The Supreme Court opened its 2026-27 term Monday with a fight that pits a Colorado county of roughly 330,000 people against two of the world's biggest oil companies — and the Trump administration jumped in on Big Oil's side. In oral arguments in Suncor Energy v. Boulder County, justices spent nearly two hours wrestling with whether local governments can use state tort law to make fossil fuel companies pay for the costs of climate change.

Boulder County and the city of Boulder sued ExxonMobil and Suncor back in 2018, accusing the companies of deceiving the public about the climate risks of their products while taxpayers were left footing the bill for wildfires, floods and other disasters. The case has bounced through lower courts for years; this was actually the second time the dispute reached the justices, who are now deciding a narrower, mostly procedural question about whether federal law — chiefly the Clean Air Act — blocks the lawsuit from proceeding at all.

The numbers explain why both sides are fighting so hard. Nearly 60 similar suits from states and cities are pending against fossil-fuel companies around the country, and Suncor's attorney, Kannon Shanmugam, warned the justices that a loss for his client would let "90,000 municipalities across the country" effectively set national energy policy by asking juries to impose "catastrophic damages." Justice Alito recused himself, leaving eight justices to decide the case, with a ruling expected sometime before the term ends next summer.

A Divided Bench

The questioning broke down largely along familiar lines. Justice Brett Kavanaugh invoked what he called "a wall of precedent" holding that interstate pollution is a federal, not a state, matter, warning that allowing "enough of these" suits could eventually "bankrupt" the oil industry. Justice Amy Coney Barrett pressed Boulder's lawyer on the premise of the suit itself, telling him flatly that "everybody agrees that state tort law is a form of regulation."

Justice Elena Kagan pushed back hard on the companies' preemption theory, demanding to know:

"WHERE'S THE TEXT FOR THAT? WHERE'S THE SUPPORT FOR THAT? WHERE'S THE PRECEDENT FOR THAT? WHERE'S THE ANYTHING FOR THAT?"

Kagan compared Boulder's suit to the state lawsuits that forced Big Tobacco and opioid manufacturers to pay for the public costs of their products — a parallel the oil companies reject. Boulder's attorney, Kevin Russell, told the Court the case "is not about emissions; it's about deception," arguing the companies should "internalize a portion of the costs of their activities" rather than regulate emissions outright. Justice Ketanji Brown Jackson, meanwhile, raised a separate concern about timing, suggesting it may be "premature" for the Court to weigh in before the case has even gone to trial.

The Trump administration's Justice Department filed a rare unsolicited brief backing the oil companies, arguing the lawsuit "egregiously exceeds constitutional limits on state authority" and that the Clean Air Act should preempt it entirely — a position consistent with the administration's broader push to shield fossil-fuel producers from climate liability suits.

A broad ruling for Suncor and Exxon could gut not just Boulder's case but the roughly two dozen other climate-accountability suits winding through state and federal courts, along with climate "Superfund" laws recently passed in Vermont and New York that aim to bill oil companies retroactively for emissions-related damage. A narrower ruling for Boulder would send the case back to trial court — but wouldn't guarantee the county ultimately wins. A decision isn't expected for months.