Supreme Court Hears Arguments in Boulder County Climate Case

The Supreme Court on Monday heard oral arguments in Suncor Energy v. County Commissioners of Boulder County, deciding whether a Colorado climate damages lawsuit against Exxon Mobil and Suncor Energy can move forward, according to Smart Cities Dive.

According to the publication, Boulder’s city and county governments allege the companies deceived the public about fossil fuel risks and should bear past and future costs related to local climate damage, including infrastructure repairs, environmental damage, emergency management and public health harms. The Colorado Supreme Court ruled in May 2025 that federal law, including the Clean Air Act, did not preempt Boulder’s claims and the case could proceed toward trial, Smart Cities Dive reported.

Arguments before the justices

According to Smart Cities Dive, the arguments centered on whether municipal lawsuits against fossil fuel producers are constitutional, whether state law or federal jurisdiction governs interstate pollution under the Clean Air Act, and whether the Supreme Court should decide the issue now or allow the case to continue in Colorado state court. Justice Samuel Alito recused himself from the case, the report said.

Justice Elena Kagan compared the case to lawsuits brought against tobacco companies in the 1990s and opioid companies in the 2010s, describing it as “chapter three,” Smart Cities Dive reported. Advocates said dozens of municipal governments, 11 states, the District of Columbia and two tribal governments have filed similar lawsuits, according to the report.

The case was first filed in 2018, and no ruling has been issued.

Reporting based on coverage by Smart Cities Dive.