Supreme Court Vacates Judgment Due to Jurisdictional Defect

1 (Slip Op inion) OCTOBER TERM, 2025 Syllabus NOTE: Where it is feasible, a syllabus (headnote) will be released, as is being done in connection with this case, at the t ime the opin ion is issue d. The syllabus constitutes no par t of the op inion of the Cour t but has been prepared by t he Report er of Decisions for the conve nience of the reader. See United States v. Detr oit Timber & Lumber Co., 200 U. S. 321, 337. SUPREME COURT OF THE UNI TED STATES Syllabus HAIN CELESTIAL GROUP, INC., ET AL. v. PALMQUIST, INDIVIDUALLY AND AS NEXT FRIEND OF E. P., A MINOR, ET AL. CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE FIFTH CIRCUIT No. 24–724. Argued November 4, 2025—Decided Februar y 24, 2026 Respondents Sarah an d Grant Palmquist fed their child E. P. baby food that was made by petitioner Hain Ce lestial Group, Inc., a nd that they purchased from petitioner Whole Food s Market, Inc. When E. P. was 2½ years old, he began exhibitin g serious developmental disorders and was diagnosed with a range of physical an d mental conditions that some doctors attributed to heav y-metal poisoning. In 2021, a subcom- mittee of the U. S. House of Repres entat ives released a staff report finding that certain baby foods, in cluding Hain’s, contained elev ated levels of toxic heavy metals. Following the report’s release, the Palmquists sued both Hain and Whol e Foods in Texas state court, al- leging state-law product liability an d negligence claims against Hain, and state-law breach -of-warranty and negligenc e claims against Whole Foods. Hain, a Delaware corp oration with a principal place of business in New York, removed the case to federal court based on di- versity of citizenship, b ut confronted a pro blem: Federal courts may exercise diversity jurisdiction only when no adverse party is from the same State, but Whole Foods and th e Palmquists are all Texas citi- zens. As a result, the Dis trict Court lacked jurisdiction a s the case stood upon removal. Hain s ought to cure this problem b y arguing in its notice of removal that Whole F oods had been improperly joined in the lawsuit and should be dismissed, which would ha ve established complete diversity between Hain an d the Palmquists. The District Court agreed with Hain, dismisse d Whole Foods, and denied the Palmquists’ motion to remand. The case then went to trial against

2 HAIN CELESTIAL GROUP, INC. v. PALM QUIS T Syllabus Hain alone in federal court. The Di strict Court granted Hain’s motion for judgment as a matter of law on all claims, ex plaining that the Palmquists had failed to present suffici ent evidence to prove causation. On appeal, the Fifth Circui t reversed the District Court ’s improper- joinder decision and dismissal of Whole Foods. Because Whole Foods had been improperly dismissed, th e Fifth Circuit co ncluded that the District Court lacked diversity j uri sdiction, that the District Court’ s judgment had to be vacated, and that the case had to be remanded to state court. This Court gra nted certiorari to res olve a divide among the Courts of Appeals on whether va catur is req uired in these circum- stances. Held: Because the District Court’s erroneous dismissal of Whole Foods did not cure the jurisdictional defect that existed when this case was removed to federal court, the Fifth Circuit correctly vacated the judg- ment in Hain’s favor. Pp. 4–11. (a) Federal courts are court s of limited jurisdiction, and a federal court of appeals must “sat isfy itself not only of its own jurisdiction, but also of that of the lower courts in a cause under review.” Mitchell v. Maurer, 293 U. S. 237, 244. In most cases, federal appellate cour ts assess the distr ict court’s jurisdic tion based on “the sta te of facts that existed at the time of filing.” Grupo Dataflux v. Atlas Global Group, L. P., 541 U. S. 567, 571. If the court of appeals concludes that the district court lacked j urisdiction over the case when it was filed in or removed to federal court, then the court of appeals typically must va- cate any judgment on the merits. One exception to this general rule is releva nt here: If a district court cures a jurisdictiona l defect before final judgm ent, then the court of appeals is not required to vacate that judgment even if, at some earlier point in the case, the dist rict court lacked jurisdiction. The Court dis- cussed this exception in Caterpillar Inc. v. Lewis, 519 U. S. 61, in which the nondiverse defendant was fully di smissed with all of the parties’ consent through a partial final judgment under Federal Rule of Civil Procedure 54(b), leaving behind a completely diverse set of parties be- fore trial commenced. In those circu mstances, the Court held that the jurisdictional defect had been cu re d and the verdict could stand despite the District Court’s ea rlier “ statutory misstep” in denying the motion to remand. Id., at 73. On the other ha nd, the Court stated, had the jurisdictional defect not been cured and ins tead “lingered through judgment,” then vacatur wo uld have been required. Id., at 76–77. Pp. 5–7. (b) The core dispute in this case is whether Whole Foods’s erroneous dismissal before final j udgment cured the jurisdictiona l defect that ex- isted at the time of removal. It did not. The District Cour t’s dismissal of Whole Foods as improperly joined was both erroneous and

