The Suncor v. Boulder SUPCO climate case

By William P. Barr
Former U.S. Attorney General
Real Clear Wire

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.

The paradigmatic example is a large lake that borders more than one state. Any individual state does not have the right to exclusively set the rules that govern that lake. Also imagine an interstate miasma that hangs over Oklahoma and Texas. Texas wants to handle it one way, and Oklahoma another. Who decides when something is one physical phenomenon that’s inherently interstate?

One suggestion is that interstate emissions have always been subject to state regulation, which is untrue. States can regulate and apply their laws to impose liability for activities in their state, but they cannot apply their laws to activities outside the state. There’s an exception if the adverse effect in the other state is directly intended and targeted, like a shooting-across-the-border, for example. But generally speaking, if Colorado doesn’t like the extent to which ExxonMobil’s activities are contributing to something that they think is harming them, they can’t sue ExxonMobil under their law for activities in Texas. That’s a basic legal principle. The law is not flexible on this.

The Clean Air Act does not change that. What it does is preserve power for the states to regulate their own emission sources. States set air quality standards that apply to fixed emission sites within their own territory. This is a complex process whereby they coordinate with other states and the EPA to work out regional plans. At the end of the day, however, it’s no surprise that one state cannot direct another state or regulate another state’s emissions.

There was a case between New York and Vermont, for example. A mill in one state was polluting the water in a way that affected the other. The other state sued in response under its own law, which isn’t legal. You have to sue under the law of the state where the mill that’s discharging the pollutant is located. That’s the rule.

In the case of these current emission lawsuits, it’s obvious that some of these energy companies were producing an emissions-causing product and selling it to those who ultimately emitted it. But they’re not being sued for selling it; they’re being sued because they contributed to interstate and international emissions. A state, however, like Colorado in Suncor, does not have the authority to unilaterally decide that it’s going to apply its own law to those emissions.

Extraterritoriality is another point that is obviously at stake in this case and reflects the same basic principle: a state generally cannot exercise its powers outside of its own territory. There is not very much wiggle room in that doctrine. I do think there’s foreign affairs preemption, but first, let’s be clear: we’re talking about preemption. The Constitution’s structure preempts it because no single state can regulate an interstate phenomenon that affects multiple states.

That’s the Clean Air Act’s whole basis: to provide for the regulation of air that’s constantly moving among states, because that movement is inherently an interstate phenomenon. The Clean Air Act was Congress’s effort to have federal supervision and rules regarding interstate emissions, while also preserving some room for the state to regulate sources in the state. The state’s regulatory authority, however, comes only from the statute.

The Clean Air Act only replaces what it replaces in federal common law. It doesn’t replace the basic precept inherent in the Constitution, that a state does not have the authority to make rules for other states. Under the Clean Air Act itself, it’s preempted as well.

There is also foreign affairs preemption. Now, as some said earlier, there are interesting questions about where to draw the line on foreign affairs preemption. But it is not necessary here. In the last thirty years since they applied it in Garamendi, the Court has not developed this doctrine, but it envisions a two-pronged test. 

First, is the state doing something that you would traditionally expect them to do? Are they exercising the normal police powers that you would expect them to? Second, if the state’s claim to be doing this as part of their traditional authority is a good one, then the Court must balance that interest against the federal government’s policy. But here this is not an exercise of traditional state power, so the measure will be struck down because it will have more than an incidental effect on U.S. foreign policy.

I can’t think of anything more intrusive into foreign policy than these states’ efforts to determine relative liability and responsibility for atmospheric greenhouse gases and the extent to which people can be found responsible for climate changes or injurious effects. Determining this liability must happen on the international level to have any meaning; otherwise, you’re playing whack-a-mole. You’re destroying American oil and gas companies with no effect on emissions because production and sale of oil and gas will just shift to other producers, like China and Russia.

That’s exactly what will happen under this sort of regime, because the countries that have state-owned energy companies—Russia, China, and Iran—which cannot be sued. U.S. companies will be the only companies paying in this scheme, which will drive up prices nationwide. This isn’t a state setting the price just for fuel within the state or “we’re going to add four cents to the cost of gasoline that’s sold in our state,” it is a coordinated effort by multiple states to swarm the industry and jack up prices. They have said this publicly. Once the first case is upheld, everyone else will come in with new cases, and we’re off to the races. It will be difficult for these public companies to survive, which is why they claim this litigation threatens them with bankruptcy. This is what we’re doing to our own industry through this state litigation, which is also beyond these states’ Constitutional power.

