My Comments on the Suncor v. Boulder Climate Case

This is a lightly edited transcript of a keynote delivered by Former U.S. Attorney General William Barr at “The Constitutional Stakes in Suncor v. Boulder,” a Civitas Institute symposium held October 1, 2026, at The University of Texas at Austin.

I am going to jettison my prepared remarks based on what I heard discussed on the panels earlier. The speech I prepared covered several different elements of Suncor v. Boulder, including practical considerations of the possible consequences of a victory for Colorado, but I worry people will think that I am evading some of the legal issues. I don’t want that to happen, so I’m going to talk more about the legal issues than I’d planned.

Suncor v. Boulder is one of approximately three dozen cases that are pending under state tort laws, nuisance cases, and other theories. States and municipalities are applying those laws to impose liability on American energy companies for the alleged global effects of fossil fuel production and use. That effort reflects the climate movement’s basic narrative, which is that climate change is the result of long-term greenhouse gases build up in the Earth’s atmosphere. Worldwide carbon gas emissions are increasing and accumulating, they claim, which is is causing climate change.

It’s important to focus on the mechanism they claim is causing injury: the greenhouse gases in the Earth’s atmosphere. Some 90% of those gases come from outside the U.S. What precisely are they trying to regulate? Their focus is not on companies’ activity in Colorado; they’re not claiming that as the basis of liability. They are saying that these companies’ worldwide oil and gas production and sale contributed to and enabled worldwide emissions, which has caused the accumulation. Therefore, they claim, these companies are responsible for climate change and the weather that has now adversely affected Colorado. Damages will ultimately be tailored to Colorado, but the activity that they are saying is the basis of liability are things that these companies do in Texas, the Middle East, or anywhere else in the world: the production and sale of fossil fuel energy, even though these countries sometimes desperately need the energy supplied by the U.S.

Some of the speakers earlier dismissed the idea of structural preemption in this case, but there’s no basis for dismissing it because it is inherent in the Constitution and in case law. Prior cases reflected the necessary rule in those situations, which is that when something is inherently interstate in nature, the rules applied to it have to be neutral federal rules. One state cannot apply its rules to another state’s detriment.