To me, the ideal outcome would be precisely the split decision alluded to by David Savage in the L.A. Times piece Kit mentioned. That is, I hope SCOTUS rules that the EPA can regulate CO2 under the Clean Air Act, but that it is not required to.
The worst possible outcome is that the EPA is given the authority and required to issue federal regs. The feds could then use this as an excuse to quash the many state regs popping up, only to initiative a study and review process that drags on interminably, is dominated by fossil fuel interests, and results in weak regulations that reduce the pressure to act.
The second worst outcome is a ruling that the EPA is not authorized to regulate CO2 under the CAA. This would put all the state regs into legal jeopardy and produce years of legal wrangling with no action.
The best outcome is a split. That would allow the EPA to sit on its hands, but would give legal support to state regs.
Basically, I want the feds to stay out of it, at least until Bush is out of office. I’d rather let states experiment for a while, and let public pressure for action build up more. At this point, any realistically possible federal regulations would be useless for everything except covering politicians’ asses.