Supreme Court Has Chance to End Legally Flawed Climate Claims
The US Supreme Court will finally hear a climate lawsuit on the merits on Oct. 5 in Suncor Energy (U.S.A.) Inc. v. County Commissioners of Boulder County. The case could have major implications for federal-state balance, separation of powers, and the availability of creative and market-disruptive lawsuits across dozens of cases nationwide.
But it won’t be the Supreme Court’s first climate change rodeo. It should issue a straightforward ruling in Suncor’s favor, based on precedent.
Boulder sued Suncor and another defendant in 2018, using novel theories to allege that the defendants’ production and marketing of fossil fuels — along with alleged representations on climate change — contributed to local harms. In May 2025, the Colorado Supreme Court held the claims could proceed under state law, rejecting arguments that they are displaced, precluded, or preempted by federal law, including the Clean Air Act.
The US Supreme Court heard a similar climate lawsuit in 2011: American Electric Power (AEP), Inc. v. Connecticut. In that case, Justice Ruth Bader Ginsburg delivered a unanimous opinion, holding that public nuisance and related claims based on alleged harms from the transboundary effects of emissions would, by default, be governed by federal common law if any were to exist.
She also held that any federal common law claims that might have existed were displaced by the Clean Air Act, where Congress expressly asserted its legislative authority over transboundary pollution, precluding more amorphous common law standards available for discovery by courts.
Any attempts to inject requirements beyond what Congress set in the Clean Air Act would upset the delicate balancing that Congress is allowed when setting national and international policy in such areas, according to Ginsburg’s opinion. Thus, climate-related claims couldn’t proceed in federal or state courts.
Since the AEP decision, plaintiffs’ attorneys have developed creative litigation strategies, and the Supreme Court has declined to intervene to reiterate that ruling. Many lawsuits have been filed in state and federal courts for public nuisance, consumer deception, and other claims against energy companies alleging climate-related liability.
The locus of law for claims (state versus federal and forum shopping for favorable state court judges), the theory of the claims, and the type of court have all shifted over time as plaintiffs have adopted new strategies in different forums as adverse or advantageous precedents have ebbed and flowed. The Supreme Court in Suncor can put an end to at least one area of this entrepreneurial lawyering that has gone on far too long.
AEP’s key findings apply to Suncor. It makes no difference that the claims in Suncor are premised on state law rather than federal law. The AEP rationale is actually stronger in Suncor, because allowing the Colorado ruling to stand would mean allowing 50 distinct state legal frameworks to potentially interfere with federal prerogatives over setting climate change policy.
It’s notable that the Obama administration supported dismissing the plaintiffs’ claims in AEP. This isn’t a red or blue issue shifting with the winds — it’s a constitutional one. In 2011, the Obama administration agreed that these kinds of cases don’t belong in the courts, without distinguishing between state and federal.
In the Tennessee Valley Authority’s brief supporting dismissal of the climate change plaintiff claims, then-Solicitor General Neil Katyal wrote that climate change is “a result of the actions of innumerable sources of various kinds of emissions from around the world over many decades,” and it impacts every person — which isn’t the type of thing we leave for courts. Something that would have innumerable defendants and plaintiffs should have neither, the brief argued.
The Supreme Court in AEP agreed with the Obama administration’s concerns. And those concerns are being advanced with equally strong force by the Trump administration in Suncor.
Chief Justice John Roberts and Justices Elena Kagan, Samuel Alito, Clarence Thomas, and Sonia Sotomayor joined the AEP opinion. They would be hard pressed to find a principled way to affirm the Colorado Supreme Court and distinguish such a decision from the 2011 ruling.
Suncor requires what could boil down to a one-line opinion: “Reversed: Been there, done that, AEP applies.”
The case is Suncor Energy (U.S.A.) Inc. v. County Commissioners of Boulder County, U.S., No. 25-170, oral arguments 10/5/26.
This article does not necessarily reflect the opinion of Bloomberg Industry Group Inc., the publisher of Bloomberg Law, Bloomberg Tax, and Bloomberg Government, or its owners.
Author Information
Donald J. Kochan is a professor and the executive director of the Law & Economics Center at George Mason University’s Antonin Scalia Law School.
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