In its original proposal, the Trump EPA relied on recent Supreme Court decisions it said restrict its authority to act on climate under current law, and close observers expect that will be the administration’s strategy.

“We expect EPA to revoke the endangerment finding for legal reasons, not scientific ones,” said Jeff Holmstead, a partner at the Bracewell law firm who served as head of EPA’s air office during President George W. Bush’s administration. “This is the only way that they can ‘drive a stake through the heart of climate religion,’ as Administrator Zeldin has said.”

If this is about law and not science, how has the law changed since 2009?

The second Trump administration had the confidence to take on the endangerment finding largely because of how the president reshaped the Supreme Court in his first term, legal experts say. In two 6-3 decisions from a conservative majority bolstered by Trump’s three appointees, the justices created new doctrine that limited the power of federal regulatory agencies like the EPA.

“We’ve had an administrative law revolution,” said industry lawyer Matthew Leopold, who was the EPA’s general counsel in Trump’s first term, speaking at a forum last fall at the American Enterprise Institute (AEI), a conservative think tank. “The playing field that the Obama administration was playing on [when it made the endangerment finding] looks entirely different today.”

The Supreme Court struck down Obama’s signature climate policy, the Clean Power Plan, in 2022. And in that case, West Virginia v. EPA, the court established its so-called “major questions doctrine,” saying regulation of greenhouse gases was an issue of such great economic and political significance that the EPA could not regulate them without explicit direction from Congress. Then, in a 2024 case over fishing regulations, the Supreme Court overturned the principle that had guided regulatory law for 40 years, saying that federal agencies were due no deference in interpreting ambiguities in the law. The court said judges, not agencies, should decide the meaning of the law, even though in the environmental realm that typically involves application of science and knowledge of the best available technologies for reining in pollution.