The U.S. Supreme Court is set on Monday to consider Bayer AG’s effort to shut down thousands of lawsuits accusing the company of failing to warn users that the active ingredient in its Roundup weedkiller causes cancer.
The justices are due to hear arguments in Bayer’s appeal of a jury verdict in Missouri state court awarding $1.25 million to a man named John Durnell who said he was diagnosed with non-Hodgkin lymphoma after years of exposure to glyphosate in Roundup.
Bayer contends that a federal law governing pesticides should prevent failure-to-warn claims like Durnell’s that are brought under state law from moving forward in court. The German drugmaking and crop science company said that the U.S. Environmental Protection Agency has repeatedly found that glyphosate does not cause cancer and approved its product labels without a warning.
More than 100,000 plaintiffs have filed cases in U.S. state and federal courts alleging a cancer link, according to the company. It has said a Supreme Court ruling in its favor should largely bring the Roundup litigation to an end.
A number of crop farming and agricultural industry groups are backing Bayer in the case, as is Republican President Donald Trump’s administration. Several environmental, farm worker and public health groups have filed court papers backing Durnell.
Bayer acquired Roundup as part of its $63 billion purchase of agrochemical company Monsanto in 2018. The torrent of litigation prompted Bayer to remove glyphosate from its consumer version of Roundup, and the company said that the lawsuits could threaten its ability to supply the herbicide to farmers.
Related: Bayer Shareholders Keep the Squeeze on CEO Over Roundup Lawsuits
Facing billions of dollars in potential liability, Bayer announced in February a proposed $7.25 billion settlement to resolve tens of thousands of current and future lawsuits. The settlement would not affect claims that stem from pending appeals or that fall outside the deal, according to the company. Those amount to nearly $1 billion, it said.
The sprawling dispute centers on a U.S. law called the Federal Insecticide, Fungicide and Rodenticide Act, or FIFRA, that governs the sale and labeling of pesticides and bars states from imposing differing or additional requirements.
The regulation notably prohibits pesticides that are “misbranded” with labels that lack an adequate warning to protect health and the environment.
Bayer has argued that Durnell’s claims are preempted by FIFRA. The EPA has repeatedly approved labels without such a cancer warning, demonstrating that these products are not misbranded, the company said, adding that labels cannot be substantially changed without the agency’s approval.
Durnell’s lawyers said that despite the EPA’s registration of Roundup, the label may still be challenged as misbranded. They also said Durnell’s claims are not preempted because Missouri state law that requires products to adequately warn of dangers imposes the same requirements as FIFRA’s prohibition on misbranding.
Durnell sued Monsanto in Missouri state court in 2019, claiming it failed to warn users of the dangers associated with Roundup and glyphosate.
He was diagnosed with a rare and often aggressive form of non-Hodgkin lymphoma, a cancer that starts in the white blood cells, and attributed the disease to his exposure to Roundup starting in 1996. For about 20 years he was the “spray guy” for a neighborhood association in St. Louis, killing weeds at local parks without protective equipment, according to court papers.
A jury sided with Durnell in 2023, and in 2025 a state appeals court upheld that verdict.
A Supreme Court ruling is expected by the end of June.
A Reuters/Ipsos poll released last week highlighted the Trump administration’s risks in backing Bayer. In it, 63% of poll respondents said they oppose protecting companies from lawsuits when they sell cancer-causing products, even if the company warns about the risk.
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