3 Cite as: 607 U. S. ___ (2026) Syllabus “[i]nterlocutory,” meaning it did “not dispose of the whole case” and “merge[d] into the final judgmen t” for “revie[w] on appeal.” Dupree v. Younger, 598 U. S. 729, 734, 735. When the Fifth Circu it reversed the District Court’s error, it restored Whole Foods to the case and thus destroyed complete diversity. As a res ult, the jurisdictional defect “lin- gered through judgment” uncured and the judgment “must be va- cated.” Caterpillar, 519 U. S., at 77. Hain argues that the correct ness of the District Court’s dis missal is irrelevant because the parties were c ompletely diverse by the time of final judgment, but the Court has never held that a district cour t can create jurisdiction t hrough its own mistakes. A rule to the cont rary would permit courts to enlarge th eir jurisdiction beyond the limits Congress imposed. Hain also appeals to efficiency, arguin g that it would be wasteful to send this cas e back to state court for a new trial. The “considerations of finality, effi ciency, and economy” recognized in Caterpillar, 519 U. S., at 75, however, were relevant only to excusing noncompliance with the removal stat ute’s requirement of complete di- versity at the time of removal afte r a jurisdictional defect has been properly and finally cured. As to the jurisdicti onal requirement itself, Caterpillar held that an uncured juris dic tional defect means that “the judgment must be vacated.” Id., at 76–77. Pp. 7–9. (c) Finally, Ha in argues that Wh ole Foods should now be dismissed under Federal Rule of Civil Proc edure 21, which pe rmits a federal court to “add or drop a party” “on just terms.” In Newman-Green, Inc. v. Alfonzo-Larrain, 490 U. S. 826, 833, 837–838, the Cou rt held that courts may use Ru le 21 “to dismiss a dispe nsable nondiver se party” in appropriate circu mstances, but must “carefully consider whether the dismissal ... will prejudice any of th e parties in the litigation.” This case is unlike Newman-Green, in which the plaintiff sought the dismis- sal, because here a defendant is seeking dism issal of another, non- diverse defendant. The identity of the party as king for the dismissal is important because “[t]he plaintiff is ‘the master of the complaint,’ ” and generally has the right t o choose whether to proceed in federal or state court. Royal Canin U. S. A., In c. v. Wullschleger, 604 U. S. 22, 35. Hain’s proposed use of Rule 21 would force the Palmquists to liti- gate this case in federal court ag ainst their wishes and despite thei r right to control the forum for this case. See Atlantic Marine Constr. Co. v. United States Dist. Court for Wester n Dist. of Tex., 571 U. S. 49, 63. The Palmquists exercised thei r right to choose a sta te forum by purposefully and proper ly joining a nondiver se defendant against whom they could not proceed in fede ral court, and diligently asserted that right by promptly moving to remand the case to state c ourt. Rule 21 does not permit a court o r a defendant to override th eir choice in these circumstances. Pp. 9–10.

4 HAIN CELESTIAL GROUP, INC. v. PALM QUIS T Syllabus 103 F. 4th 294, affirmed and remanded. S OTOMAYOR, J., delivered the opinion for a unanimous Court. T HOMAS, J., filed a concurring opinion.

_________________ _________________ 1 Cite as: 607 U. S. ____ (2026) Opinion of the Court NOTICE: This opinion is s ubject to f ormal revision before publicat ion in the United States R eports. Readers are req uested to notify the Rep orter of Decisions, S upreme Court of the United Sta tes, Washing ton, D. C. 20543, pio@supr emecourt.gov, of any t ypographica l or other f ormal errors. SUPREME COURT OF THE UNI TED STATES No. 24–724 THE HAIN CELESTIAL GROUP, INC., ET AL., PETITIONERS v. SARAH PALMQUIST, INDIVIDUALLY AND AS NEXT FRIEND OF E. P., A MINOR, ET AL. ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE FIFTH CIRCUIT [February 24, 2026] J USTICE S OTOMAYOR delivered the opinion of the Court. Federal courts are courts of limited jurisdiction and gen- erally can resolve only the cases that Congress grants them power to hear. One class of cases over which Congress has given federal courts jurisdiction is “diversity” cases between “citizens of different States.” 28 U. S. C. §1332(a). If a federal court of appeals finds that a district court lacked jurisdiction over a case (for example, because the parties turned out not to be from different States), then the district court’s judgment on the merits must be vacated. A district court’s judgment can stan d, however, if the district court “cured” the jurisdictional defect before entering final judgment, such as by proper ly dismissing a nondiverse party from the case. This case asks whether a district court’s erroneous dis- missal of a nondiverse party before final judgment can cure a jurisdictional defect that ex isted when the case was re- moved to federal court. The Fi fth Circuit held that it can- not, and this Court agrees. In these circumstances, the

