Multnomah County’s Heat Dome Case: Remand, Motions, and SCOTUS

The Multnomah County heat dome lawsuit is a climate accountability case filed in June 2023 against ExxonMobil, Chevron, Shell, BP, and roughly two dozen other fossil fuel companies and trade groups, seeking more than $51.5 billion in damages and infrastructure funding tied to the 2021 Pacific Northwest heat dome that killed dozens of county residents. The case, County of Multnomah v. Exxon Mobil Corp., is still alive in Oregon state court as of mid-2026, but motions to dismiss remain unresolved and a pending U.S. Supreme Court case could reshape or end it.¹

What the County Is Suing Over

Between June 25 and June 30, 2021, temperatures in Multnomah County reached 108, 112, and 116 degrees on three consecutive days, shattering the prior county record of 107. Researchers described the event as a one-in-a-thousand-year occurrence.²

Sixty-nine people in the county died of heat illness during that week, and 72 heat-related deaths were recorded across the summer. Statewide, at least 102 deaths were attributed to the event.³ Seventy-eight percent of the victims were 60 or older, 71 percent lived alone, nearly all died at home, and few had working air conditioning.⁴ Emergency departments logged about triple the usual heat-illness visits, and total county deaths that week nearly doubled the three-year average.²

Those deaths and the county’s emergency response costs are the factual foundation of the lawsuit.

Who Is Being Sued and for What

The county filed suit on June 22, 2023, in Oregon Circuit Court against 17 defendants. An amended complaint in October 2024 added NW Natural, a Portland-area gas utility, and other entities, bringing the total to 25. Named defendants include ExxonMobil, Shell, Chevron, BP, ConocoPhillips, Koch Industries, Peabody Energy, Marathon Petroleum, the American Petroleum Institute, the Western States Petroleum Association, and the consulting firm McKinsey & Company.⁵⁶

The complaint asserts four claims under Oregon tort law: public nuisance, negligence, fraud and deceit, and trespass.⁷ The theory has two parts. The county alleges that the defendants knew for decades that their products contributed to climate change and ran a coordinated disinformation campaign to hide the risk, block regulation, and keep selling. It also alleges that their emissions foreseeably caused the extreme weather that killed residents and burdened public services.⁸

The financial demands are among the largest in any U.S. climate suit: $50 million in actual damages, $1.5 billion in future damages, and an estimated $50 billion abatement fund to upgrade public health infrastructure and weatherproof the county against future extreme heat.⁵

Two defendants are unusual. NW Natural, added in October 2024, was described by advocates as the first gas utility named in a U.S. climate accountability suit; the county alleges it misled customers about the climate effects of burning natural gas and used front groups to greenwash its brand. NW Natural called the addition “an attempt to divert attention from legal and factual flaws in the case” and said it would vigorously contest the claims.⁹¹⁰ McKinsey & Company is accused of participating in a coordinated scheme with fossil fuel corporations to sell their products while concealing climate risks.⁸

Where the Case Stands

The defendants have fought on every available front.

Federal Remand

In August 2023, Chevron removed the case to the U.S. District Court for the District of Oregon, arguing federal question and diversity jurisdiction. Magistrate Judge Youlee You recommended remand, and U.S. District Judge Adrienne Nelson adopted those findings in June 2024, sending the case back to Oregon Circuit Court.¹¹

Motions to Dismiss

Back in state court, multiple defendants filed motions to dismiss in February 2025 on grounds including lack of personal jurisdiction, failure to state a claim, and the statute of limitations. The American Petroleum Institute and Marathon Oil filed special motions to strike under Oregon’s anti-SLAPP statute.¹ The county filed responses to all 26 opposition briefs, and defendants had until October 7, 2025, to submit rebuttals.¹² As of mid-2026, presiding Circuit Judge Benjamin Souede has not publicly ruled on those motions. His decision will determine whether the case reaches discovery and a possible jury trial.

