Key Takeaways
The U.S. Supreme Court agreed to hear a climate lawsuit in which ExxonMobil and Suncor Energy are being sued by the City of Boulder, Colorado, in state court for the greenhouse gases their facilities emit.
The oil companies believes the case should be tried in federal court because state-law claims are superseded by federal environmental laws and the federal government’s power to conduct foreign policy.
The outcome could have a wide bearing on dozens of similar lawsuits around the country, which have been pursued as part of an orchestrated national campaign.
The case will determine whether federal boundaries hold or whether local lawsuits can penalize lawful energy production and set U.S. climate policy from the courtroom rather than through legislative and regulatory processes.
The U.S. Supreme Court agreed to hear a petition from the U.S.’s ExxonMobil and Canada’s Suncor Energy over a climate change lawsuit filed against the two oil producers by the city of Boulder, Colorado. In 2018, officials from Boulder’s city government and Boulder County filed the lawsuit in state court to force ExxonMobil and Suncor to pay damages for their alleged role in increasing greenhouse gas emissions. Attorneys for ExxonMobil and Suncor argued that Boulder “cannot make energy policy for the entire country.” According to SCOTUSblog, the companies urged the state courts to dismiss the case, arguing that the state-law claims are superseded by federal environmental laws and the federal government’s power to conduct foreign policy. Taking on the case, the Supreme Court is expected to hear oral arguments in the fall, with a decision to follow sometime in 2026.
The petition filed by the oil companies requests the judges to go beyond the current case and to decide whether federal law prevents state-level claims of climate-related injury, which could have implications beyond this case. Lower courts have been divided on whether these cases belong in state court or are preempted by federal law.
U.S. cities and states have sued energy firms over their contributions to climate change. For example, Vermont and New York have set up “superfunds” that tax large fossil fuel companies to pay for perceived climate damages from their products. New York’s law mandates that the largest fossil fuel companies deemed responsible for carbon dioxide emissions from 2000 to 2018 contribute $3 billion annually to a climate mitigation fund for the next 25 years.
Both oil companies under Boulder’s suit have a facility in Colorado. Suncor’s U.S. affiliate, Suncor Energy USA, operates the Commerce City refinery, and ExxonMobil has a gas processing plant in the Piceance basin in Rio Blanco County. Boulder sued the companies, alleging that they “knowingly and substantially contributed to the climate crisis by producing, promoting, and selling a substantial portion of the fossil fuels.” According to Boulder’s suit, climate change exacerbates extreme weather, claiming that it will cost millions of dollars to respond.
Background
After Boulder filed the lawsuits in state court in 2018, the two oil producers tried to move the case to federal court. In 2019, a U.S. district court in Colorado blocked the attempt, and the Tenth Circuit Court of Appeals upheld the lower court’s ruling in 2020 and again in 2022. The oil companies then petitioned the Colorado Supreme Court to review the case’s jurisdiction, which ruled in May 2025 that Boulder could move forward with its case in state court. After the oil companies took the case to the U.S. Supreme Court, the Colorado Supreme Court agreed to pause its ruling.
In their August filing, attorneys for ExxonMobil and Suncor noted that 60 state and local governments have brought climate lawsuits against energy companies since 2017, “and more continue to be filed.” According to the oil companies’ attorneys, states have turned to local courts over federal courts since 2021, when the Second Circuit Court of Appeals dismissed a climate change lawsuit against Chevron. The Second Circuit Court of Appeals upheld the federal district court’s decision holding that municipalities cannot “utilize state tort law to hold multinational oil companies liable for the damages caused by global greenhouse gas emissions.”
The Supreme Court also indicated that it will consider whether it has jurisdiction to take up the case, meaning that members of the court could be uncertain regarding their authority to issue an opinion and may not decide on one after they hear arguments.
Analysis
Failing to convince Congress to regulate natural gas, oil, and coal to the degree they prefer, “green” activists and their local government allies sought the courts to implement their desired policies without any votes on the matter. They have been transparent about this goal, as David Bookbinder, an attorney who represented the Colorado municipalities, conceded that “[t]ort liability is an indirect carbon tax.” With the Supreme Court agreeing to review the lawsuit, the court has opened the door to potentially putting its foot down on local attempts to regulate the alleged effects of greenhouse gas emissions released around the world.
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