The Supreme Court opened its 2026-2027 term on Monday with a high-stakes climate change case, hearing oral arguments in a lawsuit brought by Boulder, Colorado, against fossil fuel giants Exxon Mobil and Suncor, a Canadian oil company. The litigation is centered on the escalating costs communities face as they grapple with a warming planet. The case is just one of dozens of similar actions filed by local governments across the United States, all seeking financial compensation from fossil fuel companies for their historical role in driving global climate change.
Because of the sweeping nature of these coordinated legal challenges, the Supreme Court’s eventual decision could ultimately decide the fate of all other pending climate accountability cases nationwide. At its core, the legal battle confronts a fundamental question that has increasingly found its way into courtrooms: whether major oil and gas companies can be held legally and financially responsible for the environmental damages caused by the extraction, promotion, and consumption of their products.
During two hours of intensive questioning, the justices gave no clear, definitive signs of how the court will ultimately rule. However, over the course of the arguments, the bench demonstrated a rare moment of unison on one central point: identifying who is legally liable for the widespread, cumulative impacts of climate change is an exceptionally difficult and deeply consequential task.
Although Boulder’s case was initially filed within the Colorado state court system, the defendant oil and gas companies petitioned the Supreme Court to intervene. The corporations argued that major climate change matters of this scale should not be allowed to play out at the local or state level. Instead, the energy companies contend, the complex arena of climate policy and greenhouse gas management belongs exclusively to the purview of Congress and the White House. Boulder, conversely, wants the high court to reject the companies’ intervention and send the case back to Colorado, where the litigation can proceed toward trial.
Eight of the justices participated in the arguments—Justice Samuel Alito recused himself and removed himself from the case—and attempted repeatedly during the session to distill the sprawling litigation into something legible and simple. Multiple times throughout the hearing, justices from both sides of the ideological spectrum posed a direct question to the attorneys: "Why make this argument so complex?" Yet, despite their shared desire for simplicity, the justices seldom openly agreed on what that simpler legal argument should actually be. Throughout the proceedings, the potential economic consequences for the oil companies weighed heavily on certain portions of the discussion, while the immediate, mounting consequences for local communities dealing firsthand with a warming planet went largely unexplored by the bench.
Some members of the court attempted to frame the dispute as a case fundamentally about reducing greenhouse gas emissions—a characterization that aligns closely with the core defense arguments presented by Exxon Mobil and Suncor. Under this judicial framing, if Boulder’s lawsuit is interpreted as an indirect attempt to curb global greenhouse gas emissions through the mechanism of a state court ruling, it opens the alarming possibility that a single state court could end up policing commercial activity, energy production, and environmental policy all over the country, and potentially the entire world. The companies argue that no single state law could possibly be appropriate or constitutional when applied to the cumulative, planetary impact of global pollution.
"This case involves an unprecedented effort to use state law to regulate global conduct," said Kannon Shanmugam, the attorney representing the oil and gas companies.
Several justices seemed receptive to that sweeping picture. Justice Brett Kavanaugh remarked that he could discern no meaningful difference between allowing a state court to order oil and gas companies to pay billions of dollars in damages for climate-related harms and allowing an individual state to effectively regulate greenhouse gas emissions worldwide. He pressed Boulder’s attorney, Kevin Russell, suggesting that the city was downplaying the severe effect the lawsuit could have on the energy industry, arguing that such massive liability could potentially "bankrupt" some of the firms involved. In his closing arguments, Shanmugam reinforced the idea that the chaotic legal consequences of the case could ultimately reach the sheer 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," Shanmugam told the court.
Ironically, these sweeping concerns were far removed from what Boulder explicitly claimed it wanted to accomplish with its lawsuit. The city has not asked the courts to stop companies from producing oil and gas, nor has it asked the judiciary to prevent consumers who burn those fossil fuels from sending greenhouse gases into the atmosphere. Rather, Boulder’s legal strategy targets corporate deception. The city wants the oil companies to pay financial compensation for allegedly misleading the public and concealing what they knew about their products producing large-scale environmental harms through climate change.
Drawing a parallel to historic litigation from decades past, Justice Elena Kagan argued that Boulder’s case bore a strong similarity to the landmark lawsuits that states brought against major cigarette companies in the 1990s. In those tobacco cases, state governments sought compensation for mounting public health care costs linked directly to tobacco consumption. The cigarette manufacturing companies were not required by the courts to shut down their operations or stop selling cigarettes entirely, but they were forced to roll back their deceptive pro-tobacco marketing and fund widespread public awareness campaigns concerning the proven health effects of smoking.
"This is not an effort to reduce emissions," Russell told the justices on behalf of Boulder. "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."
Later in the proceedings, Russell reiterated the core premise of the city’s legal theory, emphasizing the distinction between regulation and compensation. "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," he said.
Justice Kavanaugh pushed back against this explanation, labeling Russell’s phrasing as "cavalier" and pointing out that those financial costs could be extraordinarily significant for energy producers. Major oil firms, including Suncor, have repeatedly warned their shareholders in financial disclosures that the accumulating wave of climate lawsuits mounting against them could severely impact their corporate bottom lines.
If the Supreme Court allows the case to proceed in Colorado courts and Boulder ultimately prevails, Shanmugam argued that it would open the floodgates for a tidal wave of copycat litigation. "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," he warned the justices.
Justices typically hear opening arguments and pose questions at the very beginning of the court’s official term before taking several months to deliberate and finally publish a binding decision. The debate over global conduct and state authority was only one of several complex threads the justices teased apart during the arguments. Other topics included heated discussions over the constitutional boundaries of states’ regulatory authorities and the original legislative intent behind the federal Clean Air Act. Legal experts note that the judges could ultimately rely on a wide range of differing legal rationales for their final ruling, each of which would affect other ongoing climate suits against oil companies in distinct ways, given that those separate lawsuits depend on various underlying 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 legal actions "run into trouble will depend on how justices write their decision," she added.
It remains entirely possible that the justices could choose to send the case back down to Colorado without issuing a broad ruling, either by deciding that the Supreme Court was not the proper venue for this stage of the litigation, or by splitting in a 4-4 tie vote. Such an outcome would leave Boulder free to carry on with its state-level lawsuit. (Justice Alito has not publicly explained his exact reasons for removing himself from the case, though he has previously faced public scrutiny and criticism regarding personal investments in oil and gas companies unrelated to the litigation, which outside ethics advocates argued made his participation inappropriate.)
Both Kranz and Chris Winter, executive director of the Getches-Wilkinson Center at the University of Colorado Law School, noted that while it is difficult to predict with certainty whether the justices’ line of questioning signaled that the court is leaning directly toward the oil companies, it clearly demonstrated that at least several members of the bench harbor deep concerns regarding the potential financial fallout for the energy sector.
Boulder’s legal team must now successfully convince the court that the financial risk to oil and gas companies is legally beside the point, Winter explained. To achieve this, Boulder’s attorneys will need to effectively overcome persistent skepticism from the justices who suspect the city is attempting to indirectly regulate and reduce emissions through the state court system.
"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."