A coalition of U.S. states and local governments has filed a legal challenge against the Environmental Protection Agency’s repeal of federal greenhouse gas emissions requirements for fossil fuel-fired power plants.

The challenge follows the EPA’s September 14, 2026 decision to repeal most provisions of the 2024 Carbon Pollution Standards for fossil fuel-fired electric generating units. The agency also proposed rescinding the remaining greenhouse gas requirements for the power sector under Section 111 of the Clean Air Act.

On October 1, a coalition led by New York filed a petition for review in the U.S. Court of Appeals for the D.C. Circuit. The coalition includes 21 states, along with the District of Columbia, Pennsylvania’s governor, New York City, Chicago, and the city and county of Denver.

The states argue that the EPA’s repeal should be overturned, claiming the agency did not adequately consider alternatives or the health and climate-related costs associated with increased greenhouse gas emissions. They also argue that the repeal was unlawful under the Clean Air Act.

The EPA has taken a different position, stating that the 2024 standards exceeded its authority under the Clean Air Act and relied on emissions-control technologies that were not adequately demonstrated or economically reasonable at the required scale. The agency estimates that its repeal could deliver more than $300 billion in savings and support continued use of coal and natural gas generation.

The EPA is separately proposing to rescind the remaining greenhouse gas standards for power plants. That proposal is still undergoing the regulatory process and is therefore distinct from the provisions already repealed.

The legal challenge could determine the future of federal greenhouse gas regulation for the U.S. power sector and influence how emissions standards are developed under the Clean Air Act.

The development highlights the continuing regulatory uncertainty surrounding power-sector emissions, carbon management and the transition toward lower-carbon electricity generation in the United States.