2018 saw an increase in high-profile lawsuits alleging climate change-related claims against both private industry accused of creating products that aggravate the trend and governments accused of doing too little to address the issue. Federal appellate courts are likely to provide meaningful rulings on both types of cases in 2019.

In the first category, suits against private industry, state and local governments generally alleged state common law claims – public nuisance, trespass, unjust enrichment, etc. – against energy companies, seeking damages related to the current or future impact of climate change on the governments’ infrastructure. In total, since 2017, eight municipalities in California and state and local governments in Colorado, Washington, New York, Rhode Island, and Maryland filed such suits.

Federal district courts in New York and California granted defendants’ motions to dismiss in two such cases in 2018. The governmental plaintiffs appealed the decisions to federal circuit courts, where arguments will be heard in 2019. In City of New York v. BP P.L.C., No. 18-2188, the Second Circuit will consider the City’s arguments that it is entitled to pursue public nuisance and trespass claims against private energy companies that the City alleges contributed to global warming and forced the City to construct infrastructure improvements to combat the negative effects. The district court dismissed the City’s claims, holding that the federal common law and the Clean Air Act displace the City’s climate change-related state common law claims and that the climate change-related claims uniquely impact global, foreign policy and separation of powers issues that counsel against a federal district court’s intervention. City of New York v. BP P.L.C., 325 F.Supp.3d 466 (S.D.N.Y. 2018). The Second Circuit is likely to consider similar defenses on appeal.

In the Ninth Circuit, a number of municipalities continue to fight energy company defendants over whether the municipalities’ climate change-related claims belong in state or federal court. In early 2018, two Northern District of California judges issued conflicting rulings granting and denying, respectively, municipalities’ motions to remand their climate change-related state common law claims back to state courts. Compare California v. BP P.L.C., No. C 17-06011, C 17-06012, 2018 WL 1064293 (N.D. Cal. 2018) (denying motions to remand); County of San Mateo v. Chevron Corp., 294 F.Supp.3d 934 (N.D. Cal. 2018) (granting motions to remand). In both cases, federal jurisdiction hinged largely on whether the federal common law applied. In California, Judge William Alsup held that “Plaintiffs’ nuisance claims—which address the national and international geophysical phenomenon of global warming—are necessarily governed by federal common law.” 2018 WL 1064293, at *2.

In contrast to both California and the S.D.N.Y.’s decision in City of New York, Judge Vince Chhabria held in County of San Mateo that federal common law did not displace the municipalities’ state common law claims because, as the U.S. Supreme Court held in American Electric Power, Inc. v. Connecticut, the federal common law was itself displaced by the Clean Air Act in federal climate change-related claims. 294 F.Supp. 3d at 937 (citing 564 U.S. 410 (2011)). Through the appeal of the consolidated County of San Mateo cases, the Ninth Circuit will soon weigh in on whether the eight California municipalities’ state common law claims belong in state or federal court. County of San Mateo v. Chevron Corp., No. 18-15499, 18-15502, 18-15503 (9th Cir.).

In the second category, suits against governments, various environmental groups or groups of young people generally alleged that state or federal governments violated the individual plaintiffs’ constitutional rights by failing to adequately address climate change. The leading case is Juliana v. United States, No. 15-cv-1517 (D. Or.), in which a group of individual plaintiffs alleged claims against the United States under the Fifth Amendment, the Ninth Amendment, and the public trust doctrine. That case had been scheduled for trial on liability in early 2019, but in late November 2018, federal district Judge Ann Aiken granted on reconsideration the United States’ request for certification for interlocutory appeal, after the United States Supreme Court granted the United States’ request for stay of proceedings in In re United States, 139 S.Ct. 452 (2018). Juliana v. United States, No. 15-cv-1517, 2018 WL 6303774 (Nov. 21, 2018). Thus, rather than a trial on the merits at the district court level, the Ninth Circuit will address Judge Aiken’s original opinion denying the United States’ motion to dismiss in 2016. See Juliana v. United States, 217 F.Supp. 3d 1224 (D. Or. 2016) (denying United States’ motion to dismiss).

While the flurry of additional climate change-related cases seems likely to continue into 2019, the fate of all these cases may turn in the near term on the rulings issued by the Second and Ninth Circuits in 2019.