Supreme Court opens term with Boulder lawsuit

The Supreme Court heard nearly two hours of oral arguments on 5 October 2026 regarding whether local governments can sue fossil fuel companies under state law for climate-related damages. The case pits the city and county of Boulder, Colorado, against ExxonMobil and Suncor Energy. Outside the court building on Monday morning, demonstrators gathered chanting slogans accusing energy corporations of deception regarding fossil fuel emissions. Boulder officials are seeking monetary compensation from the two companies to help pay for infrastructure repairs, public health impacts, and disaster response tied to wildfires, droughts, and floods.

Competing arguments over federal and state authority

Lawyers representing ExxonMobil and Suncor Energy argued that the Clean Air Act grants exclusive authority over greenhouse gas emissions to the federal government, preempting municipal claims in state courts. Kannon Shanmugam, the attorney arguing for the energy companies, stated that climate change policy belongs with Congress and federal regulators rather than state juries. The companies asked the justices to overturn a decision by the Colorado Supreme Court that permitted Boulder to proceed with its claims.

“This case and others like it reflect an all too regrettable trend of trying to resolve major political issues in court rather than leaving them to the political branches where they belong.”

Representing Boulder, attorney Kevin K. Russell argued that the lawsuit relies on traditional state-law tort principles to recover local financial damages caused by commercial deception and corporate conduct. Russell noted that states have maintained authority since the founding of the country to provide judicial remedies for harms occurring within their borders.

“states have had the power to provide court remedies for injuries occurring within their borders.”

Justices debate litigation scope and preemption

During questioning, Chief Justice John Roberts expressed concern about the potential scale of municipal litigation across the country if Boulder wins. Roberts noted that local governments across every state could copy the pleadings to file similar actions, though he also questioned the energy companies on why state courts should be barred from addressing cross-border harms. Justice Elena Kagan pointed to legal precedents involving lawsuits against tobacco and opioid manufacturers, suggesting that the Boulder litigation followed comparable state-level liability models.

“If you prevail, a municipality in every single state will file a lawsuit.”

Conservatives on the bench, including Justice Brett Kavanaugh and Justice Amy Coney Barrett, focused on prior Supreme Court rulings framing interstate air pollution as an exclusively federal domain. Kavanaugh pointed to the court's 2011 ruling in American Electric Power Co. v. Connecticut, noting that allowing state suits could make any manufacturer or business a potential defendant. Justice Ketanji Brown Jackson questioned whether Supreme Court intervention was premature at this procedural stage.

Recusal leaves potential four-four split

The hearing took place without Justice Samuel Alito, who recused himself one week prior to oral arguments because of oil company stock holdings. Alito's absence leaves an eight-member court, creating the possibility of a four-to-four tie. Under Supreme Court procedure, an evenly divided vote would automatically uphold the Colorado Supreme Court ruling and permit Boulder's lawsuit to continue toward trial.

The outcome will affect dozens of pending climate cases nationwide, where more than 60 state and local governments are seeking billions of dollars in damages from fossil fuel producers. The Supreme Court is expected to deliver its ruling in late June or early July.