A coalition led by New York asked a federal appeals court Thursday to overturn the Environmental Protection Agency’s repeal of major greenhouse-gas limits for coal- and gas-fired power plants, opening a national legal fight over one of the Trump administration’s largest climate-policy reversals.

The challenge includes 21 states, Pennsylvania’s governor, the District of Columbia and local governments in New York, Chicago and Denver. The New York attorney general’s office said the coalition filed a petition for review in the U.S. Court of Appeals for the D.C. Circuit and separately notified EPA that it intends to sue over the agency’s failure to regulate emissions from many existing natural-gas plants. Reuters and The Associated Press independently reported the filing.

What the EPA repealed

The disputed action removes most of the 2024 Carbon Pollution Standards. According to the published final rule, EPA eliminated emission guidelines for existing fossil-fuel steam plants, carbon-capture requirements for substantially modified coal units and a second phase of carbon-capture standards for new baseload gas turbines. The repeal is scheduled to take effect November 16 unless a court intervenes.

EPA did not erase every greenhouse-gas standard in this action. It left some efficiency requirements for new and reconstructed turbines in place while issuing a separate proposal that would eliminate all remaining federal greenhouse-gas limits for fossil-fuel power plants. That distinction matters: Thursday’s petition targets a completed partial repeal, while the broader rescission is still moving through the rulemaking process.

The agency argues the earlier standards depended too heavily on carbon capture and storage that could not be deployed at the scale and speed required. An EPA technical summary says 90 percent carbon capture has not been adequately demonstrated and that the necessary pipelines and storage infrastructure are unlikely to be available by the 2032 compliance deadline. EPA also concluded that requiring some coal plants to co-fire with 40 percent natural gas would amount to impermissible generation shifting and would use natural gas inefficiently.

Competing claims over costs and authority

EPA presents the repeal as a reliability and affordability measure. The final rule estimates that, from 2026 through 2047, avoided compliance costs would have a present value of $160 billion using a 3 percent discount rate, while avoided spending on physical and labor inputs would total $280 billion under the same assumption. The agency says removing the requirements will reduce pressure to retire power plants prematurely and give utilities more flexibility.

Those figures measure costs that EPA expects the industry to avoid; they are not a forecast of an equivalent reduction in household electricity bills. The rule says it does not monetize several secondary effects, while the challengers dispute EPA’s treatment of environmental and public-health consequences. The court will therefore confront not only whether EPA had authority to revise the standards, but whether the agency’s comparison of costs, technical feasibility and foregone benefits was adequately reasoned.

The challengers argue that EPA changed course without adequately considering less sweeping alternatives or the health and climate costs of additional emissions. The New York filing says fossil-fuel power plants produce roughly one-quarter of U.S. carbon dioxide emissions. California, which joined the case with its air-resources board, said the coalition wants the court to vacate the rescission and restore the prior standards in its official account of the lawsuit.

The legal dispute turns in part on Section 111 of the Clean Air Act, which authorizes EPA to set performance standards for categories of stationary sources that significantly contribute to dangerous air pollution. EPA says the 2024 rule relied on technologies that were not adequately demonstrated and did not sufficiently account for cost and infrastructure. The states counter that the agency unlawfully abandoned its responsibility and failed to justify the consequences of reversing an existing rule.

Why the case reaches beyond climate policy

The litigation will test how much latitude a federal agency has to reverse technical findings and compliance judgments made by a previous administration. Courts generally allow agencies to change policy, but they must explain the change, address important evidence and consider significant reliance interests. The challengers are framing the repeal as arbitrary and capricious; EPA is defending it as a lawful reassessment of technology, cost and statutory authority.

The geographic breadth of the coalition also raises practical questions for states that had been preparing implementation plans under the 2024 standards. Participants include New York, Arizona, California, Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Jersey, New Mexico, North Carolina, Oregon, Rhode Island, Vermont, Washington and Wisconsin, along with Pennsylvania’s governor. Their electricity mixes and regulatory systems differ, but all face the same federal reversal.

Filing the petition does not itself suspend the repeal. The next consequential steps will be the coalition’s detailed legal briefs and any request to pause the rule before its November 16 effective date. The separate notice concerning existing gas plants could produce another case if EPA does not act. Together, the proceedings will determine whether the administration’s power-sector reset takes effect as written or whether the federal carbon limits return while the courts examine EPA’s reasoning.