Despite pointed questions from some of the U.S. Supreme Court’s conservative justices challenging the oil companies in Suncor v. Boulder, Republican attorneys general following Monday’s arguments said they came away optimistic about the case’s direction.
“We were confident coming in. I feel even better having heard the whole argument, particularly if you listen to Justice [Brett] Kavanaugh’s line of questioning,” said Alabama Attorney General Steve Marshall, speaking to reporters Monday afternoon. “Frankly, he feels like this is a fairly straightforward case.”
The Supreme Court chose the consequential climate case to open oral arguments for its 2026-27 term. Boulder County and the city of Boulder sued Exxon Mobil Corp. and Suncor Energy in 2018 under Colorado law, alleging the companies knowingly contributed to climate change through their production, promotion and sale of fossil fuels while concealing or misrepresenting their alleged dangers to the public. Boulder sought damages for harms it attributed to climate change, including wildfires, flooding and extreme weather affecting local residents and property.
The oil companies pushed back, arguing that because Boulder attributes its alleged injuries to global greenhouse gas emissions, federal law preempts the claims and prevents them from proceeding under Colorado law. The Colorado Supreme Court rejected that argument without ruling on the merits of Boulder’s underlying claims, and the U.S. Supreme Court agreed to review that decision.
During Monday’s arguments, Justice Elena Kagan compared Boulder’s lawsuit to earlier litigation against tobacco companies and opioid manufacturers.
“In multiple respects, this suit appears to be based on the old 1990s tobacco suits that were brought by states and local governments basically saying that big tobacco had made representations, misrepresentations, which had caused people to … overuse the product, causing harm to those governments,” Kagan said.
Kagan described the opioid litigation that followed as a second chapter and the climate lawsuits as a potential third.
Kavanaugh pushed back on the comparison, pointing instead to Supreme Court precedent concerning interstate pollution.
“I thought the answer was that this Court has consistently said that air and water pollution are different in our federal enclaves,” Kavanaugh said.
Marshall led a 26-state amicus brief urging the Supreme Court to take the case. Utah Attorney General Derek Brown, who also signed the brief, attended Monday’s arguments.
“Ultimately it comes down to the real issue of – they call it the sovereignty concept – of whether one state can impose their will on another state,” Brown said.
Brown argued that allowing states to impose liability for harms attributed to global emissions could force energy companies to absorb additional costs or change their practices nationwide, effectively imposing the consequences of one state’s policies on consumers in others.
“They’re imposing what’s in effect an energy tax on other states,” Brown said. “My state is right next to Colorado, and it would have an impact on my state, even though we didn’t get a vote.”
Like Marshall, Brown said he was optimistic about how the court would ultimately rule, citing questions like one from Chief Justice John Roberts about the practical implications if municipalities across the country brought similar lawsuits.
“Do we all of a sudden have this whole slew of lawsuits in which all 50 states are trying to impose burdens on the other 50 states?” Brown asked rhetorically, expanding on the concerns raised by Roberts’ questioning. “In effect, that’s why states joined the Union hundreds of years ago, because states had been imposing burdens on the other states. So we gave up that right in exchange for a uniform system.”
Roberts, Barrett and Gorsuch also posed challenging questions to the oil companies, however, pressing them on the scope and consequences of their argument that federal law preempts Boulder’s claims.
“There are a lot of familiar situations where conduct outside of a state has broad effects from other states … and yet we allow state courts in a particular state to bring litigation that affects that,” Roberts said. “I guess I’m not quite sure what makes this situation different from those, all those other ones, where we’ve allowed them to proceed in state court.”
The case could have implications far beyond Boulder. Dozens of similar climate lawsuits have been filed across the country, and the Supreme Court’s ruling could affect whether such cases can proceed under state law.
Steve Milloy, senior fellow at the Energy and Environment Legal Institute and former Trump EPA Transition Team Member, said a in statement provided to The Center Square: “After almost two hours of almost exclusively procedural argument, the case was best summed up by the oil industry layers at the very end: Allowing the Boulder lawsuit to proceed in state court would allow an unlimited number of plaintiffs to sue and unlimited number of defendants-a situation that both parties had objected to on an international level. Moreover, because of its global aspect, climate is inherently a political question that would require resolution by Congress.”