After one of largest wildfires in state history devastated Rio Blanco County, Colorado in 2025, Deirdre Macnab saw her share of horrors across the community: cows burned to death, pigs died from sunstroke, and pastures were blanketed in thick black smoke. This past summer was no different. “It was hellish,” Macnab told me. “Between the temperature and the drought, 2026 was a dress rehearsal for what we know is coming.”

Over the last few years, Macnab, a regenerative cattle rancher, and her fellow ranchers have experienced the devastating effects of climate change on their livelihood. “Every single rancher can tell stories about how their operations have been impacted and in some cases ended” she said. On Monday, their stories, along with dozens of others about the mounting climate costs in Colorado, will arrive at the US Supreme Court, which will hear oral arguments for the much anticipated case between Boulder, Colorado, and Suncor Energy and Exxon Mobil Corporation.

The case revolves around a dispute between the City and County of Boulder, which first sued the energy companies in 2018 They are arguing that Suncor and Exxon deceived the public about the dangers of climate change and should be forced to pay damages for climate-induced heat waves, wildfires, droughts, and floods. “The damages will only multiply as climate change worsens,” Boulder stated in its lawsuit. Suncor and Exxon, meanwhile, are asking the justices to kill the case before it makes it to trial—and with it a host of other state-level climate cases.

Depending on how the eight justices rule—Justice Samuel Alito announced what some considered to be an 11th hour recusal earlier this week—the case could have far-reaching consequences for people like Macnab, who submitted an amicus brief in support of Boulder along with six other ranchers But its implications extend beyond the state’s borders: dozens of other climate-related lawsuits hang in the balance of how is decided Indeed, experts say that its implications extend beyond climate to include other damages-related suits, from asbestos cases, to pharmaceuticals, to opioids.

The state of Colorado is estimated to pay $37 billion in climate damages by 2050, and Boulder is arguing that, “Alone, [the City and County of Boulder] and their taxpayers cannot pay the full costs of all that is needed to attempt to mitigate the harm caused by climate change, nor should they.”Rather, the “costs should be shared” by the energy companies, which have “acted recklessly.”In addition to Macnab and her fellow ranchers, Boulder’s case is supported by some Democratic members of Congress former Republican and Democratic EPA administrators and federally recognized Indian tribes Some lawyers hesitate even to call Boulder’s case a “climate” suit.

Alejandro Camacho, a law professor at UCLA, said, “ is not about whether climate change is real, and it’s not about who sets national emissions policy. It’s about whether a state court may hear an ordinary damages claim.”Hitching its legal wagon to climate change could hurt Boulder’s chances in front of a conservative-leaning court, Camacho says, “And that’s why I think it’s more useful for people to see it for what it is: a tort case.”

In widespread corporate liability, tort law allows a plaintiff who’s been harmed—from pesticides or medications, to the recent case against Meta for social media addiction—to sue a company for compensation.

Patrick Parenteau, Professor of Law Emeritus at Vermont Law School, described the situation more starkly. “You could call it deception, misrepresentation, but frankly it’s fraud,” Parenteau told me. “What [Boulder is] saying is, the companies lied about what they knew about the dangers of climate change. Fraud is the heart of it.”

“You could call it deception, misrepresentation, but frankly it’s fraud. What [Boulder is] saying is, the companies lied about what they knew about the dangers of climate change. Fraud is the heart of it.”In their petition, Suncor and Exxon have argued that Boulder’s lawsuit is a surreptitious attempt to regulate greenhouse gas emissions, and those who claim injury at the state level should instead defer to the federal Clean Air Act.

“Claims seeking relief for injuries allegedly caused by interstate pollution constitute an inherently federal area exclusively governed by federal law,” Suncor and Exxon stated in their filing. In other words, Colorado shouldn’t be able to seek state-level damages, in this case compensation from industry, when the harm in question is regulated by the Clean Air Act, which is a preexisting federal system. Three dozen amici briefs submitted on behalf of Suncor also demonstrate a significant show of force on the petitioner’s side, but a recent Consumer Watchdog investigation found that a majority of the briefs were written by groups with financial ties to the energy companies.

Boulder insists that it is “not asking [the] Court to stop or regulate the production of fossil fuels [or emissions] in Colorado or elsewhere.”They are arguing only that industry should help to “remediate the harm” from the production. In fact, Camacho believes Suncor’s arguments invoking the Clean Air Act are “ludicrous” given Boulder’s original complaint. “No federal statute provides a damages remedy for climate harms,” he said. “The Clean Air Act does not allow for regulation of greenhouse gases.”

Jonathan Adler, a conservative law professor at William & Mary Law School and a proponent of Boulder’s original case moving forward, agrees with Camacho on the preemption argument. “Neither the Clean Air Act nor the Constitution imposes such a rule,” Adler wrote in a brief on behalf of the Colorado county. “We can have arguments and debates about the scope of relief that [Boulder] seeks or obtains,” he told me, “but those are all separate from the preemption question.”

The Trump administration may have inadvertently undermined Suncor’s argument by rescinding the 2009 endangerment finding earlier this year As Emily Sanders pointed out in the administration is “drastically shrinking the EPA’s authority to regulate emissions under the Clean Air Act.”In 2025, the Trump administration submitted an unsolicited brief urging the justices to rule in Suncor’s favor. Department of Justice lawyers are expected to argue alongside Suncor and Exxon’s lawyers on Monday.

If the Supreme Court ultimately decides to issue a broad ruling in favor of Suncor and Exxon by establishing a sweeping preemption rule, the decision could set a precedent for the dozens of other climate lawsuits waiting for their day in court. “A broad ruling ends essentially all of them,” Camacho said during a webinar with Covering Climate Now and . A split outcome, in which the court rules that some cases can proceed while others must be halted, is also possible. None of the cases have progressed to trial yet.

Beyond the ecosystem of climate liability lawsuits, a sweeping decision against Boulder could have even further-reaching consequences. “I worry a broad preemption ruling could have implications for other areas of law, including litigation over things that occur on or through the internet,” said Adler. In a more unlikely but still possible scenario, the court could say nothing about the Clean Air Act and instead rule on another argument from industry: in this case, that Colorado’s law infringes on the federal government’s constitutional authority over foreign affairs.

“This has implications for basic asbestos litigation, pharmaceutical injuries, transboundary pollution cases, forced labor cases,” Camacho said. “It swallows up all of state tort law that involves any kind of international company.”

With a decision expected sometime next year, the legal experts I spoke with pointed out that the justices could choose to punt the case entirely by ruling they don’t have jurisdictional authority to hear it. “No one knows how the court’s going to rule,” said Mike Meno, communications director for Center for Climate Integrity. “But if there is a ruling on the preemption question, in cases across the country, communities and oil companies will be back in court arguing whether and how that ruling applies to these specific cases.”

On Monday morning, while the justices hear oral arguments, Deirdre Macnab will be outside the halls of the Supreme Court along with a coalition of Colorado ranchers, survivors of the 2021 Marshall fire and members of Boulder youth groups On our call, she described what’s at stake. “This story is much bigger than just the cattle ranchers. It’s the everyday families that are trying to afford food, who feel pressured about how much things are costing,” she said. “Government can’t fix everything, but it’s the tool we have to hold the private sector accountable.”