Experts File Friend-of-the-Court Brief in Suncor v Boulder Documenting Companies’ Climate Deception

WASHINGTON (August 3, 2026)-The Union of Concerned Scientists (UCS) alongside other experts filed an amicus curiae brief with the U.S. Supreme Court today offering a historical account of ExxonMobil's and Suncor Energy's concealment and denial of the hazards they knew would result from the normal use of their fossil fuel products. The brief supports the respondents in Suncor v. Boulder, who are asking the Supreme Court to affirm that Colorado courts have the authority to hear Colorado-law claims concerning alleged injuries in Colorado. Oral arguments are expected in October.

Below is a statement by Kathy Mulvey, accountability campaign director for the Climate & Energy team at UCS who co-authored the brief.

"Petitioning to have this case heard by the U.S. Supreme Court represents a last-ditch effort to block evidence of the fossil fuel industry's decades of deceit from being heard in courtrooms across the country. Big Oil is doing everything in its power to avoid accountability, including coordinating efforts to shut down these cases before they can proceed to trial, lobbying for sweeping immunity from liability and attempting to undermine the role of climate science in the courtroom.

"Fossil fuel corporations like ExxonMobil and Suncor can read the writing on the wall; that's why they are appealing to the Supreme Court while pressuring Congress and state legislatures to gift them get-out-of-jail-free cards. Companies don't spend huge sums to coordinate lobbying and other efforts at multiple levels and across all branches of government when they have nothing to hide. Having proven they can't be trusted to operate above board, they want to exist above the law. Meanwhile, people are forced to experience increasingly damaging fossil fuel-driven climate change."

Many previous rulings, including from this Supreme Court, have affirmed state courts as the appropriate venue for cases against fossil fuel corporations over climate damages and fraud. Currently, lawsuits filed by other states and municipalities are waiting for the outcome of this ruling to move forward with their cases in state courtrooms across the country. Justice Samuel Alito has not recused himself from the case, despite conflicts of interest-including his direct ownership of oil stocks and a friendship with Suncor investor Paul Singer-that led to his previous recusal related to Boulder's climate accountability lawsuit in 2023.

Below are excerpts from the brief.

"[In 1965] Frank Ikard, then president of the American Petroleum Institute, informed the organization's member companies-including Exxon and Suncor's predecessor Sun Oil-that then-President Lyndon Johnson's Science Advisory Committee had concluded continued fossil fuel combustion could produce significant climatic changes by the end of the 20th century. Ikard warned industry leaders the report would generate significant public concern, noting that 'there is still time to save the world's peoples from the catastrophic consequence of pollution, but time is running out.'"

"Having concluded through decades of internal research that fossil fuel combustion was driving climate change and that the resulting harms could be severe and irreversible, Petitioners [ExxonMobil and Suncor] did not communicate those conclusions to the public. Instead, they adopted a communications strategy that misrepresented uncertainty regarding both the causes and consequences of climate change, notwithstanding their own scientific findings."

"The claims asserted here by Respondents [Boulder City and County] have substantial precedent in American jurisprudence. For decades, state and federal courts have adjudicated actions alleging that manufacturers possessed substantial internal knowledge regarding the dangers of their products while simultaneously conducting coordinated public campaigns to minimize, obscure, or cast doubt upon those dangers. Tobacco litigation and lead-paint litigation provide two prominent examples. In those cases, plaintiffs alleged that manufacturers emphasized scientific uncertainty despite contrary internal knowledge, promoted alternative explanations for observed harms, financed ostensibly independent organizations and experts to disseminate those messages, and portrayed themselves as responsible corporate actors while continuing to market hazardous products. The courts did not regard such allegations as presenting novel legal theories beyond the competence of traditional state law. Rather, they applied familiar doctrines of fraud, public nuisance, consumer protection, and related state-law causes of action to determine whether the alleged misconduct had occurred."

The Supreme Court's consideration of this case comes amid a coordinated effort supported by the Trump administration to eliminate states' and communities' ability to hold the fossil fuel industry accountable for its role in the climate crisis, particularly through the courts. In April, U.S. Senator Ted Cruz and U.S. Representative Harriet Hageman introduced a bill to grant sweeping immunity to Big Oil, with similar laws passing in five states earlier this year. Industry-aligned state attorneys general have also successfully pressured for removal of the climate science chapter from a manual designed to educate federal judges on scientific issues. The Department of Justice sued states considering or pursuing lawsuits against fossil fuel companies and sought to strike down or pre-empt science-backed state Climate Superfund bills.