc.); Exxon Mobil entities (Exxon Mobil
Corp. and ExxonMobil Oil Corporation); Shell entities (Royal Dutch Shell PLC and Shell
Oil Company); Citgo Petroleum Corp.; ConocoPhillips entities (ConocoPhillips;
ConocoPhillips Company; Louisiana Land & Exploration Co.; Phillips 66; and Phillips 66
Company); Marathon entities (Marathon Oil Company; Marathon Oil Corporation;
Marathon Petroleum Corporation; and Speedway LLC); Hess Corp.; and CONSOL entities
(CNX Resources Corporation; CONSOL Energy Inc.; and CONSOL Marine Terminals
LLC).
2
public about the dangers associated with their fossil fuel products when they knew for
nearly 50 years of a direct link between their products and climate change threats. With
that knowledge, Baltimore alleges, the Defendants (1) employed a “coordinated, multi-
front effort to conceal and deny their own knowledge of those threats”; (2) discredited
“publicly available scientific evidence”; and (3) created persistent doubt within the public
sphere about the “reality and consequences of the impacts of their fossil fuel pollution.”
According to Baltimore, the “Defendants, individually and collectively, are
responsible for extracting, processing, producing, promoting, and marketing fossil fuel
products, the normal and intended use of which has led to the emission of a substantial
percentage of the total volume of greenhouse gases released into the atmosphere” for over
50 years. The Defendants’ conduct that caused these emissions, Baltimore asserts,
includes, but is not limited to, their: (1) “extraction, refining, and/or formulation of fossil
fuel products;” (2) “introduction of fossil fuel products into the stream of commerce;” (3)
“wrongful promotion of their fossil fuel products and concealment of known hazards
associated with use of those products;” and (4) “failure to pursue less hazardous
alternatives available to them[.]” The above-described conduct is allegedly a “substantial
factor in causing the increase in global mean temperature and consequent increase in global
mean sea surface height and disruption to the hydrologic cycle, including, but not limited
to, more frequent and extreme droughts, more frequent and extreme temperatures, and the
associated consequences of those physical and environmental changes since 1965.”
The Defendants’ conduct is alleged to have (1) “actually and proximately caused
the sea levels to rise,” (2) “increased coastal erosion,” (3) “increased the destructive
3
impacts of storm surges,” (4) “exacerbated the onshore impact of regular tidal ebb and
flow,” (5) “disrupted the hydrologic cycle,” (6) “caused increased frequency and severity
of drought,” “extreme precipitation events,” and “heat waves,” and (7) “caused consequent
social and economic injuries associated with the aforementioned physical and
environmental impacts . . . resulting in inundation, destruction, and/or other interference
with” Baltimore’s “property and citizenry.” These environmental events have purportedly
caused, among other things, infrastructure damage during floods, automobile accidents and
power outages when winter storms hit, and public-health illnesses amid heat waves.
At bottom, Baltimore attempts to shift the burden of its climate change costs onto
the Defendants. Specifically, Baltimore “seeks to ensure that the parties who have profited
from externalizing the responsibility for sea level rise, extreme precipitation events,
heatwaves, other results of the changing hydrologic regime caused by increasing
temperatures, and associated consequences of those physical and environmental changes,
bear the costs of those impacts on” Baltimore, rather than the City, “local taxpayers,
residents, or broader segments of the public.” Baltimore, however, alleges that it “does not
seek to impose liability on the Defendants for their direct emissions of greenhouse gases
and does not seek to restrain the Defendants from engaging in their business operations.”
Baltimore asserts five causes of action against the Defendants, all arising under
Maryland law: (1) public nuisance; (2) private nuisance; (3) strict liability for failure to
4
warn; (4) negligent failure to warn; and (5) trespass. 2 To remedy its injuries, Baltimore
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seeks compensatory and punitive damages, disgorgement of profits, and equitable relief,
including the abatement of the alleged nuisances and an injunction against future nuisances.
2. Removal Proceedings
After Baltimore’s suit was filed in state court in July 2018, the Defendants timely
removed Baltimore’s complaint to the United States District Court for the District of
Maryland. The Defendants asserted eight different grounds for removal under statutory
grants of federal jurisdiction and various legal theories. Mayor & City Council of Balt. v.
BP P.L.C., 388 F. Supp. 3d 538 (D. Md. 2019). In response, Baltimore filed a motion to
remand its complaint to the Circuit Court for Baltimore City. Id. at 550. The district court
granted Baltimore’s motion to remand in June 2019, rejecting each of the Defendants’ eight
grounds for removal. Id. at 574. The Defendants appealed the district court’s remand order
to the United States Court of Appeals for the Fourth Circuit. Mayor & City Council of
Balt. v. BP P.L.C., 952 F.3d 452 (4th Cir. 2020). That court reasoned that it could analyze
the propriety of removal only under the federal officer removal statute and that it lacked
appellate jurisdiction over the remaining seven grounds for removal. Id. at 461. The Fourth
Circuit ultimately held that federal officer removal was improper, affirming the district
court’s remand order on that sole ground. Id. at 461–70.
2
In the complaint, Baltimore also alleged design-defect claims and violations of the
Maryland Consumer Protection Act, Md. Code (2025 Repl. Vol.), Com. Law §§ 13-101–
501. Baltimore has not appealed the dismissal of those counts. Accordingly, those claims
are not before us.
5
The Defendants appealed to the United States Supreme Court, which vacated the
Fourth Circuit’s opinion and remanded the case for further proceedings. BP P.L.C. v.
Mayor & City Council of Balt., 593 U.S. 230 (2021). The Supreme Court held that the
Fourth Circuit was not divested of appellate jurisdiction over the Defendants’ other theories
of removal and remanded the case to that court for it to consider all the bases for removal
included in the district court’s remand order. Id. On remand, the Fourth Circuit evaluated
the remaining theories of removal proffered by the Defendants and affirmed the district
court’s order granting Baltimore’s motion to remand. Mayor & City Council of Balt. v. BP
P.L.C., 31 F.4th 178 (4th Cir. 2022). 3 The Supreme Court denied the Defendants’ petition
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for writ of certiorari, BP P.L.C. v. Mayor & City Council of Balt., 143 S. Ct. 1795 (2023),
and the case was remanded to the Circuit Court for Baltimore City.
3. Circuit Court’s Ruling on Defendants’ Motion to Dismiss
When the case returned to state court, the Defendants filed a motion to dismiss the
complaint for failure to state a claim upon which relief could be granted. In their motion,
the Defendants asserted that the complaint must be dismissed because Baltimore’s claims
are preempted by federal common law and the Clean Air Act. Assuming the individual
claims are not preempted by federal law, the Defendants contended that each of the claims
3
The removal grounds asserted by the Defendants were as follows: (1) federal
common law; (2) substantial issues of federal law, as well as foreign affairs, under Grable
& Sons Metal Products, Inc. v. Darue Engineering & Manufacturing, 545 U.S. 308 (2005);
(3) complete preemption under the Clean Air Act, 42 U.S.C. §§ 7401–7671q; (4) federal
enclaves; (5) the Outer Continental Shelf Lands Act, 43 U.S.C. § 1349(b)(1); (6) the
bankruptcy removal statute, 28 U.S.C. § 1452(a); (7) the admiralty jurisdiction statute, 28
U.S.C. § 1333(1); and (8) the federal officer removal statute, 28 U.S.C. § 1442(a)(1).
Mayor & City Council of Balt. v. BP P.L.C., 31 F.4th 178, 196 (4th Cir. 2022).
6
alleged by Baltimore are legally deficient under state law. After Baltimore filed a response
and following a hearing, the circuit court issued a memorandum opinion and order in July
2024 granting the Defendants’ motion to dismiss.
In its memorandum opinion and order, the court ruled that, regardless of how
Baltimore characterized its complaint, “the Constitution’s federal structure does not allow
the application of state law claims like those presented by Baltimore.” The court explained
that “[g]lobal pollution-based complaints were never intended by Congress to be handled
by individual states.” The court also determined that the Clean Air Act “speaks directly to
the domestic emissions issues in this case[]” and thus preempts Baltimore’s claims. The
court also ruled that “[f]ederal common law is still required to apply to extraterritorial
aspects of claims challenging undifferentiated global emissions.”
In addition to ruling that the claims were preempted by federal law, the circuit court
also concluded that Baltimore failed to state claims under Maryland law. The court
dismissed Baltimore’s nuisance claims because it concluded that Maryland’s common law
of public nuisance applied only to “cases involving a defendant’s use of land[,]” and did
not apply to “product liability cases.” The court dismissed the failure-to-warn claims
because the court determined that they were based on a duty to “warn the world[.]”
Regarding trespass, the court found the theories of harm too “attenuated to constitute the
control necessary to establish liability” under existing law and declined to “extend trespass
liability beyond where the Maryland Supreme Court has previously allowed.” 4 3F
4
As previously noted, see supra n.2, the court also dismissed Baltimore’s design
defect and MPCA claims, and Baltimore did not appeal the dismissal of those claims.
7
B. Anne Arundel County and Annapolis Cases
1. The Complaint
In February 2021, Anne Arundel County (“the County”) and the City of Annapolis
(“Annapolis”) each filed nearly identical suits in the Circuit Court for Anne Arundel
County against a similar list of defendants as those named in the Baltimore litigation, with
minor exceptions. The County and Annapolis both amended their complaints in June 2024.
Although the allegations set forth in the County’s and Annapolis’s complaints are
substantively similar to Baltimore’s (a point conceded by the local governments in their
brief), we briefly touch upon the allegations set forth in the County’s and Annapolis’s
nearly identical operative complaints, which total approximately 350 pages.
The County and Annapolis assert that the “Defendants are directly responsible for
the substantial increase in all CO2 emissions” for the past 50 years. The County and
Annapolis allege that the “Defendants’ individual and collective conduct, including, but
not limited to, their”: (1) “introduction of fossil fuel products into the stream of commerce
while knowing but failing to warn of the threats posed to the world’s climate;” (2)
“wrongful promotion of their fossil fuel products and concealment of known hazards
associated with the use of those products;” (3) “public deception campaigns designed to
obscure the connection between their products and global warming and the environmental,
physical, social, and economic consequences flowing from it;” and (4) “failure to pursue
less hazardous alternatives[,]” which actually and proximately caused the County’s and
Annapolis’s injuries. “In other words,” according to the County and Annapolis, the
“Defendants’ concealment and misrepresentation of their products’ known dangers—and
8
simultaneous promotion of their products for uses Defendants knew were harmful—drove
consumption, and thus greenhouse gas pollution, and thus the climate crisis.”
As examples of the tortious conduct that allegedly caused the injuries, the County
and Annapolis specifically identify the Defendants’ internal corporate policies and
communications, their membership and financial contributions to organizations that
engaged with the public and government on climate change, and their external
communication and advertising on the matter.
The County and Annapolis assert the same state law causes of action as those alleged
by Baltimore and seek the same relief—compensatory damages, disgorgement of profits,
and equitable relief, including the abatement of the alleged nuisances and an injunction
against future nuisances.
2. Removal Proceedings
Following the same playbook as the Baltimore litigation, the Defendants removed
the case to federal court. City of Annapolis, Maryland v. BP P.L.C., No. CV SAG-21-
00772, 2022 WL 458226 (D. Md. Sept. 29, 2022). The County and Annapolis filed
motions to remand to state court, which the district court granted. After the Defendants
appealed, the Fourth Circuit affirmed the district court’s judgment, concluding that there
was no valid basis for removal. Anne Arundel County, Maryland v. BP P.L.C., 94 F.4th
343 (4th Cir. 2024).
3. Circuit Court’s Proceedings on Motion to Dismiss
Upon the case’s return to the circuit court, the Defendants filed a motion to dismiss,
and the County and Annapolis filed responses in opposition. The Circuit Court for Anne
9
Arundel County entered an order in January 2025 dismissing the cases “on the grounds of
preemption for essentially the same reasons” as the dismissal of Baltimore’s case.
C. Appellate Proceedings
Baltimore, the County, and Annapolis each appealed to the Appellate Court of
Maryland. The Appellate Court consolidated the cases after the Defendants jointly moved
to consolidate the appeals. The Defendants filed an unopposed bypass petition for writ of
certiorari with this Court, and the local governments collectively filed a cross-petition for
writ of certiorari. We granted certiorari and ordered that the case be transferred from the
Appellate Court to this Court.
II
Questions Presented and Parties’ Contentions
The questions before us can be distilled as follows: (1) whether the state law claims
asserted by the local governments are displaced or preempted by federal law; and, if not,
(2) whether the claims are legally cognizable under state law.
The local governments assert that the circuit courts erred in dismissing their state
law claims. According to the local governments, the courts (1) “fundamentally
misconstrued” their cases, (2) erred in concluding that the claims involve the regulation of
emissions, (3) “recharacterized” their claims as being “entirely about addressing the
injuries of climate change,” and (4) did not accept the local governments’ description of
the goals of their complaint. Had the circuit courts properly considered the claims asserted,
the local governments contend, the courts would not have found that the claims were
preempted by the structure of the United States Constitution, the Clean Air Act, and “a
10
defunct body of federal common law that the” Clean Air Act displaced. The local
governments assert that the courts erred in failing to consider the claims, and reasonable
interferences to be drawn therefrom, in the light most favorable to the local governments.
Viewing the allegations in the complaint through the correct lens, the local governments
argue that their claims do not regulate air emissions and urge us to follow the decisions of
the Supreme Courts of Hawaii and Colorado, which have determined that similar claims
relate only to a defendant’s “use of deception to promote the consumption of fossil fuel
products,” and do not concern emissions standards. See City & County of Honolulu v.
Sunoco LP, 537 P.3d 1173 (Haw. 2023), cert. denied, 145 S. Ct. 1111 (2025) (No. 23-947)
(“Honolulu”); County Comm’rs of Boulder County v. Suncor Energy USA, Inc., No.
24SA206, 2025 WL 1363355 (Co. 2025), cert. granted, ___ S. Ct. ___, 2026 WL 490537
(2026) (“Boulder”). The local governments assert that remedying the deceptive and
commercial conduct as alleged in their complaints is “within the core of” their “state police
powers.”
The local governments also contend that they have pled actionable claims under
Maryland law, and that the Circuit Court for Baltimore City erred in dismissing Baltimore’s
claims for private and public nuisance, trespass, and failure to warn.
The Defendants argue that the circuit courts did not mischaracterize the local
governments’ claims. They assert that we should follow the Court of Appeals for the
Second Circuit, which considered similar claims and rejected the contention that they
simply relate to deceptive marketing and promotion and do not involve air emissions. See
City of New York v. Chevron Corp., 993 F.3d 81, 91 (2d. Cir. 2021). According to the
11
Defendants, when the local governments’ claims are viewed for what they are—attempts
to regulate global conduct through claims for damages and injunctive relief related to
injuries arising from climate change—the claims are preempted by the structure of the
United States Constitution and federal law.
The Defendants also argue that the Circuit Court for Baltimore City did not err in
determining that each of the state common law claims failed to satisfy key elements
necessary to establish the claims under state law.
III
Standard of Review
The questions before us are matters of law that we review de novo. Plank v.
Cherneski, 469 Md. 548, 569 (2020). They arise from the circuit courts’ dismissal of the
complaints on the ground that they fail to state a claim upon which relief can be granted.
We review a circuit court’s grant of a motion to dismiss without deference to determine
whether it was legally correct. Wheeling v. Selene Finance LP, 473 Md. 356, 374 (2021).
We assume the truth of all relevant and material facts that are well pleaded, as well as the
inferences that can be reasonably drawn from those pleadings, in the light most favorable
to the nonmoving party. Id. “A motion to dismiss on this ground may only be granted
when the allegations presented do not state a cause of action.” Id. “In the interest of
judicial efficiency, we may affirm the judgment of a trial court to grant a motion to dismiss
on a different ground than that relied upon by the trial court, as long as the alternative
ground is before the Court properly on the record.” Forster v. State, Off. of Pub. Def., 426
Md. 565, 580–81 (2012); see also City of Frederick v. Pickett, 392 Md. 411, 424 (2006)
12
(stating that an appellate court can affirm a dismissal on any ground adequately shown by
the record, whether or not relied upon by the trial court).
IV
Federal Law Background
To address the Defendants’ arguments that the local governments’ claims are
displaced or preempted by federal law, it is instructive to discuss the United States Supreme
Court’s and lower federal courts’ cases that have addressed interstate pollution. Before we
turn to the cases, however, we discuss two landmark environmental statutes that Congress
enacted in the 1970s to address pollution—the Clean Water Act and the Clean Air Act. We
describe this statutory framework because these laws play prominent roles in the discussion
of the applicable case law, as well as in our preemption analysis.
A. Federal Statutes
1. The Clean Water Act
Although Congress enacted the Federal Water Pollution Control Act in 1948, it was
significantly reorganized, and Congress expanded the law in 1972 to become what is now
commonly referred to as the “Clean Water Act.” 33 U.S.C. § 1251 et seq. (1972). Congress
enacted the Act “to restore and maintain the chemical, physical, and biological integrity of
the Nation’s waters.” Id. § 1251(a). Among its core provisions, the Clean Water Act
prohibits discharging pollutants into waters of the United States, except as authorized by a
permit issued under the National Pollution Discharge Elimination System (“NPDES”). See
id. §§ 1251(a)(1), 1311(a), 1342(a)(1). An NPDES permit places limits—called “effluent
limitations”—on the type and quantity of pollutants that can be released into the Nation’s
13
waters. The Act authorizes the U.S. Environmental Protection Agency (“EPA”) to issue
and enforce these permits, id. §§ 1319, 1342(a)(1), as well as to delegate its NPDES
permitting authority to a state, id. §§ 1342(b). 5 We address additional provisions of the
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Act in the context of our discussion of case law below.
2. The Clean Air Act
The Clean Air Act is a comprehensive federal law that regulates air emissions from
stationary and mobile sources. 6 42 U.S.C. § 7401 et seq. (1970). “It is an intricate
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regulatory regime intended to ‘protect and enhance the quality of the [n]ation’s air
resources so as to promote the public health and welfare and the productive capacity of its
population.’” N.Y. Pub. Inst. Rsch. Grp. v. Whitman, 321 F.3d 316, 319–20 (2d Cir. 2003)
(quoting 42 U.S.C. § 7401(b)(1)). In Massachusetts v. EPA, the Supreme Court held that
the Act authorizes federal regulation of emissions of carbon dioxide and other greenhouse
gases. 549 U.S. 497 (2007).
“The Clean Air Act regulates air quality through a federal-state collaboration.”
Ohio v. EPA, 603 U.S. 279, 283 (2024) (citation modified). In a nutshell, the EPA is
5
The Clean Water Act is vast and extraordinarily complex. We touch upon only
key aspects of the Act for the limited purpose of providing context for the Supreme Court’s
and lower federal courts’ displacement and preemption analysis of nuisance claims related
to interstate pollution brought under federal and state common law.
6
The Clean Air Act regulates air pollution from stationary sources, 42 U.S.C.
§§ 7401–7431, and establishes emission standards for moving sources, including motor
vehicles, id. §§ 7521–7554, aircrafts, id. §§ 7571–7574, clean fuel vehicles, id. §§ 7581–
7574; acid deposition control, id. §§ 7651–7651o; and stratospheric ozone protection, id.
at §§ 7671–7671q. It also provides a means for citizen suits, id. § 7604, and outlines a
permitting process for emission standards, id. §§ 7661–7661f.
14
required to set “national primary or secondary ambient air quality standards” (or
“NAAQS”) for common air pollutants, 7 which “represent[] ‘the maximum airborne
6F
concentration that the public health can tolerate.’” West Virginia v. EPA, 597 U.S. 697,
707 (2022) (quoting Whitman v. Amc. Trucking Ass’ns, Inc., 531 U.S. 457, 465 (2001));
see also 40 C.F.R. pt. 50 (2013). “States bear ‘primary responsibility’ for deciding how a
NAAQS should be attained.” Oklahoma v. EPA, 605 U.S. 609, 615 (2025) (quoting 42
U.S.C. § 7401(a)(3)). This is accomplished through “state implementation plans” or state
proposals that ensure compliance with the NAAQS for each criteria pollutant. See 42
U.S.C. § 7410. Through its state implementation plan, each state is required to “‘provid[e]
for [the] implementation, maintenance, and enforcement’ of a NAAQS within their
jurisdictions.” Oklahoma, 605 U.S. at 615 (quoting 42 U.S.C. § 7410(a)(1)). The Clean
Air Act authorizes the states to decide how to measure ambient air quality, 42 U.S.C. §
7410(a)(2)(B), and pick “emission limitations and other control measures[,]” id. §
7410(a)(2)(A).
“While states are responsible for promulgating” state implementation plans, “they
must do so consistently with extensive EPA regulations governing preparation, adoption
by the state, and submission to the EPA, 40 C.F.R. § 51, and all [state plans] must be
7
The Clean Air Act broadly defines “air pollutant” to include “any air pollution
agent or combination of such agents, including any physical, chemical . . . substance or
matter which is emitted into or otherwise enters the ambient air.” 42 U.S.C. § 7602(g). The
EPA has established national primary or secondary ambient air quality standards
(“NAAQS”) for six pollutants—carbon monoxide, lead, nitrogen dioxide, ozone,
particulate matter, and sulfur dioxide. See Env’t Prot. Agency, Criteria Air Pollutants (Jan.
23, 2026), https://perma.cc/37CF-4DR8; see also 40 C.F.R. pt. 50 (2013).
15
submitted to the EPA for approval before they become final.” North Carolina, ex rel.
Cooper v. Tenn. Valley Auth., 615 F.3d 291, 299 (4th Cir. 2010) (citing 42 U.S.C.
§ 7410(a)(1), (k)(2) & (3)). 8 7F Once a state implementation plan is approved, “its
requirements become federal law and are fully enforceable in federal court.” Id. (citing
§ 7604(a)) (additional citations omitted).
Although states are accorded flexibility in determining how their state
implementation plans are structured, the plans must “include enforceable emission
limitations and other control measures, means, or techniques” to ensure that each state
meets NAAQS. 42 U.S.C. § 7410(a)(2)(A). 9 “States are also tasked with enforcing the
8F
limitations they adopt in their [plans].” Tenn. Valley Auth., 615 F.3d at 299. “They must
regulate ‘the modification and construction of any stationary source within the areas
covered by the [state implementation plan],’ 42 U.S.C. § 7410(a)(2)(C), and must
8
If the EPA does not approve a state implementation plan, then the EPA must issue
a “Federal implementation plan” for the noncompliant state within two years. 42 U.S.C.
§ 7410(c)(1). A state can avoid this outcome only if it corrects the deficiency and gains
EPA approval for its revised state implementation plan before the EPA promulgates the
federal plan. Id. § 7410(k)(3), (c)(1).
9
A state must designate every area within its borders as “attainment,”
“nonattainment,” or “unclassifiable” with respect to each NAAQS, 42 U.S.C. § 7407(d),
and the state implementation plan must include permitting programs for stationary sources
that vary according to the classification of the area where the source is or is proposed to be
located, id. § 7410(a)(2)(C), (I). Areas that comply with the NAAQS are “attainment
areas” and areas that do not comply are “nonattainment areas.” See generally id. § 7410.
To prevent attainment areas from getting dirtier, the Prevention of Significant Deterioration
program requires a new or modified “major emitting facility” of “any air pollutant” in those
areas to obtain permits and install the “best available control technology” for their
emissions. Id. § 7475(a)(4). The Clean Air Act defines a “major emitting facility” as any
stationary source with the potential to emit 250 tons per year of “any air pollutant” (or 100
tons per year for certain types of sources). Id. § 7479(1).
16
implement a permit program that limits the amounts and types of emissions that each
permit holder is allowed to discharge, 42 U.S.C. §§ 7661a(d)(1), 7661c(a).” Id. “Sources
are prohibited from operating without such a permit,” 42 U.S.C. § 7661a(a), “and each
permit is intended to be a source-specific bible for Clean Air Act compliance containing in
a single, comprehensive set of documents, all [Clean Air Act] requirements relevant to the
particular polluting source.” Tenn. Valley Auth., 615 F.3d at 299–300 (citation modified).
Notably, “states must design these plans with their neighbors in mind.” Ohio, 603
U.S. at 283. “Because air currents can carry pollution across state borders, emissions in
upwind States sometime affect air quality in downwind States.” Id. at 283–84. “To address
that externality problem,” the Act contains a “Good Neighbor Provision,” which provides
that state plans “must prohibit emissions ‘in amounts which will . . . contribute significantly
to nonattainment in, or interfere with maintenance by, any other State’ of the relevant air-
quality standard.” Id. at 284 (quoting 42 U.S.C. § 7410(a)(2)(D)(i)(I)).
Additionally, before new construction or modification of a source of emission may
begin, a state implementation plan must provide “written notice to all nearby States the air
pollution levels of which may be affected by such source at least sixty days prior to the
date on which commencement of construction is to be permitted[.]” 42 U.S.C. §
7426(a)(1)(B).
“In addition to this framework, there are a number of checks built into the system
to prevent abuses and to address concerns about emissions.” Tenn. Valley Auth., 615 F.3d.
at 300. As noted above, the EPA retains the ultimate authority over NAAQS to determine
what level of emissions are acceptable and has the responsibility to modify those levels as
17
necessary. 42 U.S.C. § 7409(b)(1), (2). The Clean Air Act provides a process for what is
commonly referred to as a “Section 126 petition,” which gives a state the authority to ask
the EPA to find that specific sources of air pollution in other states are significantly
contributing to non-attainment or interfering with maintenance of federal air quality
standards in the petitioning state. Id. § 7426(b). We touch upon additional provisions of
the Act as relevant to our discussion of the case law.
B. What is Federal Common Law?
Prior to Congress’s enactment of the extensive environmental legislation
comprising the Clean Water Act and Clean Air Act, disputes concerning interstate water
and air pollution were governed by federal common law. Before we discuss the cases
applying federal common law in the interstate pollution context, we first provide an
overview of what federal common law is, including its rationale and the limited number of
situations in which it arises.
The Supreme Court famously pronounced in Erie Railroad Company v. Tompkins
that “[t]here is no federal general common law.” 304 U.S. 64, 78 (1938). Although the
Court declared that there is no general federal common law, it has recognized that there
are some limited areas in which federal common law, or a federal rule of decision is
“necessary to protect uniquely federal interests.” Tex. Indus., Inc. v. Radcliff Materials,
Inc., 451 U.S. 630, 640 (1981) (citation modified); see also Rodriguez v. Fed. Deposit Ins.
Corp., 589 U.S. 132, 136 (2020) (explaining that federal common law still exists in certain
contexts and “often plays an important role”).
18
Federal common law exists in only a “few and restricted” enclaves, Wheeldin v.
Wheeler, 373 U.S. 647, 651 (1963), where a federal court is “compelled to consider federal
questions ‘which cannot be answered from federal statutes alone,’” City of Milwaukee v.
Illinois and Michigan (“Milwaukee II”), 451 U.S. 304, 314 (1981) (citation modified).
Once Congress speaks directly to those questions, “the need for such an unusual exercise
of lawmaking by federal courts disappears.” Id. The Court of Appeals for the Second
Circuit has aptly described federal common law as the functional equivalent of “legal duct
tape”—a “‘necessary expedient’ that permits federal courts to address issues of national
concern until Congress provides a more permanent solution.” City of New York, 993 F.3d
at 90 (quoting Milwaukee II, 451 U.S. at 314).
“Despite its utility,” our constitutional architecture “restricts federal common law
to a ‘modest role.’” Id. (quoting Rodriguez, 589 U.S. at 136). There are good reasons for
the limitation. Where federal common law exists, it “pre-empt[s] and replace[s]” state law,
Boyle v. United Techs. Corp., 487 U.S. 500, 504 (1988); see also Milwaukee II, 451 U.S.
at 313 n.7 (explaining that “if federal common law exists, it is because state law cannot be
used”). “It thus threatens a potent mix of judicial lawmaking and encroachment on our
federalist structure.” City of New York, 993 F.3d at 90.
The few and restricted categories in which federal common law exists “fall into
essentially two categories: those in which a federal rule of decision is necessary to protect
uniquely federal interests, and those in which Congress has given the courts the power to
develop substantive law[.]” Tex. Indus., Inc., 451 U.S. at 640 (citation modified); see also
Am. Elec. Power Co., v. Connecticut (“AEP”), 564 U.S. 410, 421 (2011) (acknowledging
19
that federal common law “addresses subjects within national legislative power where
Congress has so directed or where the basic scheme of the Constitution so demands”
(citation modified)).
The Supreme Court has stated that “absent some congressional authorization to
formulate substantive rules of decision, federal common law exists only in such narrow
areas as those concerned with” (1) “the rights and obligations of the United States”; (2)
“interstate and international disputes implicating the conflicting rights of States or our
relations with foreign nations”; and (3) “admiralty cases.” Tex. Indus., Inc., 451 U.S. at
641 (footnotes omitted). 10 “In these instances, our federal system does not permit the
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controversy to be resolved under state law, either because the authority and duties of the
United States as sovereign are intimately involved or because the interstate or international
nature of the controversy makes it inappropriate for state law to control.” Id.
“As these narrow categories suggest, the mere existence of a federal interest does
not intrinsically call for a corresponding federal rule.” City of New York, 993 F.3d at 90
(citing Empire Healthchoice Assurance, Inc. v. McVeigh, 547 U.S. 677, 692 (2006)).
10
In Atherton v. Federal Deposit Insurance Corporation, 519 U.S. 213 (1997), the
Court declined to fashion a general federal common law standard of care for officers and
directors of federally insured institutions. As part of its discussion, the Court cited cases
in which it had created federal common law. Id. at 225–26; see, e.g., Hinderlider v. La
Plata River & Cherry Creek Ditch Co., 304 U.S. 92, 110 (1938) (concerning controversy
between two states over administration of water rights); Boyle v. United Techs. Corp., 487
U.S. 500, 504 (1988) (concerning liability of independent contractors working for the
federal government); U.S. v. Standard Oil Co. of Cal., 332 U.S. 301, 305 (1947) (pertaining
to question of federal government’s entitlement to recover losses for tort against
servicemember); Howard v. Lyons, 360 U.S. 593, 597 (1959) (concerning liability of
federal officers in the course of official duty); Banco Nacional de Cuba v. Sabbatino, 376
U.S. 398, 425 (1964) (arising in context of relationships with other countries).
20
“There also must be a conflict between that federal interest and the operation of state law.”