2 HAIN CELESTIAL GROUP, INC. v. PALM QUIS T Opinion of the Court district court’s final judgment must be vacated for lack of jurisdiction. I Respondents Sarah Palmquist and Grant Palmquist have a young son, E. P., who was born in 2014. For the first two years of E. P.’s life, the Palmquists fed him baby food that was made by petitioner Hain Celestial Group, Inc., and that they purchased from petitioner Whole Foods Market, I nc. At first, E. P.’s development progressed ordinarily, and he was a healthy child. Things changed when E. P. was 2½ years old. He began exhibiting serious developmental dis- orders and was diagnosed with a range of physical and men- tal conditions. After identifying high levels of arsenic, lead, and mercury in E. P.’s blood tests, some doctors attributed these conditions to heavy-metal poisoning. In 2021, years after E. P.’s diagnosis, a subcommittee of the U. S. House of Representatives Committee on Oversight and Reform re- leased a staff report finding that certain baby foods, includ- ing Hain’s, contained elevated le vels of toxic heavy metals. See Staff Report, Subcommittee on Economic and Con- sumer Policy, Baby Foods Are Tainted With Dangerous Levels of Arsenic, Lead, Cadmium, and Mercury 2–4 (Feb. 4, 2021). Following the report’s release, the Palmquists sued both Hain and Whole Foods in Texas sta te court. As to Hain, the Palmquists alleged state-law product liability and negli- gence claims. As to Whole Foods, the Palmquists alleged state-law breach of warranty and negligence claims based on Whole Foods’s alleged misrepresentation of H ain’s prod- ucts as safe for consumption. Hain removed the case to federal court based on the par- ties’ diversity of citizenship. At the time of removal, how- ever, Hain confronted a problem. Generally, 28 U. S. C. §1332(a) allows federal courts to exercise jurisdiction only when the parties are completely diverse, which means that

3 Cite as: 607 U. S. ____ (2026) Opinion of the Court no adverse party is from the same State, and the amount in controversy exceeds $75,000. Lincoln Property Co. v. Roche, 546 U. S. 81, 89 (2005). As the case stood upon removal, though, this requirement was not met. The Palmquists were Texas citizens. Hain was a Delaware corporation with a principal place of business in New York, and so was both a Delaware and New York citizen. Whole Foods, however, was headquartered in Texas and so was, like the Palmquists, a Texas citizen. Because Whole Foods and the Palmquists were all Texas citi zens, the parties were not completely diverse. Hain nevertheless argued in it s notice of removal that re- moval was proper because Whole Foods had been impro p- erly joined and should be dismissed, which would leave only parties who were completely diverse in federal court. The Palmquists disagreed, argued that Whole Foods was properly joined, and moved to remand the case to state court given the lack of diversity jurisdiction. 1 The District Court sided with Hain. Under Fifth Circuit precedent, which was not disputed here, a defendant is im- properly joined if the plaintiff fails to “state a claim for relief that is facially plausible” against the defendant. 103 F. 4th 294, 304 (2024); see Smallwood v. Illinois Central R. Co., 385 F. 3d 568, 573 (2004) (en banc). Applyin g that test, the District Court concluded that the Palmquists had not al- leged a plausible claim against Whole Foods. It thus dis- missed Whole Foods and denied the Palmquists’ motion to remand. The Palmquists then went to trial against Hain in federal court. After the Palmquists rested their case, Hain moved for judgment as a matter of law on all claims. The District Court granted that motion in full, explaining that the —————— 1 Improper joinder is also oft en referred to as “fraudulent joinder.” Be- cause there are no allegations of frau d by the Palmquis ts in this case, the Court uses the term “improper joinder.”

