A consumer representative group filed an amicus brief on Thursday challenging Colorado’s lawsuit against national energy companies over climate change.
Consumers’ Research’s brief alleges that Colorado’s litigation is an unconstitutional use of public nuisance law aiming to overrule federal law. The suit accuses Suncor of knowingly damaging the environment through fossil fuel production, advertising and sales.
“Colorado is trying to use lawfare to do what the Constitution forbids and regulate energy production occurring in other states and even other countries,” Consumers’ Research Executive Director Will Hild told the Daily Caller News Foundation. “If Boulder County succeeds, activist jurisdictions across the country will be empowered to weaponize the courts against any industry they dislike, including energy, firearms, and financial services, regardless of whether that conduct is perfectly legal where it occurs.”
The brief argues that Colorado’s court system ruled incorrectly by upholding Boulder County’s suit despite its interstate implications. The United States Supreme Court agreed to hear Board of County Commissioners of Boulder County v. Suncor Energy in February 2025.
Boulder Country and the City of Boulder filed suit against Suncor Energy in 2018. After judicial back-and-forth, the Colorado Supreme Court ruled that the federal Clean Air Act does not preempt the state from legal action based on its own statutes.
“In our federal system, one state cannot govern the whole Nation. Yet the Colorado Supreme Court’s judgment blesses Boulder County’s efforts to do precisely that here… the resulting patchwork of competing state-law commands would wreak havoc on consumers; nationwide commerce would be governed by the most aggressive State’s preferred policy,” the brief states. “The Constitution does not permit that result. Because Boulder County’s claims violate the doctrine of territorial jurisdiction, the judgment below should be reversed.”
The doctrine of territorial jurisdiction refers to authorities having power to enforce legal judgements and policy only within their own borders, according to the brief.
“This manifestation of the territorial-jurisdiction principle is implicated when a State uses tort law to regulate out-of-state emissions. When a State imposes damages for conduct occurring in another State, that operates as a de facto levy on that conduct—forcing producers to internalize costs dictated by a foreign sovereign or abandon the activity altogether,” Consumers’ Research brief states. “The burden is regulatory in effect: it compels out-of-state actors to conform their operations to the forum State’s standards.”
Similar cases have been thrown out at the state level. The Maryland Supreme Court in March ruled against Annapolis, Baltimore and Anne Arundel’s attempted litigation demanding billions from energy companies over climate change. The court considered emissions claims to be interstate commerce and therefore a matter of federal jurisdiction.
President Donald Trump’s Department of Justice (DOJ) also signed on to Suncor’s Supreme Court petition in September 2025.
“If, as the Colorado Supreme Court held, those theories are consistent with federal law, then every locality in the country could sue essentially anyone in the world for contributing to global climate change,” the DOJ wrote at the time.
Consumers’ Research argues that Colorado’s pursuit of damages under its own nuisance laws and torts is “effectively placing nationwide commerce under the control of whichever State’s law is most restrictive” if successful.
“Our brief makes clear that states are sovereign within their own borders, not beyond them. Allowing one state to dictate national energy policy through litigation would create chaos for consumers, drive up energy costs, and hand woke political activists power over the American economy,” Hild said. “The Supreme Court should reject this unconstitutional attempt to let one state govern the entire nation through the courts.”
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