The U.S. Supreme Court is set to consider whether federal law, including the Clean Air Act, preempts state-law tort claims brought by local Colorado governments seeking damages from fossil fuel companies for alleged climate change-related harms. The Court’s decision could have significant implications for the future viability of climate liability litigation against energy corporations.
Background
In recent years, state and local governments across the country have developed new strategies attempting to hold fossil fuel companies financially responsible for past and future harms allegedly caused by global climate change. Several states have proposed or enacted “Climate Superfund” laws that impose strict liability on the largest fossil fuel emitters for the alleged impacts of their emissions, potentially requiring those companies to contribute billions of dollars towards state-level climate adaptation projects.
Additionally, since 2017 nearly 60 state and local governments have sued energy companies for damages allegedly resulting from climate change. [1] The suits typically make state law claims such as nuisance, trespass, and violations of consumer protection statutes. One such case – now before the Supreme Court – is Suncor Energy (U.S.A.) Inc. v. County Commissioners of Boulder County (“Suncor”). In this case, Boulder County and the City of Boulder sued Suncor Energy and Exxon Mobil, alleging that the corporations’ fossil fuel production and deceptive marketing practices contributed to excess greenhouse gas emissions and, in turn, caused localized climate-related harms for which the plaintiffs seek damages.
Accordingly, the Supreme Court will have the opportunity to decide whether federal law preempts these state-law climate liability claims. Currently, there is a split in the lower courts: the Colorado[2] and Hawaii[3] Supreme Courts have allowed such claims to proceed, while the Second Circuit[4] and the Supreme Court of Maryland[5] have held that they are barred by federal law. If the Court resolves the split, it will dictate whether such suits may proceed, potentially reshaping the future of climate liability litigation nationwide. However, in taking up the case, the Court also granted certiorari on threshold jurisdictional issues, meaning it may avoid reaching the merits of the preemption question altogether.[6]
The Prospect of Preemption
On May 14, 2026, Suncor submitted its petitioners’ brief to the Court, offering three arguments in favor of federal law precluding state law claims seeking to recover for alleged harms from greenhouse gas emissions.
- First, Suncor argues that federal law precludes the state law claims based on constitutional principles that prohibit states from regulating beyond their borders and require equal sovereignty among the states. Because climate change is inherently interstate – emissions cross state lines – applying any single state’s law would impermissibly regulate extraterritorial conduct. Accordingly, Suncor argues that such disputes over injuries allegedly caused by interstate greenhouse gas emissions require uniform federal rules, historically supplied by federal common law and now governed by the Clean Air Act, and therefore that the City and County’s claims are foreclosed.
- Second, Suncor argues that the claims are precluded because they infringe on the federal government’s exclusive and constitutionally grounded authority over foreign affairs. Climate change is not just interstate, but also international, and the alleged harms for which the City and County seek damages were in part caused by emissions released outside the United States. Allowing state and local governments to pursue claims for emissions released abroad would undermine the federal government’s foreign affairs authority and potentially interfere with its foreign policy strategy.
- Third, Suncor argues that the Clean Air Act preempts the state law claims. The Clean Air Act’s statutory scheme was intended to “dominate the field” of interstate pollution regulation. State law claims for climate damages disrupt the Clean Air Act’s scheme of cooperative federalism, which positions EPA as the primary regulator of emissions and carves out a designated role for the States to regulate emissions within their own borders. However, EPA’s recent rescission of its 2009 Endangerment Finding may complicate that argument.[7] There, EPA concluded it lacks statutory authority under the Clean Air Act to regulate greenhouse gas emission standards for new motor vehicles and engines. Although that determination does not apply to stationary sources, the City and County will likely argue that, to the extent EPA has stepped back from regulating greenhouse gases, the Clean Air Act no longer occupies the field – meaning state law claims shouldn’t be preempted.[8]
Due to the substantial implications of a decision on the preemption issue, nearly 40 amicus briefs were filed in support of petitioners. The briefs represented a variety of interests, including the business community, members of Congress, former senior foreign policy officials, 27 states, former state legal officers and judges, and academics and think tanks. Collectively, these groups emphasize the equal sovereignty of the states; federalism over issues of national and international concern; and the potential, significant implications of the Colorado Supreme Court’s ruling for the energy sector, U.S. national security and the economy, insurance markets, First Amendment protected speech, and liability suits under other legal theories or against other products and activities.
Notably, the United States government filed a brief that echoes Suncor’s assertion that no single State can impose policy choices on the nation or the world, while the U.S. Chamber of Commerce emphasized the implications of such a regime: an unworkable 50-state patchwork of greenhouse gas emissions regulation that would threaten to drive up energy costs and unconstitutionally fragment national policy.
Conclusion
The Court’s decision in Suncor could significantly alter the trajectory of climate liability litigation, determining whether state-law claims are a viable tool for addressing climate-related harms. At the same time, because jurisdictional issues remain in play, the Court may leave that question unresolved – prolonging uncertainty for both plaintiffs and energy companies.
The respondents’ brief is due July 27, 2026. Oral argument could occur as soon as October 2026.
Bracewell’s environment, lands and resources team will continue to monitor developments in this case and in climate liability cases developing throughout the U.S. Please reach out with any questions.
*Bracewell summer associate Claudia Meyer provided invaluable assistance with this client alert.
[1] Petition for Writ of Certiorari at 7, Suncor Energy (U.S.A.) Inc. v. Cnty. Comm’rs of Boulder Cnty., No. 25-170 (Aug 8, 2025).
[2] Cnty. Comm’rs of Boulder Cnty. v. Suncor Energy (U.S.A.) Inc. (In re Cnty. Comm’rs of Boulder Cnty.), 586 P.3d 161 (Colo. 2025), cert. granted, ___ S. Ct. ___, No. 25-170 (Feb. 23, 2026).
[3] City & Cnty. of Honolulu v. Sunoco LP, 537 P.3d 1173 (Haw. 2023), cert. denied, 145 S. Ct. 1111 (2025).
[4] City of New York v. Chevron Corp., 993 F.3d 81, 99 (2d Cir. 2021).
[5] Mayor & City Council of Baltimore v. B.P. p.l.c., No. 11, 2026 Md. LEXIS 161 (Md. 2026).
[6] Specifically, the Supreme Court directed the parties to brief and argue whether (1) the Colorado Supreme Court’s decision is a final judgment that is reviewable under 28 U.S.C. § 1257(a) and (2) Suncor and Exxon Mobil have Article III constitutional standing.
[7] 91 Fed. Reg. 7686 (Feb. 18, 2026).
[8] But, as Suncor notes, its preemption argument “does not depend on whether EPA believes the pollutant at issue meets the standard for regulation” under the Clean Air Act. “The salient point is that the Clean Air Act does not authorize the application of state law to control out-of-state sources of emissions under any circumstances.”
