Supreme Court Considers Cancer Warning Requirement for Monsanto's Roundup

The U.S. Supreme Court heard oral arguments on April 27, 2026, in a case challenging whether Monsanto's Roundup weedkiller requires a cancer warning label. The case stems from a $1.25 million jury verdict awarded to John Durnell, who developed non-Hodgkin's lymphoma after using the product for over two decades.

Durnell, a resident of a historic neighborhood in St. Louis, used Roundup to control weeds in parks and playgrounds as part of his neighborhood association duties. He attributes his blood cancer to glyphosate, the key ingredient in Roundup. His lawsuit claims Monsanto failed to warn users of potential cancer risks.

The central issue is whether EPA approval of Roundup's label, which does not include a cancer warning, preempts state court claims for failure to warn. Durnell's attorney argued that federal law and EPA regulations do not prohibit Monsanto from adding such a warning.

Monsanto's attorneys stated that the EPA did not require a cancer warning and that the company could not unilaterally change the label without violating federal rules. Justice Brett Kavanaugh highlighted the federal law's purpose of ensuring uniformity in pesticide labeling across states.

He expressed concern that allowing state lawsuits could undermine this uniformity. Chief Justice John Roberts suggested that state lawsuits might address gaps in EPA reviews, which can occur years apart, by responding faster to new information about product risks.

The Trump administration supports Bayer in this case, arguing that federal regulations should prevail. This stance differs from the position taken by the Justice Department during the Biden administration, which allowed such lawsuits to proceed. President Trump has also promoted domestic production of glyphosate and supported congressional efforts for liability protections.

Glyphosate, introduced in the 1970s, is used in farming with genetically modified seeds resistant to it, as well as by home gardeners. The EPA regulates pesticides but has not mandated a cancer warning for Roundup. The justices did not clearly indicate a leaning during arguments, and a decision is pending.

USA TODAY Supreme Court Correspondent Maureen Groppe reported that the outcome remains uncertain, as it was difficult to discern a majority view among the nine justices.