In his dozen years on the federal appeals court that hears the most disputes over government regulatory power, Judge Brett Kavanaugh compiled an extensive record of skepticism toward the government's powers to act on climate change.

In particular, while Kavanaugh has repeatedly voiced the belief that global warming is a serious problem, he challenged the argument that Congress has given the Environmental Protection Agency authority to do something about it.

That means the 53-year-old jurist, who was confirmed on a 50-48 vote by the U.S. Senate on Oct. 6 and sworn in to replace Justice Anthony Kennedy on the U.S. Supreme Court, could harden the high court for the next generation as a blockade to climate action that isn't explicitly mandated by Congress.

Though Kennedy, who retired, was hardly a reliable vote for environmental protection, he was the pivotal vote in Massachusetts v. EPA, the 5-4 decision that in 2007 established that greenhouse gases were a pollutant that fit "well within" the EPA's authority to regulate under the Clean Air Act.

Sign up for InsideClimate News Weekly Our stories. Your inbox. Every weekend.

"Judge Kavanaugh isn't anti-environmental, but he tends to be anti-agency," said Michael Gerrard, director of the Sabin Center for Climate Change Law at Columbia University. "He's often struck down regulation that he didn't think Congress had authorized explicitly enough. He reads statutory authority very narrowly and that is a major concern for things like the Clean Power Plan," President Barack Obama's signature climate initiative.

The Clean Power Plan is dormant as the Trump administration works on a replacement, and it is uncertain if Kavanaugh will ever face it as a justice. But Kavanaugh's views could come into play on a wide range of environmental issues where the executive branch is grappling with advances in scientific understanding of threats to public health and environment on which Congress has been unable or unwilling to act.

"Although he takes as craftsmanlike and non-controversial an approach as available, he is often willing to put blinders on to support his interpretations," said Joseph Goffman, executive director of the Environmental & Energy Law Program at Harvard Law School.

"A lot of what the Clean Air Act directs—or I'd say, mandates—the EPA to do is to look at its legal authority as sufficiently expansive to take into account of changing science about public health, pollution and technology," said Goffman, who worked as a lawyer in the Obama administration's EPA during the crafting of the Clean Power Plan and other initiatives to rein in greenhouse gas emissions. "In order to support his interpretation, [Kavanaugh] simply has to ignore that reality."

Kavanaugh's Words on Clean Power Plan, HFCs

Kavanaugh articulated his narrow reading of the law during oral arguments in September 2016 on the Clean Power Plan. Kavanaugh said the Clean Air Act was "a thin statute" to support the rule, likening the program for reining in carbon emissions from electric power plants to President George W. Bush's post-9/11 move to detain a suspected enemy combatant without due process—an effort that the Supreme Court ruled unconstitutional.

"War is not a blank check," Kavanaugh said. "Global warming is not a blank check, either, for the president."

Kavanaugh also wrote the majority opinion last year striking down another important Obama climate rule—EPA's regulation of HFCs, potent greenhouse gases used in cooling—as outside the agency's authority under the Clean Air Act.

"EPA's well-intentioned policy objectives with respect to climate change do not on their own authorize the agency to regulate," Kavanaugh wrote. "... Congress's failure to enact general climate change legislation does not authorize EPA to act. Under the Constitution, congressional inaction does not license an agency to take matters into its own hands, even to solve a pressing policy issue such as climate change."

The Trump administration has appealed that decision—a case the Supreme Court has yet to decide whether to take. Legal experts say if the court does take the case, Kavanaugh almost certainly would recuse himself.

Striking Down Cross-State Pollution Rules

Goffman said one of Kavanaugh's most telling environmental opinions was his 2012 decision to strike down the EPA's rules for addressing cross-state pollution from power plants, a decision that was overturned by a 6-3 Supreme Court, including both Kennedy and Chief Justice John Roberts in the majority.

"He looked at a technical issue that involved an analysis both of atmospheric chemistry and economics, and substituted the judgment of EPA's with his own," Goffman said. "To me, it's a 'tell' of his anti-EPA mind set."

Brett Kavanaugh is currently a judge on the U.S. Court of Appeals for the District of Columbia. During the George W. Bush administration, he was assistant to the president and staff secretary. He also worked on Bush's re-election campaign with Karl Rove (left). Credit: Paul J. Richards/AFP/Getty Images

"It's a respectable philosophy that it's really Congress, rather than the executive branch, that should set policy," said Goffman. "But as with many philosophies, they don't come out that well when they meet actual reality. You end up with the judge saying, I know better than Congress what Congress should have done here, even though Congress understood the dynamics of science and set out a strategy for EPA keeping up with that science."

Kavanaugh's Concerns About Costs to Business

Kavanaugh also has expressed concern over whether the EPA is sufficiently weighing the cost to business in decisions to benefit the environment, as in a dissenting opinion against the agency's withdrawal of a Clean Water Act permit for a coal operation.

Similarly, in a 2014 dissent about EPA's regulations governing mercury emissions from coal plants, Kavanaugh said the agency should have considered the costs when considering at the outset whether it was even appropriate to control the pollutant, a powerful neurotoxin that can cause developmental disorders and other ailments.

And he has written, much as has Trump's first Supreme Court nominee, Justice Neil Gorsuch, that courts should give less deference to federal agencies where the law is ambiguous—a principle that has governed federal administrative law for 30 years.

"The takeaway message," said Ann Carlson, director of UCLA School of Law's Emmett Institute on Climate Change, writing on the institute's blog, "is that he will construe EPA authority very narrowly and virtually always, but not every single time, in favor of regulated parties and against environmental interests."

Potential Impact on Lawsuits Against Big Oil

But most environmental law experts do not see Kavanaugh's ascent triggering a radical change in direction for a Supreme Court that already was hostile territory for environmental litigants.

"Kennedy was a pivotal vote, and we got him in Massachusetts, but we lost him in other climate cases," said David Bookbinder, chief counsel of the Niskanen Center, which advocates on environmental issues from a libertarian standpoint.

For example, he said, Kennedy sided with Justice Antonin Scalia in approving the stay of Obama's Clean Power Plan in 2016.

"But Kennedy was gettable. Kavanaugh will not be. It locks in a bad majority for dealing with climate and for dealing with environmental issues in general," Bookbinder said.

Gerrard believes that will extend beyond the question of EPA's authority. He thinks Kavanaugh may not look favorably on the cases that seek to hold oil companies legally liable for the costs that society and communities are bearing on climate change. "The fact that he thinks it is Congress that should be making the key decisions on climate change, and not the EPA, would suggest that he doesn't think the courts should be making the policy either."