When the Trump administration erased one of the nation’s bedrock scientific principles on climate change this week, it set up a legal battle that’s all but certain to hinge on the Supreme Court.
And not for the first time.
The scientific principle that was killed on Thursday, the endangerment finding, which found that greenhouse gases endanger public health by heating up the world, itself resulted from a Supreme Court decision 20 years ago. The court had ordered the government to study whether greenhouse gases harm human health, and, if so, to regulate them.
But today’s Supreme Court is far more conservative.
And that, experts say, could complicate the legal strategy for the environmental groups and Democratic-led states that are already lining up to sue the Trump administration. A negative ruling at the Supreme Court could hamstring future leaders seeking to reinstate climate regulations.
“If the rule survives all-but-certain legal challenges, we reiterate that it could reshape U.S. federal climate policy by pendulum-proofing the issue against a Democrat sweep” in the 2028 general elections, Clearview Energy Partners, a consulting firm, said on Friday.
But a senior lawyer at the Sierra Club said the group was willing to take the risk that a more conservative Supreme Court might eventually uphold the Environmental Protection Agency’s decision to kill the endangerment finding.
“You can’t just stand by and let E.P.A. trash its own authority because you’re scared of a potentially negative ruling” from the Supreme Court, said Andres Restrepo, the lawyer for the Sierra Club. “I think that it’s a bigger risk to do nothing.”
It comes at a time when the role of the courts in U.S. environmental policy has been growing. The Trump administration’s full-speed-ahead push to cut environmental protections, combined with Republican control of Congress, has left the courts as one of the few remaining avenues for the administration’s opponents to fight back. And Republicans see several recent rulings limiting the power of federal agencies as bolstering their prospects in the courts.
“We looked at what the highest court in the land had said, and we used a very simple metric: If Congress didn’t authorize it, E.P.A. shouldn’t be doing it,” Lee Zeldin, the E.P.A. administrator, said at Thursday’s announcement at the White House.
The endangerment finding was the foundation of American climate regulations. It gave the government authority to regulate planet-warming emissions from cars, power plants and other sources in an effort to slow climate change and protect human health.
It would quite likely take several years for any such cases to get there, however. “The first step is to go to the D.C. Circuit,” Mr. Restrepo said. “And it’s important to remember that the D.C. Circuit has already upheld the endangerment finding.”
He was referring to the U.S. Court of Appeals for the District of Columbia, which is where disputes involving the Clean Air Act are first heard. In a 2012 case, that court upheld the endangerment finding, and many analysts expect it would do so again.
The Sierra Club is one of several groups and Democratic leaders who quickly vowed to challenge the move in court. California’s attorney general, Rob Bonta, called the administration’s actions an assault on environmental protections aimed at “putting the fossil fuel industry’s profits ahead of the health and safety of Americans.”
The E.P.A. on Friday made public the full text of its final rule, and the arguments made there suggest the agency recognizes the legal risks it faces from the inevitable court challenges. Legal experts said the document had significant changes from a draft rule released back in July, and those changes seemed designed with court battles in mind.
In the earlier version, the administration’s argument included claims disputing the science of climate change, reflecting in part a widely criticized Energy Department report drafted by researchers who reject the scientific consensus on climate change. That report itself was challenged in court.
There is broad scientific consensus that climate change is caused by the burning of fossil fuels.
So instead of disputing the science in its final rule, the administration leaned into the legal arguments. “They made the proposal look less crazy,” said Jody Freeman, director of Harvard Law School’s Environmental and Energy Law Program. “That would have attracted a lot of judicial attention and made them look irrational.”
At Thursday’s announcement, Mr. Zeldin stressed the legal argument. “We’re restoring the rule of law,” he said. “We’re grounding policy in reality. We’re giving power back to the American people.”
The final rule announced on Thursday argues that the 1970 Clean Air Act applies only to direct, localized pollution, whereas greenhouse gases spread far and wide and therefore aren’t subject to regulation. The document also argues that emissions from American vehicles play too small a role in global warming to warrant regulation. And it makes a case that rules aimed at encouraging a shift to electric vehicles have such far-reaching consequences that Congress, not regulators at a government agency like the E.P.A., would need to explicitly authorize them.
