The U.S. Supreme Court ruled unanimously (8-0) today, in the case of American Electric Power v. Connecticut, that the Clean Air Act (CAA) and EPA's implementing regulations have displaced federal common law related to the control of greenhouse gas (GHG) emissions.  The Court was split 4-4 on the separate question of whether the plaintiffs had standing to bring the case at all (Justice Sotomayor recused herself from consideration of the case since she heard arguments on it while on Second Circuit).  The even split among the Justices on the issue of standing resulted in an affirmation of the Second Circuit's holding that climate change lawsuits can be subject to the jurisdiction of federal courts.

Because the Court's ruling was based on the fact that GHG emissions are being addressed by EPA under the CAA, it seems likely that at least some of the Justices would change their vote on this case if EPA were to stop attempting to control GHG emissions.  This could happen if Congress passes a bill prohibiting EPA from regulating GHGs (as several legislators have attempted) or if EPA, under a new administration, reverses course.  The Obama administration supports EPA's efforts to control GHG emissions and filed a brief in this case urging the Court to rule in favor of the defendants.

Although the Second Circuit's standing decision is not binding on other circuit courts, the Supreme Court would presumably find standing in any similar case it considers.  This is because Justice Sotomayor would not recuse herself from a case from another circuit and would almost certainly join the four Justices who supported the plaintiffs' standing in this case.

AEP v. Conn. is a nuisance lawsuit brought by eight states, three non-profit land trusts, and New York City against a handful of the largest power producers in the country.  Two of the states, New Jersey and Wisconsin, withdrew from the lawsuit earlier this year after electing Republican governors.  The states that remain involved are California, Connecticut, Iowa, New York, Rhode Island, and Vermont.  The plaintiffs has asked the courts to impose an injunction on the defendants to restrict their carbon emissions.  As previously blogged, the case was initially dismissed by the Southern District of New York on standing grounds (political question doctrine), but reinstated by the Second Circuit in Sept. 2009.

Read more here and here.