The U.S. Supreme Court opened its October 2026 term on Monday with one of the biggest business cases on its docket: Suncor Energy (U.S.A.) Inc. v. County Commissioners of Boulder County, No. 25-170. Suncor and ExxonMobil are asking the justices to kill a Colorado lawsuit seeking damages for local climate harms, arguing that federal law blocks state-law claims tied to interstate and international greenhouse-gas emissions.
The underlying case was filed in 2018 by the City of Boulder and Boulder County, which allege the companies knew decades ago that fossil fuels would harm the environment, deceived the public, and should share the costs of adapting to heat, wildfire and drought — pointing to disasters like the 2021 Marshall Fire. Boulder's suit has survived repeated attempts to move or dismiss it, including a 5–2 Colorado Supreme Court ruling in May 2025 allowing the claims to proceed. The Trump administration backs the oil companies; Solicitor General D. John Sauer was granted time to argue on their side.
The argument unfolded before an eight-justice court. Justice Samuel Alito withdrew from the case on Sept. 28 — he owns stock in ConocoPhillips and Phillips 66, companies facing parallel climate suits — raising the prospect of a 4–4 split that would leave the Colorado ruling intact without settling the national question. The court also added its own threshold question: whether it even has jurisdiction to hear the case while it remains at the pleading stage in state court.
The stakes extend far beyond Colorado. Suncor says at least 60 state and local governments have filed similar suits, including attorneys general in California, New Jersey and Massachusetts, plus Honolulu's case against ExxonMobil, Chevron, Shell and BP. A decision is expected by the end of the term, likely in June 2027.