Id. (footnote omitted) (citing Empire Healthchoice Assurance, Inc., 547 U.S. at 692); see
also O’Melveny & Myers v. FDIC, 512 U.S. 79, 87 (1994) (stating that conflict between
federal interest and use of state law is required to be a “precondition for recognition of a
federal rule of decision”); Boyle, 487 U.S. at 507. That said, the conflict between state law
and federal interests does not need to be “intractably severe before federal common law
may spring into action.” City of New York, 993 F.2d at 90. Indeed, as the Supreme Court
has explained, the necessary conflict “need not be as sharp as that which must exist for
ordinary pre-emption when Congress legislates in a field which the [s]tates have
traditionally occupied.” Boyle, 487 U.S. at 507 (internal citation omitted). “But conflict
there must be.” Id. at 508.
C. Cases Applying Federal Law to Claims Arising from Interstate Pollution
Interstate water and air pollution are areas that the Supreme Court and lower federal
courts have determined are governed by federal common law and, therefore, leave no place
for the application of state law. As the Court of Appeals for the Second Circuit observed,
“[f]or over a century, a mostly unbroken string of cases has applied federal law to disputes
involving interstate air or water pollution.” City of New York v. Chevron Corp., 993 F.3d
81, 91 (2d. Cir. 2021) (citing AEP, 564 U.S. 421; Int’l Paper Co. v. Ouellette, 479 U.S.
481, 487–89 (1987); Milwaukee II, 451 U.S. 304, 327–28, 327 n.19; Illinois v. City of
Milwaukee (“Milwaukee I”), 406 U.S. 91, 102–03, 102 n.3 (1972); New Jersey v. City of
New York, 283 U.S. 473, 477, 481–83 (1931); North Dakota v. Minnesota, 263 U.S. 365,
374 (1923); New York v. New Jersey, 256 U.S. 296 (1921); Georgia v. Tenn. Copper Co.,
21
206 U.S. 230 (1907); Missouri v. Illinois, 200 U.S. 496 (1906); Native Vill. of Kivalina v.
ExxonMobil Corp. (“Kivalina”), 696 F.3d 849, 855 (9th Cir. 2012); Illinois v. City of
Milwaukee (“Milwaukee III”), 731 F.2d 403, 406–11 (7th Cir. 1984); Texas v. Pankey, 441
F.2d 236, 240 (10th Cir. 1971)).
1. Milwaukee I
In Milwaukee I, the Supreme Court approved of the use of a public nuisance claim
under federal common law for a suit brought by Illinois against the City of Milwaukee and
other Wisconsin cities. 406 U.S. at 91. Illinois alleged that the cities were discharging 200
million gallons of raw or undertreated sewage into Lake Michigan in violation of Illinois
law. Id. at 93. Illinois asked the Court to exercise original jurisdiction over the matter and
abate the nuisance. Id. Although the Court declined to exercise original jurisdiction, it
allowed the action to proceed in the federal district court. Id. at 101, 108. The Court stated
that “[w]hen we deal with air and water in their ambient or interstate aspects, there is a
federal common law[.]” Id. at 103. The Court quoted the Tenth Circuit’s decision in Texas
v. Pankey for the following “controlling principle:”
As the field of federal common law has been given necessary expansion into
matters of federal concern and relationship (where no applicable federal
statute exists, as there does not here), the ecological rights of a State in the
improper impairment of them from sources outside the State’s own territory,
now would and should, we think, be held to be a matter having basis and
standard in federal common law and so directly constituting a question
arising under the laws of the United States.
Id. at 99–100 (quoting Pankey, 441 F.2d at 240).
The Court acknowledged that Congress had “enacted numerous laws touching
interstate waters[,]” id. at 101, but determined that “[t]he remedy sought by Illinois is not
22
within the precise scope of remedies prescribed by Congress[,]” id. at 103. “[I]n time,” the
Court presciently noted, “[i]t may happen that new federal laws and new federal regulations
may” preempt “the field of federal common law of nuisance.” Id. at 107. But until such a
time came to pass, the Court concluded, federal courts would be “empowered to appraise
the equities of the suits alleging creation of a public nuisance by water pollution.” Id.
2. Milwaukee II and Milwaukee III
Within months after the Milwaukee I decision, Congress passed the Clean Water
Act. The Supreme Court granted certiorari in Milwaukee II to consider the effect of the
Clean Water Act on the previously recognized federal common law nuisance cause of
action. 451 U.S. at 304.
In Milwaukee II, the Court began by recounting the litigation history that ensued
following its decision in Milwaukee I. Id. at 310–12. Illinois filed a complaint in the
federal district court, seeking abatement of the public nuisance that the Wisconsin cities
were allegedly creating by their discharges. Id. at 310. 11 While that litigation was pending,
10F
the Clean Water Act was enacted, and the EPA promulgated regulations concerning
specific effluent limitations that were required to be incorporated into discharge permits,
including the discharge permits applicable to the Wisconsin cities. Id. at 310–11. Pursuant
to the EPA’s delegation of authority under the Act, a Wisconsin state agency issued
discharge permits to the Wisconsin cities’ treatment plants. Id. at 311. The cities did not
11
The State of Michigan intervened in the federal common law nuisance suit,
seeking the same relief as Illinois. City of Milwaukee v. Illinois & Michigan (“Milwaukee
II”), 451 U.S. 304, 309 (1981).
23
comply with the permit requirements, and the state agency brought an enforcement action
in state court. Id. The state court entered a judgment requiring discharges from the cities’
treatment plants to meet the effluent limitations request set forth in the permits and
establishing a detailed timetable for completion of planning and additional construction to
control sewage overflows. Id.
In the meantime, the litigation in the Illinois nuisance suit was ongoing in the federal
district court. Id. Two months after the state court entered its judgment, the district court
rendered a decision finding that Illinois had proved the existence of a nuisance under
federal common law, arising from the Wisconsin cities’ discharges of both inadequate
treatment of its sewage, as well as from overflows. Id. The district court ordered the cities
to eliminate all overflows and to achieve the specified effluent limitations on treated
sewage. Id. The district court’s order also specified a construction timetable for the
completion of overflow facilities. Id. at 311–12. The conditions established by the district
court’s order in terms of overflows and effluent limitations went “considerably beyond”
the terms of the cities’ permits issued pursuant to the Clean Water Act and the state court’s
enforcement order. Id. at 312. The Wisconsin cities appealed. Id.
The Supreme Court held that the Clean Water Act displaced the federal common
law and that Illinois had no federal common law remedy available. The Court began by
explaining that the creation of federal common law was justified only when “Congress has
not spoken to a particular issue” and “there exists a significant conflict between some
federal policy or interest and the use of state law[.]” Id. at 313 (citation modified). The
Court stated that it has “always recognized that federal common law is subject to the
24
paramount authority of Congress.” Id. at 313 (citation modified). Because federal
common law “is a necessary expedient,” the Court explained, “when Congress addresses a
question previously governed by a decision rested on federal common law[,] the need for
such an unusual exercise of lawmaking by federal courts disappears.” Id. at 314 (citation
modified). The Court noted that this point was recognized in Milwaukee I, as well as in
Pankey, which was “the lower court decision extensively relied upon in that case[.]” Id. at
314.
In conducting its displacement analysis, the Court examined the legislative history
and the text of the Act and concluded that Congress’s clear intent was to establish an “all-
encompassing program of water pollution regulation.” Id. at 318. The Court explained
that the establishment of such a program—which did not exist when Milwaukee I was
decided—“strongly suggests that there is no room for courts to improve on that program
with the federal common law.” Id. at 319. Next, the Court analyzed the particular claims
at issue, which involved discharge effluent limitations, and noted that the problem of
effluent limitations had been “thoroughly addressed through the administrative scheme
established by Congress[.]” Id. at 319–20. The Court held that “[f]ederal courts lack
authority to impose more stringent effluent limitations under federal common law than
those imposed by the agency charged by Congress with administering this comprehensive
scheme.” Id. at 320. The Court did not view the overflow claims any differently, noting
that the permits specifically addressed the problem of overflows. Id. The Court also
pointed out that the enforcement action brought by the state agency in state court resulted
in a judgment that required the elimination of overflows by a certain date. Id. at 322.
25
Given the comprehensive regulatory scheme and the enforcement action that
addressed the effluent limitations and overflows, the Court stated that there was “no
‘interstice’ to be filled by federal common law[.]” Id. at 323. The Court explained that
“[a]lthough a federal court may disagree with the regulatory approach taken by the agency
with responsibility for issuing permits under the Act, such disagreement alone is no basis
for the creation of federal common law.” Id. The Court further concluded that the
“invocation of federal common law” by the lower federal courts “in the face of
congressional legislation supplanting it is peculiarly inappropriate in areas as complex as
water pollution control.” Id. at 325. The Court pointed out that the technical nature of the
subject matter was undoubtedly the reason that Congress “vested authority to administer
the Act in administrative agencies possessing the necessary expertise” and that the general
area was “particularly unsuited to the approach inevitable under” a federal common law
regime, which Congress had criticized as being “sporadic” and “ad hoc[.]” Id. Finally, the
Court observed that Congress provided ample opportunity for a state affected by a
neighboring state’s permitting agency to seek redress. Id. at 326. At bottom, the Court
concluded, Illinois’s basic grievance was that the permits issued to the cities did not impose
stringent enough controls on their discharges. Id. The Court rejected this argument as
presenting a valid basis for the imposition of federal common law. Id. The Court
concluded that “[i]t would be quite inconsistent” with Congress’s statutory scheme of
vesting permitting authority agencies with the necessary authority “if federal courts were
in effect to ‘write their own ticket’ under the guise of federal common law after permits
26
have already been issued and permittees have been planning and operating in reliance on
them.” Id.
Although the Court held that the federal legislation now occupied the field—thereby
displacing federal common law—the Court left open the question of whether injured
parties still had a cause of action under state law. Id. at 310 n.4. The case was remanded
for further consideration, which led to Milwaukee III.
In that case, Illinois filed a nuisance action against Milwaukee under Illinois
statutory and common law, seeking to abate the alleged pollution of Lake Michigan.
Illinois v. City of Milwaukee (“Milwaukee III”), 731 F.2d 403 (7th Cir. 1984). The Seventh
Circuit ultimately remanded the case for dismissal of Illinois’s claim, finding that the Clean
Water Act precluded the application of one state’s law against a pollution source located
in another state. Id. at 414. The decision was based in part on the court’s conclusion that
the application of different state laws to a single “point source” 12 would interfere with the
11F
carefully devised regulatory system established by the Clean Water Act. Id. The court
also concluded that the only suits that were not preempted were those alleging violations
of the laws of the polluting or “source” state. Id. at 413–14. As we discuss below, the
Seventh Circuit’s decision created a circuit split with the Second Circuit’s decision in
Ouellette.
12
A “point source” is defined by the Clean Water Act as “any discernible, confined
and discrete conveyance . . . from which pollutants are or may be discharged.” 33 U.S.C.
§ 1362(14).
27
3. Ouellette
In International Paper Company v. Ouellette, the Supreme Court considered
whether the Clean Water Act preempted a common law nuisance suit filed in the Vermont
federal district court under Vermont law when the source of the alleged injury was in New
York. 479 U.S. 481, 483 (1987). The suit was brought by property owners against a pulp
and paper mill company that discharged a variety of effluents into Lake Champlain. Id. at
483–84. The discharge pipe was located in New York and ended a short distance before
the state boundary line that divided the lake. Id. at 484. The property owners alleged that
the pollutants made the water “foul, unhealthy, smelly, and unfit for recreational use,”
thereby diminishing the value of their property. Id. (citation modified). The owners sought
$20 million in compensatory damages, $100 million in punitive damages, and injunctive
relief that would require the paper company to restructure part of its water treatment
system. Id.
The paper company moved to dismiss, claiming that the Clean Water Act preempted
the property owners’ state law claims. Id. Reaching a different conclusion than the
Seventh Circuit’s decision in Milwaukee III, the Vermont federal district court concluded
that the Clean Water Act did not preempt the state law nuisance claims. Id. at 485. The
court acknowledged that federal law normally governs interstate pollution, but it found that
two provisions of the Clean Water Act—§§ 510 and 505(e) 13 (together, the “saving
12F
13
The saving clause is contained in the original Clean Water Act as §§ 510 and 505.
Section 510 of the Clean Water Act, codified at 3 U.S.C. § 1370, provides: “Except as
expressly provided . . . , nothing in this chapter shall . . . be construed as impairing or in
28
clause”)—made it clear that federal law did not entirely preempt the states’ rights to control
pollution. Id. The district court held that a state action to redress interstate pollution was
not preempted, concluding that there was no interference with the Clean Water Act because
a state’s “imposition of compensatory damage award and other equitable relief merely
supplement[ed] the standards and limitations imposed by the Act.” Id. at 486–87 (citation
modified). The district court also found that the use of state law did not conflict with the
ultimate goal of the Clean Water Act, since the objective in each case was to decrease the
level of pollution. Id. at 487. The district court certified its decision for interlocutory
appeal, and the Second Circuit affirmed for the reasons stated by the district court. Id. The
Supreme Court granted certiorari “to resolve the circuit conflict on this important issue of
federal pre-emption.” Id.
The Supreme Court affirmed the denial of the paper company’s motion to dismiss,
but “reverse[d] the decision below to the extent it permit[ted] the application of Vermont
law to [the] litigation.” Id. The Court held “that when a court considers a state-law claim
concerning interstate water pollution that is subject to the” Clean Water Act, “the court
must apply the law of the state in which the point source is located.” Id.
The Court reviewed the evolution of federal law in the sphere of interstate water
pollution, including its decisions in Milwaukee I and Milwaukee II, and the enactment of
any manner affecting any right or jurisdiction of the States with respect to the waters
(including boundary waters) of such States.” Section 505(e), codified at 3 U.S.C. §
1365(e), states: “Nothing in this section shall restrict any right which any person (or class
of persons) may have under any statute or common law to seek enforcement of any effluent
standard or limitation or to seek any other relief[.]”
29
the Clean Water Act. In summarizing Milwaukee I, the Court stated that its “opinion in
that case affirmed the view that the regulation of interstate water pollution is a matter of
federal, not state, law[.]” Id. at 488. The Court explained that “Milwaukee I therefore held
that these cases should be resolved by reference to federal common law; the implicit
corollary of this ruling was that state common law was preempted.” Id. The Court
explained that Milwaukee I recognized that “future action by Congress to regulate water
pollution might pre-empt federal common law as well.” Id. The Court then discussed its
decision in Milwaukee II and its assessment that the Clean Water Act was a “complete
rewriting” of the statute considered in Milwaukee I, and the statutory provisions were “the
most comprehensive and far reaching” provisions that Congress had ever passed in that
area. Id. at 489 (citation modified) (citing Milwaukee II, 451 U.S. at 318–18). The Court
stated its holding in Milwaukee II that “federal legislation now occupied the field, pre-
empting all federal common law.” Id. (emphasis in original). The Court noted that
Milwaukee II “left open the question of whether injured parties still had a cause of action
under state law.” Id. That window, noted the Court, resulted in the remand and decision
of the Seventh Circuit in Milwaukee III.
The Court observed that the Clean Water Act recognizes that states “should have a
significant role in protecting their own natural resources[,]” id., pointing out the provisions
of the Act that allow the federal government to delegate to the state the authority to
administer the NPDES program with respect to point sources in the state, and the state’s
ability to require discharge limitations more stringent than those required by the federal
government, id. at 490. The Clean Water Act, explained the Court, “establishes a
30
regulatory partnership” between the federal government and the source state. Id. (citation
modified).
By contrast, the Court explained that the Act “contemplates a much lesser role for
States that share an interstate waterway with the source (the affected States).” Id. The
Court observed that “[e]ven though it may be harmed by discharges, an affected State only
has an advisory role in regulating pollution that originates beyond its borders.” Id. The
Court noted that the affected state does not have the authority to block the issuance of the
permit if it is dissatisfied with the proposed standards, nor may it establish a separate permit
system to regulate an out-of-state source. Id. at 491. The Court concluded that the “Act
makes it clear that affected States occupy a subordinate position to source States in the
federal regulatory program.” Id.
Turning to the question presented—“whether the Act pre-empts Vermont common
law to the extent that law may impose liability on a New York point source[]”—the Court
began its analysis by stating the standards governing a court’s consideration whether a
federal statute preempts state law: (1) “that it is not necessary for a federal statute to provide
explicitly that particular state laws are pre-empted”; (2) preemption “may be presumed
when the federal legislation is sufficiently comprehensive to make reasonable the inference
that Congress left no room for supplementary state regulation”; and (3) “in addition to
express or implied pre-emption, a state law also is invalid to the extent that it actually
conflicts with a federal statute” and that “such a conflict will be found when the state law
stands as an obstacle to the accomplishment and execution of the full purposes and
objectives of Congress.” Id. at 491–92 (citation modified).
31
The Court determined that “[a]lthough Congress intended to dominate the field of
pollution regulation, the saving clause negate[d] the inference that Congress left no room
for state causes of action.” Id. at 492. Examining the plain text of the saving clause, as
well as the Act as a whole, its purposes and legislative history, the Court concluded that if
“affected States were allowed to impose separate discharge standards on a single point
source, the inevitable result would be a serious interference with the achievement of the
full purposes and objectives of Congress.” Id. at 493–94 (citation modified). Determining
that Congress did not intend to “undermine this carefully drawn statute through a general
saving clause,” the Court concluded that the Clean Water Act “precludes a court from
applying the law of an affected State against an out-of-state source.” Id. at 494 (citation
modified).
The Court next turned to the issue of “whether Vermont nuisance law stands as an
obstacle to the full implementation of the [Act],” explaining that “it is not enough to say
that the ultimate goal of both federal and state law is to eliminate water pollution.” Id.
(citation modified). The Court stated that a “state law also is pre-empted if it interferes
with the methods by which the federal statute was designed to reach this goal.” Id. The
Court determined that the application of Vermont law against the paper company would
allow the property owners “to circumvent the NPDES permit system, thereby upsetting the
balance of public and private interests so carefully addressed by the Act.” Id. Specifically,
the Court pointed out, the Clean Water Act envisions a balancing of interests between the
goal of the elimination of water pollution, and “competing public and industrial uses,”
while also taking into account technological feasibility. Id. at 494–95.
32
The Court concluded that “[a]n interpretation of the saving clause that preserved
actions brought under an affected State’s law would disrupt this balance of interests.” Id.
at 495. 14 The Court determined that “[a]pplication of an affected State’s law to an out-of-
13F
state source” would also “undermine the important goals of efficiency and predictability in
the permit system.” Id. at 496. The Court observed that the property owners’ interpretation
of the saving clause would subject a source to “a variety of common-law rules established
by the different States along interstate waterways[]” and noted that “[t]hese nuisance
standards often are vague and indeterminate.” Id. (citation modified). Moreover, the Court
14
The Court further elucidated the problem with such an interpretation as follows:
If a New York source were liable for violations of Vermont law, that law
could effectively override both the permit requirements and the policy
choices made by the source State. The affected State’s nuisance laws would
subject the point source to the threat of legal and equitable penalties if the
permit standards were less stringent than those imposed by the affected State.
Such penalties would compel the source to adopt different control standards
and a different compliance schedule from those approved by the EPA, even
though the affected State had not engaged in the same weighing of the costs
and benefits. This case illustrates the problems with such a rule. If the
Vermont court ruled that [the property owners] were entitled to the full
amount of damages and injunctive relief sought in the complaint, at a
minimum [the paper company] would have to change its methods of doing
business and controlling pollution to avoid the threat of ongoing liability. In
suits such as this, an affected-state court also could require the source to cease
operations by ordering immediate abatement. Critically, these liabilities
would attach even though the source had complied fully with its state and
federal permit obligations. The inevitable result of such suits would be that
Vermont and other States could do indirectly what they could not do
directly—regulate the conduct of out-of-state sources.
Int’l Paper Co. v. Ouellette, 479 U.S. 481, 495 (1987).
33
pointed out that “[t]he application of numerous states’ laws would only exacerbate the
vagueness and resulting uncertainty.” Id.
The Court stated that Congress, through the Clean Water Act, “carefully defines the
role of both the source and affected States,” and that the “delineation of authority represents
Congress’s considered judgment as to the best method of serving the public interest and
reconciling the often competing concerns of those affected by the pollution.” Id. at 497.
The Court concluded that “[i]t would be extraordinary for Congress, after devising an
elaborate permit system that sets clear standards, to tolerate common-law suits that have
the potential to undermine this regulatory structure.” Id.
Although the Court held that the Clean Water Act preempted the application of
Vermont’s nuisance common law to a New York point source, the Court stated that did not
mean that the property owners did not have a remedy. Id. The Court pointed out that the
“saving clause specifically preserves other state actions, and therefore nothing in the Act
bars aggrieved individuals from bringing a nuisance claim pursuant to the law of the source
State.” Id. (emphasis in original). The Court noted that the Clean Water Act allows states
to impose higher standards and higher statutory restrictions, which preserve common-law
suits applying the laws of the source state. Id. at 498. The Court determined that such an
interpretation of the saving clause would not frustrate the goal of the Act. First, the Court
explained, it would not “disturb the balance among federal, source-state and affected state
interests.” Id. at 499. Second, the Court reasoned, “restriction of suits to those brought
under source-state nuisance law prevents a source from being subject to an indeterminate
number of potential regulations.” Id. Moreover, the Court stated that “States can be
34
expected to take into account their own nuisance laws in setting permit requirements.” Id.
The Court concluded that the Clean Water Act “pre-empts state law to the extent that the
state law is applied to an out-of-state point source.” Id. at 500.
4. American Electric Power Co., Inc. v. Connecticut (“AEP”)
All of the above cases involved water pollution. AEP involved air emissions and
claims concerning global warming. 564 U.S. at 410. In that case, eight states, New York
City, and three private land trusts brought a public nuisance suit under federal common law
against the five largest emitters of carbon dioxide in the United States. Id. at 418. The
plaintiffs sought to redress those emitters’ “contribut[ions] to global warming[.]” Id. In
terms of relief, they sought an injunction “requiring each defendant to cap its carbon
dioxide emissions and then reduce them by a specified percentage each year for at least a
decade.” Id. at 419 (citation modified). Determining that the Clean Air Act already
“provides a means to seek limits on emissions of carbon dioxide from domestic power
plants[,]” the Supreme Court held that the Clean Air Act “displaces any federal common-
law right to seek abatement of” greenhouse gas emissions. Id. at 424.
The Court started its discussion by pointing out that, in Massachusetts v. EPA, it
held that the Clean Air Act authorizes federal regulation of carbon dioxide and other
greenhouse gases. Id. at 416. The Court noted that following its decision in Massachusetts,
the EPA undertook greenhouse gas rulemaking efforts. Id. at 416–18. The Court held
“that the Clean Air Act and the EPA actions it authorizes displace any federal common-
law right to seek abatement of carbon-dioxide emissions from fossil-fuel fired
powerplants.” Id. at 424.
35
In so holding, the Court touched upon the regulatory framework of the Act,
including the authority vested in the EPA to identify categories of stationary sources that
“caus[e], or contribut[e] significantly to, air pollution, which may reasonably be anticipated
to endanger public health or welfare.” Id. (quoting 42 U.S.C. § 7411(b)(1)(A)). The Court
also pointed out that the “Act provides multiple avenues for enforcement[]” and
summarized the various statutory mechanisms for enforcement. Id. at 425.
In determining that the Clean Air Act displaced the application of federal common
law, the Court noted that Congress, through the Clean Air Act, designed the EPA as the
“expert agency” to undertake complex balancing of interests involving greenhouse gas
emissions, stating:
The appropriate amount of regulation in any particular greenhouse gas-
producing sector cannot be prescribed in a vacuum: As with other questions
of national or international policy, informed assessment of competing
interests is required. Along with the environmental benefit potentially
achievable, our Nation’s energy needs and the possibility of economic
disruption must weigh in the balance.
Id. at 427. The Court commented on the difficulties presented by district court judges
lacking the “scientific, economic, and technological resources an agency can utilize in
coping with issues of this order.” Id. at 428. The Court concluded that having individual
federal judges determine in the first instance what amount of carbon dioxide emissions is
unreasonable, and then decide what level of reduction is “practical, feasible, and
economically viable,” in not only the underlying case, but also in numerous other cases,
could not “be reconciled with the decisionmaking scheme Congress enacted.” Id. at 428–
29.
36
Finally, the Court noted that the plaintiff also sought relief under state laws and
pointed out that the Second Circuit had addressed those claims because it held that federal
common law governed. Id. at 429. In light of its “holding that the Clean Air Act displaces
federal common law” and citing to Ouellette, the Court stated that “the availability vel non
of a state lawsuit depends, inter alia, on the preemptive effect of the federal Act.” Id. The
Court quoted that portion of the Ouellette holding that the Clean Water Act does not
preclude aggrieved individuals from bringing “a nuisance claim pursuant to the law of the
source State[.]” Id. (quoting Ouellette, 479 U.S. at 489). Because “[n]one of the parties
have briefed preemption or otherwise address the availability of a claim under state
nuisance law[,]” the Court left “the matter open for consideration on remand.” Id.
Although the United States Supreme Court has not addressed whether the Clean Air
Act preempts state law claims for damages against gas, oil, and energy companies for
injuries related to greenhouse gas emissions, lower federal courts have concluded that such
claims are preempted.
5. Native Village of Kivalina v. ExxonMobil Corp.
In Native Village of Kivalina v. ExxonMobil Corporation, a small city in Alaska
brought a public nuisance action under federal common law against numerous oil, energy,
and utility companies for their emissions of greenhouse gases. 696 F.3d 849, 854 (9th Cir.
2012). Unlike in AEP, the plaintiff did not seek abatement of emissions, but rather,
damages for global warming-related injuries, including sea-level rise and severe erosion.
Id. at 853.
37
Despite the difference in remedies, the United States Court of Appeals for the Ninth
Circuit concluded that AEP controlled. The court reasoned that the displacement of federal
common law does not turn on the nature of the remedy, but instead, on the cause of action.
Id. at 856–57 (noting that the “Supreme Court has instructed that the type of remedy
asserted is not relevant to the applicability of the doctrine of displacement”).
6. City of New York v. Chevron Corp.
In City of New York v. Chevron Corporation, the City of New York filed a lawsuit
in federal court, asserting state common law causes of action for public nuisance, private
nuisance, and trespass against five oil companies stemming from the companies’
production, promotion, and sale of fossil fuels around the world. 993 F.3d 81, 88 (2d Cir.
2021). The city sought compensatory damages for past and future costs of climate-
proofing its infrastructure and property, as well as an equitable order ascertaining damages
and granting an injunction to abate the public nuisance and trespass that would go into
effect should the companies fail to pay the court-ordered damages. Id. The companies
filed motions to dismiss the city’s complaint. Id. The district court granted the motions
and dismissed the city’s complaint. Id. After the city appealed, the United States Court of
Appeals for the Second Circuit affirmed. Id. at 88, 86.
The court held that the city could not maintain a nuisance suit seeking to recover
damages for harms caused by global greenhouse gas emissions under New York law. Id. at
- The court observed that the city was requesting damages for the cumulative impact of
conduct occurring simultaneously across just about every jurisdiction on the planet. Id. at 92–
The court determined that “[s]uch a sprawling case is simply beyond the limits of state
38law[,]” in part because a substantial damages award like the one requested by the city would
effectively regulate the producers’ behavior far beyond New York’s borders. Id. at 92.
As an initial matter, the court rejected the city’s attempt to characterize its complaint
as “merely a local spat about the City’s eroding shoreline, which will have no appreciable
effect on national energy or environmental policy.” Id. at 91. The court determined that
“[a]rtful pleading” could not “transform the City’s complaint into anything other than a
suit over global greenhouse gas emissions.” Id. In other words, explained the court, “it
[was] precisely because fossil fuels emit greenhouse gases—which collectively exacerbate
global warming—that the city [wa]s seeking damages.” Id. (citation modified). The court
concluded that a substantial damages award like the one requested by the city would
effectively regulate the producers’ behavior far beyond New York’s borders. Id. at 92–93
(citing Kurns v. R.R. Friction Prods. Corp., 565 U.S. 625, 637 (2012)). Indeed, the Second
Circuit concluded, the goal of the city’s lawsuit was “perhaps even more ambitious” than
imposing emission regulations—the city was effectively attempting to “impose strict
liability for the damages caused by fossil fuel emissions no matter where in the world those
emissions were released (or who released them).” Id. at 93. The court concluded that the
city’s claims could not be brought under state law, and any claims must arise under federal
common law.
Having determined that any claims made by the city must arise under the federal
common law, the Second Circuit next determined that under AEP, the Clean Air Act
displaced federal common law nuisance suits seeking to abate domestic transboundary
emissions of greenhouse gases. Id. at 95. The court also agreed with the Ninth Circuit’s
39
reasoning in Kivalina and held that the Clean Air Act also displaces the city’s common law
damages claims. Id. at 96.
The court next addressed the city’s argument that if the Clean Air Act displaced
federal common law, then the city’s state law nuisance claims may “snap back into action”
unless specifically preempted by statute. Id. at 98. The court summarized the city’s view
of the Clean Air Act “as having vaporized any preemptive effect that federal common law
had on state law, thereby requiring us to engage in a traditional statutory preemption
analysis.” Id. The court stated that “the City’s position is difficult to square with the fact
that the federal common law governed this issue in the first place.” Id. The court pointed
out that under Supreme Court precedent, where a federal statute displaces federal common
law, it does so in a field in which states have not traditionally occupied. Id. (citing Boyle,
487 U.S. at 507). “Consequently,” the Second Circuit reasoned, “state law does not
suddenly become presumptively competent to address issues that demand a unified federal
standard simply because Congress saw fit to displace a federal court-made standard with a
legislative one[.]” Id.
Recognizing that Congress could grant states the authority to operate in an area of
national concern, the court turned to the text of the Clean Air Act and concluded that the
Act does not authorize the type of state law claims the city sought to prosecute. Id. at 99.
The court determined that among the Act’s expansive set of enforcement mechanisms, the
only provisions that might plausibly authorize the type of state law claims pursued by the
40
city were the provisions that constitute the saving clause, 42 U.S.C. §§ 7604(e) and 7416. 15
14F
Id. The court concluded that, like the nearly identical saving clause in the Clean Water
Act, the saving clause in the Clean Air Act, “plainly permit[s] states to create and enforce
their own emissions standards applicable to in-state polluters[.]” Id. Returning to the city’s
claims as they applied to domestic conduct, the court concluded that they did not fall within
the “slim reservoir of state common law.” Id. at 100.
Finally, the Second Circuit turned to the city’s claims that concerned foreign
emissions. Id. The court noted that the Clean Air Act’s “silence on the issue of
extraterritorial reach, the fact that the Act contemplates the need for reciprocal protections
from foreign nations, and the State Department’s lead role in setting foreign policy on
environmental matters, all plainly demonstrate the Clean Air Act regulates only domestic
emissions.” Id. at 101. As a result, the court reasoned, the Clean Air Act could not displace
the city’s federal common law claims to the extent that they seek recovery for harms caused
by foreign emissions. Id. That said, the court stated that “foreign policy concerns foreclose
New York’s proposal here to recognize a federal common law cause of action targeting
emissions emanating from beyond our national borders.” Id.
