In brief, Spitzer, along with ten state AG's and the Mayor of Washington, have concluded that Global Warming is a Clear and Present Danger, and that Washington is not doing enough about it. It wants CO2 regulations of power plants. The EPA reasonably (in this writer's opinion) holds that Carbon Dioxide (CO2) is not a "pollutant," and therefore that it has no power under the Clean Air Act to limit it by regulation. It won a similar suit filed by Spitzer et al concerning automobilie emissions.
Trying to change the underlying legislation would, of course, require public debate about the global warming "myth" [I use that term in its scientific sense]. I welcome a national debate on global warming, instead of taking it for granted. I'm not sure the DC Circuit is the right place to have that debate, however. [edited at 2:25PM]