The Supreme Court on Thursday shielded Bayer from thousands of lawsuits alleging its Roundup weedkiller causes cancer, ruling 7-2 that federal pesticide law preempts state-court claims that the company failed to warn consumers about glyphosate, the herbicide's active ingredient.
The decision dismantles the legal architecture that has sustained nearly a decade of jury verdicts against Bayer, sent the German company's U.S.-listed shares up 15.75 percent to $13.09, and split the Make America Healthy Again movement from the Trump administration it helped elect. It also reverses a $1.25 million Missouri jury award to a man who blamed two decades of Roundup use for his non-Hodgkin lymphoma.
What the court held
Justice Brett Kavanaugh, writing for the majority, held that the Federal Insecticide, Fungicide and Rodenticide Act, known as FIFRA, requires uniform federal pesticide labeling and bars states from imposing different requirements through tort verdicts. Because the Environmental Protection Agency has determined glyphosate is unlikely to cause cancer when used as directed and has never required a warning label, Kavanaugh wrote, state juries cannot effectively impose one.
"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 ruling reverses a Missouri Court of Appeals judgment in favor of John Durnell, the Missouri plaintiff whose case the justices used as a vehicle. A jury sided with Durnell in 2023, awarding him $1.25 million after finding Bayer had failed to warn of cancer risks. The case now returns to the lower courts for proceedings consistent with the new federal rule.
What it means for the docket
Bayer, which acquired Roundup maker Monsanto in 2018, said in a statement that Thursday's ruling "should help significantly contain the Roundup litigation after nearly a decade of legal battles" and "should result in the dismissal of current warning-based claims and bar future failure-to-warn claims." The company also called the decision "good for science, farmers, and industries that depend on regulatory clarity for innovation."
Failure-to-warn theories have been the workhorse of the Roundup plaintiffs' bar, and their elimination removes the most common path to a verdict. Bayer's shares rose 15.75 percent to $13.09 following the ruling.
The political split
The court handed the Trump administration the legal victory it asked for. The Justice Department filed a brief supporting Bayer's petition, reversing the Biden administration's position in an earlier Roundup case. The political cost landed elsewhere.
Health and Human Services Secretary Robert F. Kennedy Jr., the figurehead of the MAHA coalition that helped return President Trump to the White House in 2024, told senators in April that he believes glyphosate causes cancer. As a private lawyer, Kennedy in 2018 won a similar failure-to-warn case against Monsanto. The department did not respond to a request for comment on Thursday's decision.
Kelly Ryerson, a MAHA activist who posts as "Glyphosate Girl," wrote on X that the ruling was "historic" in the worst sense. "Never in history has an administration so blatantly and willingly sold out our fertility, vitality, and health to corporate interests," she wrote. "It is unforgivable. We will make sure all voters know exactly how this domestic chemical attack happened."
Vani Hari, the food activist who goes by "Food Babe," said in a text message to NBC News that "[t]he decision is sickening and would have never happened had the administration not given Bayer Monsanto a favor," and called on Congress to act.
Rep. Anna Paulina Luna, R-Fla., said Thursday she would introduce legislation to strip pesticide manufacturers of liability protections. "These companies purposefully omit labeling information knowing their products cause cancer and other health problems," Luna wrote on X. "It is time they are held accountable." Luna led the successful push this year to strike a Bayer-friendly provision from the farm bill.
The dissent
Justice Ketanji Brown Jackson, joined by Justice Neil Gorsuch, dissented and accused the majority of breaking with a near-unanimous consensus in the lower courts. "In so holding, the Court departs from the near unanimous view of the many state and federal courts that have rejected this preemption argument," Jackson wrote. "In my view, the majority should have joined that chorus."
Jackson argued the Missouri claim was not additional to FIFRA's requirements but equivalent to them, because the statute's own misbranding prohibition bars sale of a pesticide whose label omits a material cancer risk. The majority's reading, she wrote, "unjustifiably closes the courthouse doors" to plaintiffs like Durnell.
The scientific record the court declined to weigh remains contested. The World Health Organization's International Agency for Research on Cancer in 2015 classified glyphosate as "probably carcinogenic to humans." The EPA reached the opposite conclusion in 2020. A federal appeals court found the agency had not adequately explained its analysis, and the EPA agreed to update its evaluation, though no new version has been published.
What comes next
The immediate test is congressional. Luna's bill, if introduced, would force Senate Republicans to choose between MAHA voters and the agrichemical lobby on the record. The EPA's overdue glyphosate reassessment now carries added weight, because any future warning label would have to come from Washington, not a Missouri jury.