I can’t think of anything more intrusive on foreign affairs than this. We have a policy of trying to resolve these environmental issues internationally. People may not like the positions we take, but we attempt to resolve them through bilateral discussions. Environmentalists might not feel like we’re moving fast enough, but they can always vote against the president if they don’t like an administration’s policy or push to pass a law.

That is what the climate movement did for many years; they tried to go through the democratic process and push for treaties and statutes but were never able to achieve the radical action they wanted. Their new strategy is to swarm the industry with these state and municipal cases. That approach runs afoul of U.S. foreign policy. We’re not dealing with tobacco or a discretionary product; we’re dealing with energy, the foundation of civilization.

Homo sapiens have been walking the earth for 300,000 years, and for most of that time, our lives have been nasty, brutish, and short. That fate only changed 300 years ago, coincident with the beginning of the fossil-fuel-based Industrial Revolution. There is a chart in Alex Epstein’s Fossil Future (2022) that shows how humanity’s well-being, life expectancy, per capita income, and population growth all coincide with our increased use of fossil fuels. Until the Industrial Revolution, human beings relied on muscles, horses, a few windmills, and burning wood, dung, and charcoal for fuel. That’s what we relied on until coal, oil, and natural gas changed everything.

Canadian environmental scientist Vaclav Smil, whose books show how dependent the world is on fossil fuels, thinks this idea that we can quickly eliminate or start drastically reducing the use of fossil fuels is an illusion. It is caused by the disconnect between the life of urban elites and the truth of what supporting our society requires: runways and flights and the fertilizers half the world depends on, which are made from natural gas and the tremendous amount of heat that process generates.

Every price increase and curtailment of fossil fuels, without a good idea of economic and effective substitutes, comes at a huge cost. This is a decision we’re choosing to make.

The states are playing in the wrong ballpark. They’re looking at this issue as though it’s a tort and asking how much damage was done, and how much the companies paid. But that issue of torts is not the issue the U.S. faces. But tort damages is not the issue that the U.S. or the world faces. The real issue is how do we sensibly try to reduce emissions without destroying our economies the way Germany has. That’s the way everyone else in the world is looking at it now.

But the climate activists don’t want a national decision. They don’t want this question to go through the political process, where there will be a discussion of the pros and cons and benefits of fossil fuel and what it means to lose those benefits. Climate activists want the jury to decide how much companies have to pay out. We can’t go into the courtroom and point out that people will die if the energy prices rise because that’s not a defense in a tort case. But questions about consequences are questions we must raise, and that requires the political process. It also requires a locus of responsibility. We need people we can hold accountable for these decisions, rather than a bunch of municipal and state judges making individual decisions across the country that cumulatively destroy the American energy industry.

And what will that destruction do? The market won’t disappear because there is no suitable energy substitute. People will still use petroleum and natural gas that will come from far less environmentally sensitive foreign suppliers. And all we will have succeeded in doing is destroying our own industry with no environmental benefit. That’s exactly why any sensible person agrees that these policies must be pursued through international agreements. Otherwise, we’re going to end up holding the bag.

The Constitution is a sensible document; the structures it builds align with reasonable common sense. The idea that the Constitution would enable local courts to make independent judgments dealing with who pays for worldwide emissions is preposterous. That would require local juries making judgments on whether the Chinese and their thousands of coal plants, for example, bear more responsibility for emissions than ExxonMobil. This is not a question the courts are best suited to answer; it is a question of whether the democratic process works. If it doesn’t, people have a remedy. It’s certainly not a case for state courts. We need national rules and approaches.

Is this the logical place to make these decisions? No, but it’s where the environmental movement likes to make policy. Federal courts don’t seem hospitable to these suits and that’s why they’re happening at the state and municipal courts. The litigants know that if they in the federal court system these cases will make their way to the Supreme Court, where all these conservatives are. So they need to find someplace else to pursue this agenda.

I hope the Court takes a stand on this because it isn’t just a run-of-the-mill decision. This issue has been percolating for years. These are public companies. They need investments. We need to know that we can fulfill our commitments to provide natural gas to the Europeans, for example. We can’t have this morass of litigation around the country hanging over us while we’re moving forward.