Throughout George Bush's presidency, the federal government has refused to support any regulation of the greenhouse gases that cause global warming. Whenever the subject comes up, officials tend to mumble(咕哝)about uncertainties. But on April 2nd, the Supreme Court at last settled one of the biggest outstanding questions: whether the government has the authority to curb emissions in the first place. The court ruled that the Clean Air Act—a law from the 1960 designed to combat smog—gives the Environmental Protection Agency (EPA)the power to regulate carbon dioxide, the main greenhouse gas. It also said the EPA would need an excuse if it decided not to use this power. It dismissed the justifications the EPA had provided for inaction—that emissions from American cars were insignificant in the grand scheme of things and that unilateral action by America would undermine efforts to achieve international consensus on global warming—as inadequate. Strictly speaking, the ruling applies only to emissions from vehicles, but a very similar case regarding coal-fired power plants is pending(未决的)in federal court. The EPA says it is now examining the ruling. The EPA might examine it for some time, of course. Any regulations it comes up with in response might still defer action into the distant future, since the law allows the EPA to delay implementation until appropriate technology can be acquired at a reasonable cost. Even if it proceeds quite swiftly, a new president and Congress with globe-cooling ideas of their own will be in place long before any new rules come into effect. That suits the environmental lobby just fine. They hope the ruling will spur Congress to address global warming with proper legislation. After all, it makes little sense for such an important issue to be tackled tangentially(无关的)through a 40-year-old taw. And if 2009 sees the inauguration of a greener president, he or she will now have the power to dictate stricter fuel efficiency, in the form. of lower CO2 emissions, without reference to Congress. California set an example. In 2002, the state assembly passed a law regulating emissions of CO2 from vehicles, based on a provision of the Clean Air Act that allows California to adopt stricter pollution standards than the federal government. Carmakers have challenged the law, in part on the ground that CO2 was not an air pollutant. The car industry quickly declared that the issue of global warming is best handled at the federal level by Congress. What is the Supreme Court's attitude towards the government's function in the control of greenhouse gases?