The Supreme Court returns to the bench Monday for the first time since late June, opening its new term with a major climate change case. The justices will hear an appeal from energy companies Suncor and ExxonMobil seeking to block dozens of lawsuits in state courts that aim to hold fossil-fuel producers liable for damage related to climate change. The long-running dispute out of Boulder, Colorado, filed in 2018, is one of dozens brought by states and local governments seeking money damages for past and future harms allegedly caused by greenhouse gas emissions. Billions of dollars are potentially at stake.

Exxon and Suncor argue in Supreme Court filings that the Constitution and the Clean Air Act preclude claims over interstate greenhouse-gas emissions, warning that upholding the Colorado ruling would authorize all fifty states and tens of thousands of municipalities to establish conflicting climate policies. The Trump administration backs the companies, calling the litigation a power grab intended to impose emission regulations. Boulder counters that it sued over allegedly deceptive marketing and production, which the Clean Air Act does not regulate, and that a global problem does not disempower states from redressing local harms.

Boulder's lawsuit, filed in state court, alleges that Exxon and Suncor's production and deceptive marketing of fossil fuels led to unchecked use of their products and a rapid rise in atmospheric greenhouse gases, forcing the city to confront extreme heat, larger and more frequent wildfires and ecosystem damage. The question before the Supreme Court is narrow but decisive: whether the suit can proceed in state court or is barred by federal law. A win for Boulder would not guarantee victory, but would let the case move forward.

The Associated Press reports that West Virginia and 25 other states are backing Suncor and Exxon Mobil, arguing that Boulder's lawsuit jeopardizes their own policy goals on energy production and environmental protection. Supporters of Boulder, including law professor Jonathan Adler, frame the case as a judgment about whether communities get to make their case at all, with the scope of any claims possibly narrowed even if they proceed. Dozens of similar state and local lawsuits could ride on the outcome.

Arguments take place Monday with eight justices sitting, and a decision is expected by summer of 2027, according to CBS News. Boulder has urged the justices to dismiss the appeal on jurisdictional grounds, noting the Supreme Court also asked both sides to address whether it can even review the Colorado Supreme Court's decision.