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Last week, as the United Nations marked World Environment Day in Baku, the U.S. Environmental Protection Agency’s rescission of the 2009 Greenhouse Gas Endangerment Finding took effect. Published as 91 Fed. Reg. 7686 on February 18 and operative since April 20, the rescission did more than dismantle federal climate regulation. It removed the factual foundation of the defense the fossil fuel industry had used for fifteen years to defeat state-court climate liability suits.1
For over a decade, when a city, county, or state filed a climate cost-recovery suit in local court, fossil fuel defendants pointed at Washington. Federal law occupies this field, they argued. The EPA is the designated regulator. State courts have no jurisdiction here. That defense rested on one fact: an active federal regulatory program existed. The EPA has now stated in writing that it never did.
The industry spent years lobbying to eliminate the regulatory apparatus it was using as a litigation shield. The Supreme Court will resolve the consequence this October in Suncor Energy, Inc. v. County Commissioners of Boulder County. State trial courts are already splitting on what to do in the meantime.
How the Displacement Defense Worked
In 2011, the Supreme Court held 8-0 in American Electric Power Co. v. Connecticut that the Clean Air Act displaced federal common law nuisance claims for greenhouse gas emissions because Congress had delegated regulatory authority over those emissions to the EPA.2 Writing for the Court, Justice Ginsburg restated the controlling principle from Milwaukee v. Illinois: the question for displacement is “whether the field has been occupied, not whether it has been occupied in a particular manner.”3 That delegation is what displaces federal common law. Not the regulations themselves. The delegation.
Defense counsel extended that holding broadly. The AEP Court reserved whether state-law nuisance claims were also displaced, remanding that question without deciding it.4 Corporate defendants filled the silence with the same logic. State-court suits were dismissed at the threshold, often before any merits discovery, on the premise that the federal regulatory scheme occupied the field.
The Rescission and the Science Problem
The EPA’s Federal Register entry is explicit: Clean Air Act Section 202(a) does not authorize the agency to prescribe standards for greenhouse gas emissions. The agency is not saying it chose not to regulate. It is asserting it lacked statutory power to do so from the beginning, that the 2009 endangerment finding was unauthorized from its inception.5
The EPA grounds this on three arguments: that “air pollution” under Section 202(a) covers only pollution with local or regional effects; that eliminating all U.S. vehicle emissions would have only “de minimis” global impact; and that the major questions doctrine requires clear congressional authorization the statute does not supply.6 Each runs directly into Massachusetts v. EPA, 549 U.S. 497 (2007), which held greenhouse gases are air pollutants under the Clean Air Act and that EPA must exercise scientific judgment in making endangerment determinations without factoring in policy or cost.
The de minimis argument is the most scientifically exposed of the three, given that U.S. cumulative emissions remain the largest of any country.
The rescission also has an administrative-law vulnerability. The EPA Administrator stated in the final rule that he “continues to harbor concerns” about the 2009 scientific analysis, but expressly declined to base the rescission on those concerns, building the case entirely on statutory reinterpretation. The reason for that choice is itself documented in court. In January 2026, Judge William Young of the U.S. District Court for the District of Massachusetts, a Reagan appointee, ruled in Environmental Defense Fund v. U.S. Department of Energy that the administration violated the Federal Advisory Committee Act when it secretly formed a Department of Energy Climate Working Group to produce a report disputing the 2009 finding.7 The EPA had cited that report twenty-two times in its draft proposal. After the ruling, the agency dropped all references when issuing the final rule.
The Inversion: Deregulation Expands Liability
The AEP Court’s own language is the problem for defendants. Displacement was satisfied in 2011 because Congress delegated regulatory authority to EPA and EPA was exercising it. An agency that declines to regulate may still occupy the field through its delegated authority, that is what AEP held. But an agency that formally asserts it lacks the authority to regulate at all is describing the absence of the delegation itself. If Section 202(a) never authorized greenhouse gas regulation, as the EPA now argues, the statutory delegation AEP relied on as the operative displacing fact did not exist.
There is also a paradox. As Ann Carlson observed at Legal Planet, if the EPA no longer has authority to regulate greenhouse gases, federal common law nuisance claims — displaced in 2011 because EPA’s authority occupied the field, may spring back to life.8 Industry defendants could face a parallel new wave of suits based on federal law claims they thought had been buried.
Suncor, The Amicus Wave, And A State-Court Split
The Supreme Court granted certiorari in Suncor, No. 25-170, on February 23, 2026, five days after the EPA finalized the rescission.9 Petitioners’ merits brief was filed May 14. Respondents’ brief is due July 27. Oral argument is set for the Court’s October 2026 sitting, with a decision expected before July 2027.
