WASHINGTON - The Supreme Court on Monday rebuked the Bush administration for refusing to regulate greenhouse gas emissions, siding with environmentalists in the court's first examination of the phenomenon of global warming.

The court ruled 5-4 that the Environmental Protection Agency violated the Clean Air Act by improperly declining to regulate new-vehicle emissions standards to control the pollutants that scientists say contribute to global warming.

"EPA has offered no reasoned explanation for its refusal to decide whether greenhouse gases cause or contribute to climate change," Justice John Paul Stevens wrote for the majority. The agency "identifies nothing suggesting that Congress meant to curtail EPA's power to treat greenhouse gases as air pollutants."

The issue at stake in the case is somewhat narrow. But environmentalists and some lawmakers said it could serve as a turning point, placing new pressure on the Bush administration to address global warming, and adding to the political momentum that the issue has received because of Democratic control of Congress and a desire from the corporate community for a comprehensive government response to the issue.

Rebuking Bush

The Natural Resources Defense Council said in a statement that the ruling "repudiates the Bush administration's do-nothing policy on global warming," undermining the government's refusal to view carbon dioxide as an air pollutant subject to EPA regulation.

The ruling could also lend important authority to efforts by the states either to force the federal government to reduce greenhouse gas emissions or to be allowed to do it themselves. New York is leading an effort to strengthen regulations on power plant emissions. California has passed a law seeking to cut carbon dioxide emissions from automobiles starting in 2009; its regulations have been adopted by 10 other states and may soon be adopted by Maryland.

The decision in Commonwealth of Massachusetts et al v. Environmental Protection Agency et al also reinforced the division on the Supreme Court, with its four liberal members in the majority and its four most conservative members dissenting. Justice Anthony Kennedy's role as the key justice in this term's 5-to-4 decisions was again on display, as he sided with Stevens and Justices Stephen Breyer, Ruth Bader Ginsburg and David Souter.

The case dates from 1999, when the International Center for Technology Assessment and other groups petitioned the EPA to set standards for greenhouse gas emissions for new vehicles. Four years later, the EPA declined, saying that it lacked authority to regulate greenhouse gases and that even if it did, it might not choose to because of "numerous areas of scientific uncertainty" about the causes and effects of global warming. Massachusetts, along with other states and cities, took the agency to court.

What the court said

The court majority said that the EPA clearly had the authority to regulate the emissions and that its "laundry list" of reasons for not doing so were not based in the law. "We need not and do not reach the question whether on remand EPA must make an endangerment finding. ... We hold only that EPA must ground its reasons for actions or inaction in the statute," Stevens wrote.

Chief Justice John Roberts wrote one dissent, which was joined by Justices Samuel Alito, Antonin Scalia and Clarence Thomas. He said that global warming may be a "crisis," even "the most pressing environmental problem of our time," but that it is an issue for Congress and the executive branch. He said the court's majority used "sleight-of-hand" to even grant Massachusetts the standing to sue.

Next page >

Get $150+ in coupons in every Sunday N&O. Click here for convenient home delivery.