Major Biden Air Rules on Chopping Block as Cases Grind to a Halt

Most lawsuits over former President Joe Biden’s biggest air emissions regulations are now frozen as the new EPA administration weighs rollbacks as part of its deregulatory effort.

Courts placed multiple cases against the Environmental Protection Agency over mercury, carbon, and other emission rules on hold at the behest of the agency and some industry and state plaintiffs. The abeyance trend marks the beginning of President Donald Trump’s promised agenda to deregulate and bolster the fossil fuel industry.

So far, litigation over coal ash, mercury, methane, power plant, and particulate matter emissions have been paused pending agency review, citing new agency leadership’s need for “sufficient time to familiarize themselves with these issues and determine how they wish to proceed.”

Ohio v. EPA, a dispute over the EPA’s traveling ozone regulations, is proceeding and will have oral arguments on April 25.

Here are notable air cases currently in abeyance at the US Court of Appeals for the District of Columbia Circuit while the Trump administration weighs the rules:

Mercury and Air Toxics

North Dakota v. EPA, No. 24-1119
An appellate panel paused a lawsuit launched by states and industry against Mercury and Air Toxics Standards, which sets emission limits based on available technology for power plants. Challengers claimed that the rule places unfair burdens and price tags on industry. Motions to govern future proceedings due on May 21.

Methane

Texas v. EPA, No. 24-01054
Red states led a legal charge against former EPA moves to clamp down on methane standards for the oil and gas industry, which were finalized in 2023 at the COP28 climate summit in Dubai. The rule aims to stem methane leaks from oil and gas operations and allow third parties to detect and report emissions. A separate rule establishing a methane leak fee is on the verge of being quashed by the Congressional Review Act. Motions to govern future proceedings due on June 9.

Power Plants

West Virginia v. EPA, No. 24-1120
Hotly contested rules that govern greenhouse gas emissions from power plants are once again in legal abeyance as the Trump administration takes another swing at setting industry-friendly standards after courts scrapped the Affordable Clean Energy rule from his first administration. Another West Virginia-led case drew firm boundaries on how far the EPA can go when setting these emission standards, and the agency is already mulling over the death of the endangerment finding that would underpin climate regulations writ large. Motions to govern future proceedings due on April 21.

Particulate Matter

Kentucky v. EPA, No. 24-1050
Litigation over new, more stringent particulate matter limits have also already been through arguments, but have been placed in abeyance by its presiding panel. The Biden administration reversed Trump’s 2020 action to leave soot standards unchanged, and then finalized tight limits that industry and some states claim go far beyond what is needed to protect human health. Motions to govern future proceedings due on April 28.

Vehicle Emissions

Kentucky v. EPA, No. 24-1087
Nebraska v. EPA, No. 24-01129
The D.C. Circuit this week paused two disputes over mobile emissions regulations, which center on the EPA’s authority to stem tailpipe pollution from light- and heavy duty-vehicles. Both rules were part of a wider suite of regulations set by the Biden administration to stem greenhouse gas and other air pollutants from the transportation sector, and Trump has vowed to prioritize ending what administration officials call an EV “mandate” that have been created by the standards. Motions to govern future proceedings are due within 60 days of the March 4 abeyance order.