The court determined that extending the federal common law to address claims
relating to foreign emissions would trigger “broad concerns over separation of powers,
intrusion on the political branches’ monopoly over foreign policy, and judicial caution with
respect to creating (or extending) federal common law causes of action.” Id. at 102. The
15
We discuss the Clean Air Act’s saving clause in more detail in our analysis below.
41
court concluded that holding producers accountable for purely foreign activity would
require them to internalize the costs of climate change, which would “presumably affect
the price and production of fossil fuels abroad.” Id. at 103. The court also pointed out that
it would “bypass the various diplomatic channels that the United States uses to address this
issue, such as the U.N. Framework and the Paris Agreement.” Id. “Such an outcome,” the
court reasoned, “would obviously sow confusion and needlessly complicate the nation’s
foreign policy, while clearly infringing on the prerogatives of the political branches.” Id.
The court further determined that “condoning an extraterritorial nuisance action here would
not only risk jeopardizing our nation’s foreign policy goals but would also seem to
circumvent Congress’s own expectations and carefully balanced scheme of international
cooperation on a topic of global concern.” Id. The Second Circuit agreed with the district
court that “any federal common law claim against the [p]roducers that is not displaced by
the Clean Air Act” fails given “the need for judicial caution in the face of delicate foreign
policy considerations.” Id.
Against the backdrop of these federal cases, we turn to the state law claims asserted
by the local governments in the cases before us.
V
Federal Displacement/Preemption Analysis
A. Baltimore’s State Tort Claims Are Displaced by Federal Common Law
As reflected in the above survey of cases, for more than a century, the Supreme
Court and lower federal courts have held that interstate pollution is an inherently federal
area necessarily governed by federal law. See Int’l Paper Co. v. Ouellette, 479 U.S. 481,
42
488 (1987) (stating that “the regulation of interstate water pollution is a matter of federal,
not state, law”); AEP, 564 U.S. at 421, 422 (reiterating that “air and water in their ambient
or interstate aspects” are “meet for federal law governance”); City of New York, 993 F.3d
at 91 (collecting cases); Kivalina, 696 F.3d at 855 (stating that “[p]ost-Erie, federal
common law includes the general subject of environmental law and specifically includes
ambient or interstate air and water pollution”); Pankey, 441 F.2d at 240 (explaining that
the impairment of the ecological rights of a state from sources outside the state’s own
territory is a “matter having basis and standard in federal common law” and “constituting
a question arising under the laws of the United States”); Kansas v. Colorado, 206 U.S. 46,
97 (1907) (explaining that allowing the law of one state to govern disputes regarding
pollution emanating from another would violate the “cardinal” principle that “[e]ach State
stands on the same level with all the rest[,]” by permitting one state to impose its laws on
another state and its citizens). Federal law governs such controversies because they
“touch[] basic interests of federalism[]” and implicate a “uniform rule of decision[.]”
Milwaukee I, 406 U.S. at 105 n.6. And because “borrowing the law of a particular State
would be inappropriate[]” to resolve such interstate disputes, federal law must govern.
AEP, 564 U.S. at 422.
Given that federal law governs claims alleging injuries caused by interstate and
international emissions, we start by asking whether the local governments’ state law
43
claims, in fact, involve the regulation of interstate pollution and are therefore permitted,
if at all, only under federal law. 16 The answer is yes. 17
15F 16F
16
The circuit courts below, as well as the Defendants and their amici, the United
States, and 24 states, explained in support of their position that the inapplicability of state
law to injuries allegedly caused by interstate and international emissions arises from the
structure of the United States Constitution. Given that federal common law originates from
principles of federalism and is developed to address a uniquely federal interest where state
law is not applicable, we agree. See AEP, 564 U.S. at 421 (explaining that “federal common
law addresses subjects within national legislative power where Congress has so directed or
where the basic scheme of the Constitution so demands”) (emphasis added); Boyle v. United
Techs. Corp., 487 U.S. 500, 504 (1988) (observing that there are some areas involving
uniquely federal interests that “are so committed by the Constitution . . . to federal control
that state law is preempted”); cf. Franchise Tax Bd. of Cal. v. Hyatt, 587 U.S. 230, 246
(2019) (explaining that the federal “Constitution implicitly forbids” states from applying
their own law to certain matters “because the interstate nature of the controversy makes it
inappropriate for state law to control”) (citation modified). Such exclusively federal areas
include “interstate and international disputes implicating the rights of States or our relations
with foreign nations” and “areas in which a federal rule of decision is necessary to protect
uniquely federal interests.” Tex. Indus., 451 U.S. at 641–42. Although we undertake a
federal displacement/preemption analysis through the framework applied in Ouellette and
City of New York, we agree with the Defendants and their amici that the development of
federal common law is rooted in the same federalism principles that underpin the structure
of the United States Constitution.
17
We pause for a moment to recognize that, at first blush, our conclusion may
appear to be at odds with the United States Court of Appeals for the Fourth Circuit’s
analysis of Baltimore’s claims in the removal context. See Mayor & City Council of Balt.
v. BP P.L.C., 31 F.4th 178, 214, 216 (4th Cir. 2022) (concluding that Baltimore’s claims
“do not involve the regulation of emissions” and do not “disturb foreign relations”). The
court acknowledged, however, that the Defendant’s alleged deception mattered only
insofar as it “drove consumption, and thus climate change.” Id. at 234.
Our analytical lens is different from that applied by the Fourth’s Circuit in the
removal context, which required it to apply a “heightened standard unique to the
removability inquiry” to determine whether Baltimore’s state law actions arose under
federal law. Id. at 203. The issue before the Fourth Circuit was whether the Defendants’
anticipated defenses could singlehandedly create federal question jurisdiction under 28
U.S.C. § 1331 in light of the well-pleaded complaint rule. Id. at 197–98; see Caterpillar
Inc. v. Williams, 482 U.S. 386, 398 (1987) (noting that “the fact that a defendant might
44
The beginning point for our federal displacement/preemption inquiry is whether
the local governments’ claims in which they seek damages for alleged impacts of climate
change, is tantamount to regulation of interstate or international pollution as the
Defendants assert, or whether the claims are limited to deceptive and misleading
commercial conduct that lies within the “core” of the local governments’ state police
powers, as argued by the local governments.
At the outset, we observe that the local governments’ claims are similar to New
York’s claims that the Second Circuit analyzed in City of New York, 993 F.3d 81. Like
New York, the local governments allege that the Defendants “have known for decades
ultimately prove that a plaintiff’s claims are preempted under [federal law] does not
establish that they are removable to federal court” (citation modified)). “A plaintiff’s
complaint ‘may not be removed to federal court on the basis of a federal defense, including
the defense of pre-emption, even if the defense is anticipated in the plaintiff’s complaint,
and even if both parties concede that the federal defense is the only question truly at issue.’”
Baltimore, 31 F.4th at 198 (quoting Caterpillar, 482 U.S. at 393).
Relatedly, the Fourth Circuit was required to determine whether the doctrine of
complete preemption applied, which is a recognized exception to the well-pleaded
complaint rule. Id. Complete preemption is a jurisdictional doctrine that has the effect of
transforming a state law cause of action into one arising under federal law because
Congress has occupied the field so thoroughly as to leave no room for state law causes of
action at all. Id. By contrast, ordinary preemption—one of the defenses asserted before
this Court—“is not a jurisdictional doctrine because it simply declares the primacy of
federal law, regardless of the forum or the claim.” Id. (citation modified).
The Fourth Circuit ultimately concluded that the face of Baltimore’s complaint did
not raise claims under federal common law. Id. at 200–07. The court made it clear that
the Defendants’ merits-based ordinary preemption defense was reserved for the state court
on remand. Id. at 198–99. Because the court was concerned only with removal jurisdiction
and the application of complete preemption, it did not “delve into the[] defenses at
Defendants’ disposal[,]” including ordinary preemption. Id. at 198 n.2. Those issues, of
course, are before this Court.
45
that their fossil fuel products pose a severe risk to the planet’s climate[]” but “downplayed
the risks and continued to sell massive quantities of fossil fuels, which has caused and will
continue to cause significant change to [plaintiffs’] climate and landscape.” City of New
York, 993 F.3d at 86–87. The local governments assert that the Defendants are
“responsible for global warming and should bear the brunt of these costs[]” even though
“every single person who uses gas and electricity . . . contributes to global warming[].”
993 F.3d at 86.
We reject the local governments’ narrow reading of their complaints to suggest that
they only seek redress for “deceptive and misleading commercial conduct” within the
sphere of their local powers and authority. As noted above, the local governments allege
that the Defendants substantially contributed to greenhouse gas pollution, global warming,
and climate change by extracting, producing, promoting, refining, marketing, distributing,
and selling fossil fuel products (i.e., coal, oil, and natural gas). The claims are not limited
to deceptive and misleading commercial conduct.
Even assuming that the claims were limited to allegations of deceptive and
misleading marketing, we reject the assertion that their sweeping claims may be pursued
under state law. Although we are required to view the local governments’ allegations in
the light most favorable to them, we are not required to defer to their characterization of
the nature of their claims. No amount of creative pleading can masquerade the fact that
46
the local governments are attempting to utilize state law to regulate global conduct that is
purportedly causing global harm. 18
17F
Assuming the truth of the local governments’ allegations, they claim that the
Defendants engaged in worldwide conduct—which allegedly inflated fossil fuel
consumption, increased greenhouse gas emissions, accelerated global warming, and
thereby created hazardous conditions in Baltimore, Annapolis, and Anne Arundel
County—including sea-level rise, flooding, storm surges, and heat waves. Put another
way, the local governments allege that the Defendants engaged in worldwide deception
and caused worldwide injuries in the form of cumulative emissions. The local
governments cannot escape this inescapable conclusion: they are seeking to apply
Maryland law to regulate conduct that occurs outside their jurisdictional borders, as well
as within the State’s borders. The local governments’ police powers do not extend beyond
their respective borders, and certainly do not authorize the policing of global conduct.
The nature and scope of the damages sought by the local governments further
reflect that their claims seek to regulate conduct outside Maryland that is causing global
18
We respectfully disagree with the Supreme Courts of Hawaii and Colorado in
their analysis of similar claims and in their conclusion that such claims do not seek to
regulate emissions or seek damages for interstate emissions. City & County of Honolulu
v. Sunoco LP, 537 P.3d 1173, 1181 (Haw. 2023), cert. denied, 145 S. Ct. 1111 (2025) (No.
23-947); County Comm’rs of Boulder County v. Suncor Energy USA, Inc. (“Boulder”), No.
24SA206, 2025 WL 1363355, at *10 (Co. 2025), cert. granted, __S. Ct. __, 2026 WL
490537 (2026) (No. 25-170). Our view of the claims here aligns with the dissent in the
Boulder case. See Boulder, 2025 WL 1633355, at *13, *16 (“While Boulder’s state law
claims masquerade as tort claims for damages, a closer look at the substance of those
claims’ allegations reveals that Boulder seeks to effectively abate or regulate interstate
emissions,” which “state law remains incompetent” to do.) (Samour, J., dissenting).
47
warming. The local governments seek damages for injuries “caused by anthropogenic
greenhouse gas emissions,” which are “all due to anthropogenic global warming.” To
state the obvious, global warming is created by global consumption. Given that Maryland
accounts for only a fraction of global carbon dioxide emissions, 19 Maryland’s emissions
18F
alone cannot possibly be responsible for causing the local governments’ alleged injuries.
In other words, if the Defendants had labeled their products differently in Maryland to
warn Marylanders about the dangers of fossil fuel consumption, and every human,
government, corporation, or other entity that consumes fossil fuels every day heeded those
warnings, it would have been but a drop in the bucket in terms of the effects of greenhouse
gas pollution, global warming, or climate change. Viewing the allegations of the
complaint in the light most favorable to the local governments, they are necessarily
seeking damages for harms attributed to all interstate and international emissions
combined—plain and simple. Baltimore mentions “emissions” 115 times in its complaint.
The local governments cannot, in one breath, disavow any intent to address interstate and
global emissions, and in another, identify such emissions as the single source of their
harms.
As of 2023, the United States is responsible for 11% of global greenhouse gas
19
emissions. Ctr. for Climate and Energy Sol., Global Emissions: Greenhouse Gas
Emissions by Top Emitters, 2023, https://perma.cc/7V6E-G6HQ. Maryland’s carbon
dioxide emissions represent less than 0.1% of the nation’s carbon emissions. U.S. Energy
Info. Admin., Energy Related CO2 Emission Data Tables, Table 1 (2023),
https://perma.cc/P73Q-UG97. Maryland’s emissions constitute a small percentage of the
United States’ emissions, let alone the globe’s.
48
We agree with the Second Circuit that “[s]uch a sprawling case is simply beyond
the limits of state law.” City of New York, 993 F.3d at 92. A substantial damages award
like the ones the local governments seek would effectively regulate the Defendants’
behavior far beyond Maryland’s borders. Because greenhouse gases, once emitted,
become well mixed in the atmosphere, AEP, 564 U.S. at 422, they cannot be traced to
their source, as they quickly diffuse and comingle in the atmosphere. City of New York,
993 F.3d at 92. Any actions that the Defendants take to mitigate their liability in
Baltimore, Annapolis, and the County will undoubtedly have a significant impact across
every state and country. One cannot isolate these local governments’ claims from the
continuum of the harmful effects of global warming on the entire planet. Addressing the
local governments’ alleged injury requires the application of Maryland law to out-of-state
and international conduct. Indeed, the fact that the United States and 24 states 20 have filed
19F
amicus briefs in support of the Defendants “aptly illustrates that this is an interstate matter
raising significant federalism concerns.” Id.
The local governments once again attempt to recast the sweeping scope of their
lawsuit by pointing out that they are not “asking the court to enjoin or reduce fossil-fuel
production or emissions.” We are unpersuaded by the local governments’ myopic view
of their claims or their attempt to ignore or minimize the effect that a significant damages
award would have on both domestic and international attempts to regulate pollution—
The states of Alabama, Alaska, Arkansas, Florida, Georgia, Idaho, Indiana, Iowa,
20
Kansas, Kentucky, Louisiana, Mississippi, Missouri, Montana, Nebraska, North Dakota,
Ohio, Oklahoma, South Carolina, South Dakota, Texas, Utah, West Virginia, and
Wyoming filed an amicus brief in support of the Defendants.
49
matters which are solely within the purview of federal law. That these local governments
are seeking damages—as opposed to injunctive relief related to the imposition of pollution
standards—does not alter our conclusion. As the Supreme Court has recognized,
“‘regulation can be effectively exerted through an award of damages,’ and ‘the obligation
to pay compensation can be, indeed is designed to be, a potent method of governing
conduct and controlling policy.’” Kurns v. R.R. Friction Prods. Corp., 565 U.S. 625, 637
(2012) (citation modified) (quoting San Diego Bldg. Trades Council v. Garmon, 359 U.S.
236, 247 (1959)); see also BMW of N. Am., Inc. v. Gore, 517 U.S. 559, 572, n.17 (1996)
(observing that “[s]tate power” can be wielded as much by the “application of a state rule
of law in a civil lawsuit as by a statute[]” and explaining that “principles of sovereignty
and comity” mean “that a [s]tate may not impose economic sanctions on violators of its
laws with the intent of changing the tortfeasors’ lawful conduct in other States”).
Environmental tort claims force defendants “to change [their] methods of doing
business[.]” Ouellette, 479 U.S. at 495. Clearly, the local governments are seeking to
impose damages on the Defendants for injuries allegedly caused by the effect of interstate
and international greenhouse gas emissions on global climate change. As a result, the
local governments’ claims fall squarely within the inherently federal areas of interstate
pollution and foreign affairs and may therefore only be brought under federal law.
Allowing each of the 50 states (and the countless individual local governments
located within them) to impose their own preferred policy solutions for climate change—
with each state naturally focused on local rather than national or international impacts,
would create a plainly “irrational system of regulation” that would lead to “chaotic
50
confrontation between sovereign states.” Ouellette, 479 U.S. at 496 (citation modified);
see also City of New York, 993 F.3d at 93 (observing that “states will invariably differ
in their assessment of the proper balance between . . . national and international
objectives”). We agree with the Second Circuit’s conclusion that “to permit th[ese]
suit[s] to proceed under state law would further risk upsetting the careful balance that
has been struck between the prevention of global warming, a project that necessarily
requires national standards and global participation on the one hand, and energy
production, economic growth, foreign policy, and national security, on the other.” City
of New York, 993 F.3d at 93; see also AEP, 564 U.S. at 427; 43 U.S.C. § 1802(1)
(declaring that some regulatory goals of promoting oil and natural gas resource
management policies are “to achieve national economic and energy policy goals, assure
national security, reduce dependence on foreign sources, and maintain a favorable
balance of payments in world trade”). We therefore conclude that any state law claims
are displaced by federal common law. 2120F
21
It is an understatement to say that we view the allegations set forth in the local
governments’ complaints—and the analytical framework that follows therefrom—
differently from the dissent. We briefly explain these differences here.
The dissent asserts that the local governments have brought a “fraud case, and the
CAA has nothing to say about fraud.” Dissenting Slip. Op. at *4. According to the dissent,
the “local injuries” for which the local governments seek damages are “caused by local
impacts of a global phenomenon, and they are alleged to have resulted from a fraud, not
from an emissions policy.” Id. at *5. The dissent posits that because this case alleges a
fraud, the local governments’ claims arise from the “state’s historic police powers,” and
therefore, we must apply a preemption framework to the local governments’ claims in a
manner similar to cases such as Virginia Uranium, Inc. v. Warren, 587 U.S. 761 (2019);
Altria Group, Inc. v. Good, 555 U.S. 70 (2008); and Cipollone v. Liggett Group, Inc., 505
51
U.S. 504 (1992). Dissenting Slip. Op. at **2, 7, 19–22, 33–38, 48, 50, 53, 73. These cases,
of course, did not involve interstate pollution. See Va. Uranium, 587 U.S. at 761 (holding
that the Federal Atomic Energy Act did not preempt Virginia’s ban on uranium mining);
Altria Group, Inc., 555 U.S. 70; Cipollone, 505 U.S. at 504 (holding in each case that the
Federal Cigarette Labeling and Advertising Act did not preempt state law claims brought
against tobacco and cigarette manufacturers).
The dissent’s reliance on these cases flows from the fact that the dissent does not
view the local governments’ claims as pertaining to or affecting interstate emissions, and
therefore, the dissent determines that the Supreme Court’s analytical framework applied in
Ouellette has no application. The dissent also contends that we have “conflate[d]
displacement and preemption[,]” which the dissent states are “distinct doctrines with
distinct standards and distinct consequences.” Dissent Slip. Op. at *48–49.
Of course, as our opinion reflects, we disagree with the dissent’s characterization
of the local governments’ claims, and the analytical framework that the dissent argues is
applicable here. First, we disagree with the dissent that the claims relate only to fraud or
deceptive marketing claims arising under state common law and that the claims are within
the local governments’ “traditional police powers.” We will not repeat our reasoning or
analysis here other than to reiterate that the local governments are clearly attempting to
utilize state law to address global conduct that is purportedly causing global harm. The
ultimate conduct is the use of greenhouse gases across the globe, and the ultimate harm
asserted by the local governments arises from global emissions. The local governments’
police powers do not extend beyond their respective borders and certainly do not
authorize the policing of worldwide conduct. We simply do not view the local
governments’ claims in the same manner as the dissent or as the high courts of Hawaii
and Colorado. Rather, our analysis aligns with the dissent from the high court of
Colorado in Boulder, 2025 WL 1363355, at *12, and the Second Circuit in City of New
York, 993 F.3d at 98.
Second, because we determine that the local governments, through their state law
claims, are attempting to address air emissions, the correct analytical framework is to
consider the claims through the lens of federal law—which is the same framework that
the Second Circuit applied to similar claims in the City of New York. That is, we
recognize that historically, claims involving interstate pollution arose under federal
common law, which displaced state law. See AEP, 564 U.S. at 421, 422. With the
enactment of the Clean Air Act, federal common law claims, in turn, were displaced by
that federal statute. See id.; City of New York, 993 F.3d at 95. The final step in the
analysis arises under the analytical framework established by Ouellette—that is, where
federal common law previously governed the conduct (such as matters affecting interstate
water and air pollution) and is displaced by a legislative enactment (such as the Clean
52
B. The Clean Air Act, In Turn, Displaces Any Federal Common Law Claims that
the Local Governments May Have Where National Emissions Are Involved
Having determined that any claims the local governments may have would arise
under federal law, we next conclude that any federal common law claims would be
displaced by the Clean Air Act. We can make short work of this analysis given the
Supreme Court’s holding in AEP. See City of New York, 993 F.3d at 95 (“In the wake
of AEP, it is beyond cavil that the Clean Air Act displaced federal common law
nuisance suits seeking to abate domestic transboundary emissions of greenhouse
gases.”); see also Kivalina, 696 F.3d at 856 (explaining that the court “need not engage
in” the “complex issue and fact-specific analysis” of whether federal common law is
Water Act and the Clean Air Act), we consider whether Congress has authorized the
states to regulate the conduct through statutory enactments or the application of state
common law. 479 U.S. at 492. We determine that this framework, which the Second
Circuit applied to similar claims, is the correct one.
The dissent also criticizes our decision not to stay this case pending the United States
Supreme Court’s decision in Boulder, 2026 WL 490537, at *1. In Boulder, the United
States Supreme Court granted certiorari to determine two questions:
1. Whether federal law precludes state-law claims seeking relief for injuries
allegedly caused by the effects of intestate and international greenhouse-
gas emissions on the global climate.
2. Whether this Court has statutory and Article III jurisdiction to hear this
case.
Id. We decline to stay this case for two reasons. First, we believe that it could be useful
for the United States Supreme Court to have the benefit of a high court’s analysis that is
different from that expressed by our colleagues on the high courts of Colorado and Hawaii.
Second, given the Supreme Court’s decision to direct the parties to brief the second
question presented above, the Supreme Court may not even reach the merits.
53
displaced by the Clean Air Act “because we have direct Supreme Court guidance” and
citing to AEP).
We agree with the Second and Ninth Circuits that the Clean Air Act displaces not
only claims for abatement, but it similarly displaces the local governments’ common law
damages claims. City of New York, 993 F.3d. at 96; Kivalina, 696 F.3d at 857–58; see
also Middlesex County Sewerage Auth. v. Nat’l Sea Clammers Ass’n, 453 U.S. 1, 21–22
(1981) (holding that displacement of a federal common law injunction action necessarily
implies that a damages action brought for the same claim is also displaced). Whether the
local governments’ claims are styled as an action for injunctive relief against the
Defendants to stop them from producing fossil fuels, or as an action for a substantial
damages award that would alter their conduct vis-à-vis the production of fossil fuels, the
practical effect is the same.
Nor does the fact that the local governments are seeking to hold the Defendants
liable for emissions released by third parties—i.e., the worldwide consumers of fossil
fuel products who purchased and consumed more fuels, allegedly because of deceptive
marketing practices—alter our conclusion. “If an oil producer cannot be sued under the
federal common law for its own emissions, a fortiori it cannot be sued for someone
else’s.” City of New York, 993 F.3d at 97 (citation modified). Any claims that the local
governments could assert under federal common law are clearly displaced by the Clean
Air Act.
54
C. Applying the Ouellette Preemption Framework to the Local Governments’
Claims, Any State Law Claims Are Preempted
We also agree with the Second Circuit’s conclusion that, given the federalism
concerns undergirding the entire rationale of federal common law, 22 “state law does not
2 F
suddenly become presumptively competent to address issues that demand a unified
federal standard simply because Congress saw fit to displace a federal court-made
standard with a legislative one[.]” City of New York, 993 F.3d at 98. We recognize,
however, that Congress can grant states the authority to operate in an area of national
concern. But “resorting to state law on a question previously governed by federal
common law is permissible only to the extent authorized by federal statute.” Id. at 99
(citation modified) (quoting Milwaukee III, 731 F.2d at 411); see also Ouellette, 479
U.S. at 492. 23 In other words, where federal common law previously governed the
22F
conduct (such as matters affecting interstate water and air pollution) and is displaced by
22
See Milwaukee II, 451 U.S. at 313 n.7 (explaining that “if federal common law
exists, it is because state law cannot be used”); Boyle, 487 U.S. at 507 (noting that where
a federal statute displaces federal common law, it does so not “in a field which the States
have traditionally occupied”) (citation modified).
23
We agree with the Second Circuit that the case law applying preemption in the
context of state law claims that were once displaced by federal common law, which, in
turn, is displaced by Congress through a legislative enactment such as the CAA, “is
admittedly not a model of clarity[.]” City of New York, 993 F.3d at 98. As the Second
Circuit observed, “[a]lthough the Supreme Court in Ouellette appeared to rely, at least in
part, on the traditional preemption analysis under which courts should not lightly infer
preemption of state law claims,” the Ouellette Court also found support for its ultimate
conclusion—that the Clean Water Act had preempted state-law nuisance claims—by
looking to Milwaukee I, which held that, even in the absence of a federal statutory
scheme, “the control of interstate pollution is primarily a matter of federal law[.]” Id. at
103 n.11 (citation modified) (citing Ouellette, 479 U.S. at 492 (citing Milwaukee I, 407
U.S. at 107)).
55
a legislative enactment (such as the Clean Water Act and the Clean Air Act), we must
determine whether Congress has authorized the states to regulate the conduct through
statutory enactments or the application of state common law.
As discussed above, Ouellette provides the analytical framework that applies here.
The Court held that the Clean Water Act preempted Vermont’s nuisance suit under
Vermont law for harms experienced in Vermont but caused by New York-sourced
pollution. 479 U.S. at 483–84, 492. Relying on the Clean Water Act’s “comprehensive”
and “pervasive regulation” of water pollution, as well as “the fact that the control of
interstate pollution is primarily a matter of federal law,” the Court framed the inquiry as
whether the Clean Water Act “specifically preserved” the application of state law to water
pollution that originated from another state. Id. The Court answered no, holding that the
statue “contemplate[d] a much lesser role” for states seeking to regulate out-of-state
pollution, id. at 490, and precluded “applying the law of an affected State” to impose
liability on “an out-of-state source[,]” id. at 494.
Critically, the Court interpreted the Clean Water Act’s saving clause, 33 U.S.C.
§ 1370—which permits states to adopt and enforce stricter standards than required by the
Act—to permit liability under state law only if “pursuant to the law of the source State.”
Ouellette, 479 U.S. at 497. A contrary rule, the Court reasoned, would subject regulated
entities “to an indeterminate number of potential [state] regulations,” id. at 499,
“undermine the important goals of efficiency and predictability in the [EPA’s] permit
system,” id. at 496, and “undermine” the statute’s comprehensive “regulatory structure,”
id. at 497.
56
Applying the Supreme Court’s analytical framework to the local governments’
claims, we conclude that the Clean Air Act does not authorize the type of state law claims
that they assert. As discussed above, the Clean Air Act is a comprehensive federal law
that sets forth detailed source- and pollution-specific control programs for nationwide air
regulation. The Act grants the EPA authority to establish nationwide standards based
upon its expert judgment when the EPA determines that emissions from, for example,
stationary sources and new vehicles meet applicable statutory standards for regulation. 42
U.S.C. §§ 7411, 7521.
Although certain aspects of the Act embrace federal-state collaboration—such as
the attainment of NAAQS through state implementation plans—the plans must be
consistent with EPA regulations and submitted to the EPA for approval before they are
final. “[S]tates are not granted unfettered discretion to impose any environmental
regulations they choose[.]” City of New York, 993 F.3d at 81. Rather, the Act simply
“permit[s] each State to take the first cut at determining how best to achieve EPA
emissions standards within its domain.” AEP, 564 U.S. at 428 (emphasis added). The Act
carefully defines roles for states, including the state implementation plan process, in which
states implement EPA-promulgated standards for in-state sources.
The Clean Air Act specifically addresses the problem of “air pollution emitted in
one State, but causing harm in other States.” EPA v. EME Homer City Generation, L.P.,
572 U.S. 489, 495 (2014). Congress added the Good Neighbor Provision to “tackle [that]
problem” by requiring remedial action taken by the source state—because downwind
states “lack[ed] authority to control” out-of-state emissions. Id.; 42 U.S.C.
57
§ 7410(a)(2)(D)(i). Other provisions of the Clean Air Act afford affected states other
narrow avenues for voicing their cross-boundary pollution concerns to the EPA for
relevant pollutants. See, e.g., 42 U.S.C. § 7607(d)(5) (permitting “any person to submit
written comments, data, or documentary information[,]” and providing that “interested
persons” have “an opportunity” to orally present “data, views or arguments”); id. §
7475(a)(2) (noting that proposed permits for major emitting facilities must be subject to a
“public hearing”); id. § 7410(a)(1) (establishing that state implementation plans be
submitted “after reasonable notice and public hearings”). As this scheme makes plain,
each state is responsible for controlling air pollution within its borders—subject to EPA
oversight—and the Act contemplates no role for states reaching out and applying their law
in other states.
And although the Clean Air Act “provides multiple avenues for enforcement[,]”
AEP, 564 U.S. at 425—several of which contemplate state involvement—“only two could
even plausibly authorize the type of state-law claims pursued” by the local governments.
City of New York, 993 F.3d at 99. Those enforcement mechanisms set forth in two
provisions of the Act—42 U.S.C. §§ 7604(e) and 7416—are commonly and collectively
referred to by federal courts as the “saving clause.” Specifically, Section 7604(e) is a
citizen-suit saving clause, which states: “Nothing in this section shall restrict any right
which any person (or class of persons) may have under any statute or common law to seek
enforcement of any emission standard or limitation or to seek any other relief[.]” Section
7416 includes a states’ rights saving clause, which states: “Except as otherwise provided[,]
. . . nothing in this chapter shall preclude or deny the right of any State or political
58
subdivision thereof to adopt or enforce (1) any standard or limitation respecting emissions
of air pollutants or (2) any requirement respecting control or abatement of air pollution[,]”
except that the “State or political subdivision may not adopt or enforce any emission
standard or limitation” that is “less stringent than the standard or limitation” set by federal
law.
Several federal circuit courts of appeals have concluded that the saving clause
of the Clean Air Act is materially identical to the saving clause in the Clean Water Act
and have adopted the same interpretation that the Supreme Court adopted in
Ouellette—that the saving clause authorizes state regulation only “pursuant to the law
of the source state.” 479 U.S. at 497 (citation modified); see City of New York, 993
F.3d at 99 (observing that the saving clause in the Clean Air Act and the Clean Water
Act are “nearly identical” and that the saving clause of the Clean Air Act, “when read
together, plainly permit states to create and enforce their own emissions standards
applicable to in-state polluters”); see also North Carolina, ex rel. Cooper v. Tenn.
