June 29, 2026

By: Frank H. Stoy , Daniel F. Pollack

Last week, the U.S. Supreme Court issued its decision in Monsanto Company v. Durnell, holding that the Federal Insecticide, Fungicide, and Rodenticide Act (“FIFRA”) expressly preempted state-law failure to warn claims where state law would have required Monsanto to add a cancer warning to its RoundUp weedkiller label. Although the case dealt specifically with the application of Environmental Protection Agency (“EPA”) regulations, the holding is significant for life sciences companies who are regulated by the Food and Drug Administration (“FDA”) and, in particular, for medical device manufacturers.

By way of background, in 2015, the International Agency for Research on Cancer (“IARC”) concluded that the active ingredient in RoundUp, glyphosate, is a “probable” human carcinogen. The EPA, however, separately analyzed the issue, and did not require Monsanto to update the RoundUp label to include a cancer warning. Nevertheless, IARC’s determination sparked over 100,000 lawsuits in state and federal courts by plaintiffs who claim to have been diagnosed with cancer after using RoundUp. Generally, these plaintiffs claim that Monsanto failed to warn that the product causes cancer. Monsanto has countered that FIFRA expressly preempts plaintiffs’ state-law failure to warn claims, as FIFRA provides that a state “shall not impose or continue in effect any requirements for labeling or packaging in addition to or different from those required under [FIFRA].” 7 U.S.C. §136v(b).

In Durnell, the plaintiff sued Monsanto in Missouri state court in 2019, claiming that he used RoundUp for 20 years, that it caused him to develop non-Hodgkin’s lymphoma, and that Monsanto failed to warn of this risk. At trial, the jury found for Mr. Durnell, and on appeal, the Missouri Court of Appeals upheld the verdict. The Supreme Court granted certiorari, agreeing to consider whether FIFRA preempts a label-based failure-to-warn claim where the EPA has not required the label to be updated to include the warning.

In a 7-2 decision, the Supreme Court reversed, holding that FIFRA expressly preempts state-law failure to warn claims. The Court explained that FIFRA authorizes the EPA to regulate pesticides and their labels. Insofar as the EPA has concluded that glyphosate—the active ingredient in RoundUp—is not likely to cause cancer, the EPA has never required a cancer warning on RoundUp’s label. Further, as the Court explained, EPA regulations require pesticide manufacturers to use EPA-approved pesticide labels, meaning that Monsanto must use the RoundUp label without any cancer warning unless and until the EPA approves or requires a different label. Indeed, in the interest of ensuring uniform labeling, FIFRA has a preemption clause which “prohibit States from imposing any pesticide labeling requirements that are ‘in addition to or different from’ the federal labeling requirements under FIFRA.” 7 U.S.C. §136v(b).

Notably, the Court analogized FIFRA’s preemption clause with the preemption clause in the Medical Device Amendments of 1976 (“MDA”) and the Court’s landmark decision in Riegel v. Medtronic, Inc., 552 U.S. 312 (2008). In Riegel, the Supreme Court addressed the preemption clause in the MDA of 1976, which is nearly identical to FIFRA’s preemption clause. Just as FIFRA directed the EPA to approve pesticides (and their labels) for sale after a safety analysis, the Medical Device Amendments direct the Food and Drug Administration to approve medical devices for sale after safety analysis. During the premarket approval process, the FDA is required to review a medical device’s label and confirm that it is neither false nor misleading, just as the EPA does for pesticides. After a medical device is approved by the FDA, the device manufacturer must use that same label and cannot make changes to the device or label without FDA approval—the same is true for pesticide labels and the EPA. The Court in Riegel concluded that the FDA’s premarket approval of medical devices imposed “requirements under” the Act’s preemption clause; thus, the FDA’s premarket approval of a medical device preempted state-law claims premised on an additional or contrary safety requirement.

In Durnell, the Court ultimately concluded that Riegel was dispositive: “[I]f FDA’s premarket approval of medical devices preempted additional state-law requirements, so too must EPA’s registration of pesticides and approval of pesticide labels.” According to Justice Kavanaugh, the similar labeling preemption clauses in federal statutes across a range of industries “reflect Congress’s judgment that the ability to sell a product throughout the country with a single label can be important to maintaining an efficient nationwide market.”

This is a significant result for manufacturers, including FDA-regulated life sciences companies. In short, it should foreclose future challenges based on the argument that the MDA and FDA’s regulatory regime somehow leave open the possibility for “parallel” state law claims. Likewise, the Court’s opinion did not include any mention of an “assumption” or “presumption” against preemption. All told, the Court reached the best possible result in Durnell.