Yesterday, in American Electric Power v. Connecticut, the U.S Supreme Court held that the Clean Air Act, which authorizes the U.S. Environmental Protection Agency (USEPA) to limit emissions of carbon dioxide from power plants, displaces any federal common law right to seek abatement of carbon dioxide emissions from power plants. Somewhat surprisingly, the U.S. Supreme Court, because it split 4-4, let stand the Second Circuit Court of Appeals' determination that it had jurisdiction over nuisance claims arising from carbon dioxide emissions. The split means that courts in that circuit continue to have jurisdiction to hear nuisance claims arising from carbon dioxide emissions. The ruling, however, does not apply to other federal circuits and thus it remains an open question outside the Second Circuit.

The case was remanded to the Second Circuit on the issue of plaintiffs' claims under state nuisance law. The Second Circuit did not reach those claims because it held that federal common law governed. In light of the Supreme Court's holding that the Clean Air Act displaces federal common law, the availability of a state lawsuit depends, inter alia, on the preemptive effect of the federal Act, and the issue of preemption was left for consideration on remand. Stay tuned.