Last Tuesday, the Supreme Court declined to consider a variety of challenges to the Environmental Protection Agency’s effort to slash greenhouse gas emissions.

But the news wasn’t a total victory for environmentalists. The court announced it would hear one challenge to the agency’s regulations: The Justice Department will have to convince the court that the EPA has the power under the Clean Air Act to put carbon-dioxide limits on so-called stationary sources — power plants, cement mixers and the like — using a powerful permitting program.

Congress passed the Clean Air Act in the 1970s, when the air pollutants of concern were substances such as lead or particulate matter. But the law’s language doesn’t fit perfectly when applied to carbon dioxide and other greenhouse gases, in part because virtually everyone and everything produces carbon dioxide.

The high court sorted through some of the confusion in 2007 with its landmark Mass. v. EPA decision, in which it confirmed that greenhouse gases are pollutants for the purposes of the Clean Air Act. Following that, the EPA set fuel-efficiency standards on cars and light trucks. The justices on Tuesday refused to reconsider their 2007 ruling and let stand the regulations on vehicles. But they agreed to hear arguments against a piece of the EPA’s move to regulate power plants.

In the absence of congressional action, the EPA’s approach — interpreting the confusing text of the Clean Air Act in light of its overriding purpose to combat threatening air pollution — is the right one.

The Washington Post (Oct.21)