The Trump administration has announced its first step toward trying to revoke one of the most consequential legal standards in the United States for acting on planet-heating fossil fuel emissions. Sixteen years ago, the Environmental Protection Agency issued its landmark “endangerment finding” that greenhouse gases heating up the planet threaten public health and welfare. Two years earlier, the Supreme Court paved the way for that finding with a determination that the EPA has the authority to limit the emissions of those gases through federal regulation.

Now the EPA, under Donald Trump, is trying to undo its own authority to take that action. 

EPA administrator Lee Zeldin announced Wednesday that the agency will undertake a “formal reconsideration” of its 2009 endangerment finding, which underpins the agency’s legal obligation to regulate carbon dioxide and other climate pollutants under the Clean Air Act. The EPA also announced that it intends to undo all of its prior rules that flow from that finding, including limits on emissions from automobiles and power plants alongside scores of other rules pertaining to air and water pollution.  

“Today is the greatest day of deregulation our nation has seen. We are driving a dagger straight into the heart of the climate change religion,” Zeldin said. 

“Instead of protecting communities reeling from the havoc caused by climate disasters, Trump and Zeldin seek to shatter the foundation that undergirds our climate safeguards.”

Climate advocates reacted with outrage. “Instead of protecting communities reeling from the havoc caused by climate disasters, Trump and Zeldin seek to shatter the foundation that undergirds our climate safeguards,” Joanne Spalding, legal director at the Sierra Club, told Sierra. “Sierra Club has been expecting and preparing for this unlawful action, and we will use every legal means available to challenge it.”

Legal experts say they expect the administration will face an uphill legal battle, with one environmental attorney pointing to unambiguous language in the Clean Air Act that may put to rest any claims that the law does not authorize climate regulations.

The endangerment finding stems from the landmark 2007 Supreme Court decision in Massachusetts v. EPA, a case in which a dozen states, along with several cities and environmental groups including the Sierra Club, challenged the George W. Bush administration EPA’s refusal to regulate carbon emissions from automobiles. The Supreme Court ruled 5-4 in favor of the states, determining that greenhouse gases are pollutants under the Clean Air Act, which requires regulation of air pollutants that are found to endanger public health and welfare. The EPA then made such a finding of endangerment, based on voluminous scientific evidence, during the first year of the Obama administration.

“The finding has since been the predicate for all of EPA’s actions on climate change under the Clean Air Act, including its regulations of greenhouse gas emissions from vehicles, power plants, landfills, and more,” Robert Sussman, an environmental lawyer and former EPA official, explained during a climate law briefing on Tuesday hosted by the Environmental Law Institute. He noted that the finding has faced political attacks and legal challenges, but has so far withstood those pressures. The EPA declined petitions to reconsider the finding during Trump’s first term. 

“Undertaken in secrecy” 

The planning around Zeldin’s move to reverse the endangerment finding happened behind closed doors. On February 26, The Washington Post first reported that Zeldin recommended to the White House that the agency strike down the finding. Other news outlets citing anonymous sources confirmed that reporting, though Zeldin’s proposal was not released publicly. 

The recommendation follows a directive from President Donald Trump in a January 20 executive order that the EPA, in consultation with other agency heads, submit recommendations within 30 days to the Office of Management and Budget “on the legality and continuing applicability” of the endangerment finding. An EPA spokesperson declined to confirm what news reports had revealed about the recommendation, saying only that the EPA was in compliance with the executive order. 

Environmental advocates and congressional Democrats have condemned Zeldin’s recommendation to revoke the endangerment finding and have also slammed the administration’s lack of transparency around its plans for doing so. 

“EPA administrator Zeldin’s recommendation to strike down the endangerment finding was undertaken in secrecy, is deeply cynical, and will hurt Americans already experiencing severe harms due to climate change,” said Environmental Defense Fund’s Peter Zalzal. “The public has a right to know why Administrator Zeldin—the head of the agency charged with protecting the public from the harms of climate change—has instead chosen to trample the science and do the exact opposite.”   

EDF filed a lawsuit last week against the EPA, arguing the agency failed to respond to the group’s Freedom of Information Act request under statutory deadlines. The group’s request sought records and communications around Zeldin’s recommendation pertaining to the endangerment finding.  

Democrats on the Senate Environment and Public Works Committee recently wrote to Zeldin with a similar request for more information and answers about the reported move to rescind the finding. The senators demanded Zeldin disclose details around his recommendation, such as who was involved or consulted. The recommendation and planning, the senators say, has happened “behind the scenes and away from public scrutiny.”  

David Bookbinder, an environmental lawyer and director of law and policy at Environmental Integrity Project, said it is not surprising that there has been so little transparency around the administration’s plans to reverse the finding. “They don’t want publicity on this,” he told Sierra.

Gutting climate regulations

Undoing the endangerment finding, legal experts say, would essentially strip away the EPA’s obligation to regulate greenhouse gas emissions, allowing the agency to axe rules meant to curb emissions in one blow without needing to replace them with weaker versions. “It’s a much simpler way to just gut climate regulations,” Ann Carlson, an environmental law professor and faculty director of the Emmett Institute for Climate Change and the Environment at UCLA Law School, told Sierra. 

“Removing it from the climate toolbox would definitely be a blow to future climate mitigation efforts,” Sussman said. 

In its announcement Wednesday, the EPA indicated it would undertake a formal administrative process to overhaul the endangerment finding, including taking public comment. The agency said it plans to “leverage the expertise of the White House Budget Office, including the Office of Information and Regulatory Affairs, White House Office of Science and Technology Policy, National Oceanic and Atmospheric Administration, and other relevant agencies.” The EPA further pledged to “follow the Administrative Procedure Act and Clean Air Act, as applicable, in a transparent way for the betterment of the American people and the fulfillment of the rule of law.” 

Revisiting Mass. v. EPA?

One key question, Sussman said, is on what basis the EPA may try to revoke the endangerment finding. The agency could attempt to contest the underlying science. E&E News reported earlier this week that the Trump administration might next be assembling a federal report that rejects the overwhelming scientific evidence on the detrimental effects of climate change. 

Alternatively, the EPA could aim to go after the legal underpinning of Massachusetts v. EPA. The Supreme Court is more conservative now than it was in 2007—three of the four justices that dissented in that ruling are still on the bench. 

Still, another recent Supreme Court decision may work against the EPA’s favor should Massachusetts come up for review. Last year, the court upended 40 years of administrative law precedent when it ruled in the Loper Bright case that courts may not defer to an agency’s reasonable interpretations of ambiguous statutory language—a practice that had come to be known as Chevron deference—but must instead make their own judgments as to the best meaning of the law in those instances.

“The decision overturning Chevron deference makes it even easier to show that the Clean Air Act was meant to regulate pollutants that affect the climate, because it says so in the [Clean Air Act] text,” Bookbinder, who previously led work on the Massachusetts case as the Sierra Club’s chief climate counsel, explained. He pointed to the statute’s definitions section, which does explicitly say that “effects on welfare”—which is part of the statute’s endangerment language—includes effects on things like weather and climate. 

The underlying climate science has also become even more robust over the years. “It’s almost laughable to take a position that greenhouse gas emissions don’t endanger public health and welfare,” Carlson said. 

“By repealing this, trashing this [endangerment] finding, the Trump administration is lying to you,” Representative Suzanne Bonamici of Oregon said during a February 28 press conference. “The science is irrefutable.”