States and cities sue EPA over repeal of endangerment climate finding

In the lawsuit filed Thursday, 24 states, plus 10 cities and five counties, asked a federal appeals court to overturn the EPA’s rescission of the 2009 “endangerment” finding—an Obama-era determination that the agency had relied on when regulating greenhouse gas emissions under the Clean Air Act. The states and local governments said the EPA’s move removed the scientific and legal basis that had been central to U.S. efforts to limit climate change.

The legal challenge centers on a rule the EPA finalized last month that revoked the 2009 endangerment finding. That finding, the plaintiffs said, had determined that carbon dioxide and other greenhouse gases threaten public health and welfare, and it served as the legal underpinning for many Clean Air Act greenhouse gas rules affecting motor vehicles, power plants and other pollution sources that contribute to warming the planet.

Plaintiffs argued that repealing the endangerment determination would do more than undo one climate regulation. The lawsuit says the rescission eliminated greenhouse gas emissions standards for cars and trucks, and it could also unleash a broader undoing of regulations for stationary sources such as power plants and oil and gas facilities.

The states and local governments filed the case in the U.S. Court of Appeals for the District of Columbia Circuit, and the suit is described as the second major challenge to the EPA’s endangerment repeal. A separate lawsuit filed last month by public health and environmental groups has already targeted the rescission.

Letitia James, New York’s attorney general, led the effort along with attorneys general from Massachusetts, California and Connecticut, according to the complaint. In remarks associated with the filing, James said, “Instead of helping Americans face our new reality, the Trump administration has chosen denial, repealing critical protections that are foundational to the federal government’s response to climate change,” positioning the lawsuit as a defense of both science and federal responsibility.

Massachusetts Attorney General Joy Campbell said, “Climate change is real, and it’s already affecting our residents and our economy,” and she added, “When the federal government abandons the law and the science, everyday people suffer the consequences.” Campbell also said Massachusetts “has long led the way in protecting our communities from the dangers of greenhouse gas emissions” and that the state is “proud to stand up once again to lead this fight for our future.”

The dispute comes in the wake of Supreme Court precedent that treated greenhouse gases as regulated pollutants under the Clean Air Act. In 2007, the Supreme Court held in Massachusetts v. EPA that carbon dioxide and other greenhouse gases are “air pollutants,” and since that decision, courts have rejected legal challenges to the endangerment finding, including a 2023 D.C. appeals court ruling.

An EPA spokeswoman, Brigit Hirsch, said the new lawsuit was “not about the law or the merits of any argument.” She said the plaintiffs “are clearly motivated by politics,” and that the agency “carefully considered and reevaluated the legal foundation” of the 2009 finding in light of recent court decisions, including a 2022 Supreme Court ruling that limited how the Clean Air Act can be used to reduce carbon dioxide emissions from power plants.

Besides New York, Massachusetts, California and Connecticut, the suit names attorneys general from Arizona, Colorado, Delaware, Hawaii, Illinois, Maine, Maryland, Michigan, Minnesota, New Jersey, New Mexico, Nevada, North Carolina, Oregon, Rhode Island, Vermont, Virginia, Washington and Wisconsin, along with the District of Columbia and the U.S. Virgin Islands. The Pennsylvania Department of Environmental Protection also joined, as did cities including Albuquerque, Boston, Chicago, Cleveland, Columbus, Denver, Los Angeles, New York and San Francisco, plus five counties in California, Colorado, Texas and Washington state.

The parties’ arguments are expected to keep moving through the courts. The lawsuit’s trajectory, as described in the reporting, is likely to end up back before the Supreme Court, which is now far more conservative than it was in 2007 when the high court issued its Massachusetts v. EPA decision.