Boulder’s Lawyer Concedes Its Climate Theory Could Reach Retailers

A lawyer for Boulder County told the Supreme Court on Monday that nothing in the county’s legal theory would prevent climate suits against large retailers of fossil fuels, as the justices weighed whether one state’s law can make energy producers pay for the effects of worldwide emissions.

Justice Clarence Thomas asked whether, if Boulder prevails, there is any limit on whom it can sue. “So you could just as easily sue large retailers of … these products?” Thomas asked. Kevin Russell, arguing for Boulder, said “nothing in the Constitution would prevent that.” Thomas pressed: “But nothing in your theory prevents that either, right?” Russell answered, “Nothing in our theory prevents that.” He said the protection against unreasonable suits is that “Congress stands at the ready to intervene.”

Boulder County and the City of Boulder sued Suncor Energy and ExxonMobil in Colorado state court on April 17, 2018. They allege that the companies’ production, marketing and sale of fossil fuels around the world contributed to climate change, and they seek money for “past and future damages and costs to mitigate the impacts of climate change” in Boulder. A divided Colorado Supreme Court let the case go forward on May 12, 2025, holding that once the Clean Air Act displaced the older federal common law of interstate pollution, Colorado’s own tort law could reach interstate emissions.

The question before the Court is whether federal law bars state-law claims “seeking relief for injuries allegedly caused by the effects of interstate and international greenhouse-gas emissions on the global climate.” The Court also told the parties to argue whether it has jurisdiction to hear the case now. Justice Samuel Alito withdrew on September 28, leaving eight justices.

Justice Brett Kavanaugh told Russell the Court has “a wall of precedent that says state tort law does not apply except for the Ouellette source state thing,” a reference to a 1987 decision allowing suits under the law of the state where pollution originates. “Anyone is a potential defendant for a suit like this,” Kavanaugh said. “Any manufacturer, any business.” Justice Amy Coney Barrett said the Court has “called it an enclave of federal common law.”

Other justices questioned whether the case belongs before them yet. Justice Ketanji Brown Jackson asked Kannon Shanmugam, arguing for the producers, “why shouldn’t we wait” until the Colorado courts finish with the case, and Justice Sonia Sotomayor pressed him on whether the Colorado ruling is the kind of decision the Court may review at all. Justice Elena Kagan asked Shanmugam where the Constitution supplies the rule he was asking for. “Where is the text for that? Where’s the support for that? Where’s the precedent for that? Where’s the anything for that?” she said.

Russell opened by arguing that “since the founding, states have had the power to provide tort remedies for injuries occurring within their borders even when the conduct causing those injuries occurred elsewhere.” Sarah Harris, the principal deputy solicitor general, argued for the United States on the producers’ side. “Boulder’s theory is that because global climate change causes some Colorado injury, Colorado can hold oil companies liable for all their fossil fuel activities worldwide,” she said.

## Texas’s stake

ExxonMobil, one of the two producers Boulder sued, is headquartered in Spring, Texas. Texas wells produced 2.1 billion barrels of crude oil in 2025, about 42 percent of the United States total, according to the U.S. Energy Information Administration.

Justice Neil Gorsuch put a Texas company into his own hypothetical. “Let’s say your defendant is … from Texas. You’d object to Colorado applying Texas law?” he asked Shanmugam, who said the producers would, while acknowledging that the Clean Air Act lets “the law of the source state” apply.

Colorado, California, 16 other states and the District of Columbia filed on Boulder’s side, telling the Court that “attempts to short circuit state court processes or preempt state law should be met with a healthy skepticism.”

Texas is on the other side. Attorney General Ken Paxton signed a brief filed May 21 by Alabama, West Virginia and 24 other states in support of the producers. “Like disputes over borders, disputes over cross-border emissions cannot be settled by one State alone,” the states wrote. “When one State’s power grows so far beyond its proper sphere, the rights of every other State risk withering away.”