4 HAIN CELESTIAL GROUP, INC. v. PALM QUIS T Opinion of the Court Palmquists had failed to present sufficient evidence to the jury to prove that “the ingestion of heavy metals can cause the array of symptoms that [E. P.] suffers from, much less any evidence of at what level those metals would have to be ingested to bring about those symptoms.” 103 F. 4th, at 300. The Palmquists appealed that judgment along with the District Court’s improper-joinder decision that had dis- missed Whole Foods. The Fifth Circuit reversed the improper-joinder decision and vacated the District Court’s j udgment. The Court of Appeals held that Whole Foods was properly joi ned because the Palmquists had plausibly alleged that Whole Foods had violated state law by misrepresenting Hain’s products as safe. Given that Whole Foods had been erroneously dis- missed, the action was not dive rse. The Court of Appeals then concluded that the District Court lacked jurisdiction and that the judgment in Hain’s favor had to be vacated. The Fifth Circuit denied en banc review. Hain and Whole Foods filed a timely petition for certio- rari seeking review of the Fifth Circuit’s holding that the District Court’s judgm ent must be vacated. One other Court of Appeals has held that vacatur is not required in these circumstances, while another agrees with the Fifth Circuit and has held that it is. 2 The Court granted certio- rari to resolve the divide among the Courts of Appeals. See 604 U. S. 1267 (2025). II It is important to emphasize at the outset “two ‘givens’ in this case.” Caterpillar Inc. v. Lewis, 519 U. S. 61, 70 (1996). First, no party asks this Court to revisit the F ifth Circuit’s holding that the District Court’s improper-joinder decision was incorrect and that Whole Foods should not have been —————— 2 Compare Junk v. Terminix Int’l Co., 628 F. 3d 439, 447, 450–451 (CA8 2010), with Henderson v. Washington Nat. Ins. Co., 454 F. 3d 1278, 1284–1285 (CA11 2 006).

5 Cite as: 607 U. S. ____ (2026) Opinion of the Court dismissed. See Brief for Petitioners 7, n. 1. Second, no party disputes that, had the District Court performed the joinder analysis correctly when the case was initially re- moved, it would have lacked jurisdiction and would have been required to remand the case to state court. See 28 U. S. C. §§1332(a), 1447(c). What remains for this Court to decide is whether the District Court, having erroneously dismissed Whole Foods, had jurisdiction to enter a final judgment as to Hain. It did not. A Federal courts “are all of limited jurisdiction, and their proceedings are erroneous, if the jurisdiction be not shown upon them.” Kempe’s Lessee v. Kennedy, 5 Cranch 173, 185 (1809) (Marshall, C. J.). Because of this limitation on fed- eral courts’ authority, a federal court of appeals must “sat- isfy itself not only of its own jurisdiction, but also of that of the lower courts in a cause under review.” Mitchell v. Maurer, 293 U. S. 237, 244 (1934). In most c ases, federal appellate courts assess the district court’s jurisdiction based on “the state of facts that existed at the time of filing.” Grupo Dataflux v. Atlas Global Group, L. P., 541 U. S. 567, 571 (2004). If the court of appeals concludes that the dis- trict court lacked jurisdiction over the case when it was filed in or removed to federal court, then the court of appeals typ- ically must vacate any judgment on the merits. See Wil- liams v. Zbaraz, 448 U. S. 358, 368 (1980); American Fire & Casualty Co. v. Finn, 341 U. S. 6, 17–18 (1951). There is, however, one exception to the general rule rele- vant to this case. If a distri ct court “cures” a jurisdictional defect prior to final judgment, then the court of appeals is not required to vacate that judg ment even if, at some earlier point in the case, the district court lacked jurisdiction. The Court discussed this exception in Caterpillar Inc. v. Lewis, 519 U. S. 61. In Caterpillar, Lewis was a citizen of Kentucky who brought a product- liability suit in state court

