On June 25, 2026, the Supreme Court held, 7-2, that the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) preempts a state-law failure-to-warn claim alleging that Monsanto failed to warn users that the weedkiller Roundup causes cancer.  The decision in Monsanto Co. v. Durnell concludes that EPA’s approval of a pesticide label without a cancer warning constitutes a federal labeling “requirement” that state tort law cannot override.

The ruling resolves a circuit split. The Third Circuit previously found preemption on these facts, while the Ninth and Eleventh Circuits and several state appellate courts had not.

What the Court Decided

Writing for the majority, Justice Kavanaugh identified two interlocking features of FIFRA’s registration regime that together produce the preemptive effect.  First, before registering any pesticide, EPA must determine that the proposed label contains all warnings “necessary and . . . adequate to protect health and the environment” and is not false or misleading.  That determination reflects the agency’s considered judgment about what a label must—and need not—say.  Second, EPA’s implementing regulations require manufacturers to use the EPA-approved label, subject to narrow exceptions not at issue in this case.  Changing the label without EPA approval, including by unilaterally adding a cancer warning, may expose the manufacturer to civil and criminal penalties under federal law.  Together, the majority reasoned, those features constitute a federal labeling “requirement” under FIFRA’s preemption clause that preempts state tort law claims imposing labeling requirements “in addition to or different from” those required under FIFRA.

The majority found support for that reasoning in Riegel v. Medtronic, Inc., which held that FDA premarket approval of medical devices preempts conflicting state-law device claims, emphasizing the similarities between that preemption clause and FIFRA’s.  It also distinguished Bates v. Dow Agrosciences LLC, which allowed state failure-to-warn claims equivalent to FIFRA’s misbranding standard, on the ground that Bates involved efficacy claims—statements EPA does not review at registration.  Safety determinations, which EPA does review, carry preemptive force that efficacy claims do not, the majority ruled.

Writing for the dissent, Justice Jackson argued FIFRA’s own misbranding prohibition is the relevant federal requirement, and a state claim that simply parallels that prohibition should not be preempted under Bates.  The majority and dissent also disagree over whether EPA’s precautionary-statement regulations reach chronic risks like cancer, as opposed to only acute hazards.  The majority concludes they do, while the dissent maintains the regulatory text addresses acute hazards only.  Because cancer is a chronic condition, the dissent argues pesticide manufacturers can add a cancer warning without EPA approval.

Justice Thomas joined the majority in full but wrote separately to question whether FIFRA’s registration scheme exceeds Congress’s Commerce Clause authority, whether FIFRA unlawfully delegates legislative power to EPA, and whether agency action can carry preemptive force under the Supremacy Clause at all.  No other Justice joined that view.

Who’s Affected

The decision most directly benefits pesticide and agrochemical manufacturers defending failure-to-warn claims premised on an EPA-approved label.  The Court’s reasoning, however, leans on a comparison to other federal statutes with similarly worded preemption clauses, which suggests the analysis may be cited in disputes involving other federally regulated, labeled products.  The opinion does not address other theories—such as design defect, manufacturing defect, or advertising-based claims—that were not before the Court in this case.

What to Watch

The Judicial Panel on Multidistrict Litigation’s pending-dockets report lists roughly 3,900 active cases in the Roundup MDL as of July 1, 2026, a population of claims against which Durnell‘s reasoning will likely be tested in dismissal motions.  EPA’s glyphosate registration posture also remains unsettled in part, since the Ninth Circuit vacated the agency’s most recent 2020 interim registration review decision in 2022.

In addition, federal lawmakers have introduced legislation to override the Court’s interpretation.  The People Over Poison Act, H.R.9528, would add language to FIFRA clarifying that the law’s preemption clause “shall not be construed to prohibit or otherwise limit a claim related to the labeling or packaging of pesticides or devices under the tort law of any State.”  The bill was introduced on June 29, 2026, by Reps. Chellie Pingree (D-ME) and Thomas Massie (R-KY) and has been referred to the House Committee on Agriculture.

The case is Monsanto Co. v. Durnell, No. 24-1068 (U.S.), petition for writ of certiorari granted January 16, 2026.  A previous post on the case, written after the Court granted certiorari, can be found here.