Valley Auth., 615 F.3d 291, 304 (4th Cir. 2010); Merrick v. Diageo Americas Supply,
Inc., 805 F.3d 685, 692 (6th Cir. 2015); Bell v. Cheswick Generating Station, 734 F.3d
188, 195–96 (3d Cir. 2013). “This no doubt holds true for both state legislation and
common law claims under state tort law.” City of New York, 993 F.3d at 100; Merrick,
805 F.3d at 690–91.
“[F]or example, a New York resident could bring a nuisance suit against a
Connecticut-based emitter under Connecticut law without upsetting the Clean Air Act’s
carefully balanced scheme, even if the alleged harm occurred in New York.” City of
59
New York, 993 F.3d at 100; see also Ouellette, 479 U.S. at 498–99 (explaining in the
Clean Water Act context why the application of the source state’s common law would
not upset the balance among federal, source-state, and affected-state interests). The local
governments’ claims here are far different and exceed the bounds of the Clean Air Act’s
saving clause.
Indeed, the Court’s concern in Ouellette about source state entities being subject
to the application of “vague” and “indeterminate” “nuisance standards” is even weightier
in the greenhouse gas context than the water-pollution context. 479 U.S. at 496. While
air pollution is generally “heedless of state boundaries[,]” EME Homer City Generation,
572 U.S. at 496, any alleged greenhouse gas effects are not traceable to any particular
domestic or global source. If all emissions attributable to the producers’ products are
deemed collectively responsible for that indivisible harm under one affected state’s law,
any one emitter could face an ill-defined patchwork of liability across all 50 states. To
permit such suits would undermine “this carefully drawn statute through a general saving
clause,” Ouellette, 479 U.S. at 494, and would “serious[ly] interfere . . . with the
achievement of the full purposes and objectives of Congress,” id. at 493–94 (citation
modified). “We thus cannot allow non-source states to ascribe to a generic savings
clause a meaning that the Supreme Court in Ouellette held Congress never intended.”
City of New York, 993 F.3d at 100 (quoting Tenn. Valley Auth., 615 F. 3d at 304).
Accordingly, we determine that the Clean Air Act does not authorize the local
governments’ state law claims and conclude that such claims concerning domestic
emissions are barred by federal law.
60
D. The Local Governments’ Nuisance Claims Impermissibly Encroach on Foreign
Policy Concerns that Are Best Left to the Legislative and Executive Branch
As discussed above, the local governments’ claims govern emissions conduct that
occurs both domestically and internationally. As such, the “question cannot be answered
by reference to the Clean Air Act alone.” City of New York, 993 F.3d at 100. “It is a
longstanding principle of American law that legislation of Congress, unless a contrary
intent appears, is meant to apply only within the territorial jurisdiction of the United
States.” Morrison v. Nat’l Aus. Bank Ltd., 561 U.S. 247, 255 (2010) (citation modified)
(quoting EEOC v. Arabian Am. Oil Co., 499 U.S. 244, 248 (1991)). “Put more bluntly,
‘when a statute gives no clear indication of an extraterritorial application, it has none.’”
City of New York, 993 F.3d at 100 (quoting Morrison, 561 U.S. at 255).
The Clean Air Act contains no such clear indication. “Indeed, the statutory scheme
is silent about extraterritorial reach, except to authorize the EPA Administrator to mitigate
domestic air pollutants that have caused or contributed to air pollution in a foreign
country—and even then, only if that country provides reciprocal protections to the United
States.” Id. at 100; 42 U.S.C. § 7415. 24 “In addition, Congress has tasked ‘the State
23F
Department—not [the] EPA—to formulate United States foreign policy with reference to
environmental matters relating to climate.’” City of New York, 993 F.3d at 101 (quoting
Massachusetts, 549 U.S. at 534). “Together, the statute’s silence on the issue of
24
For discussion of the dearth of statutory provisions and cases on the
extraterritorial application of domestic environmental laws, see Jonathan Remy Nash, The
Curious Legal Landscape of the Extraterritoriality of U.S. Environmental Laws, 50 Va. J.
Int’l L. 997, 1004 (2010).
61
extraterritorial reach, the fact that the Act contemplates the need for reciprocal protections
from foreign nations, and the State Department’s lead role in setting foreign policy on
environmental matters, all plainly demonstrate that the Clean Air Act regulates only
domestic emissions.” Id.
However, even if such claims could proceed as a matter of federal common law,
like the Second Circuit, we conclude that foreign policy concerns would foreclose “a
federal common law cause of action targeting emissions emanating from beyond our
national borders.” Id.
In both Kiobel v. Royal Dutch Petroleum Co., 569 U.S. 108 (2013) and Jesner v.
Arab Bank, PLC, 584 U.S. 241 (2018), the Supreme Court declined to extend the scope
of federal common law actions brought under the Alien Tort Statute in part due to foreign
policy concerns. As the Second Circuit observed, “[a]lthough the reasoning of Jesner
and Kiobel is, at times, specific to the context of the [Alien Tort Statute] and violations
of the laws of nations, these cases also rest on broad concerns over separation of powers,
intrusion on the political branches’ monopoly over foreign policy, and judicial caution
with respect to creating (or extending) federal common law causes of action.” City of
New York, 993 F.3d at 102; see Jesner, 584 U.S. at 265 (explaining that the “political
branches, not the Judiciary, have the responsibility and institutional capacity to weigh
foreign-policy concerns”); Kiobel, 569 U.S. at 116 (noting that Congress, not the
Judiciary, has “the facilities necessary to make fairly such an important policy decision
where the possibilities of international discord are so evident and retaliative action so
certain”) (citation modified); Sosa v. Alvarez-Machain, 542 U.S. 692, 727 (2004)
62
(cautioning that “the potential implications for the foreign relations of the United States
of recognizing [new private causes of action for violating international law] should make
courts particularly wary of impinging on the discretion of the Legislative and Executive
branches in managing foreign affairs”); Nahl v. Jaoude, 968 F.3d 173, 180 (2d Cir. 2020)
(noting that Sosa requires courts to consider “prudential concerns” such as “foreign
policy concerns raised by the executive branch” when an action for a violation of
international law is available to litigants).
We agree with the Second Circuit’s conclusions concerning the problems
associated with courts recognizing federal common law claims that may concern
disputes of international import. To hold the Defendants responsible for foreign activity
would necessarily require them to internalize the costs of climate change, which, in turn,
would presumably affect the price and production of fossil fuels abroad. City of New
York, 993 F.3d at 103. It would also bypass the various diplomatic channels that the
United States uses to address this issue, such as the U.N. Framework 25 and the Paris
24F
25
The international climate change legal landscape largely consists of the United
Nations Framework Convention on Climate Change (“UNFCCC”) and subsequent
agreements that have grown out of it. The UNFCCC is a global treaty that was adopted in
1992 and aimed to facilitate international responses to climate change. United Nations
Climate Change, About the secretariat, https://perma.cc/4GV3-CS9Q. The UNFCCC
secretariat (UN Climate Change) was formed after the adoption of the UNFCCC and is the
United Nations entity “tasked with supporting the global response to the threat of climate
change.” Id. The UNFCCC is the “parent treaty” of both the 1997 Kyoto Protocol and the
2015 Paris Agreement. Id. The U.S. Senate ratified the UNFCCC in 1992. United Nations
Framework Convention on Climate Change, May 9, 1992, S. Treaty Doc. No. 102-38, 1771
U.N.T.S. 107.
63
Agreement. 26 Id. “Such an outcome would obviously sow confusion and needlessly
25F
complicate the nation’s foreign policy, while clearly infringing” on the prerogatives of
Congress and the President. Id.
Simply put, “condoning an extraterritorial nuisance action here would not only risk
jeopardizing our nation’s foreign policy goals but would also seem to circumvent
Congress’s own expectations and carefully balanced scheme of international cooperation
Adopted in 1997 and entered into force in 2005, the Kyoto Protocol
“operationalizes” the UNFCCC “by committing industrialized countries and economies in
transition to limit and reduce greenhouse gases (GHG) emissions in accordance with
agreed individual targets.” United Nations Climate Change, Process and Meetings: The
Kyoto Protocol, https://perma.cc/KX43-37NL. Developed countries have a “heavier
burden” for emission reductions, as the Protocol “recognizes that they are largely
responsible for the current high levels of GHG emissions in the atmosphere.” Id. Under
President Clinton, the United States signed the Kyoto Protocol in 1998, but the treaty was
never ratified by the Senate, and, as such, the treaty is not binding on the United States.
26
The Paris Agreement is another international treaty on climate change that was
adopted in December 2015 and entered into force in November 2016. United Nations
Climate Change, Process and Meetings: The Paris Agreement, https://perma.cc/4S6A-
Y3MB. Its “overarching goal” is to limit the increase of the global average temperature.
Id. Under the Agreement, countries submit national climate action plans—known as
“nationally determined contributions (NDCS)”—that detail both long-term and short-term
actions the countries will take to reduce their GHG emissions, as well as the steps they will
need to take to “build resilience” to adapt to the effects of climate change. Id. Under
President Obama, the United States was a signatory of the Paris Agreement, but during
President Trump’s first term, President Trump withdrew the country. The United States,
under President Biden, then rejoined the Agreement, see Depositary Notification,
Acceptance by the United States of America, Paris Agreement, Reference C.N.
10.2021.Treaties-XXVII.7.d (Jan. 20, 2021), but President Trump recently withdrew the
country again, Exec. Order No. 14162, 90 Fed. Reg. 8455 (2025).
Despite Congress’s recognition that climate change occurs “on a global basis,” and
that “[i]nternational cooperation for the purpose of sharing the benefits and costs of a global
effort to understand climate is essential[,]” 15 U.S.C. § 2901(5), the United States is not
currently a party to global efforts and cooperation—much less Baltimore City, Annapolis,
or Anne Arundel County.
64
on a topic of global concern.” Id. Accordingly, to the extent that the local governments
could bring a federal common law claim against the Defendants that is not displaced by the
Clean Air Act, it would nonetheless fail under the reasoning supplied by Kiobel and Jesner
and the need for judicial caution in the face of delicate foreign policy considerations.
VI
Analysis of State Law Claims
Even had we not determined that the local governments’ state law claims are
displaced or preempted by federal law, we would nonetheless affirm the circuit courts’
dismissal of the state law claims as a matter of law. As noted above, the local governments
asserted five causes of action against the Defendants, all arising under Maryland law: (1)
public nuisance; (2) private nuisance; (3) strict liability for failure to warn; (4) negligent
failure to warn; and (5) trespass. To remedy their harms, they seek compensatory and
punitive damages, disgorgement of profits, and equitable relief, including the abatement of
the alleged nuisances and an injunction against future nuisances. For the reasons set forth
below, we conclude that each of the local governments’ claims fail to state legally
cognizable claims under Maryland common law.
A. Public Nuisance Claims
Under their public nuisance theory, the local governments assert that the
“Defendants, individually and in concert with each other, have created, contributed to,
and/or assisted in creating, conditions that significantly interfere with rights general to the
public, including the public health, public safety, the public peace, the public comfort, and
the public convenience.” The nuisance, according to the local governments, is “substantial
65
and unreasonable,” and will “cause and continue to cause far into the future, significant
harm to the community,” which “outweighs any offsetting benefit.”
The local governments do not state a claim under Maryland common law for public
nuisance. As we discussed in Express Scripts, Inc. v. Anne Arundel County, “Maryland has
not expanded the public nuisance doctrine beyond the traditional historical principles
embodied in the common law—namely, that a public nuisance action was not regarded as a
tort but was instead a public action by a government entity to pursue criminal prosecutions
or seek injunctive relief to abate harmful conduct.” Maryland, ___ Md. ___, at *92 (filed
March 23, 2026). “This Court has never recognized a government entity’s ability to recover
damages for public nuisance.” Id. To the extent that the local governments are seeking
damages for public nuisance, such recovery exceeds the bounds of Maryland’s public
nuisance doctrine. Moreover, assuming without deciding that there is a public right to be
free from adverse effects of climate change, “we would nonetheless decline to expand
Maryland’s common law of public nuisance to govern the conduct alleged in the” local
governments’ complaints “given the extensive federal . . . statutory and regulatory
framework that governs the highly complex conduct” of regulating air emissions. Id. at *93.
Congress has entrusted the EPA with balancing air emissions and societal reliance on fossil
fuels. Where the legislature has, through the enactment of comprehensive legislation,
entrusted such highly complex matters to an agency having expertise of the same, we decline
to expand common law nuisance to address the same conduct.
With respect to any equitable claims asserted by the local governments to abate a
public nuisance, again assuming without deciding, that there is a public right to be free
66
from adverse effects of climate change, this Court has never recognized a local
government’s ability to bring an action to abate conduct that is occurring well beyond the
boundaries of the jurisdiction, nor are we aware of any authority granted by the General
Assembly to pursue such extraterritorial claims. 27 Quite simply, the notion that a local
26F
government such as Baltimore, Annapolis, or Anne Arundel County may pursue state law
nuisance claims against the Defendants—seeking injunctive relief to abate injuries arising
from global greenhouse effects arising from worldwide conduct—is so far afield from any
area of traditional state or local responsibility that it cannot be seriously contemplated.
B. Private Nuisance Claims
The local governments also assert that the Defendants’ conduct constitutes a private
nuisance. The local governments posit that they each own, occupy, and manage extensive
real property within their borders, and that the effects of climate change have caused, and
will continue to cause, substantial and unreasonable interference with the public’s use and
enjoyment of government property. Viewing the allegations in the complaint in the light
27
In Maryland, local governments only have such authority as is granted by the
General Assembly. Although the General Assembly has granted each of the local
governments various authority to abate public nuisances within their boundaries, the
authority does not extend extraterritorially. For example, the General Assembly has
granted the State’s Attorney and County Attorney for Anne Arundel County the authority
to seek “injunctive and other equitable relief in the District Court” for “abatement of a
nuisance[.]” Md. Code (2023 Repl. Vol., 2025 Supp.), Real Property Article (“RP”) § 14-
125.1(d)(1), (b). The statute contains a definition of “nuisance” that applies within the
boundaries of Anne Arundel County, which is tied to uses of private property in violation
of the local code. Id. § 14-125.1(a)(4). The public nuisance claims asserted in this case by
Anne Arundel County far exceed the authority granted by the General Assembly in this
nuisance abatement statute.
67
most favorable to the local governments, although climate change may have adverse effects
on public property, such effects do not give rise to a cause of action for private nuisance.
As we explained in Express Scripts, Inc., public nuisance involves an unreasonable
interference with the rights of the community at large, “whereas private nuisance is a tort[,]”
and “[a] plaintiff injured by a nuisance may seek damages or injunctive relief if the plaintiff
suffers an injury that is different in kind from that suffered by other members of the public.”
Id. at *51 (citing Cook v. Normac Corp., 176 Md. 394, 397 (1939); Houck v. Wachter, 34
Md. 265, 269 (1871); Garitee v. City of Balt., 53 Md. 422, 436–37 (1880)). Assuming
without deciding that there is a general public right to be free from adverse effects of climate
change, the local governments, as owners of public land, fail to establish that they have
suffered an injury that is different in kind from that suffered by members of the public. The
local governments allege injuries arising from climate change, including sea level rise, storm
surges, extreme precipitation events, and heat waves, which have caused “consequent social
and economic injuries associated with the aforementioned physical and environmental
impact.” But this “inundation, destruction and/or interference” with the local governments’
property and citizenry are not unique in kind or different from injuries suffered by the public
generally—that is, there are no allegations of special damages.
Expanding the doctrine of private nuisance in the manner asserted by the local
governments would eliminate the distinction in our common law between public and
private nuisance—a step we decline to take.
68
C. Trespass
Turning to the trespass claim, the local governments contend that the Defendants
caused “flood waters, extreme precipitation, saltwater, and other materials to enter” their
property, rendering it unusable. The local governments assert that the “Defendants’
introduction of fossil fuel products into the stream of commerce was a substantial factor in
causing harms and injuries to” the local governments’ public and private property. The
Defendants’ acts and omissions, posit the local governments, are indivisible causes of the
injuries because “it is not possible to determine the source of any particular individual
molecule of CO2 in the atmosphere attributable to anthropogenic sources because such
greenhouse gas molecules do not bear markers that permit tracing them to their source, and
because greenhouse gases quickly diffuse and comingle in the atmosphere.” The local
governments assert that the Defendants’ wrongful conduct, as recounted in the complaint,
was committed with actual malice in that the Defendants had “actual knowledge that their
products were defective and dangerous, and acted with conscious disregard for the probable
dangerous consequences of their conduct’s and products’ foreseeable impacts upon the
rights of others,” including the local governments. In addition to injunctive relief and
compensatory damages, the local governments seek an award of punitive damages in an
amount “sufficient to punish the[] Defendants for the good of society and to deter
Defendants from ever committing the same or similar acts.”
The common law tort of trespass is generally defined as an “intentional or negligent
intrusion upon or to the possessory interest in property of another.” Litz v. Md. Dep’t of
Env’t, 446 Md. 254, 276–77 (2016) (citation modified). We have stated that “exclusive
69
control over the adjacent land or over the invading force is” not an essential or necessary
element “for an action for trespass to lie[.]” Rockland Bleach & Dye Works Co., Inc. v. H.J.
Williams Corp., Inc., 242 Md. 375, 386–87 (1966) (citation modified). “However, when an
adjacent property is invaded by an inanimate or intangible object[,] it is obvious that the
defendant must have some connection with or some control over that object in order for an
action in trespass to be successful against him[]” or her. Id. at 387 (emphasis added).
In Rockland, a general contractor working for the State Roads Commission, placed
considerable fill at the base of a construction project, which was adjacent to plaintiff’s
reservoir that supplied over 600,000 gallons of water each day to plaintiff’s bleach and dye
works company. Id. at 379. A rainstorm washed the earth from the fill into the reservoir,
completely blocking its intake and feeder pipes. Id. at 380. This Court reversed a directed
verdict for the defendant on the trespass claim. Id. at 384. The defendant argued that it had
insufficient control because it was obliged to follow the drainage plan designed by the State
Roads Commission. Id. at 386. We rejected defendant’s argument, determining that the
contract documents conferred “very significant amounts of control” over the fill materials at
issue. Id. at 387. In contrast, in JBG/Twinbrook Metro Limited Partnership v. Wheeler, we
held that a gas company contracting with a station owner to sell the company’s gas was not
liable in trespass for the subsurface percolation of gas onto adjacent property because the
company had “insufficient control” over the gasoline. 346 Md. 601, 626 (1997).
The local governments have not provided any Maryland case law that supports their
sweeping trespass claim, nor have we found any. This is not a case in which dangerous
products were directly deposited into and directly entered the land and water of the
70
plaintiff, where the defendant exercised some measure of control over the matter invading
plaintiff’s property. The local governments seek to establish a trespass upon a
determination that the Defendants’ “substantial contribution” to climate change—through
their marketing of products, the use of products in every part of the world, and the
emissions from that use—caused rainfalls, flooding, and other material to enter upon their
property without their consent. We determine that this sweeping cause of action roves too
far to establish a trespass claim. Given that global gases in the atmosphere attributable to
anthropogenic sources cannot be traced to their original source, and are attributable to all
human activity, to find an actionable trespass action, we would be forced to conclude that
these Defendants exercise some connection or control over all human activity that causes
global warming. We agree with the Circuit for Baltimore City that the link between the
Defendants’ activities and the harms alleged by the local governments, which are caused
by human activity around the world, is far too attenuated to constitute the Defendants’
connection to or control over adverse global climate effects that have invaded the local
governments’ property.
D. Failure to Warn
Finally, we turn to the local governments’ failure to warn claims. The local
governments assert a strict liability failure to warn claim, as well as a negligent failure to
warn claim. The factual assertions underlying the failure to warn claims are the same. The
local governments assert that the Defendants “had a duty to issue adequate warnings to
the” local governments, “the public, consumers, and public officials of the reasonably
foreseeable or knowable severe risks posed by their fossil fuel products.” According to the
71
local governments, the “Defendants knew or should have known from their internal
research divisions and affiliates and/or from the international scientific community, of the
climate effects inherently caused by the normal use and operation of the fossil fuel
products, including the likelihood and likely severity of global warming” and the
“associated consequences of physical and environmental changes.”
The local governments contend that the “defendants breached their duty of care by
failing to adequately warn any consumers or any other party of the climate effects that
inevitably flow from the intended use of their fossil fuel products.” “Given the grave
dangers presented by the climate effects that inevitably flow from the normal use of fossil
fuel products,” the local governments assert that “a reasonable extractor, manufacturer,
formulator, seller, or other person responsible for introducing fossil fuels into the stream
of commerce, would have warned of those known, inevitable climate effects.” As a result
of the Defendants’ failure to warn, the local governments allege that they have “sustained,
and will sustain substantial damages and expenses,” including “damage to publicly owned
infrastructure and real property, and injuries to public resources[.]” The local governments
further assert that this wrongful conduct was committed with actual malice, and they
therefore request an award of punitive damages.
A failure to warn claim brought under either negligence or strict liability requires
the plaintiff to show four elements: (1) that the defendant owed a duty to warn; (2) that the
defendant breached that duty; (3) there was a direct causal connection between the
defendant’s failure and the alleged injuries; and (4) that the plaintiff was harmed. Gourdine
v. Crews, 405 Md. 722, 738 (2008). “The major distinction between an action in strict
72
liability in tort and one founded on traditional negligence theor[ies] relates to the proof
which must be presented by the plaintiff.” Gourdine, 205 Md. at 741 (quoting Harig v.
Johns-Mansville Prods. Corp., 284 Md. 70, 84 (1978)).
In our failure to warn cases, “negligence concepts and those of strict liability have
‘morphed together[.]’” Id. at 743 (citing ACandS, Inc. v. Asner, 344 Md. 155, 168 (1996);
Phipps v. Gen’l Motors Corp., 278 Md. 337, 351 (1976); Mazda Motor of Am., Inc. v.
Rogowski, 105 Md. App. 318, 325 (1995)). “Duty, thus, is an essential element of both
negligence and strict liability causes of action for failure to warn.” Id.
“The existence of a legal duty is a question of law, to be decided by the court.” Id.
at 732 (citing Doe v. Pharmacia & Upjohn Co., Inc., 388 Md. 407, 414 (2005)). “With
respect to determining whether a duty exists, we often have recourse to the definition in
W. Page Keeton, et al., Prosser and Keeton on The Law of Torts § 53 (5th ed. 1984), which
characterizes ‘duty’ as an ‘obligation, to which the law will give recognition and effect, to
conform to a particular standard of conduct toward another.’” Id. at 745 (citation
modified). “While foreseeability is often considered among the most important” factors in
determining whether a duty exists, “its existence alone does not suffice to establish a duty
under Maryland law.” Id. at 746 (quoting Patton v. United States of Am. Rugby Football,
381 Md. 627, 637 (2004)); see also Valentine v. On Target, Inc., 353 Md. 544, 551 (1999)
(noting that “not all foreseeable harm gives rise to a duty; there are other factors to
consider”).
73
“Duty requires a close or direct effect of the tortfeasor’s conduct on the injured
party.” Gourdine, 405 Md. at 746. In Gourdine, we quoted Prosser and Keeton § 41 as
follows:
As a practical matter, legal responsibility must be limited to those causes
which are so closely connected with the result and of such significance that
the law is justified in imposing liability. Some boundary must be set to
liability for the consequences of any action, upon the basis of some social
idea or policy of justice. This limitation is to some extent associated with
the nature and degree of the connection in fact between the defendant’s acts
and the events of which plaintiff complains. Often to greater extent,
however, the legal limitation on the scope of liability is associated with
policy—with our more or less inadequately expressed ideas of what justice
demands.
Id. at 747 (emphasis added) (citation modified) (citing W. Page Keeton, Prosser and
Keeton on The Law of Torts § 41 (5th ed. 1984)).
In that case, we held that a manufacturer did not owe a common law duty to a
motorist, who was killed when a driver, who was taking a combination of insulin
medications, suffered a debilitating episode while operating her car, and struck the
motorist’s vehicle. Id. at 745–54. Examining other cases in which we held there was no
duty, we concluded that imposing a duty to warn in such circumstances would create “a
duty to [warn] the world, an indeterminate class of people,” which we had “resisted[.]” Id.
at 750 (quoting Pharmacia & Upjohn, 388 Md. at 407); see also Pharmacia & Upjohn,
388 Md. at 420–421 (holding that an employer, who employed a husband who became
infected with HIV while handling the virus in the course of his employment in a research
laboratory, owed no duty to the employee’s wife, who became infected after engaging in
unprotected marital relations).
74
In Valentine, we held that a gun dealer owed no duty to the public to exercise
reasonable care in the display and sale of handguns to prevent the theft and illegal use of
the handguns by others against third parties, noting “that a duty may exist to the public
at large without any evidence of a relationship between the parties, is simply too foreign
to our well-established jurisprudence to sufficiently advocate a different result than the
one we have reached.” 353 Md. at 555–56. We further explained that “[o]ne cannot be
expected to owe a duty to the world at large to protect it against the actions of third
parties, which is why the common law distinguishes different types of relationships when
determining if a duty exists. The class of persons to whom a duty would be owed under
these bare facts would encompass an indeterminate class of people, known and
unknown.” Id. at 553.
We determine that the duty the local governments seek to impose is, indeed, a duty
to warn the entire human race of the effects of climate change. We have resisted efforts to
find such a duty under our common law and continue to do so here. Finding such a duty
would stretch tort law beyond any manageable bounds. Accordingly, we agree with the
Circuit Court for Baltimore City that the local governments failed to state a claim for duty
to warn under both strict liability and negligence theories.
VII
Conclusion
For the foregoing reasons, we hold that the local governments’ claims are preempted
by federal law. To the extent that the claims are not preempted, the local governments
have failed to state claims under Maryland common law upon which relief can be granted.
75
IN CASE NO. 24-C-18-004219, JUDGMENT
OF THE CIRCUIT COURT FOR
BALTIMORE CITY IS AFFIRMED. COSTS
TO BE PAID BY APPELLANT, MAYOR
AND CITY OF BALTIMORE.
IN CASE NOS. C-02-CV-21-00250 AND C-02-
CV-21-000565, JUDGMENT IN THE
CIRCUIT COURT FOR ANNE ARUNDEL
COUNTY IS AFFIRMED. COSTS TO BE
PAID BY THE APPELLANTS, ANNE
ARUNDEL COUNTY, MARYLAND, AND
THE CITY OF ANNAPOLIS.
76
Circuit Court for Baltimore City
Case No. 24-C-18-004219
Circuit Court for Anne Arundel County
IN THE SUPREME COURT
Case No. C-02-CV-21-000250
OF MARYLAND
Circuit Court for Anne Arundel County
Case No. C-02-CV-21-000565
No. 11
Argued: October 6, 2025
September Term, 2025
______________________________________
MAYOR & CITY COUNCIL OF
BALTIMORE
v.
B.P. P.L.C., ET AL.
______________________________________
ANNE ARUNDEL COUNTY, MARYLAND
v.
B.P. P.L.C., ET AL.
______________________________________
CITY OF ANNAPOLIS
v.
B.P. P.L.C., ET AL.
______________________________________
Fader, C.J.
Watts
Booth
Gould
Eaves
Killough
Battaglia, Lynne A. (Senior
Justice, Specially Assigned),
JJ.
______________________________________
Concurring Opinion by Fader, C.J.
______________________________________
Filed: March 24, 2026
Respectfully, I concur in the Majority’s well-written and well-reasoned opinion. I
agree with the Majority that the local governments’ state law claims are preempted by
federal law. I therefore join fully in Parts I through V of the Majority opinion.
The determination that the local governments’ state law claims are preempted fully
resolves the case before us. Accordingly, I would stop there. I would not address the
alternative argument that the preempted claims fail to state cognizable claims under
Maryland common law. The common law is not static. I see no reason to resolve
competing contentions concerning the scope of the common law in this area until we are
presented with a case that requires us to do so. Accordingly, I do not join Part VI of the
Majority opinion.
Circuit Court for Baltimore City
Case No.: 24-C-18-004219
Circuit Court for Anne Arundel County
Case No.: C-02-CV-21-000250 IN THE SUPREME COURT
Circuit Court for Anne Arundel County
Case No.: C-02-CV-21-000565 OF MARYLAND
Argued: October 6, 2025 No. 11
September Term, 2025
MAYOR & CITY COUNCIL OF BALTIMORE
v.
B.P. P.L.C., et al.
ANNE ARUNDEL COUNTY, MARYLAND
v.
B.P. P.L.C., et al.
CITY OF ANNAPOLIS
v.
B.P. P.L.C., et al.
Fader, C.J.,
Watts,
Booth,
Gould,
Eaves,
Killough,
Battaglia, Lynne A.
(Senior Justice, Specially Assigned)
JJ.
Concurring Opinion by Gould, J.
Filed: March 24, 2026
I join the Majority’s thorough and well-reasoned opinion in full. I write separately
only to explain why, in my view, the plaintiffs’ theory of liability is incompatible with tort
law.
I
In the plaintiffs’ view, this is a case about deceptive marketing to consumers. They
contend that their complaints merely alleged that the defendants misled consumers about
the climate dangers of fossil fuels, thereby increasing fossil-fuel consumption and
increasing the harm associated with climate change.
But a fair reading of the plaintiffs’ lengthy complaints reveals that their claims of
misrepresentation take two forms. First, the plaintiffs alleged a generalized deception at
the brand level. The complaints point to advertising campaigns and corporate messaging—
slogans, branding, and statements about the industry’s environmental commitments. For
example, BP adopted the slogan “Beyond Petroleum” and a green sunburst logo while
investing a negligible fraction of its capital in non-fossil energy; Shell advertised liquefied
natural gas as a “cleaner-burning” fuel and a “critical component of a sustainable energy
mix”; and Exxon touted algae biofuels while spending 0.2% of its capital on low-carbon
energy sources.
Second, the plaintiffs alleged that the defendants engaged in a decades-long
campaign to deceive policymakers, including members of Congress and government
regulators. This campaign, the plaintiffs alleged, distorted the legislative and regulatory
processes with false information, thus preventing, for example, the adoption of stricter
emissions controls and “Kyoto-like measures” that would have constrained the industry’s
conduct.
Viewing the complaints in light of both of these types of deception allegations, the
path to recoverable damages under tort law cannot avoid the regulatory problem that the
preemption doctrine is designed to address. Aggregate emissions are a function of both
what the regulatory system permits and how much consumers choose to consume within
that context. That is, a consumer who encountered Shell’s advertisements and bought
Shell’s product was choosing among options that regulators had already defined and
constrained.