6 HAIN CELESTIAL GROUP, INC. v. PALM QUIS T Opinion of the Court against Caterpillar, a Delaware- and Illinois-based equip- ment manufacturer, and Whayne Supply, a Kentucky com- pany that serviced Caterpillar equipment. Id., at 64–65. Lewis’s insurer (a Massachusetts corporation) intervened as a plaintiff and asserted claims against both Whayne and Caterpillar. Id., at 65. At that point, complete diversity was lacking, as there was one plaintiff (Lewis) and one de- fendant (Whayne) from Kentucky. Lewis then settled his claims against Whayne. Ibid. C a t - erpillar, thinking that the settlement would result in Whayne’s dismissal from the case, promptly removed the case to federal court. Ibid. Lewis moved to remand, point- ing out that Whayne was still in the case because the in- surer had not settled its claim against Whayne. Id., at 65– 66. Without addressing Lewi s’s argument, the District Court erroneously denied the motion to remand, keeping the case in federal court. Id., at 66. Whayne eventually settled with the insurer and was voluntarily dismissed from the case via a partial final judgment under Federal Rule of Civil Procedure 54(b). See App. A to Brief for Respondents. That dismissal left three completely diverse parties in the case: Lewis (from Kentucky), the insurer (from Massachu- setts), and Caterpillar (from Delaware and Illinois). The case then went to trial, at which Caterpillar pre- vailed. 519 U. S., at 66–67. Lewis appealed, and the Sixth Circuit vacated the verdict. It hel d that the District Court should have remanded the case because, at the time of re- moval, complete diversity did not exist. Id., at 67. This Court reversed. It held that, because Whayne had been fully dismissed, “the jurisdictional defect [had been] cured, i. e., complete diversity [had been] established before the trial commenced.” Id., at 73. Because “considerations of finality, efficiency, and economy become overwhelming” after “a diversity case has been tried in federal court,” t he Court held that the verdict could stand despite the District Court’s “ statutory misstep” in denying the motion to

7 Cite as: 607 U. S. ____ (2026) Opinion of the Court remand. Id., at 73, 75, 77. On the other hand, the Court stated, had the jurisdictional defect not been cured and in- stead “lingered through judgment,” then v acatur would have been required. Id., at 76–77. B The core dispute in this case is whether Whole Foods’s erroneous dismissal before final judgment cured the juris- dictional defect that existed at the time of removal. It did not. Because the jurisdictional defect lingered through judgment, the judgment “must be vacated.” Id., at 77. When Hain removed this case to federal court, the Dis- trict Court was required to dete rmine whether it had juris- diction by ensuring that none of the plaintiffs was from the same State as any of the defendants. Because Whole Foods (a defendant) and the Palmquist s (the plaintiffs) were all Texas citizens, the District Court lacked jurisdiction. It then tried to cure that jurisd ictional defect by dismissing Whole Foods as improperly joined. That dismissal, the Fifth Circuit held, was erroneous. It was also “[i]nterlocutory,” meaning that it did “not dispose of the whole case.” Dupree v. Younger, 598 U. S. 729, 734 (2023). The “ ‘general rule’ ” is that parties cannot immedi- ately appeal interlocutory orders and must instead wait un- til the end of the case, when thos e orders “merge into the final judgment” and are “reviewab le on appeal” from that judgment. Id., at 735 (quoting Quackenbush v. Allstate Ins. Co., 517 U. S. 706, 712 (1996)). Under that general rule, once the District Court entered final judgment in Hain’s fa- vor, the court’s earlier jurisd ictional holding merged into the judgment and was reviewable by the Court of Appeals as part of the Palmquists’ post-trial appeal. On appeal, the question before the Court of Appeals was whether the District Court had correctly dismissed Whole Foods at the outset. If it had, then this case would be more like Caterpillar, where the District Court correctly and

8 HAIN CELESTIAL GROUP, INC. v. PALM QUIS T Opinion of the Court finally dismissed Whayne with the parties’ consent and left behind a completely diverse set of parties. Whole Foods, however, was not dismissed correctly, and the interlocutory nature of that dismissal meant that it was reversible on appeal from the final judgment in Hain’s fa- vor. Whole Foods thus was only temporarily and errone- ously removed from the case; it was not “gone for good.” Royal Canin U. S. A., Inc. v. Wullschleger, 604 U. S. 22, 33 (2025). When the Fifth Circuit reversed the District Court’s error, it restored Whole Foods to the case and correctly held that the jurisdictional defect had not been cured. That meant that the defect “lingered through judgment” and that the District Court’s judgment therefore “must be vacated.” Caterpillar, 519 U. S., at 77. In Hain’s view, the correctness of the District Court’s dis- missal is irrelevant because, like in Caterpillar, the parties were completely diverse by the time of final judgment. Hain is mistaken. This Court has never held that a district court can create jurisdiction through its own mistakes. A rule to the contrary would permit courts to enlarge their jurisdiction beyond the lim its Congress imposed. Cf. Kok- konen v. Guardian Life Ins. Co. of America, 511 U. S. 375, 377 (1994) (“Federal courts . . . possess only that power au- thorized by Constitution and statute, which is not to be ex- panded by judicial decree” (citations omitted)). Hain also appeals to efficien cy, arguing that it would be wasteful to send this case back to state court for a new trial. This argument also fails. To be sure, Caterpillar recognized that “considerations of finality, efficiency, and economy be- come overwhelming” after “a di versity case has been tried in federal court.” 519 U. S., at 75. Those considerations, however, were relevant only to excusing noncompliance with the removal statute’s re quirement “that there be com- plete diversity at the time of removal” after a jurisdictional defect had been properly and finally cured. Grupo Dataflux, 541 U. S., at 574. As to the jurisdictional requirement

