Supreme Court issued one of the most significant pesticide law decisions in years

Monsanto Co. v. Durnell 

The U.S. Supreme Court issued one of the most significant pesticide law decisions in years on June 25, 2026, holding in Monsanto Co. v. Durnell that the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) expressly preempts state-law failure-to-warn claims that would require pesticide labels to include warnings beyond those required by the U.S. Environmental Protection Agency (EPA). The Court’s 7-2 decision is expected to have far-reaching implications for pesticide manufacturers, registrants, and the hundreds of pending and future product liability actions challenging EPA-approved labels.

The case arose from claims that long-term use of Monsanto’s glyphosate-based Roundup^® herbicide caused the plaintiff’s non-Hodgkin’s lymphoma. Although EPA has repeatedly concluded over several decades that glyphosate is “not likely to be carcinogenic to humans” and has consistently approved Roundup^® labels without a cancer warning, a Missouri jury nevertheless found Monsanto liable under state failure-to-warn law and awarded more than $1 million in damages.

This week, the Supreme Court reversed. Writing for the majority, Justice Brett M. Kavanaugh concluded that FIFRA’s express preemption provision leaves little room for states to impose labeling obligations that differ from EPA’s approved labeling. Section 136v(b) prohibits states from imposing “any requirements for labeling or packaging in addition to or different from” those required under FIFRA. The Court emphasized that state tort duties constitute “requirements” for purposes of FIFRA preemption.

A key aspect of the Court’s reasoning was its view that EPA’s registration process is not merely administrative but establishes binding federal labeling requirements. Before registering a pesticide, EPA must determine that its labeling contains all warnings necessary to protect human health and the environment and is not false or misleading. Once EPA approves a label, manufacturers are generally required to use that label unless EPA subsequently approves or requires a change. According to the Court, allowing state juries to require additional warnings would undermine Congress’s goal of national labeling uniformity and place registrants in the untenable position of choosing between complying with federal law and avoiding state tort liability. As the Court concluded:

With respect to pesticide labels, FIFRA demands “[u]niformity” and expressly preempts state labeling requirements that are “in addition to” or “different from” federal labeling requirements. §136v(b). Durnell’s state-law failure-to-warn claim would require a cancer warning on Roundup’s label—a requirement “in addition to” and “different from” the label required by EPA under FIFRA. FIFRA therefore expressly preempts Durnell’s claim.

Notably, the Court rejected several arguments advanced by the plaintiff and accepted by other lower courts in recent years. The Court disagreed that FIFRA’s general prohibition against “misbranding” preserves state-law failure-to-warn claims that parallel federal standards. The Court determined:

The theoretical possibility that EPA could (despite its representation otherwise) try to bring a misbranding enforcement action against a pesticide manufacturer on the theory that the EPA-approved and EPA-required label had in essence become misbranded over time due to new evidence does not deprive EPA’s registration decision of their preemptive force.

The Court further rejected arguments that EPA’s registration decisions should not carry preemptive effect because FIFRA provides mechanisms for EPA to revisit registrations as new scientific information emerges. Rather than permitting juries to second-guess EPA’s determinations, the Court emphasized that FIFRA already provides processes for petitioners to amend registrations, require label changes, or cancel registrations when new evidence warrants regulatory action.

Justice Ketanji Brown Jackson, joined by Justice Neil M. Gorsuch, dissented. The dissent argued that EPA’s approval of a pesticide label should not itself be viewed as creating a binding federal labeling requirement and maintained that state failure-to-warn claims simply parallel FIFRA’s prohibition on misbranding. According to the dissent, EPA registration represents only prima facie evidence of compliance with FIFRA rather than conclusive proof that a label satisfies the statute. The dissent drew heavily on the earlier 2005 Bates v. Dow case, where the Supreme Court had ruled that FIFRA only preempts state regulations that explicitly conflict with federal labeling and packaging standards.

Although litigation concerning glyphosate and other pesticide products is unlikely to disappear, Monsanto v. Durnell represents one of the Court’s clearest statements to date that emphasizes that questions regarding pesticide labeling belong first and foremost with EPA — not fifty different state juries. For companies regulated under FIFRA, the decision provides long-awaited clarity regarding the relationship between federal pesticide regulation and state tort law.