Washington AG Joins Lawsuit Challenging EPA's Rescission of Endangerment Finding

WA Attorney General News Releases

Filed March 19th, 2026

Detected March 19th, 2026

Summary

Washington Attorney General Nick Brown joined a coalition of 24 states, DC, the U.S. Virgin Islands, and 12 cities and counties in challenging the EPA's rescission of its 2009 Endangerment Finding. This finding determined that greenhouse gas emissions from motor vehicles contribute to climate change and endanger public health. The lawsuit opposes the EPA's rollback of vehicle greenhouse gas standards.

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What changed

Attorney General Nick Brown, on behalf of Washington State, has joined a multi-jurisdictional coalition in filing a legal challenge against the U.S. Environmental Protection Agency (EPA). The challenge specifically targets the EPA's recent action to rescind its 2009 Endangerment Finding, which established that greenhouse gas emissions from motor vehicles contribute to air pollution that endangers public health and welfare. This rescission, according to the coalition, unlawfully repeals existing and future federal greenhouse gas standards for vehicles, disregarding scientific evidence and legal obligations under the Clean Air Act.

The practical implication of this lawsuit is that regulated entities, particularly in the automotive sector, may see the rollback of greenhouse gas standards reversed if the challenge is successful. The coalition argues that the EPA's action ignores the documented impacts of climate change, such as increased flooding and wildfires, which disproportionately affect vulnerable populations and state economies. Compliance officers should monitor the progress of this litigation as it could reinstate or maintain federal emissions standards for vehicles, impacting compliance strategies and potentially leading to future regulatory requirements.

What to do next

Monitor litigation challenging EPA's rescission of the 2009 Endangerment Finding.
Assess potential impact on vehicle emissions compliance strategies if the challenge is successful.

Source document (simplified)

FOR IMMEDIATE RELEASE:

Mar 19 2026

Coalition of states, counties, and cities across the country mount legal challenge in opposition to EPA’s unlawful rollback

Attorney General Nick Brown today joined a coalition of 24 states, the District of Columbia, the U.S. Virgin Islands, and 12 cities and counties to challenge the U.S. Environmental Protection Agency’s (EPA) unlawful attempt to rescind its 2009 Endangerment Finding, which determined that greenhouse gas emissions from motor vehicles contribute to air pollution that drives climate change and endangers public health and welfare.

“The administration’s actions continue to ignore the real consequences of climate change for Washingtonians: increased air pollution, more frequent flooding, rising storm surges on the coasts, reduced snowpack in the mountains, and the destruction and smoke impacts of increasing wildfires throughout the state,” said Brown. “Washington is leading the nation in addressing climate change, but the federal government has an obligation to acknowledge what’s driving it and to protect people from pollution.”

The 2009 Endangerment Finding was the direct result of the landmark 2007 Supreme Court decision in Massachusetts v. EPA, which confirmed EPA’s authority under the Clean Air Act to regulate greenhouse gas emissions that threaten public health and welfare. In response to that opinion and after years of scientific review, EPA confirmed in 2009 that greenhouse gas emissions from motor vehicles contribute to air pollution that harms public health and welfare in numerous ways. The agency then set standards that have successfully reduced greenhouse gas emissions from motor vehicles.

Now, almost two decades later, EPA has rushed a rulemaking process to rescind the Endangerment Finding and repeal all motor vehicles greenhouse gas standards, blatantly disregarding the law and science. EPA’s rescission rests on the flawed assertion — soundly rejected by the Supreme Court — that it lacks legal authority to regulate greenhouse gas emissions and ignores longstanding scientific evidence that greenhouse gases endanger public health and welfare. The rule eliminates all existing and future federal greenhouse gas standards for vehicles, violating the agency’s legal obligations and fundamental responsibility to protect public health and welfare from environmental harm under the Clean Air Act.

Greenhouse gas pollution is overheating the planet and directly harms Washingtonians in their everyday lives. Climate change drives more frequent and intense flooding, fire, and heat waves, all of which harm the health and wellbeing of Washington residents. Climate change-related health risks are often greatest for the elderly, children, those with existing chronic health conditions, individuals with greater exposure to outside conditions, those with limited access to health resources, and those who are disproportionately burdened by environmental harms. The rapidly changing climate is also significantly and adversely affecting our coasts, our mountains, and our forests, threatening the associated industries that support the state’s economy such as shellfish farming, forestry, and hydropower.

In the fall of 2025, a coalition of 23 attorneys general and seven counties and cities submitted two comment letters urging the EPA to abandon the proposal, arguing that it would violate settled law, Supreme Court precedent, and scientific consensus. The coalition also warned this action would endanger hundreds of millions of Americans — particularly communities disproportionately burdened by environmental harms — and cause unprecedented disruption to the regulatory landscape with catastrophic consequences for residents, industries, natural resources, and public investments.

Brown joins this challenge, which is led by the attorneys general of California, Connecticut, New York and Massachusetts, with the attorneys general of: Arizona, Colorado, Delaware, Hawai‘i, Illinois, Maine, Maryland, Michigan, Minnesota, New Jersey, New Mexico, Nevada, North Carolina, Oregon, Rhode Island, Vermont, Virginia, Wisconsin, the District of Columbia, and the U.S. Virgin Islands. In addition, this challenge is joined by Pennsylvania Governor Josh Shapiro; City of Albuquerque, New Mexico; City of Boston, Massachusetts; City of Chicago, Illinois; City of Cleveland, Ohio; City of Columbus, Ohio; City and County of Denver, Colorado; City of Los Angeles, California; City of New York, New York; City and County of San Francisco, California; King County, Washington; Santa Clara County, California; and Harris County, Texas.

Read the complaint here.

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