Consumer Group Files Brief Challenging Colorado Climate Lawsuit Against Energy Company

A consumer representative group filed an amicus brief on Thursday challenging Colorado's lawsuit against Suncor Energy over climate change. Consumers' Research argues that the litigation represents an unconstitutional attempt to regulate energy production occurring in other states and countries.

Consumers' Research Executive Director Will Hild stated that Colorado is trying to use lawfare to do what the Constitution forbids. He said success for Boulder County would empower activist jurisdictions to weaponize the courts against any industry they dislike.

County and the City of Boulder filed suit against Suncor Energy in 2018. The suit accuses the company of knowingly damaging the environment through fossil fuel production, advertising and sales. The Colorado Supreme Court ruled that the federal Clean Air Act does not preempt the state from legal action based on its own statutes.

The United States Supreme Court agreed to hear the case in February 2025.

Arguments in the Brief The brief contends that one state cannot govern the entire nation under the doctrine of territorial jurisdiction. It states that the resulting patchwork of competing state-law commands would wreak havoc on consumers and that nationwide commerce would be governed by the most aggressive state's preferred policy.

The brief further argues that when a state imposes damages for conduct occurring in another state, that operates as a de facto levy on that conduct. This forces producers to internalize costs dictated by a foreign sovereign or abandon the activity altogether.

President Donald Trump's Department of Justice signed on to Suncor Energy's Supreme Court petition in September 2025. The DOJ wrote that if the Colorado Supreme Court's 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.