Bayer wins Supreme Court case making it harder to sue over glyphosate in Monsanto's Roundup

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The Supreme Court in a 7-2 decision on Thursday said Bayer cannot be sued over state-level claims that the company failed to warn of cancer risks from its weedkiller Roundup and its chemical glyphosate.

The decision is a major win for Bayer and the Trump administration, which argued that failure-to-warn claims were preempted by a federal law that governs pesticides. It's also a major blow to the Make America Healthy Again movement, which helped return Trump to the White House in the 2024 election but has felt betrayed by the administration's embrace of glyphosate — the most commonly used weedkiller in agriculture that has long been linked to cancer claims.

Monsanto Co's Roundup is shown for sale in Encinitas, California.

Mike Blake | Reuters

Justice Brett Kavanaugh wrote for the majority, arguing that because the Environmental Protection Agency deems glyphosate safe when used properly and has not required a cancer warning label, the Federal Insecticide, Fungicide and Rodenticide Act preempts state-level failure to warn claims.

"With respect to pesticide labels, FIFRA demands '[u]niformity' and expressly preempts state labeling requirements that are 'in addition to' or 'different from' federal labeling requirements," Kavanaugh wrote. "And as a matter of law, state tort law may not impose labeling requirements 'in addition to' or 'different from' federal requirements imposed under FIFRA."

Bayer celebrated the decision on Thursday, saying it is "good for science, farmers, and industries that depend on regulatory clarity for innovation."

"It should help significantly contain the Roundup litigation after nearly a decade of legal battles. The ruling should result in the dismissal of current warning-based claims and bar future failure-to-warn claims," the company, which bought Roundup maker Monsanto in 2018, said in a statement.

The company's shares rose 15.75% to $13.09 following the ruling.

The case centered on a failure-to-warn claim from one man, John Durnell, who claimed his cancer was caused by repeated exposure to glyphosate. Durnell was awarded more than $1 million by a Missouri jury in 2019, after the court found Bayer had failed to warn of cancer risks. A Missouri appeals court affirmed the judgment, which the Supreme Court reversed and remanded on Thursday.

But the court's decision will likely reach far beyond just Durnell's case, with a torrent of failure-to-warn cases against Bayer over the alleged Roundup cancer risk now in legal jeopardy.

MAHA leader and now-Health and Human Services Secretary Robert F. Kennedy Jr. once won a similar case for a man in 2018 who claimed that Monsanto failed to warn of the cancer risk posed by glyphosate.

The court's decision could reverberate with political consequences for the Trump administration, as MAHA activists who backed President Donald Trump after Kennedy dropped his independent bid for president and endorsed the now-president.

"Today's SCOTUS ruling is historic. Never in history has an administration so blatantly and willingly sold out our fertility, vitality, and health to corporate interests," MAHA advocate Kelly Ryerson wrote on X. She goes by the online moniker "Glyphosate Girl."

"It is unforgivable. We will make sure all voters know exactly how this domestic chemical attack happened," Ryerson wrote.

In 2015, the World Health Organization's International Agency for Research on Cancer found that glyphosate was "probably carcinogenic to humans." The U.S. EPA has never required such a label.

Justice Ketanji Brown Jackson dissented from the court's decision, joined by Justice Neil Gorsuch.

"In so holding, the Court departs from the near unanimous view of the many state and federal courts that have rejected this preemption argument. In my view, the majority should have joined that chorus," she wrote.

"Durnell's failure-to-warn claim is not 'in addition to or different from' FIFRA's mandates; it is equivalent to FIFRA's key labeling requirement — the misbranding prohibition," she wrote.

—Luke Fountain contributed to this report.