Maryland Attorney General Anthony G. Brown has joined a coalition of 25 states, counties and cities in a petition for review filed in the U.S. Court of Appeals for the D.C. Circuit, challenging the Environmental Protection Agency's repeal of the 2024 Carbon Pollution Standards. The rule, which applied to many coal-fired and gas-fired power plants, was repealed in September 2026 under the Trump administration.

The coalition is asking the court to strike down the repeal and reinstate the emissions limits. At stake is regulatory coverage of a sector the petitioners say produces roughly one-quarter of U.S. carbon dioxide emissions — a material stream that, unlike municipal recycling streams, enters the atmosphere directly and currently faces diminishing federal control. The group also notes that the federal government has proposed ending power plant emission rules entirely.

Brown framed the litigation in terms of concrete physical and fiscal impacts on the state.

"By dismantling these protections, the Trump Administration will force Marylanders to endure more dangerous floods, face deadlier heat waves, and breathe more toxic wildfire smoke," Brown said. "We are filing this lawsuit not just to protect Maryland today, but to protect the Maryland our loved ones will inherit tomorrow."

The coalition's filing ties power sector emissions to public health outcomes and public expenditure alike. Stronger heat waves, heavier flooding and more wildfire smoke put children, older adults and outdoor workers at elevated risk, according to the group. Pollution from power plants can worsen asthma, heart disease and other respiratory illnesses, and the petitioners argue that low-income and overburdened communities absorb the heaviest exposure because a larger share of these facilities operate in those areas.

The fiscal dimension is also in the filing. State and local governments, the coalition says, must spend billions of dollars to recover from extreme weather events — costs that scale with the emissions the repealed standards once constrained.

Second front: existing gas plants

Beyond the challenge to the repeal, the coalition filed a separate notice of intent to sue the EPA over existing natural gas power plants. The group contends the agency has never fully regulated greenhouse gas pollution from many of these facilities, despite what it says is a Clean Air Act requirement to do so.

The EPA set standards for new gas plants more than a decade ago, according to the coalition, but no limits exist for the existing fleet. The gap includes "peaker" plants — units that typically run when electricity demand peaks. Many of these sit in low-income communities and communities of color, the group says, extending the same exposure disparities cited in the repeal challenge to an entire unregulated generation category.

The notice of intent initiates the formal precursor to litigation against the agency over that regulatory omission.

The coalition

Joining Attorney General Brown are the attorneys general of Arizona, California, Colorado, Connecticut, Delaware, the District of Columbia, Hawai'i, Illinois, Maine, Massachusetts, Michigan, Minnesota, New Jersey, New York, North Carolina, Oregon, Rhode Island, Vermont, Washington and Wisconsin. Pennsylvania's governor, the mayors of New York City and Chicago, and the City and County of Denver are also parties.

What decides what happens next

Two procedural milestones now govern the timeline. First, the D.C. Circuit must decide whether to vacate the EPA's September 2026 repeal of the 2024 Carbon Pollution Standards and restore the limits on coal- and gas-fired units. Second, the notice of intent on existing gas plants — including peakers — starts the clock on a Clean Air Act enforcement action that could force the agency to write first-time greenhouse gas limits for that fleet. The court's response to the petition will determine whether the power sector, the country's largest single stationary source of CO2 by the coalition's accounting, remains without federal carbon constraints.