Who’s who in Monday’s Supreme Court climate showdown
The ruling could define the reach of state law nationwide and determine whether local governments can put oil companies on the hook for climate costs.
By Lesley Clark
10/05/2026 05:00 AM EDT
A veteran Supreme Court advocate for Big Oil. A Trump administration attorney arguing alongside the fossil fuel industry. And local officials who say their taxpayers are being left with the tab for the effects of climate change.
These are among the key players converging at the Supreme Court on Monday for a blockbuster fight that could derail nearly a decade of lawsuits from local governments seeking to make oil and gas producers pay for the costs of disasters worsened by rising global temperatures.
At stake in Suncor Energy v. County Commissioners of Boulder County is the future of a legal campaign brought by nearly 40 local and tribal governments — and billions of dollars in costs the oil industry says it could face if those cases survive.
“What’s being sought are damages that would be crippling,” said former Attorney General Bill Barr, a partner at Torridon Law who has represented the fossil fuel advocacy group American Energy Institute. “It’s imperative these cases be put to rest and this whole approach be put to rest.”
On Monday, attorneys for the city and county of Boulder, Colorado, will tell the justices that oil giants ExxonMobil and Suncor helped intensify climate change while misleading the public about the risks of using fossil fuels — and should therefore help foot the bill for responding to wildfires, drought and other effects of a warming planet.
The companies will say federal law governs climate change and blocks state-level judges from hearing claims like Boulder’s. They’ll ask the justices to overturn a ruling last year by the Colorado Supreme Court that advanced Boulder’s case in state court.
But the case isn’t just about Boulder, Exxon and Suncor. Dozens of similar lawsuits have been filed in state courts from Hawaii to Rhode Island, and the Supreme Court’s decision has the potential to stop all those cases in their tracks.
The fight arrives at the nation’s highest bench as the Trump administration escalates its rollbacks of federal environmental regulations, which has complicated — in the eyes of some court watchers — the administration’s position that federal law should stamp out legal arguments that fossil fuel companies have violated consumer protection laws and other state-level claims.
“Courts don’t presume that federal law preempts states’ historic police powers just because there’s federal legislation,” said Rebecca Bratspies, an environmental law professor at Tulane University. “Especially when we’re talking about things like consumer protection, where states have traditionally occupied a significant role.”
Here are the lawyers and justices who will have the floor during Monday’s Supreme Court showdown — and the companies and people that have shaped the case behind the scenes.
Big Oil: The lawyers
In his 41st appearance before the justices, Kannon Shanmugam, who has represented Exxon for nearly a decade, will return to the Supreme Court on Monday to make the oil industry’s case that climate liability lawsuits are an improper attempt by local governments to address a global problem.
He’ll try to convince the justices to reverse his loss in Colorado Supreme Court that kept Boulder’s climate case alive in state court.
This isn’t the first time Shanmugam, who this year joined prominent Wall Street firm Davis Polk, has gone to bat for oil companies against climate liability lawsuits at the Supreme Court. In 2021, he secured a hypertechnical win for the industry in BP v. Mayor and City Council of Baltimore that edged companies closer to their goal of moving the cases from state to federal courts, where they believed they were more likely to win.
Since that ruling, many of the climate cases have been bounced back to state courts, which have reached mixed conclusions about whether the fossil fuel industry should be on the hook for climate costs.
Other industry attorneys who have been active in the climate cases but won’t be arguing at the Supreme Court include Theodore Boutrous Jr., a prominent First Amendment lawyer who has defended Chevron against climate lawsuits for more than a decade.
(Boutrous is the lead lawyer for POLITICO, MS NOW and CNN in their joint lawsuit challenging the outlets’ ban from the White House complex.)
Big Oil: The clients
Unlike some other climate lawsuits that name an array of oil giants, Boulder’s involves only U.S. oil behemoth Exxon and Canadian oil sands producer Suncor and its affiliates.
The limited number of companies directly named in Boulder’s lawsuit made the case enticing for the oil industry, which told the Supreme Court it was the “ideal vehicle” to be challenged, because fewer justices would need to bow out of the case in the event of a conflict.
As the biggest U.S. oil producer, Exxon has long been a target for climate activists. Claims that companies deceived the public about the dangers of fossil fuels were partially born out of the #ExxonKnew social media campaign, which followed investigative reports in 2015 that found Exxon was aware of climate change in the 1970s but publicly denied the scientific consensus for decades.
But Exxon and Suncor won’t be the only fossil fuel producers affected by the Supreme Court’s ruling.
In their petition to the Supreme Court, Exxon and Suncor said state courts and parties are “devoting enormous resources” to trying the climate cases. The energy industry as a whole, they warned, “is facing the threat of damages awards that could run into the billions of dollars.”
