Blue Brief 2025-2026

Natalie Jacewicz

Assistant Professor of Law

Monsanto v. Durnell: Curtailing State Tort Suits for Herbicides and Pesticides

IV.

A gricultural chemicals are facing renewed scrutiny from the American public. Young adults’ rising cancer rates in “Corn Belt” states, the “Make America Healthy Again” movement, and a confluence of other factors have spurred concern that some food production staples may be carcinogenic. One focus of debate is Roundup, an herbicide produced by Monsanto. In 2015, the International Agency for Research on Cancer deemed glyphosate, Roundup’s active ingredient, “probably carcinogenic to humans.” The Environmental Protection Agency (EPA), which regulates herbicides pursuant to the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) , nonetheless reaffirmed its longstanding position that glyphosate is unlikely to be carcinogenic. Unassuaged, Americans who developed cancer after long-term exposure to Roundup have brought tens of thousands of cases in state courts, where juries have handed down multimillion-dollar verdicts for state tort claims.

In Monsanto v. Durnell , the Supreme Court put a stop to one such strain of litigation: failure to-warn cause of action. The plaintiff, John Durnell, asserted that twenty years of using Roundup caused his non-Hodgkin’s lymphoma and that Roundup’s label should have included a cancer warning. A Missouri jury agreed and awarded Durnell $1.25 million in compensatory damages on a failure-to-warn theory. The Missouri Court of Appeals affirmed. Throughout the case, Monsanto argued that FIFRA preempts such claims. The argument turns on the statute’s regime for registering products such as Roundup. FIFRA requires that manufacturers register herbicides with EPA , a process that includes submitting information about the product’s formula, potential harmful effects, and label proposals. If EPA determines that the herbicide “will not generally cause unreasonable adverse effects” on human health and the environment and that the labeling “compl[ies] with the requirements” of FIFRA,

UNIVERSITY OF SAN DIEGO SCHOOL OF LAW | Faculty Review of 2025-2026 U.S. Supreme Court Term | Page 14