So, to calculate the damages caused by the defendants’ deception, a jury would first
need to determine—without resort to rank speculation—what the regulatory environment
would have looked like if the defendants had not engaged in the alleged campaign—that
is, what Congress would have enacted, what the Environmental Protection Agency (“EPA”)
would have required, and how global emissions trajectories would have changed as a result.
Only after resolving those issues could the jury attempt to determine—again, without resort
to rank speculation—how consumer behavior might have differed, how those differences
would have affected the climate, and how the plaintiffs’ jurisdictions would have been
impacted as a result.
As the Supreme Court explained in American Electric Power Co. v. Connecticut,
determining the appropriate level of greenhouse-gas regulation requires an “informed
assessment of competing interests” involving scientific, economic, and technological
considerations—an assessment Congress assigned to the EPA, not to courts. 564 U.S. 410,
2
427-28 (2011). The EPA has access to scientists, engineers, and economists, and bases its
decisions on a technical record developed through notice-and-comment procedures. The
EPA also has access to evolving information and can recalibrate its regulatory approach
and pivot as needed.
A jury, by contrast, deliberates once, on a record assembled by adversarial litigants.
Juries are simply not equipped to undertake the analysis the plaintiffs’ claims require.
II
There is a mismatch between the structure of tort law and the nature of the harm
alleged here. Tort law generally asks whether a defendant’s conduct created a foreseeable
risk of harm to the plaintiff. That framework presupposes that harm can be traced, in some
meaningful sense, to discrete acts by discrete actors.
Climate harm is different. No single extraction decision, no single sale of fuel, and
no single consumer transaction creates a foreseeable risk of harm to any identifiable person.
The harm alleged here could arise only from the aggregate effect of fossil-fuel consumption
across the globe and across generations. Where the risk of harm exists at that level of
aggregation, the legal tool designed to address it must likewise operate at an aggregate
level. Tort law is not up to the task.
Accordingly, I join in full the Majority opinion.
3
Circuit Court for Baltimore City
Case No. 24-C-18-004219
Circuit Court for Anne Arundel County
IN THE SUPREME COURT
Case No. C-02-CV-21-000250
OF MARYLAND
Circuit Court for Anne Arundel County
Case No. C-02-CV-21-000565
No. 11
Argued: October 6, 2025
September Term, 2025
______________________________________
MAYOR & CITY COUNCIL OF
BALTIMORE
v.
B.P. P.L.C., ET AL.
______________________________________
ANNE ARUNDEL COUNTY, MARYLAND
v.
B.P. P.L.C., ET AL.
______________________________________
CITY OF ANNAPOLIS
v.
B.P. P.L.C., ET AL.
______________________________________
Fader, C.J.
Watts
Booth
Gould
Eaves
Killough
Battaglia, Lynne A. (Senior
Justice, Specially Assigned),
JJ.
______________________________________
Concurring and Dissenting Opinion by Watts, J.
______________________________________
Filed: March 24, 2026
Respectfully, I concur and dissent. I join the conclusion expressed in Justice
Killough’s concurrence and dissent that the claims raised by local government Plaintiffs
are not displaced or preempted by federal law. See J. Killough Concurring and Dissenting
Slip Op. at 15. I agree with the concurrence and dissent’s conclusion that the local
governments have brought fraud and deceptive marking claims that survive federal
displacement and preemption. See J. Killough Concurring and Dissenting Slip Op. at 23-
26, 34. I do not join the conclusion of the concurrence and dissent, however, that the public
nuisance and negligent failure to warn claims should go forward. See J. Killough
Concurring and Dissenting Slip Op. at 72-73. 1 In particular, although I agree that none of
0F
the various claims are preempted by federal law, the circumstance remains that Maryland
does not have a recognized common law public nuisance tort under which a local
government may recover money damages or one that proscribes the conduct alleged.
1
The Majority holds that, even if Plaintiffs’ “state law claims were not displaced or
preempted by federal law, they fail to state claims under Maryland law for public and
private nuisance, strict liability and negligent failure to warn, and trespass.” Maj. Slip Op.
at 1. The Concurrence and Dissent agrees that Plaintiffs failed to state a claim for private
nuisance and trespass, and agrees that Plaintiffs failed to state a claim for strict liability
failure to warn, although on different grounds; the Concurrence and Dissent, however,
would allow the claims for public nuisance and negligent failure to warn to proceed. See
J. Killough Concurring and Dissenting Slip Op. at 74-75.
Chief Justice Fader’s concurrence makes the point that, because the Majority
concludes that the claims are displaced or preempted by federal law, there was no reason
for the Majority to assess whether the local governments adequately pled the causes of
action. See C.J. Fader Concurring Slip Op. at 1. I share Chief Justice Fader’s view that,
as a result of having concluded that the claims are displaced and preempted by federal law,
there is no reason for the Majority to have addressed the issue of the viability of any of the
various claims. See C.J. Fader Concurring Slip Op. at 1. Because I would hold that the
claims are not displaced or preempted by federal law, I note that I am of the view that the
local governments have not stated viable claims for the causes of action pled. See Maj.
Slip Op. at 1.
As is the circumstance in Express Scripts, Inc., et al. v. Anne Arundel Cnty., Md.,
Misc. No. 1, Sep. Term, 2025, these cases raise complex issues, including the questions of
whether money damages should be available to a municipality that brings a public nuisance
claim and whether there should be a public nuisance tort under which municipalities can
seek redress for the type of injuries alleged and, if so, what the elements of the tort ought
to be. As expressed in my concurring and dissenting opinion in Express Scripts, I would
conclude that, in its current posture, Maryland common law does not provide for the type
of public nuisance claim pled by the local governments and that whether there should be
such a tort involves matters of policy and scope for the General Assembly to determine.
See J. Watts Concurring and Dissenting Slip Op. at 7-8, Express Scripts, Inc., et al. v. Anne
Arundel Cnty., Md., Misc. No. 1, Sep. Term, 2025.
In sum, I join the concurrence and dissent’s conclusion that the local governments
have brought claims that survive federal displacement and preemption. See J. Killough
Concurring and Dissenting Slip Op. at 15. I concur with the Majority’s conclusion that the
public nuisance claims should be dismissed, see Maj. Slip Op. at 65, 75, but not because
they are displaced or preempted by federal law, but for a different reason—namely, the
existence and contours of public nuisance claims in Maryland such as the ones brought by
the local governments is a matter for the General Assembly to determine. Although the
Majority need not have reached the matter, given the current status of our common law, I
am in accord with the decision that the local governments have not stated legally
cognizable claims for any of the causes of action. See Maj. Slip Op. at 1.
In addition, I would have granted Appellees’ Motion to Stay Proceedings, even
-2-
though the Supreme Court of the United States has requested briefing on the issue of
jurisdiction in Suncor Energy (U.S.A.) Inc. v. Cnty. Comm’rs of Boulder Cnty., Docket
No. 25-170. The issue of whether claims like the ones brought by the local governments
in these cases are displaced or preempted by federal law is ultimately a question for the
Supreme Court of the United States, not this Court.
For the above reasons, respectfully, I concur and dissent.
-3-
Circuit Court for Baltimore City IN THE SUPREME COURT
Case No.: 24-C-18-004219
OF MARYLAND
Circuit Court for Anne Arundel County
Case No.: C-02-CV-21-000250
Case No.: C-02-CV-21-000565
No. 11
Argued: October 6, 2025
September Term, 2025
MAYOR & CITY COUNCIL OF BALTIMORE
v.
B.P. P.L.C., et al.
ANNE ARUNDEL COUNTY, MARYLAND
v.
B.P. P.L.C., et al.
CITY OF ANNAPOLIS
v.
B.P. P.L.C., et al.
Fader, C.J.,
Watts,
Booth,
Gould,
Eaves,
Killough,
Battaglia, Lynne A.
(Senior Justice, Specially Assigned)
JJ.
Concurring and Dissenting Opinion by Killough, J.,
which Watts, J., joins in part.
Filed: March 24, 2026
Federal preemption of state law is disfavored. Where Congress has not spoken
clearly, the presumption runs against preemption—not toward it. See Rice v. Santa Fe
Elevator Corp., 331 U.S. 218, 230 (1947); Medtronic, Inc. v. Lohr, 518 U.S. 470, 485
(1996). So, when a state court decides a question of federal preemption, its task is strictly
defined: determine what Congress said, not what a court thinks Congress might have
preferred, and not what the defendants say the case is about. Courts that answer a federal
preemption question through policy preference, rather than text and precedent, usurp a
function the Constitution assigns to Congress alone.
That discipline should be at its zenith when the claims before the court arise from a
state’s historic police powers—powers the Constitution reserves to the States and that the
United States Supreme Court has long cautioned may not be stripped away without a clear
congressional mandate. See Va. Uranium, Inc. v. Warren (“Virginia Uranium”), 587 U.S.
761, 773 (2019) (plurality majority). It demands, in particular, that state courts not extend
preemption doctrine into territory the Supreme Court has never sanctioned. Here, the
Majority does precisely that. It applies the federal common law displacement doctrine to
claims that are facially about deceptive marketing rather than emissions—something no
court, state or federal, has previously done. Every case the Majority cites for that
proposition involved claims brought against direct emitters of pollutants for the
consequences of their emissions—not claims against marketers for the consequences of
their deception. This Court assumes what those courts established.
The Majority does not exercise the requisite discipline in determining whether
Maryland state law is preempted. Reading the Majority Opinion, one may be forgiven for
2
believing that the local government Plaintiffs’ claims stem from BP’s and the other
Defendants’ emissions of pollutants under a federal permit regulated by the Environmental
Protection Agency (“EPA”). However, their claims are decidedly not that. See Mayor &
City Council of Balt. v. BP P.L.C., 31 F.4th 178, 216 (4th Cir. 2022) (explaining, when
considering Baltimore Plaintiff’s deceptive marketing claims at issue here, “Baltimore’s .
. . state-law claims do not involve the regulation of emissions.”); see also BP P.L.C. v.
Mayor & City Council of Balt., 593 U.S. 230, 234 (2021) (describing Plaintiffs’ claims in
these matters as “failure to warn”).
BP and the other Defendants are petroleum producers and marketers who are alleged
to have misled consumers about their products. In contrast, the Clean Air Act’s (“CAA”)
regulatory framework targets the source of the air pollution—not producers and marketers.
Br. for the U.S. as Amicus Curiae, Shell PLC v. City & Cnty. Of Honolulu, 2024 WL
5095299, at *17–18 (2024). While BP does indeed operate refineries that are stationary
sources subject to CAA permits, the operation of those refineries has nothing to do with
BP’s downstream marketing of petroleum products to consumers who then burn them.
Instead, the greenhouse gases Plaintiffs identify as the causal mechanism of harm came
from end users burning the fuel Defendants sold to them. This distinction elides the
Majority and, in turn, informs the Majority Opinion’s erroneous conclusion and its decision
to relinquish police powers traditionally reserved to the States.
What makes the Majority’s ratification of Defendants’ framing all the more
troubling is that Defendants’ constitutional structure, displacement, and preemption
arguments all depend on a single premise that this Court was not entitled to assume: that
3
Plaintiffs’ claims are about interstate emissions. Remove that premise—as the controlling
standard of review on a motion to dismiss requires—and each one of Defendants’ theories
fails. The constitutional structure argument fails because the Constitution’s federal
structure has never been held to foreclose state authority over deceptive marketing. The
displacement argument fails because displacing federal common law over interstate
pollution says nothing about deceptive marketing, an area federal common law never
governed. And the CAA preemption argument fails because the CAA has never addressed
deceptive marketing.
It is clear from the Majority Opinion that it did not decide the case Plaintiffs brought.
Rather, it decided the case Defendants described. BP and the other Defendants recast these
complaints as suits about emissions, global climate regulation, and the imposition of
Maryland tort law on the energy decisions of billions of people worldwide. They invoked
the Clean Air Act, the EPA regulatory authority, and the specter of a patchwork of state
tort regimes supplanting a uniform federal emissions policy. It was a compelling, if
misleading, frame, and the Majority accepted it entirely.
But not a single emissions regulation is implicated in this case. Plaintiffs do not
challenge any EPA permit. They do not seek to compel reductions in any Defendant’s
emissions. And they do not ask this Court to set a standard that conflicts with any federal
rule. Plaintiffs allege that Defendants knew their products were causing catastrophic harm,
concealed that knowledge from the public for decades, and profited from the resulting
delay in response. That is a fraud case, and the CAA has nothing to say about fraud.
4
For example, the City of Baltimore expressly alleged that it “does not seek to impose
liability on Defendants for their direct emissions of greenhouse gases and does not seek to
restrain Defendants from engaging in their business operations.” What the City seeks is
cost-shifting, compensation for infrastructure damage during floods, power outages during
winter storms, and public health costs during heat waves that its local taxpayers are bearing.
Those are local injuries caused by local impacts of a global phenomenon, and they are
alleged to have resulted from a fraud, not from an emissions policy. Anne Arundel County
and Annapolis allege that the Defendants’ “concealment and misrepresentation of their
products’ known dangers—and simultaneous promotion of their products for uses
Defendants knew were harmful—drove consumption, and thus greenhouse gas pollution,
and thus the climate crisis.” The Majority quotes the complaints’ description of the causal
chain running from deception to consumption to emissions to harm, and then treats that
chain as proof that the claims are about emissions. But a fraud claim does not become an
emissions regulation simply because the fraud caused environmental harm down the line.
Cf. Cipollone v. Liggett Grp., Inc., 505 U.S. 504, 518–20 (1992) (plurality opinion)
(deciding that tobacco plaintiffs’ fraud claims do not become a marketing regulation—
which is federally regulated in the tobacco industry—simply because the fraud is connected
to how the products are marketed); Altria Grp. Inc. v. Good (“Altria Group”), 555 U.S.
70, 80–87 (2008) (adopting the Cipollone plurality’s reasoning to similar claims and issues,
converting it into binding law).
What Defendants accomplished—and what the Majority ratified—was a classic
strawman. They stripped out the fraud allegations in the complaints, replaced them with
5
an emissions regulation theory Plaintiffs expressly disclaimed, then argued that the
resulting fictional lawsuit is displaced by non-existent federal common law and preempted
by the Clean Air Act. Of course, a suit demanding that Defendants emit less would be
preempted. But Plaintiffs filed no such suit, and no amount of table pounding changes this
fact.
Whether BP and the other Defendants are right that this lawsuit is a backdoor
attempt to regulate emissions is a question that cannot be answered on a bare complaint.
Discovery might have revealed that the deception allegations were pretextual—that what
Plaintiffs really wanted was to force Defendants to reduce the amount of carbon producing
fuels they produce and sell. It might have revealed the opposite—that Plaintiffs do not care
a whit about emissions or regulatory outcomes. They simply want to be compensated for
the increased costs they have incurred and will incur in the future as a result of what
Defendants concealed from the public about the catastrophic results of climate change.
That is precisely why the motion to dismiss standard exists: to test the legal
sufficiency of what is alleged, not to resolve contested factual questions about what
Plaintiffs are “really” trying to accomplish. On the face of these complaints, the claims
sound in deception. Defendants are alleged to have concealed what they knew. They
misrepresented the science. They funded disinformation campaigns directed at Maryland
consumers and regulators. The Clean Air Act has no provision addressing any of that
conduct. The Majority’s conclusion that these cases are tantamount to emissions regulation
is not a finding—it is a prediction about what discovery would show, dressed up as a legal
conclusion and deployed to close the courthouse door before discovery could confirm or
6
refute it. That is not how motions to dismiss work. And it is not how preemption analysis
works.
By accepting Defendants’ framing that the complaints seek to regulate emissions,
the Majority bypassed the controlling preemption analysis entirely. Nowhere does the
Majority apply, much less distinguish, any case that establishes that marketing is a
traditional state field, see, e.g., Altria Group, 555 U.S. at 77; Lorillard Tobacco Co. v.
Reilly, 533 U.S. 525, 541 (2001)—or Virginia Uranium’s requirement that preemption
depend on what the state did, not why it did it, see Virginia Uranium, 587 U.S. at 772
(plurality majority), 774 (lead opinion) (collecting cases). Nor does the Majority
acknowledge that the presumption against preemption operates with greatest force
precisely in fields like consumer protection and deceptive marketing. Altria Group, 555
U.S. at 77.
Instead, the Majority’s only meaningful engagement with the presumption against
preemption comes in its summary of City of New York v. Chevron Corp., 993 F.3d 81 (2d
Cir. 2021), and the Second Circuit’s snap-back analysis, id. at 90, which quotes Boyle v.
United Techs. Corp., 487 U.S. 500 (1988), for the proposition that when federal common
law is displaced by statute, it occurs in a field States have “not traditionally occupied,” and
therefore the standard presumption against preemption does not apply. But that syllogism
only works if the field is correctly identified as interstate pollution. Here it is not. See
Mayor & City Council of Balt., 31 F.4th at 207 (“Baltimore’s Complaint does not desire
relief under [the CAA].”). The face of Plaintiffs’ complaints sounds in deceptive
marketing, and on a motion to dismiss the allegations of the complaint are taken as true.
7
The Majority instead accepts Defendants’ defenses as true and uses the conclusion of its
analysis (i.e., “this case is really about emissions”) as a premise of its analysis (i.e., “there
is nothing for state courts to do about emissions claims because those claims are governed
by federal common law, which the CAA displaced”). That reasoning is circular. Courts
decide the cases before them, not the cases defendants wish had been filed.
The Second Circuit’s acknowledgement that this area of the law “‘is admittedly not
a model of clarity,’” deserves more weight than the Majority gives it. Maj. Slip Op. at *55
n.23 (quoting City of New York, 993 F.3d at 98). The Majority quotes that admission, and
then proceeds as if the doctrine is perfectly settled. That is not how an unclear doctrine
should be used. An admittedly unclear doctrine cannot overcome the presumption against
preemption, it confirms it. A court that acknowledges doctrinal confusion and then applies
that confused doctrine to extinguish historic state police powers on a motion to dismiss has
inverted the analytical order the presumption requires.
But even on its own terms—accepting Defendants’ characterization—the
Majority’s preemption analysis does not hold together. The entire architecture of the
Majority’s conclusion that the local governments’ state law claims are preempted by the
Clean Air Act rests on three pillars—the United States Supreme Court’s decisions in Am.
Elec. Power Co., Inc. v. Connecticut (“AEP”), 564 U.S. 410 (2011), Int’l Paper Co. v.
Ouellette, 479 U.S. 481 (1987), and Massachusetts v. EPA, 549 U.S. 497 (2007). Yet, a
careful examination of those cases reveals that they do not bear the weight the Majority
places on them.
8
In both AEP and Ouellette, the defendants were identifiable, actual emitters of
pollutants operating under federal permits and were sued over their emissions. Not so here.
BP and the other Defendants were not sued because of what they emitted. They were sued
over what they concealed. That factual distinction is not incidental—it is the reason why
neither case controls, and it is the reason the Majority’s analysis rests on a foundation those
cases do not supply.
AEP addressed only the displacement of federal common law by the Clean Air Act.
The Court held that the CAA, through the EPA’s authority to regulate greenhouse gas
emissions from stationary sources, displaced any federal common law right to seek
abatement of those emissions. AEP, 564 U.S. at 424. On the precise question that matters
here—whether the CAA also preempts state law claims—the U.S. Supreme Court was
explicit and unambiguous: “[T]he availability vel non of a state lawsuit depends, inter alia,
on the preemptive effect of the federal Act.” Id. at 429 (italics in original). It left that
question expressly open for consideration on remand. Id. The Majority today treats as
settled law a question the Supreme Court of the United States deliberately declined to
answer. That alone should give this Court pause. Moreover, the displacement holding in
AEP rested on the defendants’ status as direct, identified, permitted emitters whose own
emissions were the subject of the suit. That predicate is absent here. Extending AEP’s
displacement rationale to petroleum marketers whose alleged wrong is deception, not
emission, is not an application of AEP—it is an expansion into territory the U.S. Supreme
Court expressly left open.
9
Ouellette fares even worse as a foundational pillar. That case did not involve the
Clean Air Act at all. It arose under the Clean Water Act (“CWA”), and the specific
question before the Court was whether Vermont nuisance law could be applied to a New
York paper mill discharging effluent through an identifiable pipe into Lake Champlain—a
discrete point source, in an identified source state, causing identifiable downstream harm
in an affected state. Ouellette, 479 U.S. at 483–84. And critically, Ouellette did not hold
that all state law claims were preempted. It held precisely the opposite with respect to the
claims that matter here: nuisance suits brought under the law of the source state were
specifically preserved and not preempted by the CWA. Id. at 497–99. The entire Ouellette
structure—source state, affected state, permit requirement, identifiable point source—was
built around the structure of the CWA’s permitting regime. See id. at 489–91. To
transplant that architecture wholesale onto this case—where Defendants are not direct
emitters but upstream producers and marketers, where there is no identifiable source state
in the Ouellette sense, and where no CAA permit governs the conduct at issue—is not
faithful application of precedent. Simply put, Ouellette was built around a single paper
mill discharging effluent through an identifiable pipe. There is no BP smokestack for the
Majority to point to here.
In addition, the continued vitality of the third pillar of the Majority Opinion,
Massachusetts v. EPA, is in substantial doubt and will need clarification from the United
States Supreme Court. Indeed, the premise of the Majority’s preemption conclusion—that
the CAA so comprehensively occupies the field of greenhouse gas regulation that no room
remains for state law—became significantly harder to sustain after the EPA’s February
10
2026 rescission of the Greenhouse Gas Endangerment Finding, which concluded the CAA
never provided statutory authority to regulate greenhouse gases for climate purposes. See
infra Section III.F. The Majority does not acknowledge the rescission. Not once.
Whatever the ultimate legal validity of the rescission, a preemption argument premised on
federal comprehensiveness cannot rest on a foundation the federal government is
simultaneously dismantling in its own proceedings without at least acknowledging the
tension.
The Majority’s conclusion is also at odds with the considered legal judgment of
other authorities that deserve more than the Majority’s silence. In 2024, the United States
filed an amicus brief in the Hawaii climate litigation urging the Supreme Court to deny
certiorari and arguing that claims grounded in deceptive marketing are not preempted by
the CAA, because plaintiffs in those cases “do not allege the violation of a duty not to
pollute.” Br. for the U.S. as Amicus Curiae, 2024 WL 5095299, at *1, 16–17. 1 The federal
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government’s position at that time was that the CAA “regulates pollution,” not “deceptive
marketing,” and that AEP and Ouellette are inapposite to tortious marketing claims. Id. at
*14–18. The current federal administration has since reversed that position. 2 But a change
1F
1
The Majority ignores the United States amicus brief in the Hawaii case where the
federal government concluded that the Hawaiian tortious marketing claims were not
preempted by the CAA. Given the centrality of this point to the case at bar, it is a notable
gap in the Majority’s analysis.
2
The United States amicus brief in this case is a remarkable admission that the prior
legal position of the United States that deceptive marketing claims do not necessarily
conflict with the CAA—filed just months earlier in the Hawaii certiorari proceeding—was
not the result of new legal analysis, but rather the result of a change in administration. A
11
in administration does not rewrite the text of the Clean Air Act, and it does not resolve the
question the U.S. Supreme Court expressly left open in AEP. A shift in executive branch
litigation posture is entitled to no weight in construing a federal statute.
This Court’s conclusion is also in significant tension with the judgments of the only
two state supreme courts to have considered materially identical claims. 3 The Supreme
2F
Court of Hawaii held that deceptive marketing-based climate tort claims are not preempted
by federal law. City & Cnty. of Honolulu v. Sunoco LP, 153 Haw. 326, 334 (2023).
The Supreme Court of Colorado reached the same conclusion. Cnty. Comm’rs of Boulder
Cnty. v. Suncor Energy USA, Inc., 2025 WL 1363355, at *2 (Colo. 2025). The Supreme
Court of the United States has granted certiorari in the Colorado case. Suncor Energy, Inc.
v. Comm’rs Boulder Cty., 2026 WL 490537, at *1 (U.S. Feb. 23, 2026). Whatever the
Supreme Court ultimately decides about the scope of federal preemption in climate tort
litigation, that decision will come from that Court, not from ours.
Defendants themselves believed these complaints presented federal claims—that
was their entire theory of removal when they tried removing the Baltimore Plaintiff’s
claims to federal court. Defendants had four separate opportunities to convince federal
shift in litigation posture driven by a change in political administration is not a legal
argument. It is entitled to no weight in construing a federal statute whose text did not
change between administrations. The legal analysis in the 2024 brief stands on its own;
the legal analysis in the 2025 brief stands on its own; and this Court must evaluate each on
its merits, not on the basis of which administration filed it.
3
The Majority gives short shrift to the Hawaii and Colorado Supreme Court
decisions in a footnote of its opinion and asserts that they are aligned with the dissent in
the Colorado case. Maj. Slip Op. at *47 n.18.
12
courts of their position: the district court, the first Fourth Circuit panel, the Supreme Court,
and the Fourth Circuit on remand after being directed to consider every removal theory
Defendants advanced. See Mayor & City Council of Balt. v. BP P.L.C., 388 F. Supp. 3d
538, 560–61 (D. Md. 2019) (Judge Hollander rejected all eight grounds for removal and
remanded), as amended (June 20, 2019), aff’d, 952 F.3d 452 (4th Cir. 2020), vacated and
remanded, 593 U.S. 230 (2021), and aff’d, 31 F.4th 178 (4th Cir. 2022). Not one of those
courts agreed. The Fourth Circuit declined to recharacterize the Baltimore Plaintiff’s
claims and held that its “state-law claims do not involve the regulation of emissions[,]”
Mayor & City Council of Balt., 31 F.4th at 216, and remanded the case to state court, id. at
238.
If these complaints truly presented federal claims, it defies logic that four federal
tribunals would have missed it. And critically—they were not limited to the face of the
complaint. In removal proceedings, federal courts are authorized, indeed required, to look
beyond a plaintiff’s pleading labels to determine whether a cognizable federal claim is
actually present, regardless of how the plaintiff has characterized it. See, e.g., Franchise
Tax Bd. of Cal. v. Constr. Laborers Vacation Tr. for S. Cal., 463 U.S. 1, 13 (1983)
(explaining that “original federal jurisdiction is unavailable unless it appears that some
substantial, disputed question of federal law is a necessary element of one of the well-
pleaded state claims, or that one or the other claim is ‘really’ one of federal law[]”); id. at
22 (citing Avco Corp. v. Aero Lodge No. 735, Int’l Assn. of Machinists & Aerospace
Workers, 376 F.2d 337, 339–40 (6th Cir. 1967), aff’d, 390 U.S. 557 (1968), for the
proposition that “it is an independent corollary of the well-pleaded complaint rule that a
13
plaintiff may not defeat removal by omitting to plead necessary federal questions in a
complaint.”).
The artful pleading doctrine and the complete preemption inquiry exist precisely to
prevent plaintiffs from defeating federal jurisdiction by strategic labeling. The Fourth
Circuit applied those doctrines, “looked under the hood,” and unearthed no federal claim
in the Baltimore Plaintiff’s complaint. The Fourth Circuit’s opinion is exhaustive by any
measure. It considered, analyzed, and rejected every theory the defendants advanced for
why these complaints belong in federal court—the same theories the Majority accepts
today without the analysis the Fourth Circuit performed. This Court reaches the opposite
conclusion without fully acknowledging that history and by inverting what the removal
standard actually authorized the Fourth Circuit to do. See also District of Columbia v.
Exxon Mobil Corp., 89 F.4th 144, 149 (D.C. Cir. 2023) (unanimously rejecting identical
removal theories advanced by BP, Chevron, Exxon, and Shell, and holding that consumer
protection claims against energy companies for deceptive marketing of fossil fuels do not
arise under federal common law).
In short, the Majority has extinguished the state law claims of three Maryland local
governments on a motion to dismiss, before a single document has been produced and
before any factual record has been developed. It has done so on the basis of a preemption
and displacement framework that neither of its three foundational cases actually
established, applied that framework to claims that have nothing to do with Defendants’
own emissions, and applied it in disregard of the presumption against preemption that the
U.S. Supreme Court has long held runs in favor of the States. And it has reached that result
14
contrary to the Supreme Court’s preemption framework, the prior legal analysis of the
United States on deceptive marketing claims, the conclusions of the only two state supreme
courts to have addressed the question, and four federal court’s characterizations of these
exact same claims and at the precise moment when the federal regulatory floor that
supposedly forecloses all state remedies is being dismantled by the executive branch. That
is not a sound basis for the result the Majority reaches, and the local governments deserve
the opportunity to be heard on the merits of their claims. In its haste to close the courthouse
doors, the Majority has built its edifice on sinking ground.
Accordingly, I respectfully dissent from the Majority’s conclusion that Plaintiffs’
state law claims are preempted by federal law. I would hold that the claims should proceed
past the motion to dismiss stage for resolution on a developed factual record. I join the
Majority’s disposition of the private nuisance and trespass claims. I concur in the
Majority’s judgment on the strict liability claims but write separately because I reach that
result on different grounds. I dissent from the Majority’s disposition of the public nuisance
and negligent failure-to-warn claims for the reasons set forth below.
I. BACKGROUND
A. The Duty Alleged, Not the Subject Matter, Controls
The question presented asks whether the U.S. Constitution and federal law preempt
state law claims for injuries caused by out-of-state greenhouse gas emissions on the global
climate. That framing builds in an answer by describing the claims in terms of what they
touch rather than what they allege. The proper preemption inquiry does not ask what a
complaint is about in general terms. It asks what legal duty the plaintiff alleges the
15
defendant violated. Cipollone, 505 U.S. at 523–24; Oneok, Inc. v. Learjet, Inc., 575 U.S.
373, 385 (2015).
The duty alleged here is not a duty to reduce emissions. It is a duty not to deceive.
Plaintiffs do not ask this Court to order Defendants to emit less, to comply with a different
standard, or to alter their operations in any way. They ask for damages for an alleged
decades-long campaign of misrepresentation about what Defendants knew and when they
knew it. Properly framed, the question before us is this: does the Clean Air Act preempt
state law claims for deceptive marketing? The answer to that question is no.
B. The Parties’ Contentions
Plaintiffs allege that Defendants orchestrated a pervasive, decades-long
disinformation campaign designed to mislead consumers and the public about climate
change and the central role their fossil fuel products play in causing it. Beginning at least
as early as the 1960s, Plaintiffs allege, Defendants researched global warming, accurately
foresaw its catastrophic effects, protected their own assets against those dangers, and then
publicly concealed and misrepresented those risks through paid surrogates and coordinated
messaging. Plaintiffs allege this deception drove increased consumption, accelerated
climate-related harms, and caused the flooding, sea-level rise, extreme storms, and extreme
heat their residents have already suffered and will continue to suffer. Because the liability-
triggering conduct is deception-based, Plaintiffs argue their claims are not preempted by
displaced federal common law, the CAA, or the Constitution, a conclusion they say is
confirmed by the only two state supreme courts to have considered materially identical
claims—one of which the Supreme Court of the United States has since agreed to review.
