The Supreme Court opened its 2026-2027 term Monday with a climate case: a lawsuit brought by Boulder, Colorado, against ExxonMobil and Suncor, a Canadian oil company, over the costs of a warming planet. The case is one of dozens across the country in which local governments have sued fossil fuel companies for their role in driving climate change and are seeking compensation as they now deal with its effects. The Supreme Court’s decision could decide the fate of all those other cases and the idea that oil companies must pay for the damages their products caused.
The justices gave no clear signs of how the court will rule, but over the course of two hours of questioning, they did demonstrate unison on one point: It is a hard and consequential task to identify who is legally liable for the impacts of climate change.
Although Boulder’s case was first filed in Colorado courts, oil and gas companies asked the Supreme Court to step in, arguing that important climate change matters shouldn’t play out at the state level. Instead, they say, the issue belongs to Congress and the White House. Boulder wants the court to send the case back to Colorado, where it can proceed.
Eight justices — Justice Samuel Alito removed himself from the case — attempted repeatedly to cast the case into something legible and simple. Multiple times, justices from both sides of the ideological spectrum asked attorneys, “Why make this argument so complex?” Yet they seldom openly agreed on what the simpler argument would be. The consequences for oil companies weighed heavily on some parts of the discussion, while the consequences for communities dealing with a warming planet went largely unexplored.
Some judges attempted to describe it as a case about reducing emissions — a framing that aligns closely with what ExxonMobil and Suncor argue. If Boulder’s case is an attempt to reduce greenhouse gas emissions through state court, it opens the possibility that a state court could police activity all over the country, and even the world. No state law could be appropriate to apply to the cumulative impact of global pollution, the companies argue.
“This case involves an unprecedented effort to use state law to regulate global conduct,” said Kannon Shanmugam, the attorney representing oil companies.
Several justices seemed to agree with that general picture. Kavanaugh said he could see no difference between allowing a state court to order oil and gas companies to pay damages for climate-related harms and allowing a state to effectively regulate greenhouse gas emissions all over the world. He told Boulder’s attorney, Kevin Russell, that he was downplaying the effect this case could have on oil companies, arguing it could “bankrupt” some of them. In his closing arguments, Shanmugam reinforced the idea that the chaotic consequences of the case could reach the scale of climate change itself.
“Boulder could tag me … when I am in Colorado in two weeks and sue me on a nuisance claim for refilling my car and thereby contributing to global climate change,” he said.
Chet Strange / The Washington Post via Getty
Ironically, these questions were far from what Boulder claimed it wanted to do with its case. The city hasn’t asked to stop companies from producing oil and gas, or to stop those who burn them from sending greenhouse gases into the atmosphere. Rather, it wants oil companies to pay for deceiving the public into thinking those products weren’t producing large-scale harms through climate change.
Justice Elena Kagan argued Boulder’s case was similar to suits that states brought against cigarette companies in the 1990s, seeking compensation for healthcare costs linked to tobacco consumption. The companies weren’t required to stop selling cigarettes, but to roll back their pro-cigarette marketing and fund awareness campaigns around the effects of smoking.
“This is not an effort to reduce emissions,” said Russell. “Under our deception theory, they can continue to produce as much fossil fuels as they like and contribute to as much air pollution and greenhouse gas emissions as the market will bear when consumers are properly informed about the consequences of that decision.”
“It doesn’t prohibit them from engaging in the conduct. It requires them to internalize a portion of the cost of their activities by paying for some of the damage,” Russell said later.
Kavanaugh called Russell’s phrasing “cavalier,” saying that those costs could be significant to oil and gas companies. Some firms, including Suncor, have told their shareholders the accumulating climate cases against them could affect their bottom lines.
If the case is allowed to proceed in Colorado courts and Boulder wins, it could open the floodgates for other cases, Shanmugam argued: “More [suits] are being filed by the week… so given the extraordinary magnitude of these cases, where, in each of these cases, plaintiffs are seeking billions of dollars of damages, we need an answer to this question sooner rather than later.”
Justices typically hear opening arguments and ask questions at the beginning of the court’s term and then take months before publishing a decision. Ultimately, this thread was only one of several they teased apart during the arguments, including arguments over states’ regulatory authorities under the Constitution and the intent of the Clean Air Act. Judges could use a range of rationales for their ultimate ruling, each of which would affect other climate suits against oil companies differently because those suits depend on different legal bases.
“States and local governments are trying to recoup costs related to harms from climate change in a lot of different types of lawsuits,” said Erika Kranz, an attorney with Harvard Law School’s environmental and energy law program. Whether these other cases “run into trouble will depend on how justices write their decision.”
It’s also possible justices send the case back to Colorado, either by deciding the Supreme Court isn’t the right place for it or by voting 4-4, which would leave Boulder able to carry on with its state-level lawsuit. (Alito has not explained why he removed himself from the case, though he has faced accusations that his investments in oil and gas companies not related to the case made his participation inappropriate.)
Kranz and Chris Winter, executive director of the Getches-Wilkinson Center at the University of Colorado Law School, said it’s hard to know whether that emphasis showed the court was leaning toward the oil companies, but it suggested that at least some justices were deeply concerned about the case’s potential financial consequences for the industry.
Boulder’s lawyers must now convince them that this risk to oil and gas companies was beside the point, Winter said. To do that, Boulder will have to overcome justices’ claims that it’s trying to reduce emissions through the court.
“There’s a lot of concern from the oil industry, from corporate actors, and from the conservative justices about the significant consequences of these cases,” Winter said. “One way to get at that is to equate this case with previous cases, which were much more directly about regulation of pollution.”
