Two coalitions of Democratic-led states and local governments sued the Trump administration this week, challenging deregulatory moves to dismantle greenhouse gas limits for power plants and weaken fuel economy requirements for cars.
The lawsuits, filed by over 20 states and cities in two separate appeals courts, will argue that the Environmental Protection Agency and the National Highway Traffic Safety Administration (NHTSA) violated the law when they rolled back rules targeting emissions from two of the biggest sources of greenhouse gases in the country.
The rule rollbacks came as part of President Donald Trump’s broad push to remove regulations that he believes get in the way of businesses, including in the oil and gas sector. The administration has argued that greenhouse gases from power plants don’t endanger human health or the environment, and that the fuel economy standards were generally overly burdensome for industry.
Power plants rule lawsuit
The power plant rule lawsuit was filed in the U.S. Court of Appeals for the D.C. Circuit. Led by New York, the plaintiff states and governments will argue that the EPA’s move was arbitrary and capricious because it did not properly consider alternatives or calculate the “enormous health and climate costs” associated with burning fossil fuels.
The EPA repealed the power plant rules in September, eliminating requirements finalized in 2024 to drastically cut emissions from power plants. The EPA determined that carbon capture and sequestration technology that the 2024 rule relied on to demonstrate feasibility cannot achieve the reductions promised.
The EPA also proposed eliminating every other remaining greenhouse gas emissions requirements for power plants, relying on its recent repeal of the Endangerment Finding to determine that the Clean Air Act doesn’t give the EPA authority to regulate emissions based on climate change concerns.
The states also filed a notice of intent to sue the EPA over its alleged continued failure to regulate greenhouse gas emissions from many existing gas-fired power plants, including so-called “peaker” plants that operate at periods of high energy demand and are often located in low-income communities.
“The Clean Air Act unambiguously requires EPA to establish emission guidelines for existing natural gas-fired power plants and other stationary combustion turbines,” the letter said, citing Section 111(d) of that law that says the EPA administrator “shall prescribe regulations” for existing plants.
Vehicle emissions lawsuit
The vehicle emissions lawsuit was filed in the U.S. Court of Appeals for the First Circuit by a coalition led by California, and challenges relaxed Corporate Average Fuel Economy (CAFE) standards that require auto manufacturers to improve average fuel efficiency across the models they sell.
The NHTSA estimates its change will lead to a fleetwide average of 34.9 miles per gallon by model year 2031 compared to 50.4 miles per gallon under Biden-era rules.
The states said in a comment letter submitted before the standards were finalized that the new standards amount to a “radical reinterpretation” of federal law, which generally requires the Transportation secretary to set “maximum feasible average fuel economy” levels for vehicles based on energy conservation needs and practicality.
The plaintiff states said in the letter that the administration had improperly excluded electric vehicles from its calculations of what is feasible — meaning, the average only included combustion engine vehicles — and “dramatically distorted its cost-benefit analysis to make the Proposal look beneficial for Americans.”
Instead, they said that it would exacerbate climate change and increase reliance on volatile oil markets.