The Supreme Court Decides that EPA Can't Avoid Dealing with Climate Change

The Supreme Court decided that the Environmental Protection Agency can't duck the issue of carbon dioxide emissions and climate change. The New York Times sums up the decision:

WASHINGTON, April 2 — In one of its most important environmental decisions in years, the Supreme Court ruled today that the Environmental Protection Agency has the authority to regulate heat-trapping gases in automobile emissions.
The court further ruled that the agency cannot sidestep its authority to regulate the greenhouse gases that contribute to global climate change unless it can provide a scientific basis for its refusal.

EPA had argued that it could not and should not act to regulate carbon dioxide emissions from automobiles because it "lacks authority to regulate greenhouse gas emissions" in this case, and even if it could act, it has the discretion under the Clean Air Act to choose to do nothing. Writing for the majority, Justice John Paul Stevens clearly repudiates EPA's reasons for not acting:

On the merits, the first question is whether §202(a)(1) of the Clean Air Act authorizes EPA to regulate greenhouse gas emissions from new motor vehicles in the event that it forms a “judgment” that such emissions contribute to climate change. We have little trouble concluding that it does.

As for EPA's assertion that it can exercise discretion as to whether to control carbon dioxide, Justice Stevens writes that the agency's judgment must be grounded in the law:

The alternative basis for EPA’s decision—that even if it does have statutory authority to regulate greenhouse gases, it would be unwise to do so at this time—rests on reasoning divorced from the statutory text. While the statute does condition the exercise of EPA’s authority on its formation of a “judgment,” 42 U. S. C. §7521(a)(1), that judgment must relate to whether an air pollutant “cause[s], or contribute[s] to, air pollution which may reasonably be anticipated to endanger public health or welfare,” ibid. Put another way, the use of the word “judgment” is not a roving license to ignore the statutory text. It is but a direction to exercise discretion within defined statutory limits.

The Court's majority and dissenting opinions can be found here. The decision doesn't impose a specific course of action on EPA; it just means that the Bush administration is running out of excuses for doing nothing.