Supreme Court to Hear Boulder Climate Lawsuit Appeal Against ExxonMobil and Suncor Energy

The U.S. Supreme Court will hear an appeal from ExxonMobil and Suncor Energy challenging Boulder’s climate accountability lawsuit, nine months after the Colorado Supreme Court ruled the case could proceed in state court.

The Boulder lawsuit, filed by city and county officials, seeks to hold the two oil companies financially responsible for climate change impacts on the local community. According to court documents, lawyers for Boulder argue that Suncor Energy and ExxonMobil should be held accountable for their “substantial role that their production, promotion, refining, marketing and sale of fossil fuels played and continues to play in causing, contributing to and exacerbating alteration of the climate.”

The Colorado Supreme Court ruled in May 2025 that the climate impact lawsuit could move forward in state court. Fossil fuel companies have consistently argued that such disputes should be resolved in federal courts rather than state courts, a venue that legal experts say is more favorable to their arguments.

Boulder County Commissioner Ashley Stolzmann said in a statement that oil companies “have tried every avenue to delay our climate accountability case or move it to an out of state court system.” She added that “as everyone continues to face rising costs that put budgets under pressure, we must hold oil companies accountable for the significant harm they’ve caused our communities.”

Boulder Mayor Aaron Brockett framed the case as a matter of fairness, stating that “Boulder is already experiencing the effects of a rapidly warming climate, and the financial burden of adaptation should not fall solely on local taxpayers.” He expressed hope that the Supreme Court “will not hamstring our right under Colorado law to seek the resources needed to build a safer, more resilient future.”

The lawsuit claims that the companies’ actions damaged “the health, safety and welfare” of residents. According to the filing, “Climate change will bring more (and more serious) heat waves, wildfires, droughts, and floods to the State, as well as myriad other consequences caused by rapidly rising temperatures.” The suit argues that “the damages will only multiply as climate change worsens” and that plaintiffs “are taking reasonable and necessary measures to address and abate these impacts within their respective jurisdictions.”

Both ExxonMobil and Suncor Energy argued the case should be dismissed, but lower courts and the Colorado Supreme Court ruled against them. Neither company responded to requests for comment about the Supreme Court’s decision to hear their appeal.

The Trump administration and more than two dozen states filed briefs encouraging the justices to take the case. Alabama Attorney General Steve Marshall wrote on behalf of 26 states with Republican attorneys general, arguing that cities like Boulder lack legal authority to sue polluters based elsewhere for their conduct. “There is no world in which Boulder, Colorado, gets to set global energy policy,” the brief stated.

The Supreme Court’s decision to hear the Colorado case represents a shift from its previous hands-off approach to climate litigation nationwide. According to legal observers, the court has previously resisted efforts to weigh in on climate lawsuits playing out across the country.

This case joins other climate litigation on the court’s docket. In January, justices heard arguments on whether to overturn a $745 million jury verdict against Chevron, which Louisiana jurors found had contributed to the decline of the state’s shoreline and wetlands.

The Boulder case reflects a broader trend of cities and states from Baltimore to Honolulu seeking to hold oil companies financially responsible for climate change consequences in their communities.