Supreme Court rules federal pesticide law bars state lawsuits over Roundup labeling

The U.S. Supreme Court on Thursday issued a 7-2 ruling that the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) prevents state courts from hearing claims that Monsanto, now owned by Bayer, failed to include a cancer warning on the herbicide Roundup. The majority opinion, written by Justice Brett Kavanaugh and joined by Chief Justice John Roberts and six other justices, affirmed that federal law requires manufacturers to use EPA-approved labeling unless the agency mandates a change.

The decision overturns lower-court rulings that had allowed a Missouri plaintiff, John Durnell, to pursue damages for alleged failure to warn that glyphosate, Roundup’s active ingredient, caused non-Hodgkin’s lymphoma. Durnell had been awarded $1.25 million after a jury found the warning claim viable.

The Environmental Protection Agency has long classified Roundup as safe when used as directed and has not required a cancer warning on its label. While the International Agency for Research on Cancer listed glyphosate as “probably carcinogenic” in 2015, the EPA’s subsequent assessments concluded the chemical is “not likely to be carcinogenic to humans.”

Bayer, which acquired Monsanto in 2018, welcomed the ruling, stating it provides regulatory clarity for farmers and industry and should help contain ongoing litigation. The company continues to seek court approval for a $7.25 billion class settlement that would resolve current and future Roundup claims, with proposed annual payments over up to 21 years.

The Trump administration had supported Monsanto’s position, arguing that EPA determinations, not state courts, should govern pesticide labeling. The ruling is seen as a legal victory for that stance, though it may face political scrutiny from groups advocating tighter pesticide regulation.