
May 12, 2025
Colorado Supreme Court Advances Historic Climate Accountability Case Against ExxonMobil and Suncor
Boulder County and City of Boulder achieve major win in climate case against Exxon Mobil and Colorado Suncor entities
Key points:
- The Colorado Supreme Court has decided that Boulder County and the City of Boulder's lawsuit against ExxonMobil and two Suncor entities can continue.
- The court did not agree with the oil companies’ request to dismiss the case.
- The communities filed this lawsuit because the oil companies’ actions have greatly contributed to an altered climate.
- The rising costs of dealing with the climate crisis led these communities to take legal action so that the costs do not fall on taxpayers alone.
- This legal fight has been going on since 2018.
- The communities have worked hard to keep their lawsuit in a local court instead of moving it to a federal court.
- To receive this information in another language, contact Emily Sandoval by phone 303-413-7095 or email esandoval@bouldercounty.gov
Boulder, CO — The Colorado Supreme Court ruled today that Boulder County and the City of Boulder can move forward with their climate case against Exxon Mobil and Colorado Suncor entities. This case seeks to hold these companies responsible for knowingly contributing to climate change while concealing the dangers of their products.
Boulder County and the City of Boulder face significant rising costs to address the impacts of climate change—costs that would otherwise fall entirely on local taxpayers. This lawsuit aims to ensure that the corporations that caused the harm pay their fair share, rather than shifting the burden to Colorado communities.
The decision comes as the realities of climate alteration continue to mount for Colorado. Colorado is one of the fastest-warming U.S. states and continues to experience problems associated with rising temperatures. Over the next three decades, Colorado communities are expected to face costs reaching hundreds of millions of dollars or more to adapt to and mitigate the impacts of climate change.
The Colorado Supreme Court's ruling (PDF) recognized that while the case “presents substantial issues of global import,” its opinion was narrowly focused on whether federal law blocked the application of Colorado law, concluding that “defendants’ arguments do not convince us that federal law preempts Boulder’s state law claims in this case.”
This is only the second state supreme court decision to address whether this type of climate case can move forward, following a decision from the Hawaii Supreme Court in 2023 that also allowed a case filed by Honolulu to proceed. Dozens of courts around the country are looking to these decisions as they consider similar cases.
Boulder County, San Miguel County, and the City of Boulder originally sued Suncor and Exxon in April 2018 for the costs that they face due to climate harms, and for decades of misinformation. After the state district court rejected the companies’ attempt to have the lawsuit dismissed, Exxon directly petitioned the Colorado Supreme Court to overturn the result. Exxon argued that federal law bars Colorado from applying its own state law to these in-state injuries, meaning that Exxon’s actions would be beyond the reach of any law.
San Miguel County’s case is now proceeding in Denver district court and is currently on hold. This ruling sets a precedent for that case as well.
In addition to EarthRights International, the plaintiffs are represented by Kevin Hannon of Singleton Schreiber, LLP, the Law Office of Marco B. Simons, and the Law Offices of David Bookbinder.
Statements:
- “The Colorado Supreme Court’s decision validates what we have long known: our communities are already bearing the devastating impacts and mounting costs of the climate crisis,” said Boulder County Commissioner Ashley Stolzmann. “This ruling brings us one step closer to holding accountable those who are the most responsible for altering our climate—and ensuring they contribute their fair share toward addressing the damage they’ve caused.”
- “This ruling affirms what we’ve known all along: corporations cannot mislead the public and avoid accountability for the damages they have caused. Our community has suffered significantly from the consequences of climate change, and today’s decision brings us one step closer to justice and the resources we need to protect our future,” said City of Boulder Mayor Aaron Brockett.
- “This case is about remedying harm to local Coloradans. The Colorado justices were correct in holding that the plaintiffs’ claims can move forward under Colorado law,” said Richard Herz, Chief Litigation Attorney of EarthRights International.
- “This lawsuit is based on a fundamental legal principle: you have to pay your fair share for the harm that you cause. Nothing in federal law stops Colorado courts from applying that principle to the fossil fuel industry’s deception about climate change and their knowing alteration of our climate, as the Colorado Supreme Court has now found,” said attorney Marco Simons, who argued the case for the Boulder plaintiffs.
- “The Court properly ruled that Colorado law is fully capable and appropriate to address climate harms occurring in Colorado. After over seven years, Boulder County and the City of Boulder can finally have their day in court,” said Kevin Hannon, Partner, Singleton Schreiber, LLP.
The town of Lyons in Boulder County, Colorado.