The U.S. Supreme Court opened its new term on Monday, October 5, with one of the most closely watched environmental cases in years, as the justices heard arguments in Suncor Energy (U.S.A.) Inc. v. County Commissioners of Boulder County.
At stake is whether the city and county of Boulder, Colorado, can use state tort law to seek money from oil companies for the costs of climate-related harm. Boulder first sued Suncor and ExxonMobil in April 2018, claiming the companies misled the public about how their products contribute to climate change. The local governments say they have paid for wildfire response, drought and extreme heat, and want the companies to share those costs.
Colorado's Supreme Court sided with Boulder in a 5-2 ruling in May 2025, allowing the case to continue toward trial. Suncor and Exxon then asked the nation's highest court to step in, and the justices agreed to take the case in February 2026. A decision is expected by mid-2027.
"Whether a single county's jury can dictate energy policy for the entire country.
— Jason Isaac, American Energy Institute, on what the case is really about
The oil companies argue that climate change is a global problem that cannot be handled through one state's courts. In their view, federal law, including the Clean Air Act and the Constitution, pushes aside Boulder's state-law claims, because the alleged harm comes from emissions produced across many states and countries.
Boulder answers that it is not trying to regulate emissions or halt oil production. Its lawyers describe the suit as a claim about deception and about the money taxpayers have spent responding to disasters.
There is also a threshold fight. Boulder argues the Court lacks jurisdiction because the Colorado ruling was not a final judgment, a point the oil companies dispute.
Why the Ruling Matters
More than two dozen similar lawsuits brought by states and local governments are pending against fossil fuel companies. Because the justices chose to hear Boulder's case now, their reasoning could end many of those cases early, or clear the way for them to move ahead.
Main Takeaways
Boulder wants oil companies to help pay for climate-related costs under state law.
Suncor and ExxonMobil say federal law blocks the claims.
Colorado's top court ruled for Boulder, 5-2, in 2025.
A decision is expected by mid-2027.
What Comes Next
Supporters of Boulder, including 28 groups that filed friend-of-the-court briefs in August, want the case to go to trial. Industry groups and allied commentators say the question belongs with Congress, not local juries.
However the Court rules, the outcome will shape how Americans can use state courts to hold energy companies accountable, and who gets to set climate policy. Check back for coverage as the justices work toward a decision.
