Although it is difficult to determine how the Supreme Court justices might rule in a major environmental case argued on April 19, they asked several questions related to whether the courts or another branch of government should establish the nation's policies on global warming and whether, in a hypothetical common-law public-nuisance case, a federal regulation would supersede a determination by a district judge.
At issue in the case, American Electric Power v. Connecticut, is whether states and individuals can sue utilities under federal common law for contributing to global warming and force them to reduce emissions of CO?. Legal observers say it is one of the most significant environmental cases since the 2007 landmark Massachusetts v. EPA decision, which gave the Environmental Protection Agency broad legal authority to regulate greenhouse gases under the Clean Air Act.