/>i
On October 5, the United States Supreme Court will take up a recent case in which the city and county of Boulder, Colorado, sued the oil and gas firms Suncor and ExxonMobil to pay for what it alleges are the cost of local climate impacts to the community.1
It's like suing people for throwing soft drinks into a pool, which under tort causation law would mean linking a person on one side of the pool to the water quality on the other side of the pool. Except the pool is the size of the planet Earth and everyone in the pool is drinking soft drinks.
Boulder is on a quest to regulate global climate emissions, and it has tried to use state tort law to do it. This strategy is not new, as some cities and states have brought climate change tort actions against oil firms since 2017. The Supreme Court is now considering whether Boulder’s climate change case has been preempted by federal law.
Almost all of the relevant state and local climate change suits were filed in state court, and here plaintiffs fought hard to keep their case in state court. The Attorney General from California, Rob Bonta, said the quiet part out loud, observing that federal courts were less malleable and a removal to federal court "was close to being outcome determinative."
The underlying tort action is riddled with problems. What percentage of climate change is caused by natural global cycles versus energy production? How do you separate emissions by the defendants versus by non-US companies?
Since this is a legal dispute, let’s start with the evidence. An amicus brief filed by members of the US House notes that Colorado had roughly 0.23 percent of global emissions compared against the United States at roughly 10 percent.2 A jury empaneled in this Boulder case would have to decide what share of local fires or floods or pollution one county road belongs to these particular two defendant companies as opposed to every other oil and gas producer on earth, then put a damages number on it. (Oh and don’t forget the cows, I won’t elaborate on their contributions to global emissions, but you would need to include their specific contribution to Boulder’s air as well).
If some cities sue energy companies for what they do for a living, in compliance with environmental laws and in response to demand from citizens in that jurisdiction, while other cities are dependent on the oil and gas sector, you end up with the kind of contradictory interstate disputes that the Constitution was built to avoid.
The Court addressed this question as far back as 1987. In International Paper v. Ouellette, the Supreme Court held that a state claiming harm from interstate pollution cannot sue using its own nuisance law to attack another state.3
The case is about federal preemption, the outcome is about that doctrine, but it is hard to ignore the illogical outcome if preemption is not found. Is Boulder complicit in the tort because it uses the same fossil fuel energy to power the town and its own fleet of city vehicles as a customer of fossil fuel companies? Hypocrisy may not be grounds for defense at the Supreme Court, but it certainly paints the plaintiffs in a bad light.
Complex questions like a carbon tax, and whether society is ready to accept the massive hit to economic growth that accompanies it, are best left to the legislature, not the court system. And Congress has spoken on this question by adopting the Clean Air Act.
David Bookbinder, who was previously Boulder’s lawyer, agrees! He observed in a speech at the Federalist Society that "tort liability is an indirect carbon tax" and that "the people who buy those products are now going to be paying for the cost imposed by those products."4 This would end up being an effective tax on Boulder's residents.
The Supreme Court has seen this play before. In American Electric Power v. Connecticut, a unanimous court agreed that the Clean Air Act preempts common law nuisance claims over greenhouse gas, because Congress gave that matter to the EPA.5 The state law version of this holding should carry forward when the Supreme Court hears this twist on that precedent October 5.
In a related commentary on SCOTUSblog, Dean Chemerinsky wrote that "the EPA recently has denied that it has the authority to regulate greenhouse gas emissions" and he then quoted Boulder's brief for the observation "how the Court can hold that the Clean Air Act preempts claims indirectly relating to greenhouse-gas emissions when EPA maintains that the Act does not allow it to directly regulate some (perhaps any) greenhouse-gas emissions."6
Does anyone, including the Justices on the Colorado Supreme Court, question whether the next EPA Administrator appointed by a Democrat will reverse course and decide that the EPA does, in fact, have authority to regulate greenhouse gas emissions? Courts cannot pretend to ignore that reality in considering the preemption question.
The Supreme Court should make clear that one city does not get to regulate global climate emissions. Applying federal law to claims over international and interstate activity like climate change, consistent with existing preemption doctrine, and just good sense.
Endnotes
1. Suncor Energy (U.S.A.) Inc. v. County Commissioners of Boulder County, No. 25-170 (U.S.), argument set for Oct. 5, 2026, reviewing County Commissioners of Boulder County v. Suncor Energy (U.S.A.) Inc., 586 P.3d 161 (Colo. 2025).
2. Brief of 74 Members of the U.S. House of Representatives as Amici Curiae Supporting Petitioners, No. 25-170.
3. International Paper Co. v. Ouellette, 479 U.S. 481, 494-97 (1987).
4. David Bookbinder, remarks at a 2025 Federalist Society event.
5. American Electric Power Co. v. Connecticut, 564 U.S. 410, 424 (2011).
6. Erwin Chemerinsky, The court's coming climate-change case and the very confused doctrine of preemption, SCOTUSblog (Sept. 22, 2026), quoting Brief for Respondents, No. 25-170.
Disclaimer: The opinions and views expressed in this article are those of the author and not necessarily those of The National Law Review.