The petitioners’ brief makes four arguments: that state law cannot impose liability for the global climate effects of emissions originating around the world; that packaging claims as state torts makes no difference because they are preempted by federal law; that the Clean Air Act’s displacement of federal common law does not authorize state law to regulate a uniquely federal area; and that the Clean Air Act itself preempts Boulder’s state-law claims.10 Each of those four arguments rests on the same factual premise: that Congress, through the Clean Air Act, gave EPA the authority to regulate greenhouse gas emissions and that this delegation occupies the field. The EPA has now formally denied that premise in writing.
The amicus wave in support of petitioners has been one of the broadest in recent climate litigation. By the end of May, nearly forty amicus briefs had been filed urging reversal, led by the U.S. Department of Justice on the merits.11 The DOJ’s brief was blunt: “Can one city wield one State’s law to dictate how the rest of the world must address a global problem with global effects? The Constitution supplies the answer: Absolutely not.”12 Twenty-seven state attorneys general led by Alabama, seventy-eight House members led by Majority Leader Scalise, four senators, the U.S. Chamber of Commerce, the American Petroleum Institute, and a coalition of former senior national security officials all filed in support.
Two state supreme courts have reached opposite conclusions on the underlying question. In May 2025, the Colorado Supreme Court ruled 5-2 in Board of County Commissioners of Boulder County v. Suncor Energy (U.S.A.) Inc. that the Clean Air Act does not preempt Boulder’s state-law tort claims.13 In March 2026, a month after the rescission, the Maryland Supreme Court reached the opposite conclusion in Mayor & City Council of Baltimore v. BP P.L.C., lawsuits brought by Baltimore, Annapolis, and Anne Arundel County, holding that federal law preempts state-law tort claims based on global emissions.14 The dissents in Maryland identified the flaw: a preemption defense built on EPA’s regulatory occupation of the field is harder to sustain when EPA has formally vacated that field.
State trial courts are not waiting for the Supreme Court. Since April, the Washington Superior Court denied a stay in Leon v. Exxon Mobil Corp. on April 9, the Hawai’i Circuit Court denied a stay in City and County of Honolulu v. Sunoco LP on May 6, and the Oregon Circuit Court denied a stay in County of Multnomah v. Exxon Mobil Corp. on May 7. The California Superior Court granted a stay in coordinated state proceedings on April 14. And on April 29, the Washington Superior Court denied fossil fuel motions to dismiss tribal climate claims on the merits in Shoalwater Bay Indian Tribe v. Exxon Mobil Corp. and Makah Indian Tribe v. Exxon Mobil Corp., rejecting preemption, political question, and pleading-sufficiency defenses in one opinion.15
The Federal Government’s Own Contradiction
The federal government itself shows the contradiction. On May 4, 2026, the United States filed United States v. Minnesota in the U.S. District Court for the District of Minnesota to block Minnesota’s state-law climate case against fossil fuel defendants, asserting the suit was preempted by the Clean Air Act and the foreign affairs doctrine.16 That federal complaint relies on the same federal regulatory authority over greenhouse gas emissions that the EPA disclaimed three months earlier in the Federal Register. The same administration is arguing in one filing that federal law occupies the field of greenhouse gas regulation while arguing in another that no such federal authority exists.
Courts have equitable discretion in how they apply displacement and preemption principles. A defendant that successfully invoked federal regulatory occupation of the field to defeat prior liability claims — while simultaneously working to eliminate that regulatory presence — is in a different equitable position than a defendant raising these arguments for the first time. Plaintiffs in active litigation are beginning to develop the argument.
What Practitioners Should Be Watching
Three practical considerations.
First, energy sector counsel should reassess pending matters in which displacement or Clean Air Act preemption was a primary defense theory. The Maryland decision provides some short-term comfort, but Suncor will resolve the conflict between Colorado and Maryland against a post-rescission backdrop neither state court had before it.
Second, emissions-tracking and compliance infrastructure should be maintained regardless of the federal rollback. D.C. Circuit litigation over the rescission will take years to resolve. A future administration will need to re-establish the endangerment finding through a full rulemaking under Motor Vehicle Manufacturers Ass’n v. State Farm Mutual Auto. Insurance Co., 463 U.S. 29 (1983), and this time will have to engage the science rather than set it aside. State-level regulatory obligations in California, New York, Massachusetts, Hawai’i, and RGGI member states remain in full effect.
