Earlier this week, the Environmental Protection Agency’s (EPA) head, Lee Zeldin announced 31 actions aimed at rolling back a number of significant environmental regulations—including reconsidering restrictions on carbon dioxide emissions from power plants, rolling back vehicle emission standards aimed at accelerating the transition to EVs, and pushing to challenge a 2009 “endangerment finding” that determined greenhouse gasses like carbon dioxide and methane are a threat to public health.
The agency called it the “greatest and most consequential day of deregulation in U.S. history.” 
Legal experts say it’s a marked departure from the agency’s historic purpose to protect human health and the environment. “It’s an all out assault on climate regulation and environmental and public health protections,” says Michael Burger, director of the Sabin Center for Climate Change Law at Columbia University.
However, the announcement does not mean that the EPA has legal authority to institute the proposed rollbacks, experts say. “It is not within the authority of an agency to take action or to push through decisions that are directly and diametrically opposed to its mandate and the reason it was created,” says Nikki Reisch, director of Climate and Energy at the Center for International Environmental Law.
While each administration has flexibility in how they enforce agency regulations, the process of outright repealing regulations is more complicated, Reisch notes. “Merely making these pronouncements from up high does not change the law,” she says. “It doesn’t change the statutes that exist to protect clean air and clean water, and to protect the health of people throughout this country.”
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In order to roll back a statute, the EPA would have to go through a process defined in the Administrative Procedure Act, which requires federal agencies to publish notices of proposed and final rules, and provide plenty of opportunity for the public to comment on those proposed changes. “One of the signature and most important features of the process is that the agency has to make clear what it intends or proposes to do and why,” says Reisch. “It can’t just disregard these and steamroll ahead with what it intended, without explaining how it has considered and addressed those comments and why it is or isn’t taking them into account. And that can be a really important opportunity for the public to send a strong signal to an agency that something matters.”
As part of the process, the agency would have to back its proposal with scientific evidence. Among the most significant changes the agency has proposed is a reconsideration of a 2009 finding that determined greenhouse gas emissions pose a threat to public health—a finding that laid the foundation for much of the work the EPA has been able to do in the last 15 years.
To undo the finding, the agency would have to show that the scientific evidence is incorrect—disproving a globally accepted fact. Pollutants from greenhouse gasses reduce air quality, which increases individual risk for cardiovascular and respiratory diseases. “They have to [prove] the previous determination, that greenhouse gas emissions cause climate change and endanger public health and welfare, was wrong or was not based on sufficient scientific evidence. And there’s no basis for that. The science is quite clear, and the consensus is global,” says Burger.
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Experts say that any attempted rollbacks will likely be litigated, and, given the scientific evidence against the agency’s proposals, courts are not likely to rule in the administration’s favor.
But the process could take time. Meanwhile, the door is open for the administration—or corporate allies—to act in their own self interests.
“It might take some months or even a year or two to get this litigated, and maybe that’s what they’re counting on,” says Daniel Esty, an environmental law professor at Yale University. “By ignoring [prior regulations] during the time that there’s a challenge underway, they can get most of what they want.”
