Harrisburg, PA
The Legal Intelligencer
(by Casey Alan Coyle and Stefanie Pitcavage Mekilo)
According to the United Nations, climate change “is the defining issue of our time.” https://www.un.org/en/global-issues/climate-change (last visited July 28, 2025). Yet views diverge over precisely what the solutions to the issue should be—and who is authorized to pursue them. Over the years, efforts to address climate change have taken many forms, from international agreements to federal statutes to interstate compacts. As policies evolve, some state and local governments have begun exploring novel theories through existing doctrine—including the law of public nuisance—for a pathway to seek relief, through individual courts, for alleged climate‑related harms. Several recent decisions, however, reveal that the legal landscape remains in flux, with courts charting different courses through the crosswinds of federal law.
Federal Common Law and the Displacement Doctrine
Despite the proclaimed extinction of “federal general common law” in Erie Railroad Co. v. Tompkins, 304 U.S. 64 (1938), federal common law still exists today in certain areas of national concern. Am. Elec. Power Co. v. Connecticut, 564 U.S. 410, 410–421 (2011). One such area is the general subject of environmental law and, specifically, ambient or interstate air and water pollution. Id. Thus, federal common law can apply to transboundary pollution suits, and they are often based on a theory of public nuisance. Under federal common law, a public nuisance is defined as “unreasonable interference with a right common to the general public.” Restatement (Second) of Torts § 821B(1) (1979).
The right to assert a federal common-law public nuisance claim is not without limits, however. …