Supreme Court hears ExxonMobil, Suncor appeal in Boulder case

The U.S. Supreme Court is hearing arguments October 5 in an appeal by ExxonMobil and Suncor Energy seeking to block Boulder, Colorado, governments’ climate-damages lawsuit, a case that could affect similar claims nationwide. The justices are considering whether federal law precludes state-law claims over the effects of interstate and international greenhouse-gas emissions. They have not ruled on the dispute. Boulder’s city and county governments sued the companies in 2018, alleging they contributed to climate change and misled the public about the risks of fossil fuels. They seek compensation for climate-related costs, including infrastructure repairs, environmental damage, emergency management and public-health impacts. The companies have not been found liable in the case. The appeal follows a 2025 Colorado Supreme Court decision allowing the lawsuit to proceed under state law. ExxonMobil and Suncor, backed by the Trump administration, argue that federal law governs claims tied to emissions crossing state and national borders and bars Boulder’s case.