WASHINGTON (LN) — The Supreme Court on Monday heard argument in Monsanto Company v. Durnell, a preemption dispute asking whether the Federal Insecticide, Fungicide, and Rodenticide Act bars state-law failure-to-warn claims against Roundup herbicide when the EPA has repeatedly concluded that glyphosate — the product's active ingredient — does not cause cancer.
The case was brought by John Durnell, a Missouri man who sued Monsanto in 2019 after being diagnosed with non-Hodgkin's lymphoma, alleging the company should have placed a cancer warning on its Roundup labels. A jury awarded him $1.25 million in compensatory damages.
Monsanto argued that FIFRA explicitly preempts state labeling requirements that are "additional or different" from what federal law demands — and that the company could not have added a cancer warning without EPA approval, which it argued it would not have received given the agency's repeated conclusion that glyphosate does not pose a public health risk.
The Missouri Court of Appeals upheld that judgment in February 2025, holding that Monsanto had failed to show both that Missouri's labeling requirements conflicted with federal law and that it had ever actually asked the EPA to approve a cancer warning on Roundup products.
The Supreme Court agreed in January to take up the case, stepping into a split among lower courts over whether FIFRA leaves room for suits like Durnell's.
The EPA first reviewed glyphosate's safety in 1974 and has continued to clear it since. But in 2015, a working group of the International Agency for Research on Cancer — part of the World Health Organization — broke with the agency, classifying glyphosate as "probably carcinogenic to humans," a finding that touched off the litigation wave now pressing against Monsanto in courts across the country.
The justices' resolution of the preemption question will determine the fate of more than 100,000 pending U.S. lawsuits brought by Roundup users who developed non-Hodgkin's lymphoma.