The endangerment finding was a scientific conclusion by the E.P.A. that six greenhouse gases pose a threat to public health, obligating the agency to regulate them. The agency was forced to reach a determination on the matter after a 2007 Supreme Court case, Massachusetts v. Environmental Protection Agency.
That case is considered the most important environmental law matter ever decided by the court, according to the Harvard law professor Richard Lazarus in his 2020 book, “The Rule of Five: Making Climate History at the Supreme Court.”
Mr. Lazarus said on Friday that the E.P.A.’s justification for killing the endangerment finding was a “frontal attack” on the precedent set in that case. Three of the dissenting justices are still on the Supreme Court. None of the original five who ruled in favor of Massachusetts remain.
Still, Mr. Lazarus cautioned that it was “not a done deal” that the justices would decide in the agency’s favor now, pointing to what he called flaws in the agency’s arguments.
“They’re not denying these huge worldwide threats posed by climate change, by emissions around the globe,” he said of the E.P.A. “To some extent, they’re simply saying that no one sector of an economy in the United States, like transportation, does enough by itself to deal with this massive problem. So we have no authority to do anything at all. That’s absurd.”
In the Massachusetts v. E.P.A. decision, Justice John Paul Stevens wrote that climate change was a grave threat, and that the Clean Air Act obligated the E.P.A. either to act or to explain why it would not do so. “E.P.A. has refused to comply with this clear statutory command,” he wrote. “Instead, it has offered a laundry list of reasons not to regulate.”
But it was not a unanimous decision. Chief Justice John G. Roberts Jr. wrote the dissent, joined by Antonin Scalia, Clarence Thomas and Samuel A. Alito Jr.
Chief Justice Roberts wrote that, while global warming “may ultimately affect nearly everyone on the planet in some potentially adverse way,” addressing it was the function of Congress and the executive branch, not the federal courts. “Such a conclusion involves no judgment on whether global warming exists, what causes it, or the extent of the problem,” he wrote.
The E.P.A. issued the endangerment finding in 2008, but officials in the George W. Bush White House refused to open the email notifying them of the decision to avoid acting on it, The New York Times reported at the time. The finding was put into effect after Barack Obama took office.
The endangerment finding survived later legal challenges.
One critical refrain against the E.P.A.’s regulations, based on the endangerment finding, has been that they increased prices on new vehicles because manufacturers were forced to install expensive emissions-control systems and pivot to electric vehicles.
“The Obama administration designed this rule to force gas cars to go the way of the eight track,” said Attorney General John B. McCuskey of West Virginia. “But American consumers have spoken.”
He also argued that the endangerment finding was an unconstitutional overreach and that later court cases have further limited the power of federal agencies.
The auto and fossil fuel industries also face legal risks from the repeal. The E.P.A.’s oversight of greenhouse gas emissions had blocked many climate lawsuits in federal court. That’s because disputes over greenhouse gases had to be taken up with the agency, not in the courts.
One result of that has been that more climate cases, for instance, lawsuits against oil companies, have been filed in state courts in recent years. Some people now argue, though, that since the E.P.A. has killed its own power to regulate greenhouse gases, lawsuits can more easily be brought in federal court, giving environmentalists and others a new legal avenue to challenge the administration.
The repeal could also spur states to double down on their own climate regulations, leading to a patchwork of policies around the country that companies would have to navigate. That’s one reason some industry groups, like the American Petroleum Institute, urged the administration to repeal rules for vehicles but leave the ones for stationary sources of greenhouse gases, like oil and gas facilities, in place.
Dustin Meyer, the petroleum institute’s senior vice president of policy, economics and regulatory affairs, said the repeal “appropriately ends the previous administration’s E.V. mandates,” but the group continues to support “smart, effective federal regulation of emissions.”
The dual specter of a patchwork of competing state regulations and an avalanche of new litigation might also give some of the justices pause if they consider the case, Ms. Freeman said. “The justices might hesitate a bit at the chaos that would be unleashed by ruling for E.P.A. here,” she said.