In one of its most important environmental decisions in years, the Supreme Court recently ruled that the Environmental Protection Agency has the authority to regulate heat-trapping gases in automobile emissions, the New York Times reports. The court further ruled that the agency could not sidestep its authority to regulate the greenhouse gases that contribute to global climate change unless it could provide a scientific basis for its refusal. The 5-to-4 decision was a strong rebuke to the Bush administration, which has maintained that it does not have the right to regulate carbon dioxide and other heat-trapping gases under the Clean Air Act, and that even if it did, it would not use the authority. The ruling does not force the environmental agency to regulate auto emissions, but it would almost certainly face further legal action if it failed to do so. Beyond the specific context for this case — so-called “tailpipe emissions” from cars and trucks, which account for about one-fourth of the country’s total emissions of heat-trapping gases — the decision is likely to have a broader impact on the debate over government efforts to address global warming. According to the NYT, Court cases around the country had been held up to await the decision in this case. Among them is a challenge to the environmental agency’s refusal to regulate carbon dioxide emissions from power plants, now pending in the federal appeals court here. Individual states, led by California, are also moving aggressively into what they have seen as a regulatory vacuum.