Can carbon-dioxide emitters be held liable under federal common law for public nuisance claims related to global warming, or does the Clean Air Act preempt such claims?

Eight states, New York City, and three land trusts filed lawsuits against five major electric power companies, including four private entities and the Tennessee Valley Authority. The defendants were identified as the five largest emitters of carbon dioxide in the United States, collectively responsible for 650 million tons of emissions annually. This amount represents 25% of emissions from the domestic electric power sector, 10% of all domestic human activities, and 2.5% of global anthropogenic emissions.

The plaintiffs alleged that the defendants' carbon dioxide emissions contribute to global warming, creating a "substantial and unreasonable interference with public rights." They claimed this violated federal common law of interstate nuisance or state tort law. As a remedy, the plaintiffs sought injunctive relief, requesting that each defendant be required to cap and reduce their carbon dioxide emissions.

The plaintiffs filed lawsuits in the Southern District of New York in July 2004. The District Court dismissed the suits, ruling they presented non-justiciable political questions. The plaintiffs appealed this decision to the Second Circuit Court of Appeals. The Second Circuit reversed the lower court's ruling, holding that the political question doctrine did not bar the suits and that the plaintiffs had adequately alleged Article III standing. Additionally, the Second Circuit found that all plaintiffs had stated a valid claim under the 'federal common law of nuisance' and that the Clean Air Act did not displace federal common law. Following this decision, the defendants petitioned the Supreme Court, which granted certiorari to review the case.

(Ginsburg, J.)

No. Federal common law public nuisance claims related to carbon dioxide emissions from power plants are displaced by the Clean Air Act.

The Clean Air Act comprehensively addresses the regulation of carbon dioxide emissions from power plants, leaving no room for federal common law claims. Congress has delegated to the Environmental Protection Agency (EPA) the primary authority to regulate greenhouse gas emissions under the Act. This delegation reflects a clear legislative intent to entrust complex scientific and policy decisions regarding emissions to an expert agency rather than the courts. The Act provides multiple avenues for enforcement, including the setting of air quality standards, emissions limits, and permitting requirements. These statutory provisions "speak directly" to the issue of carbon dioxide emissions, thereby displacing any federal common law right to seek abatement of such emissions. The displacement doctrine recognizes that when Congress has addressed a particular issue through legislation, the need for federal common law no longer exists. In areas of special federal interest, it is the role of Congress, not the federal courts, to prescribe national policy. The EPA's expertise in dealing with the complex scientific, economic, and technological issues involved in regulating greenhouse gas emissions further supports this conclusion. The agency is better equipped than federal judges to make the difficult policy judgments and technical determinations necessary for effective emissions regulation. Allowing federal common law claims to proceed alongside the statutory scheme would potentially undermine the EPA's ability to implement a comprehensive, nationwide approach to emissions control as envisioned by Congress. The displacement of federal common law does not leave parties without recourse, as the Clean Air Act provides mechanisms for challenging EPA action or inaction through administrative processes and judicial review.

Concurrence (Alito, J.) The Court's displacement analysis is correct, but only on the assumption that the interpretation of the Clean Air Act adopted in Massachusetts v. EPA is correct. This concurrence underscores the importance of precedent in shaping environmental regulation, while also signaling potential reservations about the broader implications of Massachusetts v. EPA for future cases involving agency authority and climate change policy.