9 Cite as: 607 U. S. ____ (2026) Opinion of the Court itself, Caterpillar held that an uncured jurisdictional defect means that “the judgment must be vacated,” 519 U. S., at 76–77, regardless of how efficient it might be to leave the judgment in place. That the parties may need to litigate a new trial in state court does not change the j urisdictional analysis or make the District Court’s error an effective cure. 3 III As a fallback, Hain argues that, even if the jurisdictional defect was not cured, Whole Foods should now be dismissed under Federal Rule of Civil Procedure 21. That Rule per- mits a federal court “on its own” to “add or drop a party” “on just terms.” This argument is unavailing. 4 In Newman-Green, Inc. v. Alfonzo-Larrain, 490 U. S. 826 (1989), this Court held that, in appropriate circumstances, courts may use Rule 21 “to dismiss a dispensable non- diverse party.” Id., at 833, 837. To do so, courts must “care- fully consider whether the dismissal of a nondiverse party will prejudice any of the parties in the litigation,” as “[i]t may be that the presence of the nondiverse party produced a tactical advantage for one party or another.” Id., at 838. —————— 3 Other procedur al mechanisms may be av ailable to redu ce wasteful litigation. For instance, both partia l final judgment under Federal Rule of Civil Procedure 54(b) and cer tificat ion under 28 U. S. C. §1292(b) allow district courts to certify m atters for early appeal. Those procedures could help resolve any uncert ainty over wh ether a nondiverse party should re- main in the case at the time of removal and avoid the need to wait until a post-trial appeal. See Tr. of Oral Arg. 20–23, 34–36. 4 The Palmquists contend th e Rule 21 ar gument was forfeited, but it is fairly included within th e question presented, was raised in the petition for certiorari, and was pressed before the Fifth Circuit. See Pet. for Cert. i, 22–24 (arguing that “appell ate courts ... ha[ve] dismissed dispensable nondiverse parties in order to preserve jurisdiction a s to diverse parties” and citing Newman-Green, Inc. v. Alfonzo-Larrain, 490 U. S. 826, 834– 836 (1989)); Brief for Whole Foods in No. 23–401 97 (CA5), p. 16; see also this Court’s Rule 14.1(a).

10 HAIN CELESTIAL GROUP, INC. v. PALM QUIS T Opinion of the Court This case is very different from Newman-Green. Here, the defendants are seeking dismissal of a nondiverse de- fendant, whereas in Newman-Green, the plaintiff sought the dismissal. Id., at 829. The identity of the party asking for the dismissal is important because “[t]he plaintiff is ‘the master of the complaint,’ ” and generally has the right to choose whether to proceed in federal or state court. Royal Canin, 604 U. S., at 35. Dismissing a nondiverse party with the plaintiff ’s consent is consistent with that right, as is a plaintiff ’s ability to amend the complaint to “bring the sui t either newly within or newly outside a federal court’s juris- diction.” Id., at 35–36. Hain’s proposed use of Rule 21, however, would force the Palmquists to litigate this case in federal court against their wishes and despite their right to control the forum for this case. Hain cites no cases in which a court used Rule 21, over the plaintiff ’s consistent objections, to dismiss a properly joined defendant to pr eserve jurisdiction over an incorrectly removed case that never should have been in federal court. That lack of authority is not surprising. The prejudice to the plaintiff in such circumstances is clear, for “plaintiffs are ordinarily allowed to select whatever forum they consider most advantageous.” Atlantic Marine Constr. Co. v. United States Dist. Court for Western Dist. of Tex., 571 U. S. 49, 63 (2013). The Palmquists exercised their right to choose a state forum by purposefully and properly joining a nondiverse defendant against whom they could not proceed in federal court, and diligently asserted that right by promptly moving to remand the case to state court. The decision to structure thei r case in this way was the Palmquists’ to make; Rule 21 does not permit a court or a defendant to override their ch oice in these circumstances. 5 —————— 5 Some courts have used Ru le 21 to dismiss nondiverse parties joined after the case was properly remo ved to federal court. See, e. g., Gorfinkle v. U. S. Airways, Inc., 431 F. 3d 19, 21–23 (CA1 2005). Bec ause Whole Foods was named in the original stat e-court complaint in this case, the

