Supreme Court Hears Arguments on Preempting State Roundup Lawsuits

The U.S. Supreme Court heard oral arguments on April 27, 2026, in Monsanto v. Durnell, a case that could determine if federal law preempts state lawsuits alleging Bayer failed to warn consumers about cancer risks from its Roundup weedkiller. The plaintiff, John Durnell, developed non-Hodgkin lymphoma after using Roundup and won a $1.25 million jury award in Missouri in 2019, upheld on appeal.

Bayer, which acquired Monsanto in 2018, argues the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) gives the Environmental Protection Agency exclusive authority over pesticide labels, barring state failure-to-warn claims.

Justices appeared split during the hearing.

Justice Brett Kavanaugh expressed sympathy for Bayer's position, questioning whether varying state requirements would violate federal uniformity and probing potential retroactive liability for companies following EPA approvals. Justice Ketanji Brown Jackson voiced skepticism about the EPA's review process, noting a 15-year gap between registrations where new scientific evidence could emerge.

Paul Clement, representing Monsanto, argued that FIFRA's language explicitly preempts state labeling requirements different from federal ones, citing a 2008 Supreme Court ruling in Riegel v. Medtronic as precedent. He emphasized that the EPA's approval process ensures uniformity and that glyphosate has been deemed unlikely to be carcinogenic by the agency.

“Congress plainly wanted uniformity when it came to the safety warnings on a pesticide’s label.”

Ashley Keller, representing Durnell, countered that FIFRA does not grant blanket preemption and that the EPA's glyphosate findings were vacated by a federal appeals court in 2022 for methodological flaws. Keller highlighted that the agency has not updated its review every 15 years as required and operates with less rigorous data than the Food and Drug Administration.