In the biggest case to reach a federal appeals court so far over President Donald Trump’s dismantling of his predecessor’s climate policy, administration attorneys argued on Thursday that the Clean Air Act gives the Environmental Protection Agency only limited authority to regulate greenhouse gas emissions from electric utilities. 

President Barack Obama asserted more expansive powers in his Clean Power Plan, the centerpiece of his strategy to combat climate change, which would have cut greenhouse gas emissions by a third. 

The plan gave states the authority to set emissions goals across the power sector and encouraged them to shift away from coal to cleaner sources of power such as natural gas, wind and solar. It was challenged by industry and 27 states and blocked by the U.S. Supreme Court before Obama even left office.

Trump replaced Obama’s plan last year with something he called the Affordable Clean Energy rule, which was based on a far narrower interpretation of the Clean Air Act and empowered the EPA to seek minor emissions reductions at individual coal-fired power plants. Instead of reducing emissions by a third, greenhouse gases would fall by less than 1 percent.

The argument Thursday in the U.S. Circuit Court for the District of Columbia came in a lawsuit filed by the American Lung Association and other environmental groups, 20 Democratic states and the District of Columbia to block Trump’s limited approach on grounds that it fails to adequately safeguard public health as the Clean Air Act requires.

Jonathan Brightbill, principal deputy assistant attorney general, defended Trump’s  Affordable Clean Energy rule, saying Congress only gave the EPA authority to establish standards for power plant operators to achieve greater heat efficiency at individual power plants, thereby reducing emissions.

His long and highly technical argument, which at one point came down to a discussion of the differences between “at,” “to” and “for,” seemed far removed from the climate-amplified wildfires that have seared the West Coast or the storms that have pummeled the Gulf Coast.

And Brightbill faced tough questioning from the two Obama administration appointees on the three-judge panel, Judges Patricia Millett and Cornelia Pillard.

“I’m a little bit puzzled by the position of the government here,” said Millett. 

She said that the Clean Power Plan took a flexible, hands-off approach, with the Obama administration saying, “‘This is where we need to go as a country with emissions. We need to protect our country, our resources, our people. Ultimately, you, industry, are the wise ones to figure out how we get there.’

“Why isn’t it the pro-industry, pro-government minimal approach to do it this way?” asked Millett. “It’s more flexible.”

“It may very well be that from a policy perspective,” said Brightbill, but that wasn’t the law as Congress wrote it.

Judge Justin Walker, the third jurist on the panel and the newest member of the D.C. Circuit, ranged far from statutory language in his questioning.

Walker, 38, a Trump appointee and protege of Senate Majority Leader Mitch McConnell who was installed on the appeals court last month, at one point asked a lawyer for a group of power companies to walk him through the process of electric generation from the time that “a miner mines a piece of coal” to the time that he turns on a light switch.

At another point, he noted how much he was learning about electric grid operators. Walker also quoted from Obama’s 2015 White House ceremony for the Clean Power Plan to suggest that he viewed it as a major regulation, and therefore subject to less deference by the courts.

Walker, who like many Trump appointees, was a member of the conservative Federalist Society, sought to use a series of questions to guide the presentation of a fellow Federalist, Lindsay See, the solicitor general of West Virginia, who was arguing in support of the EPA.

“Assume … the world is warming, and the warming is manmade, and the costs are far costlier than those of this plan,” Walker said. “None of that is relevant to how we interpret this statute. What do you think this case is about?”

See agreed that the case was about the meaning of the statute.

More than 100 parties had entered on either side of the case, and oral arguments—with the lawyers and judges connecting virtually before an online audio audience—far exceeded the three hours that the D.C. Circuit set aside for the case. 

The American Lung Association, a New York-led group of states, and power companies that already had invested heavily in cleaner energy, all were seeking to have the Trump administration’s weak climate rules for power plants struck down as unlawful.

They argue that the Trump rule does not consider the full range of options for dealing with what the agency has determined is a threat to health and the environment. 

One group of energy companies argued that the Trump administration did not even have authority under the law to put weak climate rules in place.

No matter who prevails at the D.C. Circuit, the number of disputants virtually guarantees the case will be appealed to the Supreme Court. There, it could become a vehicle for a high court with three Trump appointees to shape future climate policy, no matter who wins the election in November.

The environmental community looks at the case dealing with the meaning and reach of the Clean Air Act as a high-stakes battle even though Democratic presidential nominee Joe Biden favors drafting new law to address climate change. 

Even if Congress can overcome its past logjam on climate and pass new statutes tailored specifically to reducing greenhouse gas emissions, environmentalists believe that the climate crisis will require a large array of government action, including the ability  to invoke the power of the Clean Air Act, which marked its 50th anniversary this year.

“In our view, the Clean Air Act was passed to supply the tools to meet the threats to our health and our climate from power plants,” said David Doniger, senior strategic director of the Climate and Clean Energy Program for the Natural Resources Defense Council.  “Congress told the EPA to look realistically at how each industry that it addresses actually works and to choose the systems of emissions controls that effectively reduces dangerous pollution at acceptable costs.

“The prior EPA took account of how the power sector actually works—with plants interconnected and your light bulbs and computers not caring which plants supply their electricity,” said Doniger, speaking prior to the arguments. “The Trump EPA, trying to protect and revive the coal industry…is trying to show through Houdini-like contortion that the law leaves it no choice except this do-nothing rule. And their goal is to lock that view in permanently, to cripple what a future administration can do.”