Supreme Court to Hear Arguments in Landmark Roundup Weedkiller Case

AdvertisementSKIP ADVERTISEMENTYou have a preview view of this article while we are checking your access. When we have confirmed access, the full article content will load.A victory for the manufacturer, Bayer, could end thousands of lawsuits against the company claiming that the herbicide causes cancer.Listen · 8:05 minThe Supreme Court in Washington. The Trump administration has formally backed Bayer in the case.Credit...Eric Lee for The New York TimesPublished April 26, 2026Updated April 27, 2026, 9:39 a.m. ETThe Supreme Court is set to hear arguments on Monday in a case that could lead to the dismissal of tens of thousands of lawsuits against Bayer, the pharmaceutical and biotech giant, that claim the weedkiller Roundup caused non-Hodgkin lymphoma.Developed by Monsanto in the 1970s, Roundup is one of the best-selling weedkillers in the world, but it has been dogged by controversy over its effects on human health. The company, which was acquired by the German conglomerate Bayer in 2018, has faced thousands of lawsuits, amounting to one of the largest waves of such litigation in U.S. history.Evidence in lab animals, and more limited evidence in humans, has indicated a link between Roundup’s active ingredient, glyphosate, and cancer. The World Health Organization’s International Agency for Research on Cancer in 2015 classified glyphosate as “probably carcinogenic to humans.”The Environmental Protection Agency considers the herbicide to be safe. The E.P.A. is responsible for pesticide labeling nationwide, and Bayer argues that the federal agency’s decision overrides state-level legal claims, effectively insulating it from lawsuits. The federal government faces an Oct. 1 deadline to re-examine the effects of glyphosate.Monsanto, which was acquired by Bayer in 2018, had petitioned the court to review a lawsuit brought by John Durnell of St. Louis, Mo., a gardener who used Roundup for decades. Mr. Durnell received a diagnosis of non-Hodgkin lymphoma and sued the company in 2019, alleging that his illness was a result of exposure to the pesticide and that Monsanto had failed to warn of the cancer risks.

The Trump administration has formally backed Bayer in the case, reversing a position taken by the Biden administration. In February President Trump also issued an unusual executive order invoking the Defense Production Act to guarantee production of glyphosate-based herbicides, essentially elevating Roundup to a national security priority.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe.AdvertisementSKIP ADVERTISEMENT