11 Cite as: 607 U. S. ____ (2026) Opinion of the Court IV The District Court’s erroneous dismissal of Whole Foods did not cure the jurisdictional defect that existed when this case was improperly removed to f ederal court. The Court of Appeals therefore correctly vacated the judgment in Hain’s favor. The judgment of the Court of Appeals is af- firmed, and the case is remanded for further proceedings consistent with this opinion. It is so ordered. —————— Court expresses no view on whether using Rule 2 1 to dismiss a non- diverse party added after a proper re moval is appropriate. The Court also expresses no view as to Rule 21’ s r ole in cases or iginally filed by plaintiffs in federal court. See, e. g., Publicker Industries, Inc. v. Roman Ceramics Corp., 603 F. 2d 1065, 1067, 1069 (CA3 1979).

_________________ _________________ 1 Cite as: 607 U. S. ____ (2026) T HOMAS, J., concurring SUPREME COURT OF THE UNI TED STATES No. 24–724 THE HAIN CELESTIAL GROUP, INC., ET AL., PETITIONERS v. SARAH PALMQUIST, INDIVIDUALLY AND AS NEXT FRIEND OF E. P., A MINOR, ET AL. ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE FIFTH CIRCUIT [February 24, 2026] J USTICE T HOMAS, concurring. I join the Court’s opinion in full. I write separately to note my skepticism of the do ctrine of “improper joinder, ” which the District Court invoked to dismiss Whole Foods in this case. The doctrine appear s to allow federal courts to enlarge their jurisdiction by assessing the merits of claims over which they lack jurisdiction. “Federal courts are courts of limited jurisdiction.” Kok- konen v. Guardian Lif e Ins. Co. of America, 511 U. S. 375, 377 (1994). As “an essential ingredient of separation and equilibration of powers,” the Constitution gives Congress broad power over the scope of federal courts’ jurisdiction. Steel Co. v. Citizens for Better En vironment, 523 U. S. 83, 101 (1998). “When we assume jurisdiction too hastily, we risk aggrandizing ourselves at the expense of the political branches.” Monsalvo V elazquez v. Bondi, 604 U. S. 712, 737 (2025) (T HOMAS, J., dissenting). Accordingly, if a federal court determines that it lacks jurisdiction in a case, “the only function remaining to the court is that of announcing the fact and dismissing the cause.” Ex parte McCardle, 7 Wall. 506, 514 (1869). Federal courts therefore “must determine that they have jurisdiction before proceeding to the merits.” Lance v.

2 HAIN CELESTIAL GROUP, INC. v. PALM QUIS T T HOMAS, J., concurring Coffman, 549 U. S. 43 7, 439 (2007) (per curiam). “The re- quirement that jurisdiction be established as a threshold matter spring[s] from the nature and limits of the judicial power of the United States and is inflexible and without ex- ception.” Steel Co., 52 3 U. S., at 94–95 (internal quotation marks omitted). “For a court to pronounce upon” the merits “when it has no jurisdiction to d o s o i s, b y v e r y d e f i n i t i o n, for a court to act ultra vires.” Id., at 101–102. In this case, federal jurisdiction was based on diversity of citizenship. The removing defendant, Hain Celestial Group, invoked federal jurisdiction under 28 U. S. C. §1332(a), which gives district courts jurisdiction over “civil actions where the matter in controversy ex ceeds the sum or value of $75,000 . . . and is between . . . citizens of different States.” This Court has always interpreted § 1332(a)’s lan- guage “to require ‘complete diversity,’ ” meaning that a fed- eral court can exercise jurisdicti on only if no pl aintiff shares state citizenship with any defendant. Carden v. Arkoma Associates, 494 U. S. 185, 187 (1990) (citing Strawbrid ge v. Curtiss, 3 Cranch 267 (1806)). Although the parties in this case were not completely di- verse, the District Court exerci sed jurisdiction based on the doctrine of “improper joinder.” Under that doctrine, federal courts exercise jurisdiction ov er cases that originally in- volved nondiverse defendants by first deeming the claims against those nondiverse defendants sufficiently weak on the merits and then dismissing them. See, e. g., Interna- tional Energy Ventures Mgmt., L.L.C. v. United Energy Group, Ltd., 818 F. 3d 193, 205–209 (CA5 2016). Here, the Palmquists, Texas citizens, sued both an out-of-state de- fendant, Hain Celestial Group, and a Texas defendant, Whole Foods. The District Court therefore lacked jurisdic- tion over the case when it wa s removed to federal court. The District Court nonetheless proceeded to dismiss Whole Foods based on its merits assessment that there was not a “reasonable basis to predict that [the Palmquists] could