16
Defendants contend that however labeled, these suits seek to impose Maryland tort
liability for the global effects of a century of fossil fuel consumption—conduct so diffuse
in origin and global in consequence that no single state’s tort law can constitutionally reach
it. They argue that the Constitution’s structure implicitly precludes any single state from
governing controversies of inherently interstate and international character, regardless of
how they are pleaded. Defendants further contend that the CAA occupies the field of
greenhouse gas regulation, displacing any state-law damages regime for harms caused by
those emissions, and that allowing such claims would undermine Congress’ chosen
framework and impose a patchwork of state tort rules on a uniform national problem.
C. What the Clean Air Act Actually Covers
“The CAA was enacted in 1963, and Congress declared that its express purpose was
to ‘protect the Nation’s air resources so as to promote the public health and welfare and the
productive capacity of its population[.]’” Mayor & City Council of Balt., 31 F.4th at 215
(quoting Clean Air Act, Pub. L. No. 88-206, § 1, 77 Stat. 392, 393 (1963) (codified as
amended at 42 U.S.C. § 7401(b)(1))). It established federal regulation of “air pollution
from stationary sources, emission standards for moving sources, noise pollution, acid raid,
and stratospheric ozone protection.” Id. (citing 42 U.S.C. §§ 7401–7515, 7521–90, 7641–
42, 7651-51o, 7671-71q). But “‘air pollution prevention (that is, the reduction or
elimination, through any measures, of the amount of pollutants produced or created at the
source) and air pollution control at its source is the primary responsibility of the States and
local governments[.]’” Id. (quoting Clean Air Act Amendments, Pub. L. No. 101-549, §
17
108, 104 Stat. 2399, 2468 (1990)) (emphasis in original). Nothing in the CAA’s language,
explicitly or implicitly, regulates tortious marketing.
II. GOVERNING PREEMPTION PRINCIPLES
A. The Presumption Against Preemption
The Supremacy Clause of the U.S. Constitution provides that federal law and the
Constitution “are the supreme Law of the Land.” Virginia Uranium, 587 U.S. at 767
(plurality majority) 4 (citing Art. VI, cl. 2) (cleaned up). But federal law has limits the
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Constitution itself imposes. Congress unquestionably “has the power to preempt state
law.” Crosby v. Nat’l Foreign Trade Council, 530 U.S. 363, 372 (2000). Courts have
found preemption where Congress intended federal law to occupy a field entirely, where
state and federal law directly conflict, where simultaneous compliance with both is
impossible, or where state law stands as an obstacle to the full purposes of a federal
enactment. Id. at 372–73. And where Congress has directly addressed preemption in the
4
While the Virginia Uranium Court reached a majority decision on the judgment to
affirm the lower court’s decision that the Virginia state law was not preempted, the majority
was split as to the reasons. Therefore, the lead opinion written by Justice Gorsuch, and
joined by Justice Thomas and Justice Kavanaugh, is a plurality opinion that generally only
carries persuasive value. But the concurring opinion written by Justice Ginsburg, and
joined by Justice Sotomayor and Justice Kagan, explicitly tells the reader where all six
justices do agree. Id. at 781 (Ginsburg, J., concurring). In those places where we can
ascertain where all six justices agree due to Justice Ginsburg’s guidance, I annotate the
citation with “plurality majority.” Where Justice Ginsburg and her concurring colleagues
do not agree with the lead opinion’s reasoning, I annotate the citation with “lead opinion.”
And where a proposition is only supported by the concurring majority, I annotate the
citation with “concurring.” Moreover, considering the current Supreme Court’s decisions
in West Virginia v. EPA, 597 U.S. 697 (2022); Sackett v. EPA, 598 U.S. 651 (2023); Loper
Bright Enters. v. Raimondo (“Loper Bright”), 603 U.S. 369 (2024)—explained further
infra Section II.C—had Virginia Uranium been decided today, the majority of today’s
court may have joined Justice Gorsuch’s lead opinion.
18
text of a statute, that express provision governs; there is no need to search the broader
statutory scheme for implied preemptive intent. See Cipollone, 505 U.S. at 517.
But federal supremacy is not federal omnipresence. The Constitution reserves to
the States their historic police powers, and courts have long been instructed that those
powers are not preempted by federal law unless Congress clearly said so. Altria Group,
555 U.S. at 77 (citing Rice, 331 U.S. at 230). The starting point in any preemption analysis
is the presumption against preemption. Chateau Foghorn LP v. Hosford, 455 Md. 462,
486 (2017). That presumption operates with particular force when the state power at issue
is one the States have traditionally exercised, and that Congress has never expressly
claimed. Id. at 486–88; see Altria Group, 555 U.S. at 77; David R. Hodas, State Law
Responses to Global Warming: Is it Constitutional to Think Globally and Act Locally?, 21
PACE ENVTL. L. REV. 53, 69 (2004) (“[A] federalism doctrine that bolsters the relative
power of the states and protects the dignity of state sovereignty is essential.”); Kamaile
A.N. Turcan, The Bogeyman of Environmental Regulation: Federalism, Agency
Preemption, and the Roberts Court, 109 MINN. L. REV. 2529, 2565–66 (June 2025) (“The
presumption [against preemption] operates most strongly when the federal government
looks to regulate in fields of law that were traditionally the purview of the states.”). When
considering whether a federal law preempts state law, the Supreme Court said in Virginia
Uranium that it is never “enough for any party or court to rest on a supposition (or wish)
that ‘it must be in there somewhere.’” 587 U.S. at 767 (plurality majority); see also
Oklahoma v. Castro-Huerta, 597 U.S. 629, 642 (2022) (“As [the Supreme] Court has
repeatedly stated, the text of a law controls over purported legislative intentions unmoored
19
from any statutory text.”) (citing Virginia Uranium, 587 U.S. at 778, two sentences later
for a similar proposition).
Virginia Uranium is instructive beyond the formulation that there is a presumption
against preemption. There, the Supreme Court held that the federal Atomic Energy Act
(“AEA”) did not preempt Virginia’s ban on uranium mining, even though the AEA granted
the Nuclear Regulatory Commission considerable authority over the nuclear fuel life cycle.
Virginia Uranium, 587 U.S. at 765–66 (lead opinion), 786 (concurring). The argument for
preemption—that federal dominance of one phase of the fuel cycle implicitly extended to
adjacent state-regulated activities—was precisely the kind of inference the Court refused
to draw. See id. It did not matter that Virginia’s mining ban may have been motivated in
part by radiation safety concerns that would fall within federal authority. Id. at 774–77
(lead opinion). Preemption analysis, the Court explained, should “depend[] on what the
State did, not why it did it.” Id. at 774 (lead opinion) (emphasis in original). Because
uranium mining on private land was an activity the AEA had never addressed, the federal
statute provided no basis for preemption, much less “judicial inquiry into state legislative
purpose[.]” Id. at 772 (plurality majority). “Invoking some brooding federal interest or
appealing to a judicial policy preference should never be enough to win preemption of a
state law[.]” Id. at 767 (plurality majority).
The parallel to this case is direct and compelling. The Majority finds preemption
not because the CAA addresses deceptive marketing but because the Majority believes that
the CAA’s comprehensive regulation of greenhouse gas emissions implicitly extends to
state law claims whose subject matter touches those emissions. That is precisely the
20
inference Virginia Uranium forbids. The activity Plaintiffs seek to regulate—deceptive
marketing—is one the CAA has never addressed. The federal statute therefore provides
no basis for preemption, whatever the Majority’s policy instincts about the appropriate
forum for climate-related litigation.
That conclusion is confirmed by the U.S. Supreme Court’s treatment of analogous
deceptive marketing claims in the heavily regulated tobacco context. In Altria Group, the
Court held that Maine fraud claims against a cigarette manufacturer were not preempted
by the Federal Cigarette Labeling and Advertising Act—a statute that, unlike the CAA,
actually contained express preemption provisions directed at advertising and marketing.
555 U.S. at 72–73, 78–79. The Court held that even express preemption provisions did not
reach state fraud claims, because “the duty not to deceive . . . has nothing to do with” what
the federal act regulated. Id. at 81. Critically, the trial court in Altria Group made the same
error the Majority makes here: it “recast” the plaintiffs’ fraudulent marketing claim as
something the federal statute did address, then held the recast version preempted. Id. at 75.
The U.S. Supreme Court affirmed the lower appellate court’s reversal of that decision. Id.
at 73. When the defendants argued that permitting state fraud claims would defeat the
federal statute’s purpose of preventing nonuniform warning requirements, the Court was
unmoved: “fraud claims ‘rely only on a single, uniform standard: falsity.’” Id. at 79–80
(quoting Cipollone, 505 U.S. at 529).
The principle that emerges from Virginia Uranium, Altria Group, and their
predecessors does not depend on ambiguity. The CAA is not ambiguous about deceptive
marketing. It is silent. Congress did not address it, qualify it, or gesture toward it. Where
21
a federal statute has never spoken to the subject a state law regulates, the presumption
against preemption is not even tested—there is simply nothing in the federal scheme to
conflict with the state claim. Silence is not preemption. Under the principles this Court is
bound to apply, it never has been. The local government Plaintiffs’ claims target deceptive
conduct. They do not target emissions. Under Virginia Uranium and Altria Group, that is
the end of the preemption inquiry.
B. Deceptive Marketing Is a Field of Historic State Authority
Before determining whether Congress displaced a state power, a court must identify
what power is at issue. That identification matters because the presumption against
preemption is not uniform—it operates with greatest force when the State exercises
authority it has traditionally held, and that the federal government has never claimed. Here,
the field is deceptive marketing, and it has always belonged to the States. See, e.g.,
Lorillard Tobacco Co. v. Reilly, 533 U.S. 525, 541 (2001) (Marketing is “a field of
traditional state regulation.”) (citing Packer Corp. v. Utah, 285 U.S. 105 (1932)). Every
state in the union regulates deceptive business practices under its own consumer protection
laws. See Carolyn Carter et al., Unfair and Deceptive Acts and Practices, Nat’l Consumer
L. Ctr., ch. 1.3 (11th ed. 2025), https://library.nclc.org/book/unfair-and-deceptive-acts-
and-practices/13-nature-and-strengths-udap-statutes, archived at https://perma.cc/6ZMV-
VA3A (“All fifty states, the District of Columbia, Puerto Rico, Guam, and the Virgin
Islands have enacted at least one statute with broad applicability to most consumer
transactions, aimed at preventing consumer deception and abuse in the marketplace.”).
22
The federal government has never asserted exclusive authority over deceptive
marketing claims. The Federal Trade Commission Act prohibits unfair and deceptive
practices, but it provides only federal enforcement; it does not displace state law remedies,
and it was never understood to do so. See id. Alongside that federal floor, States have
historically provided their own causes of action for fraud, misrepresentation, failure to
warn, and deceptive promotion. And, importantly, it is within “the States’ traditional
authority to provide tort remedies to their citizens[.]” Silkwood v. Kerr-McGee Corp., 464
U.S. 238, 248 (1984).
The stakes of displacing that authority are not abstract. States have a substantial
interest in ensuring fair trade practices in their markets. See Edenfield v. Fane, 507 U.S.
761, 769 (1993) (collecting cases); see also, e.g., California v. ARC Am. Corp., 490 U.S.
93, 101 (1989); Ohralik v. Ohio State Bar Ass’n, 436 U.S. 447, 462 (1978). Deceptive
marketing distorts consumer decision-making, undermines public confidence in
commerce, and causes concrete economic harm to businesses and individuals who rely on
honest dealing in the marketplace. See Lexmark Int’l, Inc. v. Static Control Components,
Inc., 572 U.S. 118, 137 (2014); Legg v. Castruccio, 100 Md. App. 748, 769 (1994); Md.
Code Ann., Com. Law § 13-102. Stripping Maryland of the power to address that harm—
and vesting it exclusively in a federal environmental agency whose statute says nothing
about marketing—would be a profound incursion into Maryland’s sovereign authority. See
Bates v. State Bar of Ariz., 433 U.S. 350, 383 (1977) (“[T]he leeway for truthful or
misleading expression that has been allowed in other contexts has little force in the
commercial arena.”). Consumer protection, Maryland’s General Assembly has
23
recognized, “is one of the major issues which confront all levels of government[.]” Md.
Code Ann., Com. Law § 13-102(a)(1). That authority cannot be taken from the States by
implication or inferences. The Constitution does not work that way, the Supreme Court
has said it does not work that way, and the consequences of holding otherwise will reach
far beyond this litigation and these Defendants.
C. Congress Must Speak Clearly Before Displacing Historic State Authority
The presumption against preemption of historic state powers has always required
clear congressional intent. Recent U.S. Supreme Court decisions in West Virginia v. EPA,
597 U.S. 697 (2022), Sackett v. EPA, 598 U.S. 651 (2023), and Loper Bright Enters. v.
Raimondo (“Loper Bright”), 603 U.S. 369 (2024), have crystallized that legal principle:
when a claimed federal power would displace authority traditionally exercised by the
States, Congress must have said so expressly in the statutory text. See 109 MINN. L. REV.
at 2533 (“[T]hese cases replace the longstanding rebuttable presumption against
preemption with an affirmative demand that Congress articulate its intent to preempt state
law expressly in the text of the operative statute implemented by agencies.”). Implication,
inferences, and the general sweep of a regulatory scheme are not enough.
In West Virginia, the Supreme Court held that when an agency claims authority of
great economic and political significance—authority that would represent a fundamental
transformation of its regulatory role—Congress must have clearly granted it. 597 U.S. at
721–23. The Court cautioned against reading into a statute something that would
essentially be a “fundamental revision of the statute, changing it from one sort of scheme
24
of regulation into an entirely different kind.” Id. at 728 (internal quotations omitted)
(cleaned up).
Applied here, transferring from the States to the EPA exclusive authority over
deceptive marketing of fossil fuel products would be precisely that kind of transformation
without an express mandate from Congress that the Supreme Court forbade in West
Virginia. The CAA is a statute that relates to the regulation of emitters of pollutants.
Reading it to preempt state fraud law would convert it into something it has never been—
a comprehensive commercial regulation statute stripping states of consumer protection
authority they have exercised since before the federal government existed. That is not a
revision courts should make on Congress’ behalf, and West Virginia says they may not.
In Sackett, the Supreme Court added a further requirement: when the power at issue
lies at the core of traditional State authority, Congress must use “exceedingly clear
language” to displace it. 598 U.S. at 679 (internal quotations omitted). The Court refused
to find that the Clean Water Act extended federal jurisdiction to a landowner’s backyard
simply because the EPA argued that the statutory language, read expansively, might reach
it. Id. at 676–77. As the Court put it, Congress does not “hide elephants in mouseholes”
by tucking fundamental expansions of federal power into vague or ancillary statutory
provisions. Id. at 677 (internal quotations omitted). Thus, not only must a Congressional
mandate be expressed, but it must also be “exceedingly clear.” Id. at 679.
The difficulty for the Majority here is the same difficulty the EPA faced in Sackett:
neither the Defendants nor the Majority can point to a single word in the CAA’s text that
grants the federal government authority to preempt a state’s right to regulate tortious
25
marketing within its own borders. See Sackett, 598 U.S. at 679–80. The CAA does not
mention marketing. It does not mention fraud. It does not mention deception. It does not
mention consumer protection. If Congress intended to occupy that field, it hid that
intention so thoroughly that it left no trace in the statute.
Finally, in Loper Bright, the U.S. Supreme Court held that courts may not defer to
an agency’s expansive interpretation of its own statutory authority, because statutory
interpretation is the judiciary’s role. Id. at 412–13. The significance for this case is
immediate. The Majority’s preemption analysis rests not on anything Congress said about
deceptive marketing but on a judicial inference that the EPA’s broad authority over GHG
emissions implicitly extends to displace state fraud claims. That is precisely the kind of
agency-driven expansion of authority Loper Bright prohibits courts from ratifying. As the
Turcan article summarizes: “properly promulgated agency regulations are federal law and
would preempt inconsistent state law; but that assumes the regulations are valid in the first
instance—an assumption that is now questionable if Congress did not expressly authorize
the agency to promulgate the type of regulations that would preempt state law.” 109 MINN.
L. REV. at 2570. Congress did not expressly authorize the EPA to displace state deceptive
marketing law. The CAA’s silence on that subject is deafening and is not a gap for courts
to fill. It is the answer.
D. The Governing Principles Applied
Three principles emerge from this line of cases and govern the analysis here. This
Court is required under Article 2 of the Maryland Declaration of Rights to apply federal
26
law as interpreted by the U.S. Supreme Court, and those interpretations speak with one
voice.
First, there is a strong presumption against preemption whenever a federal statute
is construed to displace a historic state power. That presumption is not a tiebreaker. It is
the starting point, and it requires clear affirmative evidence of congressional intent before
it yields.
Second, when Congress intends to strip States of a power they have traditionally
exercised, it must say so in the statutory text with exceedingly clear language.
Third, where preemption is premised on a constitutional limitation such as the
Commerce Clause, the state action at issue must have more than an attenuated or remote
effect on interstate commerce—indirect market influence does not clear that bar.
The Supreme Court reaffirmed all three principles in Learning Res., Inc. v. Trump
(“Learning Resources”), 2026 WL 477534 (U.S. Feb. 20, 2026), reiterating its “long
expressed ‘reluctance to read into ambiguous statutory text’ extraordinary delegations of
Congress’s powers[,]” id. at *7 (quoting West Virginia, 597 U.S. at 697) (Roberts, C.J.,
concurring) (plurality opinion), and cautioning against finding broad executive or agency
authority “on an uncertain statutory basis[,]” id. 5 The Court was addressing presidential
4F
tariff authority, but the principle applies with equal force here: where defendants—
invoking the Government’s authority—claim that the EPA holds exclusive power to
In Learning Resources, while a majority of the Court agreed as to the judgment,
5
Justices Sotomayor, Kagan, and Jackson only agreed with Chief Justice Roberts’ reasoning
in Parts I, II-A-1, and II-B of his opinion. See id. at *36–39 (Kagan, J., concurring); id. at
39–41 (Jackson, J., concurring).
27
displace a historically state-governed field, that claim requires textual foundation. It has
none—not in the text of the CAA, not in its structure, and not in its history. The federal
government has filed an amicus brief in this case arguing that the EPA, through the CAA,
holds sole authority to regulate deceptive marketing of greenhouse gas emissions. That is
precisely the kind of expansive agency-power claim Learning Resources and its collected
precedents treat with skepticism.
As noted, the CAA does not mention deceptive marketing and never has. Under the
principles this Court is bound to apply, that silence is not a drafting oversight to be
corrected by judicial inference. It is Congress’ answer. And the answer is no. As the U.S.
Supreme Court held in Puerto Rico Dep’t of Consumer Affairs v. Isla Petroleum Corp.,
485 U.S. 495, 503 (1988), “[t]here is no federal pre-emption in vacuo, without a
constitutional text or a federal statute to assert it.” The CAA provides no text governing
deceptive marketing and no federal rule of decision to replace the state law it purportedly
displaces. Preemption that leaves neither state nor federal law in its place is not
preemption—it is a legal void, and this Court has no authority to create one.
III. THE CLEAN AIR ACT DOES NOT PREEMPT PLAINTIFFS’ CLAIMS
The Majority’s preemption analysis begins from a false premise—that Plaintiffs
have sued BP and the other Defendants based on their greenhouse gas emissions. That
premise is incorrect. That is not just my conclusion, that is also the conclusion of at least
four federal court tribunals. The Defendants removed the case to federal court precisely
because they believed, and argued, that these were federal claims disguised as state law
claims. That was the entire theory of removal. The district court rejected it and remanded.
28
See Mayor & City Council of Balt., 388 F. Supp. 3d at 560–61 (Judge Hollander rejected
all eight grounds for removal and remanded), as amended (June 20, 2019), aff’d, 952 F.3d
452 (4th Cir. 2020), vacated and remanded, 593 U.S. 230 (2021), and aff’d, 31 F.4th 178
(4th Cir. 2022). When these parties and claims were before the Fourth Circuit in 2020, that
court addressed only federal officer removal and affirmed remand on that ground alone,
holding it lacked appellate jurisdiction over the other seven grounds. 952 F.3d at 461, 471.
The United States Supreme Court then vacated that decision in 2021, holding the Fourth
Circuit did have jurisdiction over all eight grounds and had to consider them all. 593 U.S.
at 246–47. On remand, the Fourth Circuit addressed all eight grounds and again affirmed
remand, see 31 F.4th at 216, which the Supreme Court then declined to review, BP P.L.C.
v. Mayor & City Council of Balt., 143 S. Ct. 1795, 215 L. Ed. 2d 678 (2023).
The Majority argues that the federal court’s analysis of these claims in the removal
context is inapposite because of the unique standard employed when considering removal
jurisdiction. Maj. Slip Op. at *51 n.21. But this assertion betrays a fundamental
misunderstanding of the removal procedure and cuts precisely the wrong way. In removal
proceedings, federal courts are not limited to accepting a plaintiff’s characterization of its
claims. While the well-pleaded complaint rule instructs removal courts to “look no further
than the plaintiff’s properly pleaded complaint” because “a plaintiff is the master of the
claim,” it establishes a baseline. Mayor & City Council of Balt., 31 F.4th at 197–98
(internal quotations omitted). The artful pleading doctrine and complete preemption
inquiry are explicit exceptions to the well-pleaded complaint rule designed to authorize
courts to look past that baseline and find federal claims that plaintiffs have deliberately
29
obscured. See, e.g., Franchise Tax Bd. of Cal., 463 U.S. at 13, 22. The entire purpose of
these doctrines is to prevent plaintiffs from artfully pleading state law labels onto what are
in substance federal claims. The Fourth Circuit applied them. Defendants argued before
that court—as they argue here—that these complaints are “necessarily and exclusively
governed by federal common law” and constitute “interstate-pollution claims that arise
under federal common law.” Mayor & City Council of Balt., 31 F.4th at 199. The Fourth
Circuit was empowered to look beyond the face of the complaints, examine the substance
of those arguments, and find federal claims if they were there. Id. at 198–99. It found
none.
This Court, by contrast, was bound by the motion to dismiss standard to accept
Plaintiffs’ allegations as true and draw all reasonable inferences in their favor. Eastland
Food Corp. v. Mekhaya, 486 Md. 1, 20 (2023). This motion to dismiss standard is not
much different than the well-pleaded complaint rule other than that the well-pleaded
complaint rule is a jurisdictional doctrine. Under the motion to dismiss standard, this Court
“is to assume the truth of the factual allegations of the [well-pleaded] complaint and the
reasonable inferences that may be drawn from those allegations in the light most favorable
to the plaintiff.” Heavenly Days Crematorium, LLC v. Harris, Smariga & Assocs., Inc.,
433 Md. 558, 568 (2013). Under this standard, essentially a cousin of the well-pleaded
complaint rule, it was not authorized to look past those allegations to divine what Plaintiffs
were really trying to accomplish. The irony is inescapable: the court with greater authority
to find hidden federal claims found none. The court bound to accept Plaintiffs’
characterization found federal claims over Plaintiffs’ objection. The Majority was less
30
deferential to Plaintiffs under the more plaintiff-protective standard. That is not a
difference in procedural posture. It is a contradiction of the basic legal standards governing
both proceedings, and the Majority’s single sentence dismissing the Fourth Circuit’s
analysis does not begin to explain it.
The Majority also invokes the phrase “‘heightened standard unique to the
removability inquiry’” as a description of the constraint under which the Fourth Circuit
operated, suggesting the Fourth Circuit’s characterization of these claims as deceptive
marketing claims was a product of that constrained standard rather than a substantive
reading of the complaints. See Maj. Slip Op. at *44 n.17 (quoting Mayor & City Council
of Balt., 31 F.4th at 203). But that phrase does not appear in the Fourth Circuit’s description
of its own standard. It appears at page 203 of the Fourth Circuit’s opinion in the court’s
explanation of why City of New York was inapplicable—precisely because that case was
filed directly in federal court and never had to apply the well-pleaded complaint rule at all.
See 31 F.4th at 202–03. The Fourth Circuit was not acknowledging a limitation on its own
analysis. It was identifying an analytical deficiency in the very template the Majority
adopts. The Fourth Circuit stated directly that City of New York “suffers from the same
legal flaw as Defendants’ arguments” and “essentially evades the careful analysis that the
Supreme Court requires.” Id. at 203. Paradoxically, the Majority has taken the Fourth
Circuit’s criticism of the Majority’s own analytical template and converted it into a defense
of that template. The Majority’s own citation refutes its argument.
The Majority’s insistence that its holding is consistent with the Fourth Circuit’s
analysis is contradicted at every turn by that court’s actual holdings. Contrary to the
31
Majority’s central thesis in this case, the Fourth Circuit held that the Baltimore Plaintiff’s
state law claims “do not involve the regulation of emissions.” Id. at 216. It “resoundingly
agreed” with Baltimore that the suit has “nothing to do with any body of federal common
law”— rejecting the foundation on which the Majority’s entire preemption structure rests.
Id. at 195. It specifically rejected Defendants’ attempt to characterize Baltimore’s claims
as “interstate-pollution claims that arise under federal common law”—the same
characterization the Majority accepts without examination. Id. at 195, 199. It found that
Defendants “never establish a significant conflict between Baltimore’s state law claims and
any federal interests”—a finding the Supreme Court has described as fatal to the creation
of federal common law. Id. at 200. It held that the CAA does not completely preempt
Plaintiffs’ state law claims (a more demanding standard than an ordinary preemption
analysis on a motion to dismiss), leaving unexplained how the Majority clears the lower
bar of ordinary preemption when the higher bar was found uncleared. Id. at 214–20. It
held that Baltimore’s complaint “does not desire relief under the CAA”—refuting the
Majority’s causal chain argument that deception driving consumption driving emissions
transforms these claims into emissions regulation. Id. at 207. And it held that Baltimore’s
claims do not “disturb foreign relations” and that Defendants failed to identify any express
foreign policy conflicting with state tort law—the same foreign affairs argument the
Majority accepts. Id. at 213–14, 216. Eight grounds for removal considered. Eight
rejections. The Majority accepts the premise underlying every one. I simply disagree with
my colleagues that the Majority Opinion here is consistent with the Fourth Circuit’s
analysis.
32
The Majority’s final argument—that its opinion is consistent with the Fourth Circuit
because that court performed a complete preemption analysis while the Majority applies
ordinary preemption—is its most curious argument, because it concedes the central failure
this dissent identifies throughout Sections III.A through C. See Maj. Slip Op. at *44 n.17.
The Majority never actually performed an ordinary preemption analysis. Ordinary
preemption requires this Court to identify the legal duty the plaintiff alleges was violated,
determine what field that duty occupies, and ask whether the CAA speaks to that duty either
expressly, through field occupation, or through direct conflict. See Cipollone, 505 U.S. at
516–17; Altria Group, 555 U.S. at 76–77; Oneok, 575 U.S. at 385–86. The Majority
performs none of these steps. It never identifies the duty alleged. It never identifies a CAA
provision that speaks to that duty. It never identifies an actual conflict between the state
law duty and a specific federal requirement.
What the Majority offers instead is circular reasoning based on a false premise: these
claims are about interstate emissions regulation, therefore the Ouellette framework applies,
therefore the claims are preempted because Ouellette preempts interstate pollution
regulation claims. The characterization does all of the analytical work, and the
characterization was never established—only assumed. That is not an ordinary preemption
analysis. It is field preemption applied to a field the Majority defined by assuming its own
conclusion, the precise analytical move the presumption against preemption forbids. See
Virginia Uranium, 587 U.S. at 767 (plurality majority) (“Invoking some brooding federal
interest or appealing to a judicial policy preference should never be enough to win
preemption of a state law.”). The result is what Section III.C below describes in detail:
33
displacement/preemption alchemy—the fusion of AEP’s displacement rationale and
Ouellette's preemption framework, applied to claims neither case addressed, in a sequence
neither case authorized, to avoid an analysis both cases left open. The Majority insists this
is ordinary preemption. It is not ordinary. And it is not analysis.
A. The Majority Ignores the Controlling Framework
The Majority’s preemption analysis contains a conspicuous and consequential
absence. The Supreme Court has twice held that state law fraud and deceptive marketing
claims survive federal preemption even when the subject matter of those claims is federally
regulated: Cipollone and Altria Group. Those cases establish the controlling framework
for evaluating whether a state tort claim grounded in deception is preempted by a federal
regulatory statute. They require courts to identify the legal duty the plaintiff alleges was
violated and hold that a duty not to deceive is not displaced by federal regulation of the
underlying product or activity. The Majority cites Cipollone and Altria Group but engages
with neither. It does not explain why the analytical framework they establish does not
govern claims against petroleum marketers that are structurally identical to the claims
against tobacco companies those cases preserved. Acknowledging the existence of
controlling precedent and declining to engage with it is not a distinction. It is a concession
that no distinction is available.
Instead of engaging in the Supreme Court’s prescribed analysis, the Majority does
the opposite on a motion to dismiss and looks past the complaints’ allegations and
substitutes its own characterization of what the claims involve. The Majority
acknowledges the local governments’ argument that their claims are limited to deceptive
34
and misleading commercial conduct, then summarily rejects it, concluding that the claims
“are not limited to deceptive and misleading commercial conduct[]” without performing
the legal analysis that conclusion requires. Maj. Slip Op. at *46. 6 In its place, the Majority
5F
offers a rhetorical flourish: “No amount of creative pleading can masquerade the fact that
the local governments are attempting to utilize state law to regulate global conduct.” Id. at
*46–47. That is not a legal conclusion based on an analysis of the controlling authority. It
is an assertion dressed as one, and it substitutes judicial conjecture for the standard of
review this Court just recited. 7 Courts in this posture do not get to look past a complaint’s
6F
allegations to divine their underlying purpose, see, e.g., Virginia Uranium, 587 U.S. at
774–77 (lead opinion)—particularly when Plaintiffs have expressly stated in both their
complaints and their briefing that they “do not seek to impose liability on Defendants for
6
The Majority’s response to the dissent’s preemption analysis is to repeat its
conclusion. See Maj. Slip Op. at *51 n.21. The Majority does not engage with the dissent’s
argument that the duty-based inquiry Oneok, Cipollone, and Altria Group require governs
here—an omission that is fatal to its analysis. It does not distinguish those cases other than
to say they did not involve interstate pollution. It does not explain why the duty alleged
here—a duty not to deceive—falls outside their reach. It simply reiterates that “the local
governments are clearly attempting to utilize state law to address global conduct[.]” Id.
That characterization is not only counterfactual to the allegations in the complaints, but
also antithetical to the motion to dismiss standard, which requires courts to accept those
allegations as written, not rewrite them in Defendants’ favor. Repetition is not rebuttal.
