Over the summer I pondered the fate of Connecticut v. American Electric Power, a case argued before the Second Circuit in June 2006. The case, a suit filed by several states against several utilities alleging their emissions of carbon dioxide contributed to the "public nuisance" of global warming, was of particular interest because one of the judges on the case was then-Circuit Judge Sonia Sotomayor.

Today, some three years and three months later, an opinion has finally issued, and it's a whopper. The 139-page opinion, in which Judge Sotomayor did not participate, reverses the district court's dismissal of the case and allows the states' suit to proceed. The opinion begins:

In 2004, two groups of Plaintiffs, one consisting of eight States and New York City, and the other consisting of three land trusts (collectively "Plaintiffs"), separately sued the same six electric power corporations that own and operate fossil-fuel-fired power plants in twenty states (collectively "Defendants"), seeking abatement of Defendants' ongoing contributions to the public nuisance of global warming. Plaintiffs claim that global warming, to which Defendants contribute as the "five largest emitters of carbon dioxide in the United States and . . . among the largest in the world," Connecticut v. Am. Elec. Power Co., 406 F. Supp. 2d 265, 268 (S.D.N.Y. 2005), by emitting 650 million tons per year of carbon dioxide, is causing and will continue to cause serious harms affecting human health and natural resources. They explain that carbon dioxide acts as a greenhouse gas that traps heat in the earth's atmosphere, and that as a result of this trapped heat, the earth's temperature has risen over the years and will continue to rise in the future. Pointing to a "clear scientific consensus" that global warming has already begun to alter the natural world, Plaintiffs predict that it "will accelerate over the coming decades unless action is taken to reduce emissions of carbon dioxide."

Plaintiffs brought these actions under the federal common law of nuisance or, in the alternative, state nuisance law, to force Defendants to cap and then reduce their carbon dioxide emissions. Defendants moved to dismiss on a number of grounds. The district court held that Plaintiffs' claims presented a non-justiciable political question and dismissed the complaints. See id.

On appeal, Plaintiffs argue that the political question doctrine does not bar adjudication of their claims; that they have standing to assert their claims; that they have properly stated claims under the federal common law of nuisance; and that their claims are not displaced by federal statutes. Defendants respond that the district court's judgment should be upheld, either because the complaints present non-justiciable political questions or on a number of alternate grounds: lack of standing; failure to state a claim; and displacement of federal common law. In addition, Defendant Tennessee Valley Authority ("TVA") asserts that the complaints should be dismissed against it on the basis of the discretionary function exception.

We hold that the district court erred in dismissing the complaints on political question grounds; that all of Plaintiffs have standing; that the federal common law of nuisance governs their claims; that Plaintiffs have stated claims under the federal common law of nuisance; that their claims are not displaced; and that TVA's alternate grounds for dismissal are without merit. We therefore vacate the judgment of the district court and remand for further proceedings.

I've a few other things to attend to, so a more complete analysis will have to wait, but here's a quick take. First, the court's failure to affirm the district court is not too surprising, as the political quesiton argument was always a bit of a stretch. It's also no surprise that, post-Massachusetts v. EPA, the court found that the states had standing. Indeed, the case for parens patriae standing is actually stronger here than in Massachusetts. What is surprising to me, however, is the court's decision is that the federal common law claims are not preempted. Prior to Massachusetts v. EPA this would have been a reasonable conclusion. After the Supreme Court's conclusion that greenhouse gases are pollutants under the Clean Air Act — and are thus subject to extensive federal regulation — preemption of the federal claims would seem to follow under Milwaukee v. Illinois (though the state common law claims could still proceed). I'll be curious to see how the court justified this surprising result.

UPDATE: The New York Law Journal reports here.