Fight Over Scientific Studies

In September 2025, Chevron moved to strike two studies published in Nature in April and May 2025 that the county had cited, alleging that lead counsel Roger Worthington had partially funded one study and hosted pre-publication drafts of the other on his firm’s website without disclosing either connection. Chevron called it a “fraud on the court.”¹³

Judge Souede denied the motion on October 30, 2025, finding insufficient evidence of fraud, but ruled that reliance on the two studies “will carry absolutely no weight” in the proceedings and said of Worthington’s conduct, “This is simply not an appropriate way to practice law in the courts of the state of Oregon.”¹⁴ No disciplinary action against Worthington had been reported as of late 2025.¹³

No Pause for the Supreme Court

The defendants asked Judge Souede to freeze the case while the U.S. Supreme Court considers a Colorado climate case that could preempt state-law claims nationally. On May 7, 2026, the judge denied the stay, citing the risk of fading witness memories and lost evidence and noting that a Supreme Court ruling might not resolve every claim in the Multnomah County case. Claims against one defendant, TotalEnergies Marketing USA, were dismissed without prejudice in October 2025; the reason and any refiling plans have not been publicly reported.¹

Outside Forces That Could Kill or Delay the Case

Trump Executive Order

In April 2025, President Trump signed an executive order titled “Protecting American Energy from State Overreach,” directing the U.S. Attorney General to take “all appropriate action to stop the enforcement” of state and local laws addressing climate change, environmental justice, and carbon penalties. The order gave Attorney General Pam Bondi 60 days to report on whether such enforcement actions were necessary; as of July 2025 it was unclear whether that deadline had been met.¹² The order targets roughly 40 lawsuits filed by local governments against the fossil fuel industry nationwide. Attorneys for Multnomah County warned it could grant fossil fuel companies effective “total immunity” for climate-related damages.¹⁵

The Maryland Ruling

In March 2026, the Supreme Court of Maryland ruled that state common-law tort claims brought by Baltimore, Anne Arundel County, and Annapolis against oil companies are displaced by federal law. Writing for the majority, Judge Brynja Booth held that the claims were an attempt to regulate international conduct beyond local police powers, and that allowing individual jurisdictions to impose climate-damage remedies would create an “irrational system of regulation.”¹⁶ Two justices dissented in part, arguing that the Clean Air Act does not preclude fraud-based claims.¹⁷ The Maryland ruling does not bind Oregon courts, but defendants will cite it.

Suncor v. Boulder County at the Supreme Court

The U.S. Supreme Court agreed in February 2026 to hear Suncor Energy v. Boulder County, which asks whether federal law bars state-law claims seeking relief for injuries allegedly caused by interstate and international greenhouse gas emissions. All nine justices are participating. Oral arguments are expected in October 2026 and a decision before July 2027. The Court has also asked both sides to address whether the EPA’s recent rescission of its greenhouse gas endangerment finding affects the preemption analysis.¹⁸ A ruling for the industry could end or severely limit the pending municipal climate lawsuits, including Multnomah County’s. Multnomah County’s suit is one of at least 29 such cases nationally.¹⁹

What Happens Next

The immediate question is whether Judge Souede grants or denies the pending motions to dismiss. If he denies them, the case moves toward discovery on a $51.5 billion set of claims that would put internal fossil fuel industry documents and marketing decisions on the record in Oregon. If he grants them, the county can appeal. Either way, the Supreme Court’s ruling in Suncor, expected by mid-2027, will likely determine whether Multnomah County or any other local government in the country can use state tort law to make oil and gas producers pay for climate damage.¹

1
Climate Case Chart. County of Multnomah v. Exxon Mobil Corp. Docket
2
OPB. Portland Remembers People Who Died in Heat Dome One Year Ago
3
Oregon Health Authority. Oregon Heat-Related Illness and Death After the June 2021 Extreme Heat Event
4
Multnomah County. 2021 Heat Killed 72 People in Multnomah County
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Multnomah County. Multnomah County Sues Oil Companies Over 2021 Heat Dome Disaster
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OPB. Multnomah County Adds NW Natural to Fossil Fuel Heat Dome Lawsuit
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Multnomah County. Climate Accountability Litigation
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CLX Toolkit. Multnomah County v. Exxon Mobil
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Oregon PSR. Multnomah County Adds NW Natural to Climate Lawsuit
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New York Times. Natural Gas Utility Named in Climate Change Lawsuit
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Multnomah County. Federal Judge Remands Multnomah County’s Climate Accountability Lawsuit to State Court
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OPB. Multnomah County Lawsuit Against Big Oil Faces Trump Delays
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E&E News. Chevron Lawyer in $51B Lawsuit Failed to Disclose Support for Climate Research
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Columbia Law School. Climate Litigation Updates
15
Politico Pro. Oregon Democrats Tell Trump to Back Off State Climate Efforts
16
Courthouse News. Maryland High Court Rejects Localities’ Plea for Climate Change Damages
17
Maryland Courts. Mayor & City Council of Baltimore v. B.P. P.L.C.
18
Columbia Law School. Supreme Court Agrees to Hear Fossil Fuel Companies’ Appeal in Boulder Climate Case
19
Atmos. The Supreme Court Case That Could End Local Climate Suits