Reasserting a conclusion does not answer the argument that the conclusion was never
established.
7
The Majority also asserts that “[e]ven assuming that the [Plaintiffs’] claims were
limited to allegations of deceptive and misleading marketing, we reject the assertion that
their sweeping claims may be pursued under state law.” Maj. Slip Op. at *46. That
assertion cannot be reconciled with the Supreme Court’s Altria Group/Lorillard doctrine
establishing that marketing is a traditional state field and the Majority’s failure to even
mention those cases, much less an attempt to distinguish them.
35
their direct emissions of greenhouse gases and do not seek to restrain Defendants from
engaging in their business operations.”
Having substituted its own characterization for Plaintiffs’ allegations, the Majority
then attempts to justify that substitution with a word count. The Baltimore complaint, the
Majority observes, uses the word “emissions” 115 times—which the Majority treats as
dispositive evidence that the claims are really about regulating emissions and therefore fall
within the CAA’s preemptive scope. Maj. Slip Op. at *48. This argument does not survive
scrutiny. The frequency with which a complaint uses a word tells a court nothing about
the legal duty that is the predicate of the claim. A products liability complaint against a
tobacco company will use the word “smoke” hundreds of times. A complaint against a
pharmaceutical manufacturer for fraudulent marketing will use the name of the drug and
its chemical effects repeatedly. A failure-to-warn claim against the manufacturer of a
defective airbag will necessarily discuss how the airbag deploys. That does not mean the
claim is about regulating automotive safety standards. In none of those cases has any court
held that the subject matter of a complaint determines preemption. What determines
preemption is the duty whose violation the plaintiff alleges. See Oneok, 575 U.S. at 385–
86; Cipollone, 505 U.S. at 523–24. The Supreme Court has been explicit: the preemption
inquiry requires the court to identify “the target at which the state law aims[.]” Oneok, 575
U.S. at 385 (italics in original). The Majority identifies that target by counting words rather
than analyzing duties. That is not the Oneok inquiry.
A fraud claim against a company that concealed the health risks of its product will
necessarily discuss those health risks at length. That discussion does not transform a fraud
36
claim into a product regulation claim, and no court has ever held that it does. The local
governments’ extensive discussion of greenhouse gas emissions and climate effects is the
same thing: a description of the mechanism of harm, not an assertion of a duty to control
that mechanism. The duty alleged is a duty not to deceive—a duty that arises from common
law fraud and products liability principles that predate the Clean Air Act by decades and
that the CAA nowhere addresses.
The Majority’s word-count approach also proves too much. Under its logic, any
state tort claim that discusses out-of-state conduct extensively enough becomes preempted
by whatever federal regulatory scheme touches that subject matter—not because Congress
said so, not because there is a direct conflict between the state duty and a federal standard,
but because the plaintiff thoroughly describes the mechanism of harm at issue in the case.
The Supreme Court rejected exactly this approach in Altria Group. See 555 U.S. at 82–83.
If the Majority’s word-count approach were correct, Altria Group would have come out
the other way. So would Cipollone, whose complaint necessarily discussed cigarettes and
their health effects at length. The entire line of cases holding that fraud and deceptive
marketing claims survive preemption even when the subject matter is federally regulated
would be in question. Because the Majority opinion ignores Altria Group and Cipollone,
it offers no account of that inconsistency.
Had the Majority applied Cipollone and Altria Group—as it was required to do—
the result here would have been different. Those cases establish that a duty not to deceive
survives federal preemption even when the subject matter is federally regulated. The CAA
37
does not preempt a duty not to deceive, and the Majority’s silence on Cipollone and Altria
Group offers no basis for concluding otherwise.
What the Majority’s word-count approach implicitly concedes is equally significant.
By resting its preemption conclusion on the rhetorical content of the complaints rather than
on an analysis of what the Clean Air Act actually forecloses, the Majority signals that it
cannot identify a specific CAA provision, a specific EPA regulation, or a specific
congressional purpose that is actually in conflict with the duty the local governments
allege. There is a reason for that: no such provision exists. The CAA does not regulate
deceptive marketing. The EPA has no rule governing corporate communications about
climate science. Congress, in enacting the CAA, did not speak to the question of whether
fossil fuel companies owe their customers and the public a duty of honest dealing about
the environmental consequences of their products. Where Congress has not spoken, there
is nothing to preempt. Counting the word “emissions” does not supply what the statutory
text omits.
Defendants and the Majority further contend that allowing Plaintiffs’ claims to
continue would constitute a de facto regulation of greenhouse gas emissions because a
damages award might influence Defendants’ behavior, and this de facto regulation is
preempted by the CAA. 8 Maj. Slip Op. at *47–50. That argument has been considered
7F
and rejected. The mere fact that tort litigation may influence market behavior does not
render it preempted. Bates v. Dow Agrosciences LLC, 544 U.S. 431, 445 (2005) (citing
8
Presumably, the only behavioral shift sought by Plaintiffs in this case is for BP
and the other Defendants to stop deceiving the public about fossil fuels.
38
Cipollone, 505 U.S. at 524). As the Supreme Court instructed in Bates, “[t]he proper
inquiry calls for an examination of the elements of the common-law duty at issue . . . it
does not call for speculation as to whether a jury verdict will prompt [a regulation of
emissions].” Id. Tort law has always exerted a quasi-regulatory effect on conduct without
becoming preempted by every federal statute that touches the same industry. If it were
otherwise, state products liability law would have been preempted decades ago.
The inquiry prescribed by the Supreme Court is disciplined: what legal duty does
the plaintiff allege the defendant violated? Here the answer is plain—a duty not to deceive.
No provision of the Clean Air Act governs that duty. No EPA regulation sets a standard
for corporate honesty. No congressional committee report so much as mentions tortious
marketing. The Majority cannot find preemption in the CAA because it is not there. What
it finds instead is a policy preference—the conclusion that these cases should not proceed
—and works backward to a doctrinal rationale. That is what the Majority cannot find: a
provision of the Clean Air Act that speaks to the duty alleged.
Lest it be lost on anyone, courts in this posture do not investigate complaints for
hidden purposes. On a motion to dismiss, they read them “in the light most favorable to
the plaintiff[.]” Eastland Food Corp., 486 Md. at 20. Courts are required to assume the
truth of well-pleaded allegations and draw reasonable inferences in the plaintiff’s favor.
Id. The Majority does the opposite and draws all inferences in the Defendants’ favor. Its
sole justification is an unexplained assertion that courts need not defer to Plaintiffs’
characterization of their own claims—a proposition for which the Majority cites no
authority, because none supports it. The cases the Majority relies upon do not support it.
39
Ouellette was decided on summary judgment, on a developed factual record, and against
defendants who were identified point-source emitters operating under federal permits. 9 8F
AEP involved coal-fired power plants whose emissions were the undisputed subject of the
suit. Neither case involved the question that is contested here: whether, on a bare
complaint, a court may look past a plaintiff’s express allegation of a duty not to deceive
and substitute the defendant’s characterization on what the allegations in the case concern.
The answer to that question on a motion to dismiss is no. It has always been no. The
Majority does not explain why it should be yes in this case, and it cites no authority holding
that it is.
The Majority claims to be “[v]iewing the allegations of the complaint in the light
most favorable to the local governments[.]” Maj. Slip Op. at *48. But it never identifies
which facts support its conclusion that these claims involve global emissions regulation.
The City expressly alleged that it “does not seek to impose liability on Defendants for their
direct emissions of greenhouse gases.” That is a well-pleaded fact. “[T]he local
governments are attempting to utilize state law to regulate global conduct that is
purportedly causing global harm[,]” id. at *47, in stark contrast, is not a well-pleaded fact—
it is an allegation. The Majority does not acknowledge it, much less explain how a court
accepting all well-pleaded allegations as true can simultaneously ignore the most directly
9
Justice Gould’s concurrence, whatever its ultimate merits, addresses questions that
have no place in a motion to dismiss analysis. Every element of causation and damages
Justice Gould identifies as problematic is an element the Plaintiffs would need to prove at
trial—that is precisely where those arguments belong. If anything, his concurrence
reinforces the point that dismissal of these cases, as in Ouellette, should be on a developed
factual record.
40
relevant one. The Majority’s conclusion that “the ultimate harm . . . arises from global
emissions[,]” id. at *51 n.21, confuses the mechanism of harm with the duty alleged—
precisely the substitution Oneok prohibits, 575 U.S. at 385.
There is a final and consequential omission to the Majority’s analysis that deserves
explicit mention. The Majority quotes Boyle, 487 U.S. at 507—which involved the
immunity of a military contractor, not preemption—for the proposition that the conflict
required for federal common law displacement “need not be as sharp as that which must
exist for ordinary pre-emption when Congress legislates in a field which the [s]tates have
traditionally occupied.” Maj. Slip Op. at *21 (internal citations omitted). In doing so, the
Majority unwittingly identifies the question it never answers: is deceptive marketing a field
the States have traditionally occupied? It certainly is—as the U.S. Supreme Court has
confirmed in Lorillard, Cipollone, and Altria Group. Had the Majority asked that question,
Boyle’s own language would have required it to apply the more demanding preemption
standard. It never asked and its omission is not incidental. Without it, the Majority’s result
was not possible.
B. Neither AEP Nor Ouellette Support the Majority’s Holding
Even setting aside the Majority’s failure to apply the controlling Cipollone/Altria
Group/Oneok inquiry, the two cases the Majority does rely upon—AEP and Ouellette—do
not support the weight placed on them. 10 A careful examination of what those cases
9F
actually held, who the defendants were, what conduct was at issue, and what questions
10
It is also important to note that, at oral argument, Defendants conceded that AEP
was the strongest case in support of their position.
41
were left open reveals that neither case controls here. The Majority’s opinion is an
extension of precedent into territory neither case addressed, in service of a result neither
case required.
AEP arose from a public nuisance suit brought by eight states, New York City, and
three private land trusts against the five largest domestic emitters of carbon dioxide in the
United States—coal-fired power plants that were directly and continuously pumping
greenhouse gases into the atmosphere under federal operating permits. 564 U.S. at 418–
- The plaintiffs sought an injunction requiring each defendant to cap its emissions and
reduce them by a specified percentage each year. Id. at 419. The defendants were emitters.
Id. at 415. The claims were about emissions. Id. The relief sought was a cap on emissions.
Id. The Court held that the Clean Air Act, by vesting authority in the EPA to regulate those
very emissions from those very sources, displaced the federal common law nuisance cause
of action the plaintiffs had asserted. Id. at 424. The displacement rationale is intelligible
only in that context: the EPA was already doing, through its statutory authority, exactly
what plaintiffs wanted a federal court to do through common law.
That is all AEP held. The Court did not hold that the CAA preempts state law
claims. It did not hold that deceptive marketing claims are preempted. It did not hold that
upstream fuel producers who are not themselves direct emitters are insulated from state tort
liability. On the contrary, the Court was explicit and unambiguous on the state law
question: “[T]he availability vel non of a state lawsuit depends, inter alia, on the
preemptive effect of the federal Act” and “[n]one of the parties have briefed preemption or
otherwise addressed the availability of a claim under state nuisance law” so that question
42
should be answered on remand. Id. at 429 (italics in original). The Majority today treats
as resolved a question the Supreme Court of the United States deliberately and expressly
declined to answer. 11 That is a foundational error from which the Majority’s entire analysis
10F
does not recover.
The distinction between AEP’s defendants and Defendants here is not a
technicality—it goes to the heart of the preemption analysis. The AEP defendants were
direct emitters operating coal-fired power plants whose emissions were directly regulated
by the CAA’s New Source Performance Standards and the EPA’s greenhouse gas
rulemaking under § 111, 42 U.S.C. § 7411. AEP, 564 U.S. at 416–18. The displacement
rationale depended entirely on the existence of an EPA regulatory program that already
addressed the identical conduct plaintiffs sought to govern through federal common law.
Defendants here are not coal-fired power plants. They are upstream fossil fuel producers
and marketers—companies that extracted, refined, and sold fuel products, and that
allegedly conducted decades-long campaigns of deception about the climate consequences
of those products. Federal common law no longer exists in this area—nor did it ever exist
with regard to deceptive marketing—and no provision of the Clean Air Act regulates the
marketing of fossil fuel products. No EPA rule sets standards for corporate
11
The Majority also cites Native Village of Kivalina v. ExxonMobil Corp., 696 F.3d
849 (9th Cir. 2012), throughout its opinion. But like AEP, that case is of little help to the
Majority because it is a federal common law nuisance case that involved claims against the
defendant for its own emissions, not for deceptive marketing. In short, Kivalina is a
straightforward application of AEP’s displacement holding to a federal common law claim
by direct emitters.
43
communications about climate science. No CAA permitting regime applies to a fuel
producer based on the downstream emissions of its customers. When Congress has not
spoken to the conduct at issue, there is nothing to preempt state law. See Milwaukee v.
Illinois & Michigan (“Milwaukee II”), 451 U.S. 304, 316 (1981). And there is absolutely
nothing to displace state law because, as explained infra Section III.C, displacement is
what happens when Congress speaks to an area formerly regulated by federal common law.
See Jonathan H. Adler, Displacement and Preemption of Climate Nuisance Claims, 17 J.L.
ECON & POL’Y 217, 222, 233–47 (2022) (“Displacement concerns which branch of the
federal government is responsible for the development of legal standards. Preemption
concerns the effect of federal common law on the laws of the several States.”).
This precise distinction was drawn by the United States Department of Justice
(“DOJ”) in its 2024 amicus brief in the Hawaii climate litigation. The DOJ explained that
AEP is inapposite to claims like those here, because plaintiffs bring “tortious marketing”
claims—not claims alleging a “violation of a duty not to pollute[]”—and that the CAA
“does not categorically preempt [Plaintiffs’] deceptive-marketing claims.” Br. for the U.S.
as Amicus Curiae, 2024 WL 5095299, at *14–18, *18 n.3. The Majority’s opinion does
not engage with this analysis, does not explain why it is wrong, and does not acknowledge
that it represents the considered legal position of the federal government—the same federal
government whose later reversal of that position the Majority implicitly credits.
The Majority also relies on the Second Circuit’s decision in City of New York v.
Chevron Corp., 993 F.3d 81 (2d Cir. 2021), as though it forecloses the deceptive marketing
distinction. It does not. The DOJ itself explained in 2024 that City of New York is
44
distinguishable because the claims in that case “targeted fossil-fuel products themselves”
and were framed as challenges to the production and sale of fossil fuels as such. Br. for
the U.S. as Amicus Curiae, 2024 WL 5095299, at *20. The causal chain in City of New
York ran directly from the products themselves: defendants produced fossil fuels, those
fuels were combusted, emissions caused climate change, and New York City was harmed.
993 F.3d at 88–89. In other words, the duty implicitly alleged was a duty not to produce
and sell products whose inherent properties cause global warming.
In the present case, the causal chain is different. Defendants allegedly knew their
products were contributing to climate change. Plaintiffs’ complaints allege that Defendants
deliberately concealed that knowledge through a sustained disinformation campaign.
Plaintiffs claim that deception prevented consumers and governments from responding,
causing consumption to continue at higher levels than it otherwise would have, accelerating
harm as a result. Selling the product is not the wrong. Lying about what the product does
is the wrong.
That distinction matters legally because it changes what remedy would satisfy the
claim. In City of New York, the only way to cure the wrong is to stop or limit production.
Here, the wrong is cured by holding Defendants accountable for the consequences of their
deception—relief that requires no alteration of Defendants’ operations and no conflict with
any emission standard. The Majority suggests that even a deception-based damages award
could effectively regulate production by making fossil fuel marketing financially
punishing. Maj. Slip Op. at *47–50. But the Supreme Court resolved that tension in
Cipollone: a damages award for deception does not become preempted simply because it
45
might influence behavior in a federally regulated industry. 505 U.S. at 522. The proper
inquiry is the duty alleged, not the practical effect of a verdict. Oneok, 575 U.S. at 385–
- That is Supreme Court authority, not a pleading argument, and the Majority does not
engage with it. 12
11F
In any event, City of New York did not resolve the deceptive marketing question.
The plaintiff there “targeted fossil fuel products themselves,” while Plaintiffs here target
the deception the Defendants employed to conceal what they knew about those products.
Different causal chain, different duty, different legal theory. Using City of New York to
foreclose a theory it never addressed is precisely the analytical move the Supreme Court
cautioned against in Oneok, where it held that preemption requires “detailed examination”
of “the target at which the state law aims[.]” 575 U.S. at 385 (emphasis in original). The
target here is deception. City of New York never aimed at that target.
Ouellette is, if anything, an even weaker foundation for the Majority’s holding. That
case did not involve the Clean Air Act. It involved the Clean Water Act, an identifiable
paper mill in New York discharging effluent through a specific pipe into Lake Champlain,
and harm to Vermont property owners on the other shore. Ouellette, 479 U.S. at 483–84.
The defendant was a point source. Id. There was an identified source state. Id. at 483.
There was an identified affected state. Id. at 484. There was a permit issued to the
defendant under the Clean Water Act’s comprehensive permitting regime. See id. at 495.
12
Nor does the Majority engage with the District of Columbia Circuit Court’s
persuasive explanation that “there is no link” between Defendants’ regulated activities “and
the damages at issue in this lawsuit.” District of Columbia, 89 F.4th at 157. This case is
explored further in the next section.
46
The entire analytical structure of Ouellette was constructed around and for that specific
factual and statutory structure. Id. at 495–99. It was designed for a world of identified
point sources discharging through identifiable pipes into bounded bodies of water. It was
not designed for multinational petroleum marketers whose alleged wrong is not emission
but deception, and whose products were combusted by billions of end users across the
globe.
Transplanting Ouellette’s framework to this case requires answers to foundational
questions—which source state? which permit? which identifiable emitter?—that Ouellette
presupposes but this case cannot provide. 13 Here, there is no “source state” in the Ouellette
1 F
sense. There is no permit requirement—or any CAA permit—governing a fuel producer’s
marketing conduct. There is no regulatory scheme under the Clean Air Act that assigns
these Defendants to a source state, an affected state, or any defined role in an interstate
permitting system. The Ouellette structure has no footing here because Defendants do not
fit the factual predicate that analysis requires.
The Majority is aware of this problem and uses it—paradoxically—to strengthen
rather than undermine its preemption holding, reasoning that because greenhouse gases
As noted above, the procedural posture in this case compounds the error.
13
Ouellette was not decided on a motion to dismiss. It was decided on a developed factual
record that established with precision the identity of the defendant, the location of the
discharge, the nature of the permit, and the downstream harm to identifiable property
owners. Ouellette, 479 U.S. at 483–86. The Ouellette framework was built on those
established facts. Applying that framework to dismiss a complaint before discovery has
identified any analogous facts is not application of Ouellette. It is assumption of the very
predicates Ouellette requires.
47
cannot be traced to their source, allowing state lawsuits would create an even more chaotic
regulatory patchwork than the water pollution context in Ouellette. Maj. Slip Op. at *59–
- But this reasoning misapplies Ouellette in a fundamental way. The globally diffuse,
untraceable nature of atmospheric greenhouse gases is not a reason to apply Ouellette’s
approach more aggressively—it is a reason to question whether Ouellette and its progeny
applies at all. A doctrine built around the identifiability of sources and source states cannot
be extended, by force of analogy, to cases where that identifiability is absent. The absence
of Ouellette’s predicate conditions is a reason to look elsewhere for the governing rule, not
a reason to apply the framework anyway and reach a more sweeping result.
C. The Majority Conflates Displacement and Preemption
Defendants presented this Court with an argument structured, whether intentionally
or not, to allow the Court to sidestep the demanding preemption analysis that Cipollone,
Altria Group, and Oneok require—and in doing so produced the error most fatal to the
Majority’s analysis: the conflation of displacement and preemption. By leading with the
argument that these claims are really about interstate emissions—and therefore governed
by federal common law—Defendants gave the Court a threshold characterization question
to answer instead of a preemption question. If the Court accepted that characterization—
that the case is about emissions—the displacement of federal common law by the CAA
would follow almost automatically from AEP, and the harder question—whether the CAA
actually preempts state deceptive marketing claims—would never need to be asked. The
Majority accepted that offer. The conflation of displacement and preemption that follows
is the consequence: a holding assembled from AEP’s displacement rationale and
48
Ouellette’s preemption framework, applied to claims neither case addressed, in a sequence
neither case authorized, to avoid an analysis both cases left open.
A careful examination of the case law illustrates that displacement and preemption
are distinct doctrines with distinct standards and distinct consequences. Collapsing them
produces a result neither doctrine independently supports. Displacement is what happened
in AEP. “When Congress legislates to displace federal common law, the statute governs
the extent to which state law is preempted.” District of Columbia, 89 F.4th at 152–53
(citing Milwaukee II, 451 U.S. at 312–13). 14 The AEP Court was explicit: “Legislative
13F
displacement of federal common law does not require the ‘same sort of evidence of a clear
and manifest congressional purpose’ demanded for preemption of state law.” AEP, 564
U.S. at 423 (quoting Milwaukee II, 451 U.S. at 317) (cleaned up).
The bar is lower for displacement of federal common law because “it is primarily
the office of Congress, not the . . . courts, to prescribe national policy in areas of special
federal interest[.]” AEP, 564 U.S. at 423–24. Federal common law is generally disfavored,
see Erie R.R. Co. v. Tompkins, 304 U.S. 64, 78 (1938), and should only be created by courts
in exceptional circumstances where Congress has not spoken, see Tex. Indus., Inc. v.
Radcliff Materials, Inc., 451 U.S. 630, 641 (1981). But once Congress has spoken, the
need for judicially created federal common law “disappears.” Milwaukee II, 451 U.S. at
14
The suit in District of Columbia is virtually identical to the ones brought here. 89
F.4th at 149 n.1. There, plaintiffs were also “alleging that energy companies have
promoted fossil fuels while concealing their impacts on climate change.” Id. While the
District of Columbia court was considering the issues in the removal context, as explained
supra Section III regarding the Fourth Circuit’s removal opinion, its conclusions regarding
similar issues and plaintiffs are persuasive.
49
314. The legislative action via statute, for example, becomes the leading authority on
whatever question the federal common law had directly spoken to. See Tenn. Valley Auth.
v. Hill, 437 U.S. 153, 195 (1978) (“[I]n our constitutional system the commitment to the
separation of powers is too fundamental for us to pre-empt congressional action by
judicially decreeing what accords with ‘common sense and the public weal.’”).
Displacement wipes out federal common law. It says nothing about state law.
Preemption is a different and more demanding inquiry—one that, as explained
above, the CAA cannot satisfy with respect to deceptive marketing claims. See supra
Sections II and III.A and B. Preemption must be analyzed under the CAA as a statutory
matter, not derived from displaced federal common law. See District of Columbia, 89
F.4th at 153 (“Whether the District’s suit may go forward thus depends on the preemptive
effect of the Clean Air Act, not on the preemptive effect of federal common law.”). The
Majority moves from AEP’s displacement holding directly to preemption of state law
without accounting for that difference or the presumption against preemption that applies.
See id. at 153. AEP itself said otherwise: the Court expressly left the state law question
open and noted that preemption is a separate inquiry governed by the preemptive effect of
the federal statute. 564 U.S. at 429. The Majority performed that separate inquiry, but
under Ouellette’s framework—built for point-source emitters under the Clean Water Act,
not for fuel marketers under the Clean Air Act. Maj. Slip Op. at *55–60.
What Defendants are actually asking—and what the Majority ratifies—is something
more aggressive than just a misapplication of AEP. They are asking this Court to
constitutionalize that misapplication—to treat the historical existence of federal common
50
law over interstate pollution as itself constitutionally dispositive, rendering the statutory
preemption inquiry irrelevant. Under that theory, once a court has identified a subject as
having been governed by federal common law, no further analysis is needed—the
Constitution forecloses state law regardless of what Congress said or did not say. But that
theory, as the Supreme Court has recognized, would call into question the constitutionality
of saving clauses and cooperative federalism provisions throughout federal law. See Isla
Petroleum Corp., 485 U.S. at 503–04. If Defendants are right, Congress could not
authorize state law remedies in any field that has ever been governed by federal common
law: not in water pollution, not in air pollution, not in any area judges have once deemed
suitable for a uniform federal rule. That cannot be the law. Congress’ prerogatives include
the right to decide for itself the extent to which federal law should preempt state law, and
courts are not authorized to override that choice by elevating the prior existence of federal
common law into a constitutional trump card.
That theory is also an attempt to bypass the statutory preemption analysis
altogether—an analysis that, as demonstrated above, the CAA cannot satisfy with respect
to deceptive marketing claims. If the Constitution forecloses state law the moment federal
common law has ever governed a field, courts need never ask whether Congress spoke
clearly, whether a saving clause preserves state remedies, or whether the presumption
against preemption applies. The difficulty of that statutory analysis is not a reason to
bypass it through constitutional inference. It is a reason to perform it carefully.
All three of the theories Defendants advanced—that the Constitution’s federal
structure independently forecloses state law, that state law cannot revive once federal
51
common law is displaced, and that the CAA preempts these claims under Ouellette—
appear in the Majority’s opinion. The problem is that the Majority never performed the
analysis those theories require. The Majority never explains whether any one of them is
independently sufficient, whether they depend on each other, or how they interact. That
failure is not a matter of drafting. It is a matter of analysis. Each theory rests on a different
predicate, and none of those predicates are established here.
The Majority reverses the sequencing that the Supreme Court established in AEP.
The core of the Majority’s preemption holding—pages 43 through 60 of its opinion—
contains no independent analysis. The Majority opens by announcing a “federal
displacement/preemption inquiry[,]” Maj. Slip Op. at *45, fusing two doctrinally distinct
concepts into a single hyphenated phrase. But AEP establishes a specific order of
operations. First, ask whether the CAA displaces federal common law. AEP, 564 U.S. at
- Second, separately ask whether the CAA preempts state law. Id. at 429. Those are
two distinct questions asked in that sequence. The Majority reverses the sequence. It first
declares state law claims “displaced by federal common law”—which misuses
displacement doctrine—and then in its next section says, “[h]aving determined that any
claims the local governments may have would arise under federal law, we next conclude
that any federal common law claims would be displaced by the Clean Air Act.” Maj. Slip
Op. at *53. That is backwards. It treats step two as the predicate for step one. This is a
foundational error that allows the Majority to avoid the preemption analysis it was required
to perform.
52
As established by the U.S. Supreme Court in Oneok and Altria Group, the threshold
question in any preemption analysis is what subject matter the state law claim actually
occupies: what duty is alleged, what conduct is targeted, and what field of law governs that
conduct. See supra Sections I.A and III.A; infra Section III.D. The Majority never asks
that question. Instead, the Majority immediately overlays City of New York as its analytical
template, asking not what the preemption doctrine requires, but whether the complaints
here resemble the complaint the Second Circuit considered in that case. The Majority’s
answer rests on a word count: Baltimore’s complaint mentions “emissions” 115 times.
Moreover, City of New York is not binding authority on this Court. It is a persuasive
decision from a federal circuit court, and its reasoning is only as persuasive as the premises
underlying it. Notwithstanding the Fourth Circuit criticism of the applicability of the City
of New York decision to these facts, 15 the Majority adopted those premises without
14F
examination.
The Majority then states without any legal authority that even if the claims were
genuinely limited to deceptive marketing, they still could not proceed under state law. Maj.
15
See Mayor & City Council of Balt., 31 F.4th at 203–04. Quite fittingly, the Fourth
Circuit described the City of New York as “suffer[ing] from the same legal flaw as
Defendants’ arguments: It fails to explain a significant conflict between the state-law
claims before it and the federal interests at stake before arriving at its conclusions.” Id. at
203. And the Fourth Circuit is not the only tribunal that has rejected identical arguments
posed by Defendants BP, Exxon Mobil, Chevron, and Shell. The D.C. Circuit also rejected
the argument that federal common law persists for jurisdictional purposes even after being
displaced on the merits. See District of Columbia, 89 F.4th at 152 (“We can find no support
for the suggestion that federal common law has the Schrödinger quality advanced by the
Companies—where one does not know if it is alive or dead until the case is removed to
federal court.”).
53
Slip Op. at *47–48. It offers no authority for that proposition because there is none. And
it concludes that “any state law claims are displaced by federal common law[,]” id. at *51,
using the word “displaced” for a doctrine that describes when a federal statute replaces
federal common law, see AEP, 564 U.S. at 423.
The constitutional structure argument requires that interstate emissions are the
relevant field—a predicate the Majority assumes by accepting Defendants’
characterization of the claims rather than reading the complaints as written. The
displacement argument requires that federal common law once governed the specific
claims at issue. But federal common law never governed deceptive marketing, and the
Majority never establishes that it did. The Ouellette argument requires that these
Defendants are the functional equivalent of a point-source emitter operating under a federal
permit, a predicate that is flatly contradicted by the record. The Majority assumes all three
predicates without establishing any of them. That is not analysis. It is conflation.
The willingness to invoke every theory Defendants offered—without scrutiny,
without acknowledging the distinct predicate each requires, and without explaining how
theories resting on different premises can simultaneously support a single holding—is a
measure of how far the Majority’s opinion strays from the discipline the U.S. Supreme
Court’s preemption jurisprudence requires. 16 Defendants’, and amici United States’,
15F
16
It is also worth noting that the Majority’s novel preemption holding is unnecessary
on its own terms. Public nuisance and deceptive marketing claims of the kind Plaintiffs
assert, carry within them significant built-in limiting principles that courts apply at
summary judgment and beyond. Causation—the requirement that plaintiffs demonstrate a
traceable causal chain from specific defendants’ conduct to specific local harms—is a
54
argument that the federal structure of the U.S. Constitution implicitly preempts Plaintiffs’
claims, notably, was advanced as a fallback after the statutory and displacement arguments
proved inadequate on their own terms, and it is a theory no appellate court has
independently accepted as sufficient. See Cnty. Comm’rs of Boulder Cnty., 2025 WL
1363355, at *11. The U.S. Supreme Court declined to review it in the Hawaii litigation at
the urging of the United States. See Sunoco LP v. City & County of Honolulu, 145 S. Ct.
1111 (2025); Shell PLC v. City & County of Honolulu, 145 S. Ct. 1111 (2025); Br. for the
U.S. as Amicus Curiae, 2024 WL 5095299, at *6–7. The Majority’s decision to treat it as
established law in this case—without analysis, without citation to a case that has so held,
and without acknowledging the Supreme Court’s recent refusal to endorse it—is not a
minor oversight. It is the Majority’s analytical method in miniature: accepting without
examination what the controlling cases require courts to demonstrate, not assume.
