Supreme Court hears arguments on Exxon Mobil and Suncor bid to dismiss Boulder climate lawsuit

The U.S. Supreme Court opens its new term on October 5, 2026, by hearing a high-stakes climate lawsuit brought by Boulder, Colorado, against ExxonMobil and Suncor Energy. Boulder seeks compensation for local climate damages, alleging the companies misled the public about fossil fuel risks. Backed by the Trump administration, the energy firms argue that federal laws like the Clean Air Act block such state-level claims. With Justice Samuel Alito recused, a potential 4-4 tie looms, which would leave the Colorado Supreme Court's pro-Boulder ruling intact.

U.S. Supreme Court proceedings

• ▪The U.S. Supreme Court asked lawyers to address whether the high court has jurisdiction to review the Colorado Supreme Court decision, as the Boulder case has not yet reached a final judgment.
• ▪U.S. Supreme Court Justice Samuel Alito recused himself from participating in the Boulder County climate lawsuit because he owns stock in several oil and gas companies.
• ▪The U.S. Supreme Court will begin its new nine-month term on Monday, October 5, 2026, by hearing oral arguments in the case of Suncor Energy and Exxon Mobil vs. Boulder County.

Arguments supporting the energy companies

• ▪West Virginia Solicitor General Michael Williams and 25 other states filed an amicus brief backing Suncor Energy and ExxonMobil, arguing that Boulder's lawsuit threatens other states' energy and environmental policies.
• ▪ExxonMobil and Suncor Energy argue that the federal Clean Air Act and the U.S. Constitution preclude state-law claims seeking damages for harms caused by interstate and international greenhouse-gas emissions.
• ▪The Donald Trump administration filed briefs in support of ExxonMobil and Suncor Energy, arguing that federal law bars Boulder's state-law claims and that such lawsuits interfere with federal control over foreign affairs.

The Boulder climate lawsuit

• ▪The Colorado Supreme Court ruled 5-2 in favor of Boulder County, allowing the 2018 lawsuit to proceed under state common law claims of public nuisance, unjust enrichment, and civil conspiracy.
• ▪In 2018, Boulder, Colorado, sued ExxonMobil and Suncor Energy for contributing to climate change and misleading the public about fossil fuel risks, seeking monetary damages for infrastructure repairs, environmental cleanup, emergency management, and public health impacts.

Impact of climate disasters on residents

• ▪The 2021 Marshall Fire in Boulder County, Colorado, destroyed the home of resident Tawnya Somauroo and caused an estimated $2 billion in total damages, making it the costliest wildfire in Colorado history.
• ▪Boulder County resident Tawnya Somauroo spent nearly five years rebuilding her home with fire-resilient materials, expressing that the oil and gas industry should help pay for climate-related disaster recovery.

Similar climate lawsuits nationwide

• ▪California Attorney General Rob Bonta filed a lawsuit in 2023 against the five largest oil companies, alleging decades of deception regarding the environmental dangers of a warming climate.
• ▪Nearly 60 state and local governments across the United States have filed similar climate-damages lawsuits against fossil fuel companies, seeking billions of dollars in damages.

Debatable claims

• ▪State courts are an appropriate venue for climate-change liability lawsuits
• ▪Fossil fuel companies misled the public about the environmental risks of their products
• ▪Fossil fuel companies should help pay for local climate disaster recovery
• ▪Climate lawsuits against oil companies are comparable to historic tobacco litigation