Washington — Supreme Court on Monday Handle complex disputes An effort involving the city and county of Boulder, Colorado, to hold energy companies accountable for the effects of global climate change.
Eight of the court’s nine justices heard nearly two hours of oral arguments in Suncor Energy v. Boulder County Commissioners. Judge Samuel Alito I recuse myself from this casethe Supreme Court said last week.
Alito gave no reason for his decision to sit on the sidelines. His 2025 financial disclosure shows that he personally holds stock in two energy companies, ConocoPhillips and Phillips 66. Alito did not report personal stock holdings in Exxon Mobil or Suncor Energy, two companies Boulder filed suit against in 2018.
Alito’s recusal made it possible that the Supreme Court would deadlock 4-4 in the case. The outcome means the Colorado Supreme Court’s ruling will stand, allowing Boulder’s case to proceed.
Boulder’s dispute with ExxonMobil and Suncor is still in its early stages. At issue before the Supreme Court is whether the lawsuit can proceed or is barred by federal law. The high court also asked attorneys for both sides to resolve whether it has jurisdiction to review the Colorado Supreme Court’s ruling.
In questions to Kannon Shanmugam and Chief Deputy Attorney General Sarah Harris, who are representing Exxon and Suncor, Justice Brett Kavanaugh repeatedly said that four Supreme Court decisions since 1972 have made clear that interstate air and water pollution falls under federal law.
“We don’t have to reinvent the wheel, because we’ve said this many times, Congress, presumably when it wrote the Clean Air Act and the Clean Air Act Amendments, already relied on this court’s precedent to determine that this pollution is a matter of federal law unless Congress says otherwise,” he said.
In the case, the Trump administration sided with Exxon Mobil Corp., the largest U.S. oil company, and Suncor Corp., which operates two refineries in Colorado. Harris said Boulder’s lawsuit “grossly exceeds” constitutional limits on state power.
“Interstate air pollution is essentially federal jurisdiction, and Congress has not yet authorized this lawsuit in the Clean Air Act,” she said.
But Justice Ketanji Brown Jackson stressed that the Supreme Court’s review was “premature.”
“It feels like we don’t really know enough to be confident that the theory you’re proposing actually applies here,” she told Harris.
Boulder files lawsuit against Suncor, Exxon Mobil
The lawsuit from the city and county of Boulder is one of dozens filed in state court against energy companies by states and local governments seeking compensation for past and future damages caused by the buildup of greenhouse gases in the atmosphere that contribute to global warming.
Boulder claims in the lawsuit that ExxonMobil and Suncor’s actions caused or contributed to climate change, which in turn forced the city and county to face extreme heat, larger and more frequent wildfires, and damage to ecosystems.
The city and county have filed several claims under state law, arguing that the energy company’s fossil fuel production and allegedly deceptive marketing led to “uncontrolled” use of its products, contributing to a rapid rise in greenhouse gas concentrations in the atmosphere.
ExxonMobil and Suncor attempted to move the case to federal court, but the effort was unsuccessful. The companies also asked the Boulder County District Court to dismiss the case, arguing that federal law nullifies claims against them. When a state court denied the request, the companies asked the Colorado Supreme Court to intervene.
The state’s high court sided with the city and county of Boulder, and Suncor and Exxon appealed to the U.S. Supreme Court.
“It’s taken a long time to get to this point, but it’s very positive that the efforts we started eight years ago at this site have made their way to the Supreme Court and hopefully the next step will be a full hearing in court,” Boulder Mayor Aaron Brockett said Monday after a rally in downtown Boulder.
“People in Boulder care deeply about climate change. They recognize the existential threat climate change poses to our society, so people are very supportive of this lawsuit,” Brockett added.
Supreme Court Arguments
Shanmugam, who argued on behalf of Exxon and Suncor, told the judge during arguments that the Constitution and the Clean Air Act preclude claims aimed at addressing harm caused by interstate greenhouse gas emissions. He also warned that efforts like the one in Boulder aimed at mitigating the effects of air pollution undermine the government’s control of foreign affairs.
Shanmugam called Boulder’s lawsuit an “unprecedented effort” to use state law to regulate global behavior, something the country’s constitutional system does not allow.
“A state does not have the authority to regulate out-of-state conduct solely based on diminished impact on the state,” he said.
Shanmugam warned that if Boulder’s lawsuit is allowed to proceed, 90,000 cities could file similar challenges and “have the power to shape national and international energy policy by asking juries to impose catastrophic damages on select fossil fuel producers.”
Chief Justice John Roberts also noted that if Boulder prevails at the Supreme Court, local governments in every state will file lawsuits similar to Boulder’s.
“How do you think this will work on the ground?” he asked Kevin Russell, who was arguing on behalf of Boulder.
Russell stressed that even if Boulder’s case moves forward, more litigation over the details of the lawsuit will follow.
But Roberts also said that in other cases, the Supreme Court has allowed state courts to hear lawsuits involving far-reaching issues.
“There are many familiar situations where actions outside one state have widespread effects in other states, but we allow lawsuits that affect that effect to be brought in state courts in a particular state, whether it’s mass torts or complaints about Internet operations,” the chief justice said. “I guess I’m not quite sure how this situation differs from all the other situations where we allow them to be heard in state courts.”
Judge Elena Kagan, meanwhile, said the case against the energy companies appeared similar to lawsuits filed against tobacco and pharmaceutical companies in the 1990s over the opioid epidemic.
“This is Chapter 3,” she said, noting that state claims against the companies may continue.
But Kavanaugh later said, “This court has always said that air and water pollution in our federal enclaves are different.”
Lawyers for the city and county of Boulder urged the Supreme Court to reject the appeal, arguing it lacked jurisdiction. If the justices choose not to do so, they said the Colorado Supreme Court ruling should be upheld.
“Since the founding, states have had the right to provide tort remedies for harms occurring within their borders, even if the conduct causing those harms occurred elsewhere,” Russell told the justices.
He also believes Congress “stands ready” to intervene and enact federal laws to replace “unreasonable state laws.”
“This lawsuit is not an attempt to address climate change issues; it simply requires petitioners to bear a fair share of local costs incurred in part as a result of their violations,” Russell wrote in a filing.
He also told the judge that Boulder was not suing over emissions, which are regulated under the Clean Air Act, but over alleged deceptive marketing and production, which is not regulated under the law.
“This is not an effort to reduce emissions,” Russell said. “Under our theory of deception, they can continue to produce as much fossil fuels and create as much air pollution and greenhouse gas emissions as possible, and when consumers properly understand the consequences of this decision, the market will absorb the loss.”
The Supreme Court is expected to rule in the summer of 2027.