Supreme Court Rules 7-2 to Shield Bayer's Monsanto from Roundup Failure-to-Warn Suits

The U.S. Supreme Court on Thursday limited the scope of cancer-related lawsuits against Bayer's Monsanto unit, ruling 7-2 that federal pesticide law preempts state-level claims that the company failed to warn consumers about cancer risks associated with its Roundup weedkiller and its active ingredient, glyphosate.

Justice Brett Kavanaugh wrote for the majority, holding that because the Environmental Protection Agency has determined glyphosate is safe when used properly and has never mandated a cancer warning label, the Federal Insecticide, Fungicide and Rodenticide Act bars state tort claims that would impose additional or different labeling requirements.

"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."

The case originated with John Durnell, who alleged that repeated glyphosate exposure caused his cancer. A Missouri jury awarded Durnell more than $1 million in 2019 after finding Bayer had not adequately warned of cancer risks. A Missouri appeals court had upheld that judgment, which the Supreme Court reversed and remanded on Thursday.

The ruling's reach extends well beyond Durnell's case, placing a torrent of similar failure-to-warn claims against Bayer in legal jeopardy.

Bayer said in a statement the decision is "good for science, farmers, and industries that depend on regulatory clarity for innovation," adding that it "should help significantly contain the Roundup litigation after nearly a decade of legal battles." The company's shares rose 15.75% to $13.09 following the ruling.

Bayer acquired Roundup maker Monsanto in 2018, inheriting a liability overhang tied to glyphosate claims. The World Health Organization's International Agency for Research on Cancer classified glyphosate as "probably carcinogenic to humans" in 2015, though the U.S. EPA has never required a corresponding warning label.

The Trump administration had argued in favor of preemption, aligning with Bayer's position. That stance drew sharp criticism from Make America Healthy Again advocates, who backed Trump in the 2024 election but have grown increasingly at odds with the administration over its support of glyphosate use.

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

Justice Ketanji Brown Jackson dissented, joined by Justice Neil Gorsuch. She argued the majority departed from a near-consensus among state and federal courts that had previously rejected the preemption argument.

"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," Jackson wrote.

The decision is likely to reshape the litigation landscape for Roundup-related claims and will test how far the FIFRA preemption doctrine extends across other pending cases — a question plaintiffs' attorneys and state courts will be navigating for years to come.

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