A divided Supreme Court grappled Monday with just how much power Congress intended to give the EPA in the Clean Air Act, in a case that could determine how much of an end run President Obama can do around Capitol Hill as he seeks to impose his own solutions to climate change.
The complex case involves a narrow segment of potential greenhouse gas emitters. Some of the justices said that 3 percent of carbon emissions were tied up in the factories and other sources of pollution that the Environmental Protection Agency is targeting in the rules in question.
But those on both sides said the case poses significant questions about how agencies are supposed to grapple with sometimes outdated federal laws. At a time when Congress is gridlocked, the court’s ruling could determine how much leeway Mr. Obama has to stretch laws.
“As far as the Supreme Court is concerned, it now has the opportunity to end this latest abuse of the Constitution by the Obama administration,” said Senate Minority Leader Mitch McConnell, Kentucky Republican, who was in the courtroom for oral arguments.
He and other Obama administration opponents said the administration should have come back to Congress rather than reinterpreted the law on its own.
But the administration said the law requires it to act, and given the choice between ignoring the law or tinkering with some of its definitions, tinkering was the best option.
Justice Stephen G. Breyer seemed to agree, saying inaction might lead to unthinkable outcomes from climate change.
“Either we have to interpret the trigger provision with flexibility so that there are written exceptions — unwritten exceptions — in it, one way or the other, or we have to say you can’t do that, and therefore they don’t apply to all. Which is worse?” he said.
Justice Antonin Scalia, however, questioned whether it was right for the court to step in and weigh those two options.
“But what is supposed to be unthinkable — that greenhouse gases should not be regulated? Maybe that is unthinkable. But the issue is, is it unthinkable that Congress did not intend to regulate greenhouse gases when it enacted the current provisions of the statute?” he said.
Under a previous Supreme Court ruling, greenhouse gas emissions count as air pollution, which brings them under EPA’s purview. But the part of the Clean Air Act before the justices Monday requires anyone who annually emits more than 250 tons of a pollutant to go through a permitting process — an absurdly small threshold for carbon emissions.
EPA officials decided to come up with their own threshold for permitting, arguing that they were caught between a law requiring them to act and a definition in the law that was illogical.
The U.S. Chamber of Commerce and industry groups challenged the EPA, but even they have internal disagreements about how the Clean Air Act should be read, which likely strengthens the EPA’s argument that it has a reasonable interpretation.
The oral argument covered six cases that have been consolidated into one, Utility Air Regulatory Group v. EPA.