3 Cite as: 607 U. S. ____ (2026) T HOMAS, J., concurring recover from Whole Foods” under Texas products-liability law. App. to Pet. for Cert. 25a–26a. After dismissing Whole Foods, it adjudicated the claims against Hain Celestial on the merits. The Fifth Circuit vacated that meri ts judgment for lack of jurisdiction, but not because it thought that conducting an improper-joinder inquiry was inappropriate. 103 F. 4th 294, 302–307 (2024). It simply thought that the Palmquists possibly stated meritorious claims against Whole Foods un- der Texas law. See id., at 305–307. It reaffirmed that the improper-joinder doctrine allows federal courts to engage in a “Rule 12(b)(6)-type analysis” of claims against nondiverse defendants, albeit with legal ambiguities resolved in the plaintiffs’ favor. Id., at 306. Federal Rule of Civil Proce- dure 12(b)(6) dismissals, of course, are merits determina- tions. See Federated Department Stores, Inc. v. Moitie, 452 U. S. 394, 399, n. 3 (1981). Other federal courts adopt a similar approach to dismiss claims against nondiverse parties. See, e.g., Johnson v. Midwest Div. - RBH, LLC, 88 F. 4th 731, 735–736 (CA8 2023); Jerome-Duncan, Inc. v. Auto-By-Tel, L. L. C., 176 F. 3d 904, 907–909 (CA6 1999); Legg v. Wyeth, 428 F. 3d 1317, 1324, 1320–1325 (CA11 2005). Courts justify this ap- proach based on a group of this Court’s earl y-20th-century precedents that recognized a doctrine called fraudulent joinder. See, e. g., Alabama Great Southern R. Co. v. Thompson, 200 U. S. 206, 217 (1906).* —————— *Many Circuits still use the “fraudul ent joinder” term today, even when they engage in the same merits analysis that the Fifth Circuit more accurately calls improp er joinder. See, e. g., Johnson, 88 F. 4th, at 735– 736 (holding that “joinder ... was fraudulent” because state-law claim was unlikely to succeed on the merits); Jerome-Duncan, Inc., 176 F. 3d, at 907–909 (affirming “fraudulent joinder” dismissal be cause of weak- ness of claim under state law); Cline v. Dart Transit Co., 804 Fed. Appx. 307, 312 (CA6 2020) (holding that “fraudu lent joinder occurred” becau se plaintiff lacked “a colorable cause of action”).

4 HAIN CELESTIAL GROUP, INC. v. PALM QUIS T T HOMAS, J., concurring But this Court’s precedents do not support the lower courts’ more recent approach. As I read them, this Court’s “fraudulent joinder” precedents concerned only whether the plaintiff avoided federal diversity jurisdiction by bad faith or actual fraud—such as lying about a party’s conduct or citizenship. See Alabama Great Southern R. Co., 200 U. S., at 218 (asking whether the plai ntiff “attempt[ed] to commit a fraud upon the jurisdiction of the Federal courts”); Illinois Central R. Co. v. Sheegog, 215 U. S. 308, 316 (1909) (asking whether a claim was “fraudulent and false”); Mecom v. Fitz- simmons Drilling Co., 284 U. S. 183, 190 (1931) (asking whether the plaintiff committed “actual fraud”). These precedents were limited to cases of “extreme abuse.” Mur- riel-Don Coal Co. v. Aspen Ins. UK Ltd., 790 F. Supp. 2d 590, 596 (ED Ky. 2011) (Thapa r, J.). Unlike the lower courts’ more recent decisions, they did not appear to turn on the strength of the claims on the merits. Federal courts sitting in di versity likely cannot dismiss nondiverse parties based on their view of the merits of the claims against those parties. Doing so appears unfaithful to Congress’s limits on our dive rsity jurisdiction and incon- sistent with this Court’s precedents. As Judge Thapar has put it, the improper-joinder doctrine “requires federal courts to exercise jurisdiction where none exists over ques- tions of state law that the stat e courts are better suited to address themselves.” Id., at 597. In a future case where the issue is briefed and squarely presented, this Court should consider the propriety of the improper-joinder doc- trine.