US Supreme Court to hear arguments in Colorado climate lawsuit against Exxon and Suncor

The battle over local climate liability

On Monday, the US Supreme Court will open its new nine-month term by hearing oral arguments in Suncor Energy v. County Commissioners of Boulder County. The dispute originates from a 2018 lawsuit filed by the city and county of Boulder, Colorado, against ExxonMobil and Canadian producer Suncor Energy. Local authorities argue that the energy companies knowingly contributed to global greenhouse gas emissions since the 1960s while misleading the public about fossil fuel hazards. Boulder seeks monetary compensation to fund infrastructure repairs, emergency response systems, and environmental remediation tied to climate disasters like the December 2021 Marshall Fire. Suncor, which operates a refinery in Colorado, and ExxonMobil appealed to the justices after the Colorado Supreme Court rejected their dismissal petitions.

This case represents whether or not we believe as a society that corporations should be held to the same standards that all of us are, right? If you know you are going to cause harm, and you don't tell someone, then you should help clean up that harm.

Federal preemption and corporate arguments

The energy companies, supported by the administration of President Donald Trump, maintain that global emissions cannot be regulated through local courtrooms. Industry attorneys argue that the federal Clean Air Act and the US Constitution preempt state common-law claims regarding cross-border air pollution. Defense briefs contend that permitting local tort claims would produce conflicting regional standards and impose crippling financial burdens across the energy sector. Former Environmental Protection Agency officials from both Democratic and Republican administrations filed opposing briefs, asserting that federal statutes do not bar state-level claims. Former Attorney General Bill Barr, representing the American Energy Institute, argued that the Supreme Court must halt the ongoing wave of municipal litigation.

What's being sought are damages that would be crippling. It's imperative these cases be put to rest and this whole approach be put to rest.

Evolution of climate litigation strategy

The Boulder dispute represents the culmination of more than two decades of municipal environmental litigation across the United States. In 2006, California sued General Motors and five other automakers, but federal district judge Martin Jenkins dismissed the action in 2007 as a political question for Congress. In 2011, the Supreme Court ruled unanimously in American Electric Power v. Connecticut that federal common-law claims over interstate emissions were displaced by federal statute. Municipalities adapted by refiling claims under state statutory and common law, generating between 40 and 60 active lawsuits nationwide. Environmental law scholars note that the pending ruling will influence these state-level cases as well as corporate liability under state climate superfund legislation.

Bench dynamics and expected timeline

Only eight justices will take the bench on Monday following the recusal of Justice Samuel Alito. Watchdog and environmental groups urged Alito to step aside due to his reported stock holdings in ConocoPhillips and Phillips 66, alongside a luxury fishing trip with a company investor. Alito explained to Bloomberg that recusal was the prudent step after considering arguments presented by both sides. His absence leaves a 5-3 conservative bench, meaning an evenly divided 4-4 ruling would affirm the Colorado Supreme Court decision permitting Boulder's case to proceed. The court is scheduled to hear arguments on Monday and will deliver its final decision before the summer recess in late June or early July 2027.