Supreme Court shields Monsanto from Roundup warning lawsuits

The Supreme Court on Wednesday shielded Monsanto from state-law lawsuits claiming Roundup should have carried a cancer warning, a ruling that will freeze thousands of existing and future failure-to-warn cases across the country. In Monsanto Co. v. Durnell, the justices held 7-2 that federal pesticide law can preempt state warning claims when the Environmental Protection Agency has not required a cancer warning on the label.

Justice Brett Kavanaugh wrote the majority opinion, and Justice Ketanji Brown Jackson dissented. The dispute turned on the Insecticide, Fungicide, and Rodenticide Act, the federal statute governing pesticide labeling, and whether it leaves room for state courts to impose different warning duties on Roundup makers. The ruling gives Bayer a broad shield against claims that Monsanto should have warned consumers about alleged cancer risks tied to glyphosate, Roundup’s active ingredient.

John Durnell filed the case in January 2019, saying Roundup caused his non-Hodgkin lymphoma. A Missouri jury later awarded him $1.25 million in compensatory damages after a September 2023 trial, and the Missouri Court of Appeals affirmed the verdict before the Supreme Court took up the case. The ruling wipes out the legal theory that drove that award and upends other cases built on the same state-law failure-to-warn claims.

Bayer, which acquired Monsanto in 2018, has faced more than 100,000 Roundup-related claims in state courts. The litigation has already produced multibillion-dollar verdicts and a proposed $7.25 billion settlement. The EPA has repeatedly concluded that glyphosate is not likely to cause cancer. Bayer said the decision should significantly contain the litigation after nearly a decade of legal battles and should lead to the dismissal of current warning-based claims, even as the company continues to seek final approval of a broader class settlement.