The Supreme Court handed Bayer's Monsanto a sweeping victory on Wednesday, ruling 7–2 that federal pesticide law blocks state-level lawsuits claiming the company failed to warn consumers that Roundup causes cancer.

Writing for the majority in Monsanto v. Durnell, Justice Brett Kavanaugh held that the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) expressly preempts state failure-to-warn claims when the EPA has not required a cancer warning on the product label. "Because Durnell's state tort claim would impose a pesticide labeling requirement 'in addition to or different from' the label required by EPA, FIFRA expressly preempts Durnell's claim," Kavanaugh wrote.

The decision is a hammer blow to more than 100,000 pending lawsuits from people who developed non-Hodgkin lymphoma they attribute to glyphosate exposure. The World Health Organization's IARC classified glyphosate as a "probable human carcinogen" in 2015, but the EPA has repeatedly concluded it is not likely to cause cancer — and has never mandated a cancer warning on Roundup labels. Bayer has already paid billions in jury awards and settlements, and had proposed a $7.25 billion class action deal to resolve future claims.

Justice Ketanji Brown Jackson, joined by Justice Neil Gorsuch in dissent, warned the majority "misunderstands FIFRA's requirements, misinterprets the scope of FIFRA's preemption, and ultimately leaves Durnell without a remedy for the significant harms he has suffered." The ruling's reach extends beyond glyphosate: Syngenta faces thousands of similar lawsuits over paraquat, a weed killer linked to Parkinson's disease, and those failure-to-warn claims may now be blocked as well.

Sources: The Guardian, NPR, The New Lede