On Oct. 1, a coalition of 21 states and the District of Columbia sued the U.S. Environmental Protection Agency (EPA) over its repeal of major greenhouse gas emissions requirements for fossil fuel-fired power plants. The coalition filed the lawsuit in the U.S. Court of Appeals for the D.C. Circuit.

New York Attorney General Letitia James (D) led the challenge, which also includes Pennsylvania Gov. Josh Shapiro (D) and the mayors of New York City and Chicago and the City and County of Denver. The plaintiffs are asking the court to vacate EPA's repeal and restore the previous emissions requirements.

EPA finalized the partial repeal on Sept. 14. The agency eliminated three main parts of the Biden administration's 2024 Carbon Pollution Standards, including emissions guidelines for existing fossil fuel-fired steam-generating units and carbon capture requirements for certain new natural gas-fired power plants.

The states argue that EPA violated the Clean Air Act when it repealed the requirements.

The lawsuit is the latest legal challenge between states and the federal government over the scope of EPA's authority to regulate greenhouse gas emissions from the power sector. The outcome could determine whether EPA must restore major portions of the 2024 standards governing emissions from coal, oil, and natural gas-fired power plants.

The dispute also comes as EPA seeks to eliminate the remaining federal greenhouse gas standards for power plants, including certain efficiency requirements for new and reconstructed natural gas turbines and modified steam-generating units.

The Biden administration finalized the Carbon Pollution Standards in April 2024 under Section 111 of the Clean Air Act. The standards established greenhouse gas emissions requirements for new natural gas-fired power plants and guidelines for states to limit emissions from existing fossil fuel-fired power plants.

On Sept. 14, 2026, EPA Administrator Lee Zeldin announced the partial repeal. The EPA estimated the repeal would save $310 billion across the economy from 2026 through 2047. The agency argues that the changes will reduce regulatory costs and support reliable and affordable electricity.

The states contend that EPA lacks a lawful basis for eliminating the 2024 requirements and are asking the D.C. Circuit to restore the repealed standards.

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