Published July 21, 2026
By Charles Slidders, Manager and Senior Attorney, and Conor MacDonald, Attorney, for Financial Strategies at the Center for International Environmental Law (CIEL).
This piece was originally published as an opinion by Forward Law Review.
Pending decisions by the Supreme Court and Congress could determine whether climate claims remain in state courts or return to federal oversight, write Conor MacDonald and Charles Slidders at the Center for International Environmental Law.
During its October 2026 term, the Supreme Court of the United States will hear a landmark case that could shape whether climate liability lawsuits against fossil fuel companies can proceed under state law. At the same time, Congress is considering legislation that would block these types of claims altogether.
Both institutions should resist efforts to put climate accountability beyond the reach of state law and deny access to justice for victims.
Climate lawsuits have proliferated in state courts as cities, counties and states seek to hold fossil fuel companies accountable for climate-related harms. Drawing on longstanding principles of state tort and consumer protection law, plaintiffs argue that major oil and gas companies should bear some responsibility for the costs associated with increasingly severe climate impacts. As more communities face devastating floods, storms, wildfires and other extreme weather events, these cases have emerged as some of the most significant legal battlegrounds in the broader debate over climate accountability.
Critics of these lawsuits argue that they are not ordinary tort and state law claims at all. Instead, they contend that the cases amount to attempts to regulate greenhouse gas (GHG) emissions through the courts — a matter they say belongs exclusively to the federal government. Because climate change is a global phenomenon, defendants argue that energy policy is national in scope and federal law displaces or pre-empts these state law claims. If accepted, that argument would sharply limit state court efforts to seek compensation for climate-related harms from fossil fuel companies.
That framing, however, overlooks a critical distinction: the plaintiffs in these cases are not asking courts to set emissions limits, dictate national energy policy, or regulate GHG emissions. Rather, they rely on traditional state law causes of action to argue that fossil fuel companies should be held accountable for the consequences of their alleged conduct. Whether those claims ultimately succeed is a matter for the courts. But those claims should be allowed to proceed under the laws of the states where the alleged harms occurred.
That debate is now headed to the US Supreme Court. In Suncor v Boulder County, the court will review a decision of the Colorado Supreme Court allowing climate liability claims brought by Boulder County and the City of Boulder to proceed under state law.
Diverging state court decisions
The Boulder plaintiffs allege that oil company Suncor and its affiliates misled consumers and the public about the climate risks associated with fossil fuel products. Like similar lawsuits filed by Baltimore and other jurisdictions, the case rests on allegations that the defendants knew of the harmful consequences of fossil fuel use while concealing or misrepresenting those risks for decades. The defendants nevertheless argue that these claims are, in substance, attempts to regulate emissions and energy policy and are therefore pre-empted by federal law.
The Colorado Supreme Court rejected that characterisation. In May 2025, it held that federal interests in interstate pollution, climate change and energy policy were insufficient to displace Colorado law.
More importantly, the court rejected the argument that Boulder was effectively seeking to regulate GHG emissions. As the court explained, Boulder’s claims “do not seek to regulate GHG emissions” but instead “seek compensation for allegedly tortious conduct.” Colorado is not alone. In 2023, the Hawaii Supreme Court reached a similar conclusion in City and County of Honolulu v Sunoco, allowing comparable state-law claims to proceed.
Not every court has agreed. In Mayor and City Council of Baltimore v BP et al, Maryland’s highest court held that similar claims brought by the local government were pre-empted and displaced by federal law. Although the plaintiffs argued that their lawsuit targeted deceptive and misleading conduct, the court concluded that the claims were effectively an attempt to regulate interstate and international pollution.
In the court’s view, local governments were attempting to use state law to address a problem that implicated federal legislation and the US’s role in international relations. The claims, the court reasoned, were less about alleged deception and more about regulating GHG emissions by another name.
That reasoning echoed the Second Circuit’s approach in City of New York v Chevron, which similarly treated climate liability claims as an impermissible effort to influence matters of “energy production, economic growth, foreign policy, and national security” through state law. The Supreme Court may now resolve this split between the state courts.
The Supreme Court and big oil litigation
In February, the US Supreme Court granted Suncor’s petition for certiorari in Boulder.
In a brief to the Supreme Court, Suncor acknowledges that GHG emissions contribute to climate change. But it characterises Boulder as an attempt to use state tort law to address the effects of global climate change, rather than as a case about alleged deception and misrepresentation of the risks associated with fossil fuel products.
That characterisation overlooks the plaintiffs’ express statements that the municipalities are not asking the court to regulate fossil fuel production or GHG emissions, in Colorado or elsewhere. Instead, they seek compensation for alleged misconduct.
As Maryland Supreme Court Justice Killough noted in a separate opinion in Baltimore, “not a single emissions regulation is implicated in this case,” and the alleged harms “have resulted from a fraud, not from an emissions policy.” Whether the plaintiffs ultimately prevail remains to be seen. But the claims fall squarely within traditional tort law.
The EPA’s Endangerment Finding
Suncor argues that the Clean Air Act establishes a comprehensive federal framework for regulating greenhouse gas emissions, leaving little room for state law claims. The company relies in part on the Supreme Court’s decision in American Electric Power Co v Connecticut, which held that federal law displaced federal common law claims seeking to curb carbon dioxide emissions from fossil-fuel-fired power plants.
Recent Environmental Protection Agency (EPA) action has weakened that argument. Earlier this year, the EPA rescinded the 2009 Endangerment Finding. That finding, issued after the Supreme Court’s decision in Massachusetts v EPA, became the regulatory foundation for many federal GHG rules. If the EPA is scaling back federal GHG regulation, it is harder to argue that federal law leaves no room for, and displaces, state law climate liability claims.
Legislative efforts to grant industry immunity
The courts are not the only battleground. In April, Republican lawmakers Representative Harriet Hageman and Senator Ted Cruz introduced the Stop Climate Shakedowns Act of 2026, legislation that would dismiss pending climate liability lawsuits and shield oil and gas companies from liability for their contribution to climate change.
The bill follows sustained lobbying by the fossil fuel industry. The American Petroleum Institute (API), the nation’s largest oil and gas trade association, described what it calls “abusive state climate lawsuits” as a top priority. In a joint statement, the API and the American Fuel and Petrochemical Manufacturers thanked the bill’s sponsors for introducing the legislation.
Ryan Meyers, senior vice president and general counsel at API, told Forward Law Review this week: “Climate policy should be debated and decided by Congress, not outsourced to a patchwork of courts.”
He continued: “We welcome the Supreme Court’s decision to step in and provide clarity on this coordinated campaign against an industry that powers everyday life, drives economic growth, and continues to deliver real emissions reductions.”
The push for federal immunity reflects growing industry concern about the expansion of climate liability lawsuits and the emergence of state climate superfund laws. Rather than contest these claims in court, the bill would effectively end them before judges have the opportunity to decide their merits.
The future of climate liability litigation may ultimately be shaped by Congress, if not the Supreme Court. As the court prepares to hear Boulder during its October 2026 term, it should allow these common law tort claims to proceed and avoid crafting a judicial exception or special carve-out for climate-related harms.
Congress, for its part, should resist efforts to grant the fossil fuel industry a special exemption from accountability. These claims should be allowed to rise or fall on their merits under state law — not be recast by the Supreme Court as federal regulation or shut down by Congress.
Suncor was approached for comment.