WASHINGTON — A coalition of 21 states and four cities sued the Trump administration Thursday over its move to erase all limits on planet-warming emissions from power plants.

The lawsuit was filed in the ​U.S. Court of Appeals for the District of Columbia. The mostly Democratic-run states and cities, led by New York, contend that the Environmental Protection Agency acted unlawfully when it repealed Biden-era regulations on carbon dioxide emissions from power plants that burn gas and coal.

The electricity sector is America’s second-biggest source of emissions of carbon dioxide, a heat-trapping gas. During the Biden administration, the EPA imposed sweeping rules that would have required the nation’s coal plants to eliminate nearly all their planet-warming pollution by 2039 or shut down. The rules would have also capped emissions from new natural gas plants.

Those regulations were contentious at the time, and multiple electric utilities and nearly two dozen Republican-run states led by West Virginia sued to block them, saying the limits were unachievable and would have destabilized the power grid.

President Donald Trump has pushed to dismantle federal policies that tackle climate change. As part of that effort, the EPA announced last month that it was rescinding the power-plant rules. The agency also argued that greenhouse gases from power plants did not endanger human health or the environment, and therefore, the EPA lacked the legal authority to regulate these emissions under the Clean Air Act.

If courts uphold this argument, it could prevent future administrations from imposing similar regulations on power plants.

In their lawsuit, the states and cities led by New York plan to argue that the EPA did not properly consider the health and climate costs of allowing more planet-warming pollution into the atmosphere. The rollback, they say, was “arbitrary and capricious” and should be struck down.

“This administration’s insistence on giving the nation’s biggest polluters a free pass will set our country back decades in the fight against climate change,” said Letitia James, the attorney general of New York. “Dismantling these protections is a betrayal of American families.”

A spokesperson for the EPA said the agency does not comment on pending litigation.

Besides James, the other plaintiffs in the lawsuit are the attorneys general of Arizona, California, Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Jersey, New Mexico, North Carolina, Oregon, Rhode Island, Vermont, Washington, Wisconsin and the District of Columbia, as well as the governor of Pennsylvania and the mayors of New York City, Chicago and Denver. All the officials are Democrats.

Separately, the coalition of states led by New York sent the EPA a notice of intent to sue over the fact that the agency hasn’t regulated planet-warming emissions from existing power plants that burn natural gas. While the Biden administration never imposed greenhouse gas limits on these plants either, the plaintiffs argue that the EPA has an obligation to do so and that some of the gas plants are pumping harmful air pollution into low-income neighborhoods.

In addition to rolling back the power plant regulations, the Trump administration’s EPA has also eliminated greenhouse gas standards for car tailpipes and eased restrictions on planet-warming chemicals used in air conditioners and refrigerators. Most consequentially, the agency repealed the scientific determination that gave it the legal authority to combat climate change.

In March, a coalition of Democratic-run states, including Massachusetts, California, New York and Connecticut, filed a lawsuit challenging the EPA over the repeal of the so-called endangerment finding, the 2009 document that concluded that carbon dioxide and other greenhouse gases threatened public health and welfare. The plaintiffs in that case argued that the EPA had presented no new science to overturn that determination.

That case is pending in court.

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This article originally appeared in The New York Times.

By Brad Plumer/Benjamin Raasmussen
c. 2026 The New York Times Company