More than 20 Democratic attorneys general sued the U.S. Environmental Protection Agency and Administrator Lee Zeldin on Thursday, Oct. 1, 2026, asking the U.S. Court of Appeals for the District of Columbia Circuit to restore greenhouse gas emissions standards for power plants that the agency repealed in September. Reuters, citing the filing, counted 25 states and cities in the coalition.

The target of the lawsuit is the EPA's repeal of the 2024 Carbon Pollution Standards, signed by Zeldin on Sept. 14, 2026. Those standards required fossil-fuel-fired power plants to cut greenhouse gas emissions by installing carbon capture technology. The agency said the 2024 rules adversely affected the nation's energy systems and estimated the rollback would save $310 billion, mostly in compliance costs that power companies would no longer have to pay to reduce emissions.

"The Trump administration has come in to protect American energy and to make sure you can afford to keep the lights on," Zeldin said in the statement announcing the final rule. "Americans will see a decrease in electricity prices."

Who is suing?

The plaintiffs span both coasts and the industrial Midwest. Beyond California and New York, the attorneys general of Arizona, Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Jersey, North Carolina, Oregon, Rhode Island, Vermont, Washington, Wisconsin and the District of Columbia joined the petition, Spectrum News reported.

The coalition also includes:

• The governor of Pennsylvania
• The mayors of Chicago and New York City
• The City and County of Denver

What does the complaint argue?

The states contend the repeal violates the Clean Air Act. The complaint says the rollback "significantly undermines efforts to address climate change and exposes communities to greater environmental harm by undoing climate regulations on power plants," according to Spectrum News.

The coalition argues the EPA revoked the regulations without considering "reasonable alternatives" and without factoring in the health and climate costs of allowing more pollution into the atmosphere, Reuters reported.

New York Attorney General Letitia James, whose state and city are both plaintiffs, framed the stakes in a post on X: "I'm suing to stop this administration from giving the nation's biggest polluters a free pass to set our country back decades in the fight against climate change." She wrote that "the Trump administration is pushing for catastrophic rollbacks of federal limits on greenhouse gas pollution."

California Attorney General Rob Bonta said uncontrolled emissions from electricity generation would increase heat waves, wildfires, severe storms, flooding, disease and air pollution, and harm regional ecosystems.

A second front: existing gas plants

The litigation does not stop at the repeal. Alongside its petition, the coalition notified the EPA that it will sue over the agency's continued failure to fully regulate pollution from existing natural gas power plants, Reuters reported. That notice opens a separate track of liability for the agency beyond the carbon capture rule.

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

How big is the power plant emissions stream?

The material at issue is substantial. Power plants are the second-largest source of U.S. greenhouse gas emissions after vehicles and account for one-quarter of U.S. carbon dioxide emissions, Reuters reported.

The EPA estimated in 2022 that electric power plants accounted for 24 percent of domestic CO2 emissions from burning coal, oil and natural gas — second only to transportation at 29 percent. The U.S. Energy Information Administration said in 2023 that about 60 percent of U.S. electricity generation came from fossil fuels, against 19 percent from nuclear and 21 percent from renewables.

What happens next?

The D.C. Circuit will now weigh whether the Sept. 14 partial repeal survives Clean Air Act review — the decision that determines whether the carbon capture mandate returns to the books.

A second regulatory milestone is already on the calendar. The EPA has proposed rescinding the greenhouse gas findings for fossil fuel-fired power plants and repealing its power plant greenhouse gas regulations outright under Section 111 of the Clean Air Act. The agency scheduled a virtual public hearing on that proposal for Oct. 1 and 2, 2026, according to its website. That proceeding, running parallel to the litigation, could eliminate the statutory foundation the states are fighting to restore.