A coalition of environmental and public health groups representing 17 organizations has filed a petition in the U.S. Court of Appeals in Washington, DC, challenging the U.S. Environmental Protection Agency’s final rule that repealed the primary basis for federal regulation of greenhouse gas emissions and eliminated vehicle emissions standards. Additional lawsuits are expected after the EPA’s latest action, with challenges likely to reach the US Supreme Court.
“In its repeal, the Trump EPA is repeating legal arguments that the Supreme Court already considered and rejected in Massachusetts v. EPA,Earthjustice, representing six of the litigants, said in a statement that the court’s finding that the agency has legal authority to regulate greenhouse emissions as a pollutant set the stage for it to issue its 2009 “danger finding.” Using a science-backed determination, the court listed six greenhouse gases, including carbon dioxide and methane, as harmful to public health and subject to emissions regulation under Section 202(a) of the Clean Air Act.
In a statement, EPA Administrator Lee Zeldin said the rule exceeded the powers Congress gave the agency to regulate vehicle and engine emissions, based on a “robust analysis of the law after the [high court] decision in Loper Bright Enterprises v. Raimondo and West Virginia v. EPA.”
The EPA’s decision is “totally at odds with the public interest and the best available science,” said Gretchen Goldman, president and CEO of the Union of Concerned Scientists, one of the plaintiffs. “Heat-trapping emissions and global average temperatures are rising, primarily from the burning of fossil fuels, contributing to a growing human and economic toll across the country.”
But the EPA also pointed to costs when it announced the repeal and elimination of the emissions standards, saying the moves will save $1.3 trillion, and $2,400 per vehicle, “by eliminating regulatory requirements to measure, report, certify, and comply with federal motor vehicle GHG emissions standards, and repealing compliance programs and associated credit reporting obligations.” The agency did not explain how it had calculated those savings.
Environmental and clean energy groups argue that any such savings would be offset by other resulting costs.
“Reduced tailpipe standards have real economic consequences, from higher fuel costs for consumers to significant job losses in the transportation and manufacturing sectors,” Michael Berube, CEO of the clean technology transportation group CALSTART, said in a statement. He pointed to an October 2025 report by climate policy think tank Energy Innovation that estimated a $310 billion cost to consumers, based on associated higher gas costs, and a loss of 110,000 industry jobs. “Private-sector manufacturers and innovators have invested hundreds of billions of dollars in developing cutting-edge, cleaner and more efficient vehicle technologies.”
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While the hazard finding’s most direct impact has been on vehicle emissions, Doug Hastings, a partner at the law firm Morgan Lewis with a focus on environmental law, said it “is also a key scientific finding that has supported the EPA’s assumptions about climate impacts in other regulations.” He noted that “EPA did not finalize its alternative climate science findings in its current final rule.” In July 2025, the US Department of Energy issued a report from its climate task force, perceived as an attempt to use science to undermine the conclusions of the hazard finding determination. The findings were refuted by dozens of climate experts.
Depending on whether, and how, the Supreme Court ultimately rules, its decision could affect emissions regulations in other sectors, including buildings and industrial facilities.
Although the EPA is removing federal restrictions on tailpipe emissions, regulations still exist at the state level, including California and states that conform to California’s tailpipe emissions standard, such as Oregon, Washington and New York. and some states may introduce new regulations. “California also has other, more stringent regulations related to GHGs,” Hastings told ENR, including a greenhouse gas reporting program and a climate-related financial risk disclosure program.
Still, other states are expected to follow the EPA’s lead, most recently Alabama, whose legislature passed a bill on Feb. 17 that would prohibit state regulation of pollutants and hazardous substances beyond levels set by the federal government.
Meanwhile, the EPA’s decision is creating uncertainty in its wake, from court challenges to construction investment decisions that may have to weigh the removal of federal restrictions against local, state and international requirements and trends. It can also leave construction facing a constellation of clashing policies across the country.
The oil and gas industry has already publicly and privately lobbied the EPA not to roll back its existing methane rules. “To be sure, the industry has asked the EPA to revise a few requirements to make them more reasonable, but it prefers the federal rules to the state requirements, which many states would impose if the EPA’s methane regulations were repealed,” said Jeff Holmstead, a partner at the law firm Bracewell and former head of the EPA’s Office of Air and Radiation in the George W. Bush administration.
Later, he added, “this could force Congress to get involved in reaching a bipartisan deal on current climate change legislation, probably not during the Trump administration, but the business community would like to have the long-term certainty that would come with bipartisan legislation.”
