Supreme Court Hears Boulder's Climate Liability Case Against Energy Giants

The Supreme Court convened on a Monday in October to hear arguments in a case that could reshape how cities and states pursue climate damages against fossil fuel producers. Eight justices—Justice Samuel Alito recused himself without explanation—sat through nearly two hours of oral arguments in Suncor Energy v. Commissioners of Boulder County, a lawsuit that began eight years earlier when Boulder, Colorado filed suit against Exxon Mobil and Suncor Energy, seeking compensation for climate-related harms.

Alito's absence from the bench was notable. His 2025 financial disclosures showed individual holdings in ConocoPhillips and Phillips 66, though not in either of the two companies Boulder sued. The recusal creates an unusual possibility: if the eight remaining justices split 4-4, the Colorado Supreme Court's decision allowing Boulder's case to proceed would stand automatically, effectively handing Boulder a victory without a full Supreme Court ruling.

Boulder's complaint centers on a straightforward claim: Exxon and Suncor's production and marketing of fossil fuels caused the city and county to face extreme heat, larger and more frequent wildfires, and ecosystem damage. The companies tried to move the case to federal court, then asked state courts to dismiss it on the grounds that federal law barred such claims. When those efforts failed, they appealed to Colorado's highest court, which sided with Boulder. Now the U.S. Supreme Court was being asked whether the lawsuit could proceed at all.

Kannon Shanmugam, arguing for the energy companies, warned the justices that Boulder's case represented an "unprecedented effort" to use state law to regulate global conduct. He told the court that the Constitution and the Clean Air Act precluded claims seeking relief from interstate greenhouse-gas emissions. If Boulder prevailed, he cautioned, roughly 90,000 municipalities could file similar lawsuits, effectively allowing local juries to set national and international energy policy through damage awards. Chief Justice John Roberts echoed this concern, asking how the legal system would function if every state and locality filed comparable suits.

But the justices were not uniformly persuaded. Justice Brett Kavanaugh pressed both sides on four decades of Supreme Court precedent establishing that interstate air and water pollution are federal matters—unless Congress explicitly authorizes state action. Yet Justice Ketanji Brown Jackson suggested the court's review was premature, telling the government's lawyer that the justices did not yet know enough to apply the theories being proposed. Justice Elena Kagan drew a parallel to tobacco litigation in the 1990s and opioid cases more recently, noting that state courts had been permitted to proceed in those contexts. Chief Justice Roberts himself acknowledged that the Supreme Court had allowed state lawsuits with broad interstate effects to move forward in other contexts, from mass torts to internet regulation.

Kevin Russell, arguing for Boulder, stressed that states have held the power since the nation's founding to provide tort remedies for injuries within their borders, even when the conduct causing those injuries occurred elsewhere. He emphasized that Boulder was not suing over emissions themselves—those are regulated by the Clean Air Act—but over what he characterized as deceptive marketing and production practices that fall outside federal regulation. He argued that Congress could intervene at any time to preempt unreasonable state laws, and that Boulder's lawsuit was not an attempt to solve climate change but simply to ask the companies to bear their fair share of local costs.

Boulder Mayor Aaron Brockett spoke to supporters after the arguments, calling the moment a vindication of an effort that began in that same location eight years prior. He noted that Boulder residents view climate change as an existential threat and broadly support the lawsuit. The case remains in its early stages—the Supreme Court was hearing arguments on whether the lawsuit could proceed at all, not on the merits of Boulder's underlying claims.

A decision is expected by the summer of 2027. If the court deadlocks, Boulder advances. If the justices rule on the merits, they will be deciding whether states can hold energy companies financially accountable for climate damages, a question with implications for dozens of similar lawsuits filed by states and municipalities across the country.