Three presidents have used the Clean Air Act to curb planet-warming pollution. If President Donald Trump gets his way, they will be the last.
But the 1963 law has always been an imperfect and insufficient vehicle to address climate change. Just ask the lawyers who worked on the landmark 2007 Supreme Court case that affirmed the law allows EPA to regulate greenhouse gases.
“No one thought the Clean Air Act provided the best template for addressing climate change,” said Richard Lazarus, a Harvard Law School professor and author of “The Rule of Five” book on the Massachusetts vs. EPA case. “It was clear there was authority, but the hope was that it would help prompt new legislation.”
Instead, Trump has torn down U.S. climate policy. Last month, EPA repealed the so-called endangerment finding, which states that climate pollution harms public health and welfare — a prerequisite for regulating pollutants under the Clean Air Act. If the repeal survives legal challenges, the federal government will lose its primary tool for limiting climate pollution.
It’s a big change. Over the past 19 years, EPA has used the Clean Air Act to curb emissions from three broad sectors: motor vehicles, power plants, and oil and gas.
The track record on those rules has been mixed.
Supporters credit the Obama administration’s tailpipe rules with helping electric vehicles gain a foothold in the U.S. and slashing emissions. But attempts to limit climate pollution from power plants have failed, with three power sector rules terminated by subsequent administrations, the courts, or both. And while some Biden-era methane curbs for oil and gas remain in effect, state plans to limit methane for existing fossil fuel infrastructure are on hold until 2027 to give EPA time to weaken them.
Some veteran observers say that for sectors other than motor vehicles, the Clean Air Act simply doesn’t afford the sweeping reductions that climate science demands. Others blame the whipsaw of presidential politics for undermining climate policy. And one architect of Massachusetts vs. EPA criticized the Obama and Biden EPAs for being too slow to wield the power the Supreme Court conferred upon them to regulate a full suite of high-polluting industries.
“It’s been a huge disappointment,” said David Bookbinder, the Sierra Club’s chief climate counsel and one of a handful of lawyers who worked on Massachusetts on behalf of the state and environmental petitioners.
“There are huge swaths of the economy that can be regulated,” he said. “Some of the biggest source categories — cement, iron and steel, refineries. Enormous source categories that no one wanted to touch — either Obama or Biden — presumably for fear of political consequences.”
Always Plan B
The Clean Air Act became the primary vehicle for federal climate policy by default rather than design.
When the Supreme Court ruled on April 2, 2007, that greenhouse gases qualified as pollutants, many of the lawyers who delivered the victory didn’t see that as the end goal.
“Even those of us who were convinced the Clean Air Act could be made to work to address the problem agreed that there’s got to be a better way to regulate greenhouse gasses,” said James Milkey, who led the environmental protection division of the Massachusetts attorney general’s office and delivered the oral arguments for the petitioners before the Supreme Court.
The law was first enacted in 1963, with major amendments in the 1970s and 1990. Climate pollutants passed the test that Congress set for EPA to identify additional pollutants that posed a risk.
But while the law allows the government to regulate pollutants not mentioned in the statute, Lazarus said, “it doesn’t directly set up a regulatory program with those kinds of pollutants in mind.”
In the immediate aftermath of the court’s decision, the arc of history seemed to be bending toward climate legislation. Long-time opponents signaled a new openness. The court’s decision required EPA to weigh whether tailpipe emissions from new motor vehicles endangered the public, but carmakers didn’t want to be the only sector caught in the agency’s crosshairs.
“When the Court ruled in our favor, the assumption we all — on all sides of the case — had was that it would lead to congressional action in the form of some form of cap-and-trade statute or similar measure,” Milkey said.
Moments after the ruling came out, the Alliance of Automobile Manufacturers released a statement demanding “a national, federal, economy-wide approach to addressing greenhouse gases.” Then-House Energy and Commerce Chair John Dingell (D-Mich.), who had spent years shielding the auto sector from tougher fuel economy standards and had disputed that the Clean Air Act covered climate pollution, called for the same.
The Bush administration never delivered a greenhouse gas endangerment finding. But two years after the rule, President Barack Obama entered the White House, the more-progressive Rep. Henry Waxman (D-Calif.) replaced Dingell as Energy and Commerce chair, and Senate Democrats brought their majority up to 60.
Under Obama, the 2009 endangerment finding set the stage for congressional action. By giving the Obama administration a “Plan B” to regulate climate pollution, Lazarus said, the Supreme Court had also created an incentive for industry and reluctant lawmakers to negotiate on legislation.
The ‘grand bargain’
The same qualities that made the Clean Air Act a less-than-ideal climate regulatory tool — at least for sectors like power — also made it inflexible for industry.
“It’s just not a good fit,” Lazarus said.
The decades-old statute was designed with local and regional pollution in mind. Most of its programs sought to control pollution on site at individual facilities. But greenhouse gases have the same atmospheric effect no matter where in the world they’re released, making them an ideal candidate for a more flexible emissions capping policy or a tax on emissions.
