This story originally appeared on BigPivots.com on May 13, 2025.
By a Colorado Supreme Court vote of 5 to 2, Boulder and Boulder County won the right to move forward with their lawsuit against two fossil fuel companies.
But if the vigor of the writing were the deciding factor, the dissent authored by Justice Carlos Samour Jr. with concurrence of Justice Boatright would carry the day.
That’s not how the law works, of course. The written opinion — echoing what was verbally decided several weeks ago — found that federal law did not preempt Boulder’s claims under state law in this case. In other words, the argument by the city and county against Exxon Mobil and Colorado Suncor can be heard in a Colorado district court.
“We express no opinion on the ultimate viability of the merits of Boulder’s claims,” said the majority in an opinion written by Justice Richard J. Gabriel.
Many similar lawsuits have been filed in the United States by local jurisdictions, and this is only the second one, after a Hawaii Supreme Court decision in 2023 — that has been deemed to move forward. In New York, justices ruled against a similar climate change lawsuit.
Boulder and Boulder County along with San Miguel County originally sued Suncor and Exxon in April 2018. They allege they have and will continue to incur costs and losses as a result of climate harms, such as increased costs for wildfire abatement, and for decades of misinformation.
A state district court rejected the attempt by the two companies to have the lawsuit dismissed. Exxon then directly petitioned the Colorado Supreme Court to overturn the result.
San Miguel County’s case in Denver District Court has been on hold, although this decision sets a precedent for it.
The lawsuit pivots upon several arguments, most notably the federal Clean Air Act, the law passed by Congress in 1970. In dispute was whether this law precludes efforts in Colorado to seek claims from the fossil fuel companies.
Boulder alleges that it has incurred and will continue to incur millions of dollars in costs to protect its property and residents from the impacts of climate change.
Along with the county, it asserts that the fossil fuel companies, “because they knowingly caused and contributed to the alteration of the climate by producing, promoting, refining, marketing and selling fossil fuels at levels that have caused and continue to cause climate change,” should be forced to share the costs.
They also accuse the two companies of “concealing and/or misrepresenting the dangers associated with fossil fuels’ intended use.”
The local jurisdictions also have various public nuisance, private nuisance and trespass claims. Under the latter heading is the “invasions of its property in the form of floodwaters, fires, hail, rain, snow, wind and invasive species.”
But again, this case did not decide the merits of those complaints. It was to decide whether a district court in Colorado had standing to hear the case. The oil companies argued that the Clean Air Act preempted state authority in the matter.
As in other cases heard in other states, the district court judge in Colorado found no language in the Clean Air Act that expressly pre-empted state common law tort claims. Nor, said the justice, did that federal law completely occupy the field of greenhouse gas emissions.
Congress has the power to preempt state law — on that the two factions of the Colorado Supreme Court agree. Their disagreement come down to whether the Clean Air Act expressly allowed for state authority in this area of pollution — or even whether it needed to offer a green light. Indeed, according to the majority opinion, the federal law itself makes clear that “air pollution prevention … and air pollution control at its source is (sic) the primary responsibility of states and local governments.”
The majority opinion goes on for nearly three-dozen pages, so you might want to read it yourself. Here’s a key passage:
At root, defendants appear to be arguing that a vague federal interest over interstate pollution, climate change, and energy policy must preempt Boulder’s claims,” it said. But a 2019 U.S. Supreme Court opinion had held that “invoking some brooding federal interest or appealing to a judicial policy preference should never be enough to win preemption of a state law; a litigant must point specifically to ‘a constitutional text or federal statute’ that does the displacing or conflicts with state law.
Did the oil companies point to a federal state or constitutional text that preempts Boulder’s claims? No, said the state justices.
True, in New York’s Second Circuit ruled otherwise. But that court had engaged in backwards reasoning, said the Colorado state justices.
The arguments also involved whether Boulder and Boulder County are trying to set foreign policy, which is a no-no. Again, the majority of the justices found that the arguments of the oil companies fell short.
In his dissent, Justice Samour, who was joined by Justice Boatright, came to different conclusions in almost every point.
We are but one individual nation. Yet, the majority in this case gives Boulder, Colorado, the green light to act as its own republic,” he wrote in a nod to a colloquial reference to Boulder. “More specifically, the majority concludes that Boulder may prosecute state-law claims that both effectively regulate interstate air pollution and have more than an incidental effect on foreign affairs. And, alarmingly, the majority’s decision isn’t cabined to Boulder – all other Colorado municipalities may bring such claims. Indeed, at least one (San Miguel County) already has.
Added Samour in a later section. “I am concerned that permitting Boulder to proceed with its claims will interfere with both our federal government’s regulation of interstate air pollution and our federal government’s foreign policies regarding air pollution.” This has produced a worry that “we are headed for regulatory chaos.”
Samour’s dissent is entertaining to read as he talks about Boulder whistling past the federal-common-law graveyard, or the attempt by the Boulder jurisdictions to “treat federal common law as chopped liver.”
His bottom line is that the question is not whether the Clean Air Act expressly allowed states to have authority in this area. It did not, he says. It’s a flip side of the coin of the majority opinion.
In a footnote, he says that he would not rule out the possibility that Boulder could bring suit under Colorado law to recover damages allegedly caused by emissions resulting from the energy companies’ activities within Colorado. “But that’s a far, far cry from what Boulder is seeking to do here – with the majority’s blessing, no less.”
Again, it comes back to the Clean Air Act. It does not, he says, gives states authority to independently regulate or otherwise control out-of-state sources of pollution.”
Allen Best publishes the e-journal Big Pivots, which chronicles the energy transition in Colorado and beyond.