Background
Baltimore City filed suit in 2018, and Anne Arundel County and the City of Annapolis followed with nearly identical suits in 2021, each targeting 26 multinational oil and gas companies including BP, Chevron, ExxonMobil, and Shell. The local governments alleged that the defendants extracted, refined, promoted, and sold fossil fuels while knowing for decades that doing so drove greenhouse gas emissions and climate change—and while actively deceiving the public about those risks. The plaintiffs sought compensatory and punitive damages, disgorgement of profits, and injunctive relief to shift the costs of sea-level rise, flooding, extreme weather, and related infrastructure damage from local taxpayers onto the companies that profited from fossil fuel sales.
All three suits asserted five Maryland common-law causes of action: public nuisance, private nuisance, trespass, strict liability failure to warn, and negligent failure to warn. After years of parallel removal battles—culminating in the U.S. Supreme Court’s 2021 ruling in BP P.L.C. v. Mayor & City Council of Baltimore, 593 U.S. 230 (2021), which required the Fourth Circuit to examine all removal grounds—the cases were ultimately remanded to state court. The Circuit Court for Baltimore City dismissed in July 2024; the Circuit Court for Anne Arundel County dismissed in January 2025. Both courts held the claims preempted by federal law and legally deficient under state law.
The local governments appealed to the Appellate Court of Maryland, which consolidated the cases. The Supreme Court of Maryland then granted a bypass writ of certiorari to decide directly whether Maryland local governments may bring state common-law tort claims against fossil fuel companies to recover damages caused by global greenhouse gas emissions.
The Court’s Holding
The Supreme Court of Maryland unanimously affirmed dismissal, holding that the local governments’ state-law claims are displaced and preempted by federal law. Writing for the Court, Justice Booth explained that for over a century the U.S. Supreme Court has held that regulation of interstate pollution arises under federal common law, not state law. Under that framework, any state-law claims targeting interstate air emissions are displaced by federal common law. And under American Electric Power Co. v. Connecticut, 564 U.S. 410 (2011), the Clean Air Act in turn displaces that federal common law. Applying the preemption framework of International Paper Co. v. Ouellette, 479 U.S. 481 (1987), the Court concluded that the Clean Air Act’s saving clause does not rescue the broad state-law claims the local governments asserted. The Court also held that federal common law would not extend to claims targeting emissions from foreign sources, an area the U.S. Supreme Court has assigned to the political branches given foreign-policy concerns.
The Court independently held that, even setting aside preemption, each cause of action fails on its own terms under Maryland law. Maryland has not expanded public nuisance beyond traditional common law—it is a public enforcement action for criminal prosecution or abatement, not a vehicle for government damage claims, and the Court declined to extend it given the comprehensive federal regulatory regime for air emissions. The private nuisance claim failed because the alleged injuries are not different in kind from those suffered by the general public. The trespass claim failed because the causal chain between the defendants’ conduct and the atmospheric conditions invading local property is far too attenuated to establish the required connection or control. And the failure-to-warn claims—whether grounded in strict liability or negligence—failed because the duty the plaintiffs sought to impose amounted to a duty to warn the entire human race about climate change, stretching Maryland tort law beyond manageable bounds.
Key Takeaways
- State common-law tort claims seeking damages for global greenhouse gas emissions are displaced by federal common law, which is itself displaced by the Clean Air Act, leaving no state-law avenue to regulate interstate or international air emissions through litigation.
- The Clean Air Act’s saving clause does not preserve the broad state tort claims asserted here; the Ouellette framework bars states from using their own common law to impose standards on out-of-state (and foreign) emission sources.
- Maryland’s public nuisance doctrine does not authorize government entities to recover damages; the tort remains confined to abatement and criminal enforcement under traditional common-law principles, and the Court refused to expand it for climate litigation given Congress’s comprehensive statutory scheme.
- Climate-injury claims for private nuisance, trespass, and failure to warn each independently fail under Maryland law for lack of particularized injury, insufficient causal connection, and an unbounded duty, respectively.
- The decision aligns Maryland with the Second Circuit (City of New York v. Chevron Corp., 993 F.3d 81 (2d Cir. 2021)) and rejects the approach taken by the Hawaii and Colorado supreme courts, creating a circuit-level conflict that the U.S. Supreme Court may soon resolve—the Court has already granted certiorari in the Colorado case.
Why It Matters
This decision is one of the most significant state-court rulings in the wave of municipal climate litigation that has wound through courts for nearly a decade. By holding that federal law forecloses state tort liability for global greenhouse gas emissions regardless of how plaintiffs frame their claims—whether as product-defect, deceptive-marketing, or failure-to-warn theories—the Supreme Court of Maryland sharply limits the tools available to local governments seeking to make fossil fuel companies bear the costs of climate change. The ruling reinforces that these disputes belong in the federal legislative and regulatory arena, not in state courtrooms.
For practitioners, the opinion offers a comprehensive roadmap of the preemption analysis under AEP and Ouellette as applied to climate tort suits, and it independently narrows Maryland’s public nuisance doctrine by confirming that government-plaintiff damage claims remain unrecognized under state common law. With the U.S. Supreme Court having granted certiorari in the parallel Colorado litigation, the ultimate resolution of these federal preemption questions—and whether any state-law climate claims can survive—may be on the horizon.