Supreme Court weeds out $28 million Roundup ruling

The high court reversed a California man's victory against Monsanto over the agricultural giant's failure to warn of Roundup's cancerous risks, dooming similar cases in the future.(CN) — The Supreme Court on Tuesday tossed a $28 million ruling against agricultural biotech giant Monsanto, likely ending any future path for failure-to-warn claims over the herbicide Roundup.“We are pleased with the court’s decision and will urge the California appellate court to vacate the verdict in this case,” a Monsanto spokesperson told Courthouse News.Mike Dennis, a resident of Carlsbad, California, sued Monsanto — since acquired by Bayer — in San Diego Superior Court over product liability and fraud in 2021. He claims exposure to Roundup caused him to develop mycosis fungoides, a rare form of non-Hodgkin lymphoma.According to Dennis, Monsanto knew of Roundup’s carcinogenic risks and sold the product without sufficient warnings anyway, in violation of state law.At trial, a jury found Monsanto liable for failing to warn Dennis of Roundup’s cancer risk, awarding him $332 million — $7 million in compensatory damages and $325 million in punitive damages.While the court denied Monsanto’s subsequent request for a new trial, it eventually reduced the company’s punitive damages to $21 million in 2024, finding the original sum unconstitutionally excessive.Monsanto again appealed, asserting Dennis’s failure-to-warn claims were preempted by the Federal Insecticide, Fungicide and Rodenticide Act, or FIFRA. A California appeals panel disagreed, affirming the ruling in November 2025.Monsanto then sought judicial review by the U.S. Supreme Court. While the high court initially denied the company’s petition, it shortly thereafter granted a highly favorable ruling in a nearly identical case.In 2019, Missouri farmer John Durnell sued Monsanto and Bayer, claiming their failure to warn him of Roundup’s carcinogenic risks violated state law and caused him to develop non-Hodgkin lymphoma.A Missouri jury ruled in favor of Durnell in 2023, awarding him $1.25 million in damages. Monsanto appealed, arguing the claims were preempted by federal law; a Missouri appeals panel rejected their appeal last year.However, the U.S. Supreme Court granted Monsanto certiorari in January, sending the case to the high court for oral arguments in April.In June, the court issued a 7-2 ruling in favor of Monsanto, ultimately agreeing with the company that federal law preempted state claims.Because the Environmental Protection Agency had repeatedly approved Roundup’s labels that omitted a warning, it has repeatedly determined the weedkiller does not cause cancer, Justice Brett Kavanaugh wrote in the majority’s opinion.Furthermore, as federal law requires herbicide labels to be uniform nationwide, any state law requiring additional or alternative labels is preempted, he added.“Durnell’s state-law failure-to-warn claim would require a cancer warning on Roundup’s label — a requirement ‘in addition to’ and ‘different from’ the label required by EPA under FIFRA,” the Donald Trump appointee wrote. “FIFRA therefore expressly preempts Durnell’s claim.”Justices John Roberts, Clarence Thomas, Samuel Alito, Sonia Sotomayor, Elena Kagan and Amy Coney Barrett joined Kavanaugh in concurrence. Justices Ketanji Brown Jackson and Neil Gorsuch dissented.In light of the Supreme Court’s June ruling in favor of Monsanto, the high court granted the company’s petition for a writ of certiorari, vacated the California appeals panel’s ruling in favor of Dennis and remanded for the appeals panel to reconsider the trial court’s decision.A legal representative for Mike Dennis could not be reached for comment.Subscribe to our free newslettersOur weekly newsletter Closing Arguments offers the latest about ongoing trials, major litigation and rulings in courthouses around the U.S. and the world, while the monthly Under the Lights dishes the legal dirt from Hollywood, sports, Big Tech and the arts.Additional Reads