Monsanto v. Durnell: Supreme Court Finds FIFRA Preemption For Failure-to-Warn Claims

On June 25, 2026, the U.S. Supreme Court issued a significant decision for manufacturers regulated by the Federal Insecticide, Fungicide, and Rodenticide Act (“FIFRA”), narrowing one avenue plaintiffs use in product liability litigation.

In Monsanto Co. v. Durnell, the Court ruled in favor of Monsanto, finding that FIFRA expressly preempted plaintiff’s failure-to-warn claim because the claim would require Monsanto to add a cancer warning to its labels which was “in addition to”, and “different from”, the label required by the U.S. Environmental Protection Agency (“EPA”) under FIFRA.

The 7-2 decision resolves a federal circuit and state court split regarding the scope of FIFRA’s preemption provision and reinforces that EPA’s labeling determinations carry preemptive force under FIFRA.

Background

Monsanto (a subsidiary of Bayer AG) manufactures and distributes Roundup, a glyphosate-based herbicide. Durnell developed against the backdrop of thousands of lawsuits, many of which relied on failure-to-warn theories for alleged cancer risks associated with Roundup. However, EPA has repeatedly evaluated glyphosate and determined it is not likely to cause cancer. Accordingly, EPA has not required glyphosate-based pesticides to provide a cancer warning under FIFRA.

John Durnell sued Monsanto in Missouri state court, alleging that he used Roundup for decades which caused him to develop non-Hodgkin’s lymphoma. He argued that Roundup’s label should have included a cancer warning. A Missouri jury agreed and awarded him approximately $1.25 million on his failure-to-warn theory. The Missouri Court of Appeals affirmed the verdict and rejected Monsanto’s preemption arguments under FIFRA. Monsanto appealed to the U.S. Supreme Court where the question before the Court was whether FIFRA preempts a state law failure-to-warn claim when EPA has not required such a warning on the product’s label.

The Court’s holding

The Supreme Court concluded that Durnell’s failure-to-warn claim is expressly preempted by FIFRA.

Writing for the majority, Justice Kavanaugh explained that under FIFRA, EPA must approve pesticide labels by determining that the label has all warnings necessary to “protect health and the environment” and that the label does not have “false or misleading” statements. Once EPA approves a label, manufacturers must use that label unless EPA subsequently approves or requires a label change and amends the registration. EPA approved a label for Roundup that does not have a cancer warning.

Under FIFRA’s express preemption clause, a state cannot impose labeling or packaging requirements that are “in addition to or different from” those required by FIFRA. The Court in Durnell noted that state tort duties constitute state labeling requirements for preemption purposes. Thus, because Durnell’s claim would require a cancer warning on Roundup’s label that EPA had not required, the claim imposed a labeling requirement that was “in addition to”, and “different from”, the applicable federal requirements.

The Court also relied on its previous decision in Riegel v. Medtronic which discussed FDA’s premarket approval of medical devices. That case addressed the preemption clause in the Medical Device Amendments of 1976, which has a preemption clause similar to FIFRA’s preemption clause. The Court in Durnell reasoned that if FDA’s premarket approval process preempts additional state law requirements, then EPA’s registration and approval of pesticide labels must also preempt additional state law requirements.

Implications for regulated manufacturers

• Strengthened Preemption Defenses. The decision provides substantial support for manufacturers using preemption defenses against failure-to-warn claims involving labels approved by EPA under FIFRA.
• Future/Remaining State Law Claims. Future and remaining product liability litigation will address the boundaries of this holding. Durnell addressed a failure-to-warn claim associated with labeling requirements specifically. The Court did not explicitly address other state law claims, such as those alleging negligence, design defect, and/or manufacturing defect. To the extent future claims do not involve label or packaging requirements that are “in addition to”, or different from”, those required by FIFRA, the claims may survive preemption. Defendants may be able to argue that other state law torts that implicate EPA-approved labels remain preempted for the same reasons outlined in Durnell (e.g., that the claim requires a warning not required by EPA). Manufacturers should remember that FIFRA still allows states to “regulate the sale or use” of federally registered pesticides under 7 U.S.C. § 136v(a).
• Applicability to Other Statutes. The Court’s discussion of Riegel reminds us that other federal regulatory statutes contain similar preemption provisions. The Court’s reasoning in Durnell may impact litigation beyond pesticides; influencing future disputes over state law preemption involving other federally regulated products.
• EPA’s Review of Associated Risks. The Court’s decision relied in part on the fact that EPA repeatedly assessed glyphosate and determined cancer warnings were not required. Future litigants may try to argue that different reasoning should apply where the alleged risk has not been specifically addressed by EPA.