For Paul Chinowsky, a civil engineer and professor emeritus at CU-Boulder, studying the costs of adapting roads, bridges and other infrastructure to climate-fueled risks was for years confined to his classroom or computer.
It was part of his work, not his life. That is until flames and burning homes were visible in his rearview mirror.
Chinowsky’s home in Louisville was one of the thousands evacuated as the Marshall Fire raced across Boulder County grasslands in 2021. Escaping the fire and becoming a survivor added new urgency to studying what communities would have to do to fend off climate-driven disasters.
“It was no longer just an academic exercise,” Chinowsky said of his work. Rather it became part of his mission “to minimize the number of people that have to go through these.”
That’s also a focus of the city and county of Boulder, who have spent years seeking what they say is accountability from oil companies for local harm caused by climate change. In 2018, Boulder sued ExxonMobil and Suncor Energy for damages, alleging that they lied about the dangers of burning fossil fuels, and should pay a share of preparing for and adapting to disasters.
On Monday, the Supreme Court will review the case, which has survived repeated attempts to be dismissed and spent more than eight years bouncing between lower courts.
The Supreme Court is not delving into the facts, or merits, of Boulder’s lawsuit. But the justices may end up deciding a much broader question, about whether “climate accountability” cases like Boulder’s can move forward at all.
There are about two dozen such cases plodding through state courts nationwide, which seek a variety of damages from oil companies. An expansive ruling that favors the companies could hamper them all.
“A broad ruling against the county ends essentially all of them,” said Alejandro Camacho, a UCLA law professor, on a webinar about the case.
Chinowsky hopes that Boulder’s case survives its stint in the Supreme Court, and is eventually heard by a jury in Colorado. In 2018, his consulting firm published a report on the costs Boulder would incur to deal with climate change. He said those numbers have only increased, a trend that applies nationwide.
“The cost of being resilient is not going down,” he said. “The question of who’s responsible for that cost needs to be answered.”
Boulder and Exxon did not comment on the case, and instead pointed to legal briefs they submitted to the court. Suncor declined to comment.
Two questions, a torrent of opinions
In their 2018 lawsuit, both the city and county of Boulder argued that oil companies like Exxon and Suncor had known about the risks of burning fossil fuels, but continued to market their products anyway. As a result, Boulder alleged it was dealing with a deluge of climate-related expenses to address floods, wildfires, drought and more.
The 2018 report from Chinowsky’s firm showed that Boulder would have to spend between $96 million to $157 million to prepare for just some of its climate impacts. Since then, costs to prepare for scorching summers and to rebuild roads ravaged by extreme weather and rain have only grown, Chinowsky said.
Boulder’s claims, filed under state law, are similar to public interest lawsuits against big tobacco, opioid companies and even tech giants, said Chris Winter, executive director of the Getches-Wilkinson Center at CU Boulder’s law school.
“State courts are able to hold those national and multinational companies accountable … for the harm that manifests to the citizens of that state,” he said.
In 2025, the Colorado Supreme Court cleared the way for Boulder’s case to continue. But less than a year later, the U.S. Supreme Court pumped the brakes, and agreed to hear the oil companies’ challenge to that ruling.
The Court asked two questions in agreeing to take the case. The first is whether federal law should preclude, or overrule, Boulder’s claims in state law about the harms it’s allegedly suffering from climate change.
The second is whether the Supreme Court even has the authority to review the case at this stage, before a trial or judgment.
“One-percenter hippies”
In their legal briefs to the Court, Exxon and Suncor argue that Boulder’s claims are trumped by the powers of the federal government. They argue that the Boulder governments are trying to use state law to address the thorny, complicated problem of global climate change and to “impose potentially crushing monetary liability” on oil companies.
The companies also say that the Clean Air Act, the landmark 1970s law that regulates pollution, should prevent Boulder’s claims, because it gives the federal government power to regulate air quality.
The Trump administration supports the oil companies’ view, and said in its own legal brief that Boulder was making a run around the federal government to regulate emissions.
“Can one city wield one state’s law to dictate how the rest of the world must address a global problem with global effects?” their brief said. “The Constitution supplies the answer: Absolutely not.”
Todd Zywicki, a law professor at George Mason University who submitted a brief in support of the oil companies, was more direct in a webinar about the case.
“This case is about a bunch of one-percenter hippies in Boulder County who want to tell the rest of us how we have to live,” he said, “and want to tell poor people around the world that they should not be allowed to have access to inexpensive fossil fuels.”
Phil Goldberg, special counsel for the Manufacturers’ Accountability Project, which is part of a major manufacturing trade group, opposes Boulder’s suit and said that previous Supreme Court precedent should block it and other climate litigation from proceeding.
Goldberg also said that policymaking around greenhouse gas emissions should be done through legislatures and agencies, not courts.
“This is really, at the end of the day, a public policy question about how to deal with an important societal-wide issue,” he said. “And the way to deal with that and make those decisions are through Congress and federal agencies and the state agencies.”
Other entities, like an industry group for insurance companies, chambers of commerce, red states and even large tribes, support the oil companies’ position. An August report by the left-learning advocacy group Consumer Watchdog found that two-thirds of the amicus briefs in support of the companies had some level of ties to the fossil fuel industry or what Consumer Watchdog calls climate-denial groups.
Boulder’s day in court
Boulder, for its part, argues that it’s too early for the court to review the case — there’s been no trial and certainly no judgment against the oil companies. Typically, the Supreme Court takes up cases after they’ve run their course in lower courts, or in emergency appeals.
The city and county also claim in a brief that nothing about the Constitution or the Clean Air Act should stop their suit, because they are not seeking to regulate greenhouse gases. Instead, Boulder said its claims fall well outside the boundaries of the Environmental Protection Agency’s responsibilities.
“[The Clean Air Act] certainly does not charge the EPA with regulating deceptive marketing of fossil fuels,” the brief said.
Seven Colorado ranchers also submitted a brief that said their industry was being drastically affected by climate change. Andy Breiter, a rancher in Boulder County, said that this year’s drought parched some of the forage that his cows graze on.
That meant he had to spend more to move his cows around, and will pare back his herd size to save on hay costs when winter rolls around.
He said he supported Boulder’s suit, so that some money can go towards helping the city and county prepare.
“The businesses have made a lot of money … off of their practices, which are having a negative impact on climate change,” he said. “And it seems to me that as a result, they should also suffer some of those consequences.”
This week, Breiter took his herd near Boulder’s iconic Flatiron mountains, to have them graze on overgrown grass and help the city cut down its wildfire risk.
“The next Lahaina”
The Supreme Court could rule in many ways. It could uphold the Colorado Supreme Court ruling, which would allow the case to proceed, or it could rule that the case is not yet ripe for review.
The Court could also quash Boulder’s legal theories, and similar cases like it, depending on the scope of its ruling.
Camacho, the environmental law professor, said that a very broad ruling that finds that federal law preempts Boulder’s claims could hamper similar climate accountability cases and potentially even climate Superfund laws in Vermont and New York.
“And the public, frankly all of us, end up footing the bill before the case can even be heard,” he said on a webinar about the case.
Camacho also said a broad ruling for the companies could also shield them from state-level liability in cases well outside of greenhouse gas emissions, like those dealing with contaminated groundwater or PFAS.
Chinowsky said that if the case stops now, places like Boulder may be stuck just reacting to disasters, instead of ramping up their spending to prepare for them.
“These [disasters] are going to happen,” he said. “And the people who are going to suffer are going to be the next LA, the next Boulder, the next Lahaina, the next Texas floods.”
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