Boulder: The lawyers
Kevin Russell will make the case to the justices that Boulder and other local governments have the power under their own state laws to hold oil companies financially accountable for climate change.
Russell, a co-founder of the boutique law firm Russell & Woofter, is an experienced Supreme Court litigator who previously worked in the appellate section of the Justice Department’s Civil Rights Division under former Presidents Bill Clinton and George W. Bush.
Monday won’t be the first time Russell and Shanmugam have squared off at the high court. The pair went head to head in a November 2024 fight over a Facebook data breach in the lead-up to the 2016 presidential election. Russell’s client effectively won that matchup when the court took the rare step of finding it should not have heard the case in the first place.
Also on Boulder’s team is Marco Simons, former general counsel for EarthRights International, who has been on the Boulder case since it was filed in 2018 and successfully argued on the city and county’s behalf before the Colorado Supreme Court.
Another prominent lawyer for the local governments who won’t be at the lectern Monday is Vic Sher, co-founder of the San Francisco law firm Sher Edling. The firm filed some of the nation’s first climate liability lawsuits and serves as outside counsel in the litigation to 10 states, the District of Columbia, two Indian tribes and 12 local governments.
Sher argued against Shanmugam in BP v. Baltimore at the Supreme Court and faced off against Boutrous in the same case in a lower court.
Boulder: The clients
Boulder first sued the oil industry in 2018, following in the footsteps of eight California cities and counties, as well as New York City.
Then-Boulder Mayor Suzanne Jones said oil companies “need to pay their fair share” of the costs of adapting to climate change.
Jones has since been replaced by Aaron Brockett, who was elected in 2021.
“This lawsuit is about accountability, protecting our community and ensuring the companies that knowingly contributed to the climate crisis share responsibility for the costs our communities now face,” he said recently.
Boulder County Commissioner Ashley Stolzmann, who took office in 2023, said the county this year experienced one of its driest winters on record and is facing deepening drought.
She said the Supreme Court needs to allow Boulder’s case to continue and “not bail out the oil companies before hearing the facts.”
Trump’s team and the EPA factor
The Trump administration, which has aggressively sought to roll back climate protections and challenged several states’ lawsuits, will share the lectern with the oil industry Monday.
Deputy Solicitor General Sarah Harris will make the administration’s case. She argued in a brief to the court that climate lawsuits “severely interfere with the federal government’s constitutional and statutory responsibilities.”
EPA isn’t directly involved in the Supreme Court climate case, but moves by the agency overseen by Administrator Lee Zeldin may have complicated the Trump administration’s position in the fight.
Advocates for Boulder and other local governments say EPA’s decision to rescind its carbon emissions rules for motor vehicles and power plants undercuts the administration’s argument that EPA — and not states — is the nation’s sole climate regulator.
Trump officials and Republican-led states have argued that EPA still retains that power even if it’s not regulating — and that federal common law and the Constitution still prevent state and local governments from controlling interstate emissions.
Justices to watch
It takes five justices to build a majority ruling, and Justice Samuel Alito’s last-minute decision to step back from the case due to his stock holdings in oil companies has complicated the math.
Observers are also looking at whether any of the other Republican-appointed justices — in particular, John Roberts, Brett Kavanaugh and Amy Coney Barrett — will side with the court’s liberal justices to keep Boulder’s case and others like it alive.
Roberts is closest to the center and has supplied the fifth vote in several tight decisions, including joining the court’s liberals in a 5-4 ruling that upheld Obamacare. Kavanaugh and Barrett often side with Roberts.
Another wild card may be Justice Neil Gorsuch, who joined Roberts, Barrett and the court’s liberal minority earlier this year to strike down Trump’s sweeping global tariffs.
The court has not acknowledged calls from conservative groups for liberal Justice Elena Kagan to step away as part of a larger effort to discredit a judicial educational manual.
Without Alito — who owns stock in ConocoPhillips and Phillips 66, companies involved in the broader climate liability litigation — it’s possible the court could reach a 4-4 tie, which would leave the Colorado Supreme Court decision in place.
There’s also an outside chance the justices won’t resolve the question about whether federal law blocks the climate lawsuits. The court asked the parties to discuss whether it has the authority to take up the case before it’s been fully heard in Colorado. As of now, the Colorado Supreme Court has only allowed Boulder’s lawsuit to proceed — but has not decided whether Exxon and Suncor are financially responsible for climate impacts.
But legal observers say they’re not convinced the court will use the question to skirt the case.
“It’s certainly a way out of deciding the case,” said Sam Sankar, Earthjustice’s senior vice president for programs. “But I don’t think this court took this case to get out of deciding it.”
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