Two dozen states, 10 cities sue EPA over repeal of 'endangerment' finding central to climate fight

The repeal eliminates all greenhouse gas emissions standards for cars and trucks and could unleash a broader undoing of climate regulations on stationary sources such as power plants and oil and gas facilities.

The lawsuit, filed in the U.S. Court of Appeals for the District of Columbia Circuit, is the second major challenge to the endangerment repeal, following a suit filed last month by public health and environmental groups.

The new lawsuit asserts that EPA’s rescission of the endangerment finding abandons a core responsibility to the American people.

“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," said New York Attorney General Letitia James, who led the suit along with attorneys general of Massachusetts, California and Connecticut.

In all, 24 states, 10 cities and five counties joined the lawsuit. All are led by Democrats.

“Climate change is real, and it’s already affecting our residents and our economy,” said Massachusetts Attorney General Joy Campbell. “When the federal government abandons the law and the science, everyday people suffer the consequences."

Massachusetts "has long led the way in protecting our communities from the dangers of greenhouse gas emissions and we are proud to stand up once again to lead this fight for our future,” she said.

The U.S. Supreme Court, in a landmark 2007 case, ruled that carbon dioxide and other greenhouse gases are “air pollutants” under the Clean Air Act. Since the high court’s decision, in a case known as Massachusetts v. EPA, courts have uniformly rejected legal challenges to the endangerment finding, including a 2023 decision by the D.C. appeals court.

EPA spokeswoman Brigit Hirsch said the latest lawsuit was “not about the law or the merits of any argument.” Instead, the plaintiffs “are clearly motivated by politics," she said.

The EPA “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 law can be used to reduce carbon dioxide emissions from power plants, Hirsch said.

In addition to New York, Massachusetts, California, and Connecticut, the case was joined by attorneys general of Arizona, Colorado, Delaware, Hawaii, Illinois, Maine, Maryland, Michigan, Minnesota, New Jersey, New Mexico, Nevada, North Carolina, Oregon, Rhode Island, Vermont, Virginia, Washington and Wisconsin, as well as the District of Columbia and U.S. Virgin Islands.

The Pennsylvania Department of Environmental Protection also joined the case, along with the cities of Albuquerque, Boston, Chicago, Cleveland, Columbus, Denver, Los Angeles, New York and San Francisco, and five counties in California, Colorado, Texas and Washington state.

The dispute is likely to end up back before the Supreme Court, which is now far more conservative than it was in 2007.