Supreme Court weighs energy company liability in Boulder climate lawsuit

When the justices return to the courtroom after their summer recess, they are hearing arguments in one of the most significant business cases of the 2026-27 term. In Suncor Energy Inc. v. County Commissioners of Boulder County, the court is deciding whether a lawsuit filed in a Colorado state court can move forward, or whether federal law bars such claims.

The dispute dates back to 2018, when the city and county of Boulder filed a lawsuit seeking compensation for the costs incurred in protecting property from the effects of climate change. The defendants include Suncor, a subsidiary of one of Canada’s largest energy companies operating in Colorado, and ExxonMobil, the largest energy company in the United States. Boulder contends that these companies deceived the public about fossil-fuel products and played a role in climate change through producing, refining, and marketing fossil fuels.

The Path Through State Courts

After the energy companies unsuccessfully tried to transfer the case to federal court and failed to get a dismissal from the state trial court, they turned to the Colorado Supreme Court. That state court agreed to decide whether Boulder’s state-law claims were superseded by federal law and ultimately concluded that the district court erred in letting the claims go forward. Suncor and ExxonMobil then petitioned the U.S. Supreme Court, which granted review.

Arguments Over Court Authority and Federal Law

Before examining the merits, the justices must determine whether they have the legal authority to review the case, as the Supreme Court normally reviews only final decisions by state courts. The energy companies argue that the Colorado Supreme Court proceeding was a separate, original proceeding rather than a standard appeal, and that an exception under the case Cox Broadcasting Corp. v. Cohn applies because the state court decided federal-law issues. Boulder counters that the proceeding was not self-contained and that the companies still have other federal defenses they can raise later.

On the merits, the energy companies contend that the structure of the Constitution prevents individual states from regulating transboundary issues like global climate change, and that the Clean Air Act bars Boulder’s claims by establishing a comprehensive regulatory scheme through the Environmental Protection Agency. Boulder pushes back, arguing that the Constitution does not silently forbid applying state law to cross-border harms, that the Clean Air Act regulates point-source emissions rather than money damages for climate harms, and that Congress has not enacted legislation granting the companies immunity.

What This Means for Local Communities and Businesses

The stakes are high because Boulder is seeking millions of dollars in compensation, and dozens of similar lawsuits are pending across the country. Energy companies warn that such lawsuits could bankrupt the industry by imposing massive carbon taxes. Meanwhile, business groups and the federal government argue that allowing state courts to address a global problem could cause the federal system to disintegrate. For ordinary people, the outcome of this case will help determine whether local governments can pursue large corporations in state courts for costs related to environmental changes.

If you are facing legal questions regarding environmental claims, business liabilities, or local property disputes, talking to a qualified lawyer may help you understand your rights and options.

This article is general information based on SCOTUSblog and court or agency records available at publication time. It is not legal advice; laws and deadlines differ by state and by case. Published October 2, 2026.