Here is the AP's initial write-up, and Lyle Denniston has this early analysis on SCOTUSBlog. The AP reports Justice Alito and Chief Justice Roberts seemed particularly hostile to the petitioning states' arguments. Denniston concurs, and suggests that Justice Kennedy's vote will likely determine whether the petitioners have standing. Now it's time for the Georgetown program on C-Span. More later . . .
UPDATE: The Georgetown event is worth a watch. I was not at the oral argument, and have not yet read the transcript, but I have a few thoughts in response to the panel. First, I agree with the panelists (and Lyle Denniston) that the standing issue is likely to split the Court, and that Justice Kennedy is likely to control this issue. Recall that he wrote the controlling concurrence that narrowed Justice Scalia's majority opinion in Lujan v. Defenders of Wildlife.
Second, I think that the Brown & Williamson argument is stronger than most of the Georgetown panelists. For nearly thirty years, Congress has acted as if the Clean Air Act does not grant EPA any authority to regulate greenhouse gases as such. Until the Clinton Administration, this was the unbroken approach of the EPA as well (as well as the opinion of prominent Clean Air Act experts). Two EPA general counsels, Jonathan Cannon and Gary Guzy, wrote memos to the contrary, but the Bush Administration's conclusion that the EPA lacks such authority was the first time the agency expressed a view as part of a notice-and-comment rulemaking. The Cannon and Guzy memos, by contrast, were written in response to Congressional inquiries (and Congress responded with appropriations riders barring the use of any funds to regulate greenhouse gases). Further, the overall structure of the Clean Air Act is a poor fit with greenhouse gas regulation. By this, I do not mean simply that it would be "inefficient," but that it would not work. Certain provisions that could be triggered by a finding that greenhouse gases are pollutants under the Act make no sense if applied to globally dispersed pollutants with global effects. In sum, if the FDA did not have the authority to regulate tobacco, as the Court found in Brown & Williamson, I think there is a strong argument that the EPA lacks the authority.
As I've noted before, I think the petitioners are on much stronger ground when they argue that, if the EPA has authority to regulate greenhouse gases, it did not decline to regulate in a permissible fashion. As several of the Georgetown panelists argued, the EPA is not allowed to argue, as it did, that it declined to find that greenhouse gases can be reasonably anticipated to harm public health (the "endangerment" finding) because it does not wish to adopt the climate policies that the Clean Air Act would then require. The way the law is written, if the EPA concludes that greenhouse gases can be "reasonably anticipated" to have a given effect, they must initiate regulatory action.
One way for the EPA to win this portion of the argument is for the Court to conclude that the EPA should be given more leeway in declining to act on a petition filed with the agency, but I still think this argument is hard to square with the arguments EPA provided in the Federal Register. Moreover, the EPA's refusal to find "endangerment" is also difficult to defend given other things that the EPA and other agencies have done and said on climate change. Thus, even if the petitioners win a narrow victory, and the issue is sent back to the EPA for another try, the EPA would have a difficult time sustaining its refusal to regulate on remand.
I'll have more once I've read the transcript.