April 2, 2007, may eventually turn up in the history books: On that day, the Supreme Court slapped down the Bush administration's claim that the Environmental Protection Agency has no authority to regulate carbon dioxide under the Clean Air Act. To the contrary, the court ruled, the greenhouse gas is an air pollutant like any other. NRDC was joined in the suit by 12 states, led by Massachusetts; the cities of Baltimore, New York, and Washington, D.C.; and many other environmental groups. NRDC's David Doniger helped hone the persuasive legal arguments that ultimately held sway in the land's highest court. "We've broken the legal logjam on global warming," Doniger says. "Now it's time to break the political one."