But the justices also wondered whether it would make much difference in the long run. All sides agreed that the EPA has the power to regulate greenhouse gases, but they differed on how the agency should go about it. Even if the government lost, some justices said, it would make only a small difference in the number of facilities that could be regulated.
“It’s a question of whether they do exactly the same thing under one provision or another provision,,” said Justice Stephen G. Breyer.
The back-and-forth suggested the possibility of a narrow ruling that limits the EPA’s regulation to those plants and factories already subject to regulation because of other pollutants.
Justice Anthony M. Kennedy — who provided the decisive vote in a 2007 ruling that said greenhouses gases met the definition of pollutants subject to EPA regulation — is likely to be the decider in this case as well.
On the one hand, he seemed uninterested in revisiting the court’s earlier decision, as some objecting states had asked. But he also questioned whether the EPA had gone too far in reinterpreting the part of the law it is using to regulate the facilities.
“I couldn’t find a single precedent that strongly supports your position,” Kennedy told Solicitor General Donald B. Verrilli Jr., who was defending the EPA’s rulemaking.
Verrilli acknowledged that the EPA might be moving quickly.
“This is an urgent environmental problem,” Verrilli said. “The effects are cumulative and they’re delayed, and so every year we wait, we make the hole deeper and we create an even greater threat to future generations.”
The legal battle in part results from the failure of the administration and Congress to find common ground on the issue of global warming.
The court ruled in the 2007 case, Massachusetts v. EPA, that carbon dioxide and other greenhouse gases are pollutants that can be regulated under the Clean Air Act. That case, which was brought by states that said the EPA under President George W. Bush was not doing enough to fight global warming, concerned regulating motor vehicles.
The Obama administration later reasoned that “stationary sources” — factories, power plants and other structures — were also subject to the permitting requirements in certain parts of the act.
A unanimous panel of the U.S. Court of Appeals for the District of Columbia Circuit agreed with that view. It said that court precedents made the agency’s readings of its powers “unambiguously correct.”
But the EPA has acknowledged that the permitting thresholds set by law in the Clean Air Act do not fit well with something like carbon dioxide, which is ubiquitous in the environment. While the law said pollution limits of 100 to 250 tons per year triggered permitting requirements, the EPA had to raise those to 75,000 to 100,000 tons per year for greenhouse gases to identify the facilities most in need of regulation.
Justice Samuel A. Alito Jr. said that went too far.
“In the entire history of federal regulation, what is the best example you can give us of an agency’s doing something like that, where it has taken a statute with numbers and has crossed them out and written in the numbers that it likes?” Alito asked.
Chief Justice John G. Roberts Jr. also pointed out the difference between trying to control greenhouse gases and limiting other pollutants, where scrubbers and filters remove the pollution. Controlling greenhouse gases “relates to energy consumption as opposed to particulate emission,” Roberts said.
Justice Elena Kagan acknowledged the agency seemed to want “complete discretion to do whatever it wants, whenever it wants to.” But she was also a tough questioner of Washington lawyer Peter Keisler, representing industry, and Texas Solicitor General Jonathan Mitchell, who spoke on behalf of the objecting states.
Kagan said that by adjusting the threshold requirements, the agency was simply trying to identify the facilities with the biggest problem. The result was less regulation, rather than more.
She and Justice Sonia Sotomayor noted the challengers had trouble agreeing on exactly what the court should do even if they won. “That to me is the quintessential ambiguity in a statute where we give deference to the agency,” Sotomayor said.
The discussion was often dense, but Breyer said at one point he was relieved to learn from Verrilli that a human was not a “net emitter” of carbon dioxide. “That means I’m a part of sustainable development,” Breyer said to laughter.
The combined cases are known as Utility Air Regulatory Group v. EPA.