The U.S. Supreme Court heard arguments Monday over whether Boulder can pursue a state-law lawsuit seeking damages from oil companies for climate-related harms, leaving the case’s outcome—and the future of similar lawsuits—uncertain. The justices are considering whether federal law preempts Boulder’s claims. They are also weighing whether a Colorado Supreme Court ruling that allowed the case to proceed gives the U.S. Supreme Court authority to review it. The dispute matters beyond Boulder: dozens of state-court lawsuits around the country seek climate-related damages from fossil fuel companies. A ruling against Boulder could limit those cases, while a decision allowing the city’s claims to proceed could leave local governments with a path to seek damages in state court. During arguments, Justice Brett Kavanaugh appeared receptive to the companies’ position that federal law displaces the state claims, pointing to what he described as a substantial body of precedent. Justices Sonia Sotomayor and Ketanji Brown Jackson appeared more sympathetic to Boulder’s case, while other justices’ views were less clear, according to legal analysts. Chief Justice John Roberts pressed Boulder’s lawyer on the potential consequences of letting municipalities bring such suits, asking whether cities across the country could file similar cases. That concern about the practical effects of allowing the lawsuits to continue appeared to resonate with several justices. UCLA law professor Alejandro E. Camacho said the court could rule narrowly in favor of the companies. He assessed Roberts, Justices Neil Gorsuch and Clarence Thomas as uncertain, and said Justice Amy Coney Barrett appeared to lean toward the companies, though not necessarily on their broadest arguments. Camacho serves on the board of an organization that supports Boulder’s position. Justice Samuel Alito recused himself. If the court divides evenly, the Colorado ruling would remain in place, allowing Boulder’s case to proceed, but the tie would not establish a nationwide precedent on whether federal law blocks these state claims. A narrower ruling could distinguish claims based on emissions from lawsuits alleging deceptive business practices, leaving some avenues for state and local action intact. The court’s decision will determine whether Boulder can continue its case and could influence how communities across the country seek accountability for climate-related costs.