The U.S. Supreme Court heard oral arguments on Oct. 5 in Suncor Energy v. Boulder County, a case concerning whether federal law prevents state and local governments from using state law to seek damages from oil companies for the effects of global greenhouse gas emissions.

According to the question presented, the justices are also considering whether the Supreme Court has jurisdiction to hear the companies' appeal at this stage of the litigation. The issue arises because the Colorado Supreme Court's decision came before trial, while the U.S. Supreme Court typically reviews state court cases after a final judgment. If the Court determines that it lacks jurisdiction, it could dismiss the appeal without deciding whether federal law preempts the claims.

Boulder County and the city of Boulder sued ExxonMobil and Suncor Energy under Colorado law, seeking compensation for local costs associated with climate change. The Colorado Supreme Court allowed the lawsuit to proceed. Exxon and Suncor appealed to the U.S. Supreme Court.

The companies argue that federal law preempts state-law claims seeking damages for the effects of interstate and international greenhouse gas emissions. The Trump administration also appeared before the Court in support of the companies' position. Boulder officials argue that their claims concern the companies' conduct and alleged misrepresentations about fossil fuels and can proceed under Colorado law.

According to ExxonMobil and Suncor Energy, nearly 60 similar lawsuits are pending across the country in which state and local governments seek damages from oil and gas companies for alleged climate-related harms. The Supreme Court's eventual ruling could determine whether some of those lawsuits can proceed under state law.

The case also raises a federalism question about the boundary between state and federal authority over climate-related claims. A ruling could clarify how far federal authority extends in limiting states' ability to apply their own tort laws to alleged climate-related harms.

Boulder County, the city of Boulder, and San Miguel County originally filed the lawsuit together in 2018, alleging that Exxon and Suncor contributed to climate change and misled the public about the risks associated with oil and gas. San Miguel County's claims were later severed into a separate case, now pending in Denver District Court. The case before the U.S. Supreme Court involves only Boulder County and the city of Boulder, who seek monetary damages for climate-related costs, including infrastructure and public health expenses.

The Colorado Supreme Court ruled in May 2025 that the lawsuit could proceed. Exxon and Suncor appealed, and on Feb. 23, 2026, the U.S. Supreme Court agreed to hear the case. The Court directed the parties to address both whether federal law preempts the Colorado claims and whether the Court has jurisdiction to hear the case.

Justice Samuel Alito recused himself from the case. Alito owns stock in other oil companies, including ConocoPhillips and Phillips 66, that face similar climate-related lawsuits. The Court did not provide a reason for his recusal. The Court is expected to issue a decision by the end of its current term in June 2027.

The case also relates to debates over corporate environmental responsibility and whether companies should be held financially accountable for climate-related harms, issues that intersect with ESG policy.

Ballotpedia tracks support for and opposition to the environmental, social, and corporate governance (ESG) investing movement. To learn more about arguments for, against, and about ESG, click here. For more information on reform proposals related to ESG policy, click here.