On June 20, 2011, the U.S. Supreme Court issued its decision in the case of American Electric Power Co., Inc., v. Connecticut, reversing the Second Circuit Court of Appeal’s ruling that would have allowed a group of states, cities and land trusts, including New York State and New York City, to pursue federal public nuisance lawsuits against certain large U.S. electric power plants with regard to their carbon dioxide emissions. In its decision, the Supreme Court unanimously held that the U.S. Clean Air Act and the U.S. Environmental Protection Agency’s implementation of that Act displace any federal common law right to seek abatement of CO2 emissions from fossil fuel–fired power plants. However, in another key part of its decision, the Court affirmed the Second Circuit Court’s decision that at least some of the plaintiffs had standing to bring their claim.