Third, the industry’s parallel legislative push for a federal liability shield, flagged by the American Petroleum Institute as a top 2026 priority, signals the courtroom defense is no longer enough.
The federal regulatory presence is gone. The displacement defense that depended on it is in serious jeopardy. What follows is litigation, in state courts, in the D.C. Circuit, and one month from now at the Supreme Court of the United States.
Gregg Goldfarb is founder of Gregg M. Goldfarb, LLP in Florida, where his practice focuses on plaintiff-side mass torts, environmental litigation, and corporate accountability. He represents individuals in complex litigation against corporate defendants.
Disclosure: The author and his firm are not currently representing any party in any of the litigation discussed in this article, including Suncor v. Boulder, the Maryland or Colorado climate cases, the pending D.C. Circuit challenges to the EPA rescission, or the state-court matters in Washington, Hawaii, Oregon, California, or Minnesota.
The opinions expressed are those of the author and do not reflect the views of his firm, its clients, or any other affiliated organization.
Endnotes
1. Rescission of the Greenhouse Gas Endangerment Finding and Motor Vehicle Greenhouse Gas Emission Standards Under the Clean Air Act, 91 Fed. Reg. 7686 (Feb. 18, 2026) (effective Apr. 20, 2026).
2. Am. Elec. Power Co. v. Connecticut, 564 U.S. 410 (2011) (Ginsburg, J., delivering the opinion of the Court; 8-0 holding, Sotomayor, J., took no part; Alito, J., joined by Thomas, J., concurring in part and concurring in the judgment).
3. Id. (quoting Milwaukee v. Illinois, 451 U.S. 304, 317 (1981) (Milwaukee II)).
4. Id., slip op. at 15-16 (remanding the state-law claims for consideration on remand because the parties had not briefed the preemption issue).
5. 91 Fed. Reg. 7686 (Feb. 18, 2026).
6. Id. at 7701-12; see also West Virginia v. EPA, 597 U.S. 697 (2022) (major questions doctrine); Harvard Environmental & Energy Law Program, Eliminating the Foundation: Vulnerabilities in and Implications of EPA’s Endangerment Finding Rescission (Mar. 2, 2026), eelp.law.harvard.edu.
7. Envtl. Def. Fund v. U.S. Dep’t of Energy, No. 1:25-cv-12249-WGY (D. Mass. Jan. 30, 2026) (Young, J.) (Federal Advisory Committee Act violations “established as a matter of law”).
8. Ann Carlson, The Tangled Web of the Boulder v. Suncor Cert Grant, Legal Planet (Feb. 25, 2026), legal-planet.org.
9. Suncor Energy (U.S.A.) Inc. v. Cty. Comm’rs of Boulder Cty., No. 25-170, cert. granted (U.S. Feb. 23, 2026).
10. Brief for Petitioners, No. 25-170 (U.S. May 14, 2026).
11. See Complete Colorado, Amicus Briefs Flood SCOTUS in Boulder Climate Lawfare Case (May 28, 2026), completecolorado.com.
12. Brief for the United States as Amicus Curiae Supporting Petitioners, No. 25-170 (U.S. May 2026).
13. Bd. of Cty. Comm’rs of Boulder Cty. v. Suncor Energy (U.S.A.) Inc., 2025 CO 21 (Colo. May 12, 2025).
14. Mayor & City Council of Baltimore v. BP P.L.C., No. SCM-PET-0052-2025 (Md. Mar. 23, 2026) (Booth, J.).
15. Leon v. Exxon Mobil Corp., No. 25-2-15986-8 SEA (Wash. Super. Ct. Apr. 9, 2026); City & County of Honolulu v. Sunoco LP, No. 1CCV-20-0380 (Haw. Cir. Ct. May 6, 2026); County of Multnomah v. Exxon Mobil Corp., No. 23CV25164 (Or. Cir. Ct. May 7, 2026); In re Climate Cases, California Judicial Council Coordinated Proceeding (Cal. Super. Ct. Apr. 14, 2026); Shoalwater Bay Indian Tribe v. Exxon Mobil Corp. and Makah Indian Tribe v. Exxon Mobil Corp., Nos. 23-2-25215-2 SEA, 23-2-25216-1 SEA (Wash. Super. Ct. Apr. 29, 2026); all reported in Sabin Center for Climate Change Law, Climate Litigation Updates (May 29, 2026), climate.law.columbia.edu.
16. United States v. Minnesota, No. 0:26-cv-02456 (D. Minn., filed May 4, 2026).
