Attorneys for three cancer patients began a trial against Bayer's Monsanto unit on Tuesday, September 29, 2026, in St. Louis, Missouri. The plaintiffs allege that the company failed to adequately test its Roundup weedkiller before selling it to the public. The trial serves as a test case for legal claims that were not directly addressed by a U.S. Supreme Court ruling earlier this year.
The litigation involves three women—Theresa Aretino, Cynthia Fernandez, and Betty Larkin—who used Roundup regularly and were later diagnosed with non-Hodgkin lymphoma. Fernandez died before the trial commenced. These plaintiffs are not participating in a separate $7.25 billion proposed class-action settlement currently under review by a different Missouri state court judge.
During opening statements, plaintiffs' attorney Greg Dovel told the jury that Monsanto never performed the necessary safety testing. Bayer's attorney, Paul Boehm, denied these claims, stating that the company's position is supported by decades of safety reviews from international regulatory bodies. Bayer has maintained that glyphosate, the active ingredient in Roundup, is safe and does not cause cancer.
The legal dispute centers on "design-defect" claims, which argue the product is unsafe for sale. This follows a June 2026 U.S. Supreme Court ruling that barred a different category of lawsuits—those alleging that Roundup’s warning label failed to adequately caution consumers. The Supreme Court ruled that federal law requires manufacturers to use the exact label approved by the U.S. Environmental Protection Agency (EPA), which has concluded that a cancer warning is not required.
For the average consumer and agricultural worker, this litigation highlights a disagreement between legal claims and federal regulatory standards. While the EPA has estimated it will complete a new re-evaluation of glyphosate by the end of 2026, the current EPA-approved labels do not include cancer warnings. Plaintiffs argue these federal reviews are based on incomplete science, while Bayer relies on them to assert the product's safety. Users of the product will see no immediate change to warning labels or availability, but the financial pressure of these suits has already cost Bayer billions and influenced its market valuation since the 2018 acquisition of Monsanto.
The trial acts as a precedent for whether herbicide manufacturers can be held liable for the physical composition of their products even if they comply with federal labeling laws. If the jury finds in favor of the plaintiffs, it could open a path for the remaining 65,000 claims to proceed despite the recent Supreme Court victory for Bayer. A final decision on the $7.25 billion settlement is still pending from a Missouri state court judge, and the EPA's safety re-evaluation remains ongoing through late 2026.