U.S. Supreme Court Holds FIFRA Preempts State Failure-to-Warn Claims Challenging EPA-Approved Labeling

In a significant victory for federally regulated product manufacturers, the U.S. Supreme Court held in Monsanto v. Durnell, by a 7-2 vote, that the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) preempts state-law failure-to-warn claims seeking labeling requirements beyond those approved by the U.S. Environmental Protection Agency (EPA). The Court reversed a Missouri judgment awarding more than $1 million to a plaintiff who alleged that Roundup should have included a cancer warning.

The decision reinforces FIFRA’s express preemption provision, confirming that states may not impose labeling requirements that are “in addition to or different from” those required under federal law. The ruling substantially strengthens preemption defenses for pesticide manufacturers and may have broader implications for other industries operating under comprehensive federal labeling regimes.

Background

Monsanto’s glyphosate-based herbicide, Roundup, has been the subject of extensive litigation alleging that exposure to glyphosate causes non-Hodgkin’s lymphoma. Much of this litigation followed the International Agency for Research on Cancer’s (IARC) 2015 classification of glyphosate as “probably carcinogenic to humans.”

The EPA, however, has repeatedly reached a different conclusion. After reviewing the scientific evidence, the agency has continued to determine that glyphosate is not likely to be carcinogenic to humans and has approved Roundup’s labeling without requiring a cancer warning.

The Missouri Litigation

Plaintiff Durnell alleged that approximately two decades of Roundup use caused him to develop non-Hodgkin’s lymphoma and asserted that Monsanto failed to warn consumers of the alleged cancer risk. A Missouri jury returned a verdict in the plaintiff’s favor, awarding more than $1 million in damages, and the Missouri Court of Appeals affirmed the judgment.

Monsanto sought Supreme Court review, arguing that the plaintiff’s state-law failure-to-warn claim was expressly preempted by FIFRA because it sought to require labeling different from that approved by the EPA. See 7 U.S.C. § 136v(b).

The Supreme Court’s Decision

The Supreme Court agreed with Monsanto, holding that FIFRA expressly preempts the Missouri failure-to-warn claim. The Court concluded that requiring Monsanto to include a cancer warning not required by the EPA would impose a state-law labeling requirement “in addition to or different from” the labeling required under FIFRA, which the statute expressly prohibits. Monsanto v. Durnell, No. 24-1068, 609 U.S. ___ (2026).

The Court’s Reasoning

The majority emphasized that EPA’s registration process reflects the agency’s determination that a pesticide’s labeling complies with FIFRA, is not false or misleading, and includes the warnings necessary to protect human health and the environment. Because the plaintiff’s claim sought to impose an additional warning that the EPA had not required, the claim conflicted with the federal regulatory framework and was therefore preempted.

The Court rejected the notion that state tort law may effectively require manufacturers to alter federally approved labels, explaining that permitting such claims would undermine the uniform national labeling scheme Congress established through FIFRA.

Broader Implications

The decision provides important clarity regarding the scope of FIFRA’s express preemption provision and is expected to strengthen defenses available to manufacturers facing state-law failure-to-warn claims involving EPA-approved pesticide labeling.

More broadly, the Court’s reasoning may influence preemption disputes involving other federally regulated products—including pharmaceuticals, medical devices, and consumer products—where federal agencies exercise significant authority over product labeling. Defendants in those cases may increasingly rely on Monsanto v. Durnell to argue that state-law claims seeking additional or different warnings are preempted when federal regulators have approved the challenged labeling.

What Companies Should Do

Manufacturers of products subject to comprehensive federal labeling requirements should consider:

• Reviewing pending and anticipated failure-to-warn litigation to determine whether plaintiffs seek labeling obligations beyond those required by federal regulators.
• Evaluating whether federal preemption provides a basis for early dismissal or summary judgment.
• Continuing to monitor regulatory developments and agency determinations regarding product labeling, as those decisions may play a critical role in future preemption defenses.
• Assessing whether the Supreme Court’s reasoning may support preemption arguments beyond the pesticide context where federal law establishes uniform labeling standards.

The Supreme Court’s decision marks one of the most significant preemption rulings in recent years and is likely to reshape litigation involving federally regulated product labeling well beyond the pesticide industry.

This client alert is for general informational purposes only and does not constitute legal advice. For questions, readers should contact Michael R. Blumenthal or another member of Frantz Ward’s Environmental Practice Group.