In a defeat for the Bush administration, a closely divided Supreme Court ruled that a U.S. government agency incorrectly determined it lacks the power to regulate greenhouse gas emissions that spur global warming.

The nation's highest court said the U.S. Environmental Protection Agency "has offered no reasoned explanation" for its refusal to regulate carbon dioxide and other emissions from new cars and trucks that contribute to climate change. [...]

Greenhouse gases are air pollutants under the landmark environmental law, Justice John Paul Stevens said in his majority opinion.

The court's four conservative justices -- Chief Justice John Roberts and Justices Samuel Alito, Antonin Scalia and Clarence Thomas -- dissented.

The Wife of Bath at DKos, points us to this article last year from the NY Times for some background regarding the issues at stake in its discussion of the arguments made before the Supreme Court in this case last year:

By the end of the argument there appeared a strong likelihood that the court would divide 5 to 4 on the standing question, with Justice Anthony M. Kennedy holding the deciding vote. His relatively few comments were ambiguous. Early in the argument he challenged the assertion by Mr. Milkey, the states’ lawyer, that the case “turns on ordinary principles of statutory interpretation and administrative law” and that there was no need for the court “to pass judgment on the science of climate change.”

That was “reassuring,” Justice Kennedy said. But, he added, “Don’t we have to do that in order to decide the standing argument, because there’s no injury if there’s not global warming?”

The justices eventually discussed the substance of the Environmental Protection Agency’s position. Mr. Garre said the agency had “responsibly and prudently” reached the conclusion that “Congress has not authorized it to embark on this regulatory endeavor.”

But the government lawyer seemed defensive when challenged by Justice Scalia on the agency’s view that carbon dioxide was not an air pollutant within the meaning of the Clean Air Act. Mr. Garre referred several times to “the conclusion the agency reached,” an unusual locution that seemed something short of the full embrace that lawyers from the solicitor general’s office usually offer the agencies whose positions they defend.

The Bush administration’s conclusion that the Clean Air Act does not authorize the E.P.A. to address climate change marked an about-face from the agency’s previous view of its legal authority.

I guess we can thank conservative Justice Kennedy for seeing through the bullshit arguments made by global warming deniers (often funded by the large oil companies like Exxon Mobil). What effect this will have in the short term is unknown, as I doubt the Bush administration is going to proceed full speed ahead to regulate carbon emissions. However, it will prove significant should we get a Democrat in the White House in 2008. Why? Because now Big Oil can't claim the the Clean Air Act doesn't cover greenhouse gas emissions. Thus, a Democratic President in 2009 can simply proceed to order EPA to regulate carbon emissions without the necessity of any further legislation by Congress.

Can't wait to see when (not if) Ann Coulter calls for Justice Kennedy to be assassinated. This decision clearly marks him as one of those damn activist judges conservatives love to rail about.