So when EPA proposed its endangerment finding in April 2009, it was expected to serve as a cudgel to bring reluctant lawmakers and stakeholders to the table to pass cap-and-trade legislation. Waxman and then-Rep. Ed Markey (D-Mass.) introduced their bill to cap emissions the following month. Senate Environment and Public Works Chair Barbara Boxer (D-Calif.) and Sen. John Kerry (D-Mass.) rolled out a similar draft of their own.
Joe Goffman, who would later shape climate policy at EPA under former presidents Barack Obama and Joe Biden, was wrapping up a stint on Capitol Hill in early 2009 as Boxer’s senior counsel on the committee. He said the message coming from the Obama administration in those months was that they preferred a dedicated climate law to Clean Air Act regulations.
“The thinking was that Congress could work with a freer hand in putting together a decarbonization policy than EPA could,” he said, noting that legislation could also target economic stimulus in the aftermath of the Great Recession.
While the House bill passed that chamber in June 2009, the Senate bill never received a floor vote. The chamber’s leaders chose to prioritize Obama’s signature health care bill instead, and then lost their 60-vote majority in January 2010.
Goffman became EPA’s senior attorney focused on climate change in the autumn of 2009. The following year, EPA and the Transportation Department finalized the first tailpipe emissions rules for greenhouse gases — a “grand bargain” with California, industry and unions. Experts say that was eased by the fact that the federal government had just lent U.S. carmakers roughly $80 billion to help them weather the economic downturn and retool their operations.
David Doniger, one of the lawyers who contributed to Massachusetts vs. EPA briefs as a senior attorney with the Natural Resources Defense Council, said the Obama auto standards cut the sector’s greenhouse gas emissions in half between 2012 and 2025.
“All by itself, if nothing else, that’s a huge achievement,” said Doniger.
‘The shortcut doesn’t exist’
EPA hasn’t been able to duplicate that success with power plants, despite more than a decade of trying. Doniger said both the statute and the politics of power plant regulations make forging agreement difficult.
The sector is heterogeneous, he said.
“The investor-owned [utilities] and the co-ops don’t see eye to eye,” Doniger said. “The coal mining industry is trying to protect itself.”
The rules for coal- and gas-fired generation are also written under a Clean Air Act provision that depends on state implementation — giving red states more opportunity to scuttle them than the clean car rules.
Both the Obama and Biden administrations were also slow to issue power plant rules, with the administrations ending long before judicial review of the rules concluded.
The Obama EPA signed a settlement agreement with environmental petitioners in 2010 that obligated it to finalize climate standards for power plants by May 2012. But the agency didn’t propose the Clean Power Plan until 2014, finalizing it the following year.
That 2015 rule took a “system-wide” approach to emissions reduction, seeking to shift the broader U.S. power mix away from coal and toward gas and renewables. The Supreme Court stayed the rule from taking effect and ultimately found that gridwide approach illegal in 2022’s West Virginia vs. EPA decision.
“The Supreme Court in the West Virginia opinion did significant damage to the Clean Air Act’s usefulness as a tool for dealing with climate in the power sector,” Goffman said.
Limiting EPA to what can be achieved at individual coal- and gas-fired power plants, Goffman said, was “a severe distortion of the reality of how the power sector works.”
In 2024, when Goffman was EPA air chief, the agency finalized a rule that would require existing coal-fired power plants and some new gas plants to capture most of their greenhouse gas emissions. EPA is now in the process of pulling those standards back.
Technology-based rules of that kind are “not worthless,” Goffman said, but they don’t take advantage of the “actual existing menu of strategies for decarbonizing the electricity sector.”
Something closer to the Clean Power Plan, that achieved reductions through generation-shifting and demand reduction, would be more efficient and effective, he said.
Goffman said the Clean Air Act has always worked best “in dialogue” with legislation. That authority backstopped Obama administration’s push for cap and trade, then worked alongside the 2022 climate spending law to deliver more reductions at a lower cost, he said.
EPA’s analysis for the Biden-era power plant rules, for example, showed the Inflation Reduction Act’s tax incentives and other programs would do more to reshape the grid than the rule alone.
Lazarus said he admired the policy design of the Clean Power Plan, but had always had doubts about whether it was sufficiently grounded in the language of the Clean Air Act’s rarely used section 111 (d).
“Just because something is a great approach doesn’t by itself necessarily mean it’s legal,” he said.
The next chapter of U.S. climate policy might depend more on voters than on the Supreme Court or any individual administration’s willingness to tackle greenhouse gases via existing law, Lazarus said.
“The shortcut doesn’t exist,” he said. “You’ve got to elect people who are willing to vote for transformative legislation. That’s the only way to do it. And it’s not easy, but it’s compelling, ultimately, because of the threats we face.”
