Eight justices hear Boulder climate suit as Alito steps aside

The US Supreme Court returns to the bench on Monday with a climate case that may end before the merits, and with only eight justices sitting. In Suncor Energy v. County Commissioners of Boulder County, Exxon Mobil and Suncor ask the court to stop a Colorado lawsuit that seeks to hold them responsible for local harm from climate change. Justice Samuel Alito has recused himself. A 4-4 tie would leave the Colorado Supreme Court ruling, which let the claims proceed, in place.

Boulder and Boulder County sued Exxon Mobil, the largest US energy company, and Suncor, which runs two refineries in Colorado. The suit is still at an early stage. The question for Monday is not damages. It is whether federal law precludes the state-law claims, and, before that, whether the US Supreme Court has jurisdiction to review the Colorado decision at all. The court asked both sides to address jurisdiction. It can normally review only final judgments of state courts. This one may not be final, because the Colorado ruling let the case go forward rather than ending it.

The Colorado Supreme Court sided with the city and county. Suncor and Exxon petitioned in August 2025. The justices granted review in February. SCOTUSblog noted that the case is among the significant business disputes of the 2026-27 term. A win for the companies would give other energy defendants a federal bar to use against similar city and county suits. A loss, or a tie, would send Boulder back toward discovery. Discovery is the stage the companies have been trying not to reach.

Alito's recusal was announced on 28 September. The court gave no reason. His 2025 financial disclosure listed individual holdings in ConocoPhillips and Phillips 66. Those are not the defendants. They are energy stocks. Recusal removes his vote. With eight justices, an even split affirms the lower court without an opinion. That is the mechanical consequence Boulder lawyers will have in mind if the argument splits. An affirmance by tie does not bind other circuits. It ends this appeal.

The jurisdictional issue can dispose of the case without a word on climate. If the Colorado ruling is not final, the Supreme Court may say it cannot hear the appeal yet. The companies would then face the state-court case they asked the justices to stop. If the court finds it does have jurisdiction, it reaches the preclusion question: whether the Clean Air Act or some other federal scheme has taken this subject away from state courts. CBS reported that both questions are in Monday's order.

Boulder's claim is local and specific in form. It names a city, a county, and two companies with Colorado operations, including Suncor's two refineries. It is also one of a set of similar suits by local governments. A merits ruling here would travel. A jurisdictional dismissal would not settle the others. A tie would settle only this appeal. The refineries are the Colorado hook. Exxon is in the case as a producer whose products were sold into the state, on the city's theory. The companies say that theory is a federal question wearing a state caption.

Monday is the first argument since late June. The calendar choice puts the energy case at the opening of the term, with one justice absent and two questions on the order: power to hear the case, then power of state law to reach the companies. The result that requires no fifth vote is the one that leaves Colorado's decision standing. Argument is Monday. An opinion, if the court reaches the merits and does not tie, will come later in the term. The tie, if it happens, needs no opinion at all.