The Majority’s uncritical adoption of City of New York, the Second Circuit’s snap-
back reasoning, as applied here, is questionable at best. City of New York rejected the
argument that state law claims “snap back into action” once federal common law is
displaced by statute, unless Congress specifically preserves them. 993 F.3d at 98. The
Second Circuit held that “state law does not suddenly become presumptively competent to
address issues that demand a unified federal standard simply because Congress saw fit to
displace a federal court-made standard with a legislative one[.]” Id. (citing People of Ill.
demanding standard. Product identification presents a related challenge: Plaintiffs must
demonstrate which Defendants’ products caused which portion of the harm. These are not
trivial hurdles.
55
v. City of Milwaukee (“Milwaukee III”), 731 F.2d 403, 410 (7th Cir. 1984)). The premise
underlying that conclusion is that where “federal common law exists, it is because state
law cannot be used.” Id. at 90 (quoting Milwaukee II, 451 U.S. at 313 n.7). Accepting
without examination the premise that the relevant field is interstate pollution, over which
States have never had primary authority, then the Second Circuit’s logic is internally
coherent. Federal common law governs nuisance claims involving emissions. On those
facts, state law never had authority to begin with, so there is nothing to snap back.
That logic does not survive the field identification problem the Majority never
solves. The “snap back” reasoning only works if the relevant field is correctly identified
as interstate pollution. Here it is not. Deceptive marketing is a different field—one the
States have always governed and federal common law never touched. The Colorado
Supreme Court rejected that premise directly, concluding that claims grounded in deceptive
marketing occupy a different field than interstate emissions regulation regardless of how
the causal chain is traced. See Cnty. Comm’rs of Boulder Cnty., 2025 WL 1363355, at *8–
- Moreover, as explained earlier in this section, federal common law only exists where
the legislature has not yet spoken. And once the legislature speaks, everything it says and
does not say becomes the supreme law in that now legislated area. If state law addresses
an area not preempted by the legislature, then it sure can “snap back.” But even if there
were a “snap back” problem, it does not arise here because State authority over deceptive
marketing was never removed. The Second Circuit’s confused displacement reasoning in
City of New York, see 993 F.3d at 98–100, correctly applied, confirms rather than
undermines that conclusion: the presumption against preemption protects traditional state
56
fields; deceptive marketing is a traditional state field; and nothing in the displacement of
federal common law over a different field—interstate pollution—removed that protection.
No federal court—not one—has ever preempted a state law deceptive marketing or
consumer protection claim under the Clean Air Act. Not in the climate context. Not in
any context. The Majority cites no such case because there is no such case. What the
Majority describes as a settled analytical framework is displacement/preemption alchemy.
Its holding is assembled from pieces of cases that addressed different defendants engaged
in different conduct, involving different claims, and arising under different statutes—fused
together for the first time by this Court to produce a result none of those cases ever reached.
Courts do not preempt state law claims on theories no court has ever accepted. When a
court applies established doctrine, its result can be checked against the cases it cites. When
a court applies doctrine that has never been applied before, to claims it has never reached
and defendants it has never covered, it is not applying precedent. It is making it. That is a
legislative function, and it requires the clear congressional mandate the Majority never
found.
D. CAA’s Saving Clause Preserves State Remedies
Even if the Majority’s Ouellette analysis were otherwise sound, the CAA’s saving
clause would independently preserve Plaintiffs’ claims. The CAA’s structure is that of “a
regulatory floor, not a ceiling.” Bell v. Cheswick Generating Station, 734 F.3d 188, 197–
98 (3d Cir. 2013). Section 7416, titled “Retention of State Authority,” provides that
“nothing [aside from exceptions previously mentioned] in this chapter shall preclude or
deny the right of any State or political subdivision thereof to adopt or enforce (1) any
57
standard or limitation respecting emissions of air pollutants or (2) any requirement
respecting control or abatement of air pollution[,]” except that state emission standards
may not be “less stringent” than applicable federal standards. 42 U.S.C. § 7416. The CAA
further states that “[a] primary goal of [the CAA] is to encourage or otherwise promote
reasonable Federal, State, and local governmental actions, consistent with the provisions
of [the CAA], for pollution prevention.” Id. § 7401(c). Congress built State authority into
the statute’s structure. The Majority reads that authority out of it.
While courts should “not interpret a saving clause as preserving a state law that
would so conflict and interfere with a federal enactment that it would defeat the federal
law’s purpose or essentially nullify it[,]” In re Volkswagen “Clean Diesel” Mktg., Sales
Pracs., & Prods. Liab. Litig., 959 F.3d 1201, 1213–14 (9th Cir. 2020), that conflict must
be an actual conflict, not one which might occur, see, e.g, In re JUUL Labs, Inc., Mktg.,
Sales Pracs., & Prods. Liab. Litig., 497 F. Supp. 3d 552, 593 (N.D. Cal. 2020) (finding no
conflict preemption where defendants speculatively argued that the state law claims could
conflict with the federal statute); Silkwood, 464 U.S. at 248 (“[S]tate law is . . . preempted
to the extent it actually conflicts with federal law[.]”). The Majority identifies no provision
of the CAA that would be nullified or defeated by holding petroleum marketers liable for
allegedly deceiving the public about climate science. It cannot, because there is none. The
CAA regulates emissions, not honesty. Those are different things, and the conflict between
them is imaginary.
The U.S. Supreme Court’s Oneok decision confirms this analysis. There, the Court
held that the Federal Natural Gas Act did not preempt state antitrust claims against pipeline
58
companies even though the pipelines were extensively regulated under federal law, because
the Act “was drawn with meticulous regard for the continued exercise of state power[.]”
Oneok, 575 U.S. at 384–85 (internal quotations omitted). The Court focused on the target
of the state law—antitrust claims aimed at retail pricing practices firmly within state
authority—and held that field preemption requires “detailed examination” convincing the
Court that the “matter falls within the pre-empted field as defined by [the Court’s]
precedents.” Id. at 385. The CAA, like the Natural Gas Act, was drawn with meticulous
regard for state authority—its saving clause expressly says so. And the target of Plaintiffs’
state law claims—deceptive marketing—falls firmly within state authority, just as retail
pricing practices did in Oneok. The Majority’s contrary conclusion does not reckon with
Oneok’s analysis or explain why the result should differ.
The Majority’s logic, taken to its conclusion, produces a further problem it does not
acknowledge. If the existence of prior federal common law over interstate pollution means
that state law cannot be operative without express congressional authorization—as the
Majority’s fusion of displacement and preemption implies—then the CAA’s own saving
clause is rendered a nullity. Congress enacted that clause to preserve state authority. Under
the Majority’s approach, that congressional choice is overridden not by anything Congress
said, but by the sheer fact that courts once governed this field through federal common law.
That inverts the constitutional hierarchy. It is Congress, not prior judicial lawmaking, that
determines the scope of federal preemption. The saving clause is Congress speaking. The
Majority’s approach makes it speak to nothing.
59
E. Engine Manufacturers Distinguished
A comparison to a case where the Supreme Court did find CAA preemption of state
law—Engine Mfrs. Ass’n (“Engine Manufacturers”) v. S. Coast Air Quality Mgmt. Dist.,
541 U.S. 246 (2004)—illustrates precisely why preemption is unwarranted here. In Engine
Manufacturers, the Court was tasked with deciding whether a local California agency could
regulate the “purchase of vehicles, rather than their manufacture or sale[,]” id. at 249
(emphasis added), when the CAA includes a preemption clause that “prohibits the adoption
or attempted enforcement of any state or local ‘standard relating to the control of emissions
from new motor vehicles or new motor vehicle engines[,]’” id. at 251 (quoting 42 U.S.C.
§ 7543(a)). The lower courts reasoned, and defendants argued, that “‘[w]here a state
regulation does not compel manufacturers to meet a new emissions limit, but rather affects
the purchase of vehicles, as the [rules from the local agency do], that regulation is not a
standard.’” Id. at 251–52 (quoting Engine Mfrs. Ass’n v. S. Coast Air Quality Mgmt. Dist.,
158 F. Supp. 2d 1107, 1118 (C.D. Cal. 2001)). The Court disagreed. See Engine
Manufacturers, 541 U.S. at 252. It explained that other sections in the CAA proved that
“Congress contemplated the enforcement of emission standards through purchase
requirements[]” showing that purchase regulations could be standards. Id. at 254. It also
found that “treating sales restrictions and purchase restrictions differently for pre-emption
purposes would make no sense” because “[t]he manufacturer’s right to sell federally
approved vehicles is meaningless in the absence of a purchaser’s right to buy them.” Id. at
- For these reasons and others, it held that “at least certain aspects of the [local agency’s
rules] are pre-empted.” Id. at 258.
60
That is the opposite of this case. The CAA contains no express preemption
provision addressing marketing, deception or a duty of fossil fuel companies to
communicate honestly about the climate consequences of their products. Cf. Fenner v.
Gen. Motors, LLC, 113 F.4th 585, 596, 590, 600–02 (6th Cir. 2024) (holding that state
consumer protection claims based on defendants’ misrepresentations to consumers
regarding emissions were not preempted by CAA); In re Chrysler-Dodge-Jeep Ecodiesel
Mktg, Sales Pracs., & Prods. Liab. Litig., 295 F. Supp. 3d 927, 1003 (N.D. Cal. 2018)
(holding that claims based on marketing deception were not preempted by the CAA).
Congress considered preemption when it drafted the CAA and included provisions
explicitly limiting what states may regulate—42 U.S.C. §§ 7543 and 7573 among them. 17 16F
None of those provisions contemplate regulating the marketing of fossil fuel products.
That deliberate congressional choice confirms the expressio unius exclusion alterius
principle the Supreme Court applied in Cipollone: “Congress’ enactment of a provision
defining the pre-emptive reach of a statute implies that matters beyond that reach are not
pre-empted.” 505 U.S. at 517. Congress drew the boundary of CAA preemption.
Deceptive marketing is outside it. Courts are not authorized to redraw that boundary
because the subject matter feels sufficiently related to what Congress did address.
17
While the text of the CAA supports this point, the legislative record provides the
cherry on top. See National Research Council, State and Federal Standards for Mobile-
Source Emissions 65–75 (2006).
61
F. The EPA’s Rescission Undermines the Majority’s Preemption Architecture
The EPA’s recent rescission of the 2009 Greenhouse Gas Endangerment Finding
concluded that the CAA never provided statutory authority to regulate greenhouse gases
for the purpose of addressing global climate change—the very premise on which
Massachusetts v. EPA rested. See Rescission of the Greenhouse Gas Endangerment
Finding, 91 Fed. Reg. 7686, 7711–12, 7717–18, 7726–27 (Feb. 18, 2026). Though the
rescission does not reach every greenhouse gas emission finding made by the EPA, and its
legal validity is already being challenged in court, 18 the direction is unmistakable—the
17F
federal government is in retreat. See 91 Fed. Reg. at 7723–27.
The Majority’s reliance on AEP and Massachusetts v. EPA is now even less
persuasive in light of that rescission. The AEP Court’s displacement holding rested on the
premise that Congress had delegated to the EPA authority to do what plaintiffs wanted
courts to do—regulate GHG emissions from power plants. AEP, 564 U.S. at 416–17, 424.
The Massachusetts v. EPA Court established that the CAA covers greenhouse gases. The
Majority’s holding, read together with the rescission, produces a result the Massachusetts
v. EPA court never contemplated: nobody can address the problem in Maryland. Not the
state or local governments, because today’s decision has barred them from the courthouse
to litigate deceptive marketing. Not the federal government, which has abandoned the
field. That is not a result the Clean Air Act was designed to produce. And it is a result that
18
See Am. Pub. Health Ass’n v. EPA, No. 26-1037 (D.C. Cir. filed Feb. 18, 2026);
Venner v. EPA, No. 26-1038 (D.C. Cir. Feb. 18, 2026).
62
this Court should not impose—let alone on a motion to dismiss, before a single document
has been produced.
The Majority’s rationale would bar the States from the courthouse while the federal
government simultaneously abandons the field. The Clean Air Act does not mandate such
an absurd result, and it is not one this Court should impose here—particularly on a motion
to dismiss. See Silkwood, 464 U.S. at 251 (“It is difficult to believe that Congress would,
without comment, remove all means of judicial recourse for those injured by illegal
conduct.”).
IV. THE COMMERCE CLAUSE DOES NOT BAR PLAINTIFFS’ CLAIMS
Defendants and their amici argue that even if the CAA does not preempt Plaintiffs’
claims, the Commerce Clause and its dormant counterpart do. That argument fails, and
this Court need not reach it at all.
“The Commerce Clause of the [United States] Constitution grants Congress the
power ‘to regulate Commerce with foreign Nations, and among the several States[.]’”
Maine v. Taylor, 477 U.S. 131, 137 (1986) (quoting Art. I, § 8, cl. 3) (cleaned up). But the
Clause “includes a negative component[]” called the Dormant Commerce Clause (“DCC”).
Mallory v. Norfolk S. Ry. Co., 600 U.S. 122, 157 (2023) (Alito, J., concurring). The DCC
says that a State violates the Commerce Clause “when [a state] law discriminates against
interstate commerce or when it imposes ‘undue burdens’ on interstate commerce.” Id. at
160 (quoting South Dakota v. Wayfair, Inc., 585 U.S. 162, 173 (2018)). When evaluating
whether a state regulation violates the DCC, courts implement a balancing test, which says
that “[l]aws that even-handedly regulate to advance a legitimate local public interest . . .
63
will be upheld unless the burden imposed on interstate commerce is clearly excessive in
relation to the putative local benefits.” Id. at 160–61 (cleaned up). Moreover, it should go
without saying that States do not violate the Commerce Clause simply by regulating local
marketing activity despite a product or business’ interstate nature. See Packer Corp., 285
U.S. at 112 (“Whatever may be the limitations upon the power of the state to regulate
solicitation and advertisement incident to an exclusively interstate business, the commerce
clause interposes no barrier to its effective control of advertising essentially local.”).
Defendants and the United States (through the DOJ), and 24 of our sister states, 19 18F
as amici, argue that allowing Plaintiffs to hold Defendants accountable for deceptive
marketing would violate the DCC. In its amicus brief in the matter before this Court, the
DOJ argues that the United States Constitution bars Plaintiffs’ claims based on the
Commerce Clause. 20 And while the DOJ in City & Cnty. Of Honolulu did not address
19F
19
The Majority finds significance in the fact that the United States and twenty-four
states filed amicus briefs in support of the Defendants, suggesting this “‘aptly illustrates
that this is an interstate matter raising significant federalism concerns.’” Maj. Slip Op. at
*49 (quoting City of New York, 993 F.3d at 92). With respect, the filing of amicus briefs
reflects the political salience of an issue, not its legal resolution. Courts have always faced
politically charged questions, and the number of voices urging a particular outcome has
never been a substitute for legal analysis. If anything, the fact that this question has
attracted such intense political interest from state governments across the country—states
whose own regulatory interests and policy preferences on fossil fuel production vary
considerably from Maryland’s—is a reason for this Court to be more cautious about getting
ahead of the U.S. Supreme Court, not less. Maryland’s sovereign interest in protecting its
residents from deceptive conduct within its borders is no less legitimate because other
states have chosen different policy priorities. The Tenth Amendment reserves those
judgments to each state, not to a coalition of its neighbors.
20
In its amicus brief in this Court, the United States also argues that allowing
Plaintiffs to bring their tortious marketing claims would violate the Due Process clause of
64
these constitutional arguments because they had “not been addressed by the Hawaii
Supreme Court” nor the “trial court[,]” it said that the “constitutional arguments may
ultimately be held to foreclose [plaintiffs’] state-law claims to the extent they are based on
emissions or other conduct outside Hawaii.” Br. for the U.S. as Amicus Curiae, 2024 WL
5095299, at *6–7. As the DOJ counseled against review of the Due Process Clause and
the Commerce Clause arguments in City & Cnty. Of Honolulu, this Court should also not
prematurely review these arguments. Id. at *7. As Plaintiffs state in their supporting brief,
the trial court in Baltimore City did not, nor did the trial court in Annapolis, address these
two constitutional provisions. Until the trial court sufficiently reviews whether Plaintiffs’
claims are barred by the Due Process Clause and/or the Commerce Clause of the United
States Constitution, this Court should stay silent on the issue.
Nevertheless, under the DCC’s balancing test, a court would be hard-pressed to find
that holding businesses accountable for deceptive marketing imposes a clearly excessive
burden on interstate commerce in relation to the putative local benefits. Deceptive
marketing is a legitimate local interest. See Governor of Md. v. Exxon Corp., 279 Md. 410,
435 (1977) (“The promotion of the economic welfare is a legitimate interest of a state[.]”);
Edenfield, 507 U.S. at 769 (“[T]here is no question that [a State’s] interest in ensuring the
accuracy of commercial information in the marketplace is substantial.”) (collecting cases).
the United States Constitution. But that argument is based on the idea that Plaintiffs are
attempting to hold Defendants accountable for activities beyond state lines. As explained,
Plaintiffs are attempting to hold Defendants accountable for tortious activities that occurred
in the state. So, this argument is inapplicable insofar as Plaintiffs are only bringing tortious
marketing claims against Defendants for marketing that occurred within state lines. Thus,
this argument will not receive attention outside of this footnote.
65
And “[a] State has a legitimate interest in regulating activities conducted within its
borders[.]” Mallory, 600 U.S. at 162.
Moreover, any burden on interstate commerce would be slight, especially since, as
previously explained, each state has similar tortious marketing laws. See, e.g., Minnesota
v. Clover Leaf Creamery Co., 449 U.S. 456, 472 (1981) (explaining that the state regulation
at issue imposes a minor burden on interstate commerce where the product can still move
freely across the state’s border and the inconvenience to the company in dealing with
different States’ requirements is “slight”).
Finally, there is “no approach with a lesser impact on interstate activities” for
holding businesses accountable for deceptive marketing. Minnesota, 449 U.S. at 473
(internal quotations omitted). Tortious marketing claims are the way that States’ and their
citizens hold businesses accountable for such a harm. So, here, while there may be an
incidental burden on interstate commerce, it is not clearly excessive in relation to the
putative local benefits.
Exxon Corp. v. Governor of Md., 437 U.S. 117 (1978), and Sackett v. EPA, 598 U.S.
651 (2023), illustrate how the Court has previously applied these principles when analyzing
whether a federal statute preempts state law.
In Exxon Corp., the statute at issue was a Maryland statute regulating retail oil
service stations in the state. See 437 U.S. at 119–20. The oil companies argued “that
because the economic market for petroleum products is nationwide, no State has the power
to regulate the retail marketing of gas.” Id. at 128. The Court responded that “[i]n the
absence of a relevant congressional declaration of policy, or a showing of a specific
66
discrimination against, or burdening of, interstate commerce, [it could not] conclude that
the States are without power to regulate in this area.” Id. at 128–29. The oil companies
also argued that the state law was preempted because it created a conflict with federal law.
Id. at 130. But the Court found that “the existence of such potential conflicts is entirely
too speculative in the present posture of [the] case” and such “hypothetical conflict is not
sufficient to warrant pre-emption.” Id. at 131 (emphasis added).
In Sackett, the EPA argued that it could regulate the water on plaintiff’s land because
Congress gave it that authority under its Commerce Clause power to regulate “channels of
interstate commerce[]” which includes “certain navigable waters.” Sackett, 598 U.S. at
686–87 (Thomas, J., concurring). But Justice Thomas, joined by Justice Gorsuch,
explained that, while the EPA’s claim was correct, it only had the narrow power to regulate
those waters “to keep them open and free from any obstruction to their navigation and to
remove such obstructions when they exist.” Id. (internal quotations omitted). It did not
have the power to regulate “activities that merely affect water-based commerce[.]” Id. at
688 (internal quotations omitted).
The Commerce Clause was designed to prevent States from erecting barriers to
interstate trade—from discriminating against out-of-state products, burdening the free
movement of goods, or regulating conduct occurring beyond their borders. It was not
designed to immunize multinationals from state tort liability for deceiving the residents of
the states in which they operated. As the Supreme Court recognized in Exxon Corp., the
mere fact that a product moves in interstate commerce does not place its marketing beyond
a state’s regulatory reach. 437 U.S. at 128–29. And the hypothetical conflicts Defendants
67
conjure—that a Maryland verdict might influence conduct in other states or ripple through
national energy markets—are precisely the kind of speculative burdens the Court in Exxon
Corp. held insufficient to establish preemption or constitutional invalidity. Id. at 130–31.
On this record, on a motion to dismiss, before any factual development of how Defendants’
marketing reached Maryland consumers and what its effects were, these constitutional
arguments are not ripe for resolution. The 2024 DOJ correctly counseled the Supreme
Court to leave them for the trial court in the first instance. Br. for the U.S. as Amicus
Curiae, 2024 WL 5095299, at *6–7. We should do so.
V. FOREIGN AFFAIRS PREEMPTION
The Majority’s foreign affairs analysis has a structural problem it never addresses:
it is directed at the wrong claims. The Majority’s entire foreign affairs section concerns
federal common law causes of action targeting international emissions—the theory the
Second Circuit rejected in City of New York. Maj. Slip Op. at *61–65. But Plaintiffs are
not asserting federal common law claims for international emissions. They are asserting
state tort claims for deceptive marketing conduct directed at Maryland consumers. The
Majority disposes of the foreign affairs preemption question in the same analytical breath
as it disposes of international federal common law claims, as though the two were
interchangeable. They are not. That conflation repeats, in the foreign affairs context, the
same error the Majority makes throughout.
The “foreign affairs power” is a federalism limit on state power that “resides in the
President’s fundamental executive powers” and “in certain powers granted to Congress,
such as the power to regulate commerce with foreign nations[.]” 21 PACE ENVTL. L. REV.
68
at 67. Therefore, “duly ratified treaties and the federal statutes that implement them are
the supreme law of the land” and preempt inconsistent state laws. Id. at 75; See Am. Ins.
Ass’n v. Garamendi, 539 U.S. 396, 416–17 (2003). But where no treaty or statute
“expressly” preempt an area of law, preemption “rest[s] on [an] asserted interference with
the foreign policy those agreements embody.” Garamendi, 539 U.S. at 417. In such cases,
and where the preemption question applies to a historic state police power, courts should
“consider the strength of the state interest, judged by standards of traditional practice, when
deciding how serious a conflict must be shown before declaring the state law preempted”
by foreign policy. Id. at 420.
The Majority and Defendants fail to engage in the balancing analysis required by
Garamendi. Both fail to discuss the States’ historic power to regulate deceptive marketing
and fail to consider that historic power’s strength. There is no discussion deciding how
serious a conflict must be shown before declaring the state law preempted by foreign
policy. Therefore, the Majority holds that the foreign affairs power preempts Plaintiffs’
state law deceptive marketing claims because they said so. The Garamendi Court says that
is not enough.
Most fatal to Defendants’ foreign affairs preemption argument is that they do “not
identify any express foreign policy of the federal government that conflicts with state tort
law. . . [n]or do the [D]efendants indicate how [Plaintiffs’] claims pose an obstacle to our
federal government’s dealings with any foreign nation.” Cnty. Comm’rs of Boulder Cnty.,
2025 WL 1363355, at *11 (citing Mayor and City Council of Balt., 31 F.4th at 213–14).
The Majority sua sponte invokes the Paris Agreement and the U.N. Framework
69
Convention—but only by borrowing that reference from City of New York, not by
independently analyzing whether those instruments have any preemptive effect on state
tort law. See Maj. Slip Op. at *63–64. Those agreements address international obligations
to reduce emissions. Plaintiffs do not seek to alter emissions obligations, international or
otherwise. A Maryland verdict holding petroleum marketers liable for deceiving their
customers does not rewrite the Paris Agreement, does not alter any nation’s emissions
commitments, and does not implicate any diplomatic channel the United States uses to
address climate change. State law is not preempted merely because it has “some incidental
or indirect effect in foreign countries”— “that is true of many” unobjectionable state laws
and has never been sufficient. Clark v. Allen, 331 U.S. 503, 517 (1947). Moreover, the
President’s policy preference—outside of any statutory or constitutional authority—for
avoiding state tort regimes that might complicate foreign climate negotiations has no
preemptive effect on state law absent congressional agreement. The Supremacy Clause
gives priority to “the Laws of the United States,” not the “priorities or preferences of federal
officers.” Kansas v. Garcia, 589 U.S. 191, 212 (2020) (internal quotations omitted).
Consider Massachusetts v. EPA. When the EPA denied a petition to regulate
greenhouse gases from motor vehicles in 2003, it argued in part that doing so “might impair
the President’s ability to negotiate with key developing nations” on emissions reductions.
Massachusetts, 549 U.S. at 533 (internal quotations omitted). The Supreme Court rejected
that rationale, holding that vague allusions to foreign affairs consequences could not justify
the EPA’s refusal to exercise its statutory authority. Id. at 533–34. The same logic applies
here with equal force: if speculative foreign affairs concerns could not excuse the EPA
70
from acting on its statutory mandate, they cannot foreclose state courts from hearing claims
that fall within the States’ historic authority over deceptive marketing. As Professors Lin
and Burger have observed, the Supreme Court’s rejection of EPA’s foreign affairs
argument in Massachusetts v. EPA signals that “similar allusions” should not “foreclose
the availability of state common law claims[.]” Albert C. Lin & Michael Burger, State
Public Nuisance Claims and Climate Change Adaptation, 36 PACE ENVTL. L. REV. 49, 65–
66 (2018) (quoting Massachusetts, 549 U.S. at 533).
In sum, no treaty, no statute, and no executive agreement addresses deceptive
marketing of fossil fuels. The foreign affairs doctrine does not fill that void.
VI. THE INDIVIDUAL TORT CLAIMS
With respect to the individual tort claims, I join the Majority’s decision to affirm
the Baltimore City Circuit Court’s finding that Plaintiffs in that matter along with Plaintiffs
in the other matters should have their private nuisance and trespass claims dismissed for
failure to state a claim.
I also concur with the Majority’s decision to affirm the Baltimore City Circuit
Court’s finding to dismiss Plaintiffs’ strict liability failure-to-warn claim in that case. And
I agree that the other Plaintiffs’ strict liability failure-to-warn claims should also be
dismissed. But dismissal should be on the ground that oil and gas or other fossil fuels, are
lawful and widely used consumer products, and do not generally give rise to strict liability
absent an actionable defect or ultrahazardous activity. See Gourdine v. Crews, 405 Md.
722, 740 (2008) (listing the elements of a strict liability failure-to-warn claim). Imposing
broad strict liability would extend tort law beyond its historical and doctrinal limits.
71
I respectfully dissent from the Majority’s opinion regarding Plaintiffs’ public
nuisance and negligent failure-to-warn claims. I would reverse the Baltimore City Circuit
Court’s finding that Plaintiffs’ public nuisance and negligent failure-to-warn claims should
be dismissed for failure to state a claim. Consequently, I would hold that each Plaintiffs’
public nuisance and negligent failure-to-warn claims may proceed to discovery as Plaintiffs
have stated a claim in which relief may be granted.
Though the application of nuisance law must be carefully constrained to prevent
open-ended liability, I do not believe that our case law categorically bars public nuisance
claims arising from lawful products, including fossil fuels. What matters is whether the
defendant’s conduct unreasonably interferes with a right common to the public, including
public health, safety, or comfort. Cases such as Adams v. Comm’rs of Trappe, 204 Md.
165 (1954), and Maryland v. Exxon Mobil Corp., 406 F. Supp. 3d 420 (D. Md. 2019), make
clear that liability may attach when a defendant substantially participates in creating
widespread harm, even absent direct control or land invasion. In this case, the allegations
that Defendants deceptively marketed and suppressed information about foreseeable
harms to Maryland residents, thereby causing localized and concrete public-rights impacts,
are sufficient to state a public nuisance claim and survive the motion to dismiss stage.
Properly cabined, this approach preserves accountability while avoiding the open-ended
regulation of lawful commercial activity.
The Baltimore City Circuit Court’s decision on Plaintiffs’ failure-to-warn claims
should also be reversed insofar as those claims are localized. Plaintiffs may pursue their
claims if they plausibly allege that Defendants knew or should have known of the risks and
72
suppressed or misrepresented that information. However, there is no global duty to warn
every user worldwide, which would violate due process and exceed the bounds of
foreseeability.
CONCLUSION
The Majority’s preemption holding rests on a false premise, applied through the
wrong framework, to claims none of its foundational cases addressed. The Clean Air Act
regulates emitters. It has never regulated deception. No provision of the CAA, no EPA
rule, and no congressional purpose conflicts with state authority to hold corporations
accountable for lying to their customers. That the Majority reached a different conclusion
is possible only because it never engaged the controlling authority: Cipollone and Altria
Group establish that state fraud and deceptive marketing claims survive federal preemption
even when the subject matter is federally regulated, and the Majority offers no explanation
why they do not govern here. Had the Majority engaged those controlling cases, the
reframing of these complaints as emissions regulation cases could not have survived
scrutiny. The States have always governed deceptive marketing. Where Congress has not
spoken clearly, the presumption runs against preemption—not toward it. Nothing in
federal law currently takes that authority away from Maryland. Novel arguments designed
to bypass that conclusion—by constitutionalizing displacement doctrine or
recharacterizing fraud claims as emissions regulation—are not a substitute for the
preemption analysis the controlling cases require. The Majority performed neither.
I do not presume to know how the Supreme Court will ultimately resolve the
question of whether state law claims like these are preempted by federal law. That question
73
is now before that Court, and it will answer it in due course. What I am confident of is
this: whatever the Supreme Court decides, it will decide it by applying its own preemption
precedents to the claims as actually pleaded—not by recharacterizing those claims into
something Plaintiffs disavowed, and not by superimposing a displacement theory designed
for federal common law onto causes of action that exist entirely under state law. The
discipline this Court did not exercise here is the discipline the Supreme Court will apply in
deciding this question.
The Majority “believe[s] that it could be useful for the United States Supreme Court
to have the benefit of a high court’s analysis that is different from that expressed by our
colleagues [in Colorado and Hawaii].” Maj. Slip Op. at *51 n.21. With respect, that is not
this Court’s role. A state supreme court’s role on a question of federal law that the Supreme
Court has accepted for review is not to stake out a position designed to influence that
court’s deliberations. It is to apply the law the Supreme Court has already articulated. That
is what this dissent attempts to do. The Majority, by its own account, is doing something
else.
For the reasons above, I dissent from the Majority’s preemption decision. Justice
Watts has authorized me to state that she joins in my dissent of the Majority’s preemption
decision. I join the Majority’s decision that Plaintiffs failed to state a claim on their private
nuisance and trespass claims. I concur in the Majority’s decision that Plaintiffs failed to
state a claim on their strict liability failure-to-warn claims, though on different
grounds. And I dissent from the Majority’s decision that Plaintiffs failed to state a claim
74
on their public nuisance and negligent failure-to-warn claims, which I would allow to
proceed.
75
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