The U.S. Supreme Court has agreed to hear the next major chapter in Boulder’s long-running climate lawsuit against ExxonMobil and two Suncor entities, a decision that could determine whether the local case can proceed toward trial and shape the future of climate liability cases nationwide.
The move marks the latest escalation in a high-stakes legal battle closely watched in Boulder, where officials say climate costs are mounting, and across the country, where cities and states are testing whether courts can force fossil fuel companies to help pay for those impacts.
The court will review a Colorado Supreme Court decision that allowed the City of Boulder and Boulder County’s lawsuit to proceed under state law. The companies argue federal law should block such claims.
The case, filed in 2018, alleges the companies knowingly contributed to climate change while misleading the public about its risks and that local governments should not have to shoulder those costs alone.
Now, after nearly eight years of procedural fights, the dispute is headed to the nation’s highest court. At the heart of the case is a sweeping legal question: Can state courts hold fossil fuel companies financially responsible for climate damages, or does federal law prevent it?
In their petition, the oil companies argued that letting Boulder proceed would allow one municipality to shape national energy policy.
“Boulder, Colorado, cannot make energy policy for the entire country. The Court should grant review and clarify that state law cannot impose the costs of global climate change on a subset of the world’s energy producers chosen by a single municipality,” according to the companies’ petition for a writ of certiorari filed in the U.S. Supreme Court in August 2025.
The Supreme Court’s decision to take the case signals that at least four justices believe the issue is significant enough to warrant review and potentially resolution.
The justices are expected to decide whether federal environmental law, including the Clean Air Act, shields companies from state-level claims tied to their greenhouse gas emissions.
What Boulder’s lawsuit seeks
The City of Boulder and Boulder County argue that climate change is already imposing measurable costs locally, from wildfire response to public health and infrastructure planning.
Their lawsuit seeks damages to help cover those expenses and fund future adaptation efforts. The case is an effort to shift some of the financial burden from taxpayers to companies that plaintiffs say played a major role in causing the problem.
“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. We move forward with renewed energy and purpose for the next step toward justice,” said Boulder County Commissioner Ashley Stolzmann.
“Local communities are living with the mounting costs of climate change. The Supreme Court should affirm Colorado’s right to hold these companies accountable for the harm they have caused in Colorado,” said City of Boulder Mayor Aaron Brockett.
“Our case is, fundamentally, about fairness. Boulder is already experiencing the effects of a rapidly warming climate, and the financial burden of adaptation should not fall solely on local taxpayers. We are hopeful that the Supreme Court will not hamstring our right under Colorado law to seek the resources needed to build a safer, more resilient future,” said City of Boulder Climate Initiatives Director Jonathan Koehn.
Boulder’s lawsuit is one of dozens filed nationwide as cities, counties and states attempt to use civil litigation to recover climate-related costs and hold companies accountable for suppressing information and action related to the dangers of their products.
But Colorado’s case has been closely watched for two reasons: It is one of the few from an inland state claiming direct damages from climate change, and it could be among the first where courts consider the substance of such claims, not just procedural questions.
So far, most of the legal battle has focused on where the case should be heard, not whether Boulder’s claims are valid.
The Colorado Supreme Court ruled last year that the lawsuit could proceed in state court, rejecting arguments that federal law automatically blocks it. The U.S. Supreme Court will now decide whether that ruling stands.
“This case is about remedying harm to local Coloradans. Exxon’s argument that state law cannot provide damages for in-state harms has no basis in the Constitution. The Supreme Court has rejected similar arguments, and should reject this one,” said Richard Herz, chief litigation attorney of EarthRights International.
The Supreme Court’s involvement dramatically raises the stakes for Boulder and for similar lawsuits nationwide, and legal observers say the ruling could influence whether other climate liability cases move forward or stall.
“I’m disappointed SCOTUS agreed to hear this case, since lower courts have consistently recognized that state courts are the appropriate venue for state-law claims about deception and local damages,” said Dr. Carly Phillips, a research scientist with the Science Hub for Climate Litigation at the Union of Concerned Scientists.
“This comes at a moment when the fossil fuel industry is pursuing all possible pathways to avoid accountability, including lobbying Congress and state legislatures for legal liability waivers, raising serious concerns about their coordinated effort to shut down these cases before they can proceed to trial.”
If the justices rule in favor of the companies, the decision could effectively shut down many state-level climate lawsuits across the country.
If the court sides with Boulder, it could open the door for cases seeking billions of dollars in damages to move forward. After years of procedural battles, the ruling could determine whether Boulder’s case finally moves toward trial or ends before the evidence is ever heard.
One long-sought goal of the litigation is reaching the discovery phase, when internal company documents, emails and other records could become public, a process that played a major role in past cases against the tobacco industry.
Legal analysts note the court’s conservative majority has recently limited federal environmental authority in certain cases and taken a cautious view of lawsuits that could reshape national policy through the courts.
The court will likely hear arguments later this year, with a ruling expected in 2027. In the meantime, the lawsuit remains paused.