On Feb. 11, 2025, the Missouri Court of Appeals for the Eastern District in Durnell v. Monsanto Co., upheld a jury verdict awarding $1.25 million in compensatory damages to plaintiff John Durnell from defendant Monsanto Co. The verdict was based on strict liability for failure to warn about risks associated with Monsanto’s herbicide, Roundup.
While federal preemption often serves as a strong defense against failure-to-warn claims, the court found that Durnell’s claim was not preempted because Missouri’s state labeling requirements aligned with the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) requirements and compliance with both was possible. This decision underscores a divide among federal and state courts regarding the scope of federal preemption under FIFRA in state failure-to-warn claims.
Durnell brought strict liability failure-to-warn, strict liability defective design and negligence claims against Monsanto, alleging that exposure to glyphosate in Roundup caused him to develop non-Hodgkin’s lymphoma. The jury returned a verdict in favor of Durnell on the strict liability failure-to-warn claim and found for Monsanto on the strict liability defective design and negligence claims. Monsanto subsequently sought a judgment notwithstanding the verdict and, in the alternative, a new trial, arguing that Durnell’s failure-to-warn claim was expressly and impliedly preempted by FIFRA.
Failure to Warn
Most U.S. states recognize strict product liability claims for failure to adequately warn consumers about inherent dangers in a product, sometimes called a “marketing defect.” In these cases, a plaintiff typically must demonstrate: (1) foreseeable use of the product involves a risk not apparent to an ordinary consumer; (2) the risk was known or knowable at the time of sale; (3) the manufacturer or seller failed to provide adequate warnings; and (4) the lack of warnings was a proximate cause of the plaintiff’s injuries. Warnings analyses often focus on labeling, with courts evaluating factors such as the clarity of the warning, its intensity relative to the danger and its accessibility. This includes the warning’s language, size and color; whether the warning was provided in multiple languages; use of pictures; and whether the warning was placed in a prominent location. Adequacy is generally assessed based on whether the warning would prompt a reasonable person to exercise appropriate caution given the product’s potential danger.
Preemption Defense and Missouri Court Analysis
For some regulated products, federal law can preempt state failure-to-warn claims, particularly when federal labeling regulations are in place. In Durnell, Monsanto argued that FIFRA expressly and impliedly preempted Durnell’s failure-to-warn claims. The court rejected both arguments.
Express Preemption
The court explained that express preemption occurs when a federal statute explicitly prohibits local regulation in a specific area. FIFRA regulates the use, sale and labeling of pesticides and provides that “a state shall not impose or continue in effect any requirements for labeling or packing in addition to or different from those required” under the statute. The court’s analysis turned on what constitutes “in addition to or different” requirements — language that has been read broadly in failure-to-warn cases under other statutes. The court found that Missouri’s strict liability failure-to-warn cause of action and any labeling requirements that might apply are “fully consistent with” and not “in addition to or different” from labeling obligations under FIFRA. The court reasoned, “the ‘practical effect’ of both FIFRA’s prohibition on misbranding [by failing to contain a warning or caution statement] and a strict liability failure to warn claim in Missouri are the same: both require a pesticide manufacturer to adequately warn users of the potential dangers of using its product, regardless of the manufacturer’s knowledge or intent.”
Implied Preemption
Federal law also can impliedly preempt state labeling requirements when there is an “irreconcilable conflict” between state and federal requirements. Monsanto argued that Durnell’s claims were impliedly preempted by FIFRA because it requires EPA approval for pesticide labels. Because the EPA has approved Monsanto’s labels, Monsanto asserted it is not free to change these labels to comply with any warning that Durnell’s claim under Missouri law would require. Monsanto pointed to the EPA’s consistent approval of their product labels without warning of cancer risks and the EPA’s conclusion that glyphosate is “not likely to be carcinogenic to humans.” To show irreconcilable conflict, however, the court determined Monsanto would need to prove that “(1) Monsanto fully informed the EPA of the justifications for the warning that Missouri law would impose; (2) the EPA informed Monsanto that it would not approve changing the label to include the warning; and (3) the EPA undertook its action pursuant to authority that carries the force of law.” The court determined Monsanto did not meet this “demanding” burden of proof.
Additional Authority
Courts disagree on whether FIFRA preempts failure-to-warn claims. In 2024, the U.S. Court of Appeals for the Third Circuit held in Shaffner v. Monsanto Corp. that FIFRA preempted Pennsylvania law in a similar claim against Monsanto alleging strict liability for failure to warn of potential cancer risks. In contrast, the Eleventh and Ninth circuits have determined similarly situated plaintiffs’ state law-based failure-to-warn claims against Monsanto were not expressly or impliedly preempted by FIFRA. See Carson v. Monsanto Co. (11th Cir. 2024); Hardeman v. Monsanto Co. (9th Cir. 2021). State courts are similarly split with regard to FIFRA preemption. The Court of Appeals of Oregon and a California Court of Appeals also found that FIFRA does not preempt state failure-to-warn claims in Johnson v. Monsanto Co. (2024) and Pillion v. Monsanto (2021).
The Durnell court found Shaffner unpersuasive and declined to extend several U.S. Supreme Court holdings that state failure-to-warn claims for products regulated under the Food, Drug, and Cosmetic Act are impliedly preempted “to pesticide products regulated under FIFRA.” See Mutual Pharmaceutical v. Bartlett (2013); PLIVA v. Mensing (2011); and Wyeth v. Levine (2009).