The United States Supreme Court has sided with the maker of the weedkiller Roundup in a ruling that is expected to block thousands of lawsuits because the court failed to warn people that the product could cause cancer.
Thursday’s verdict was related to one case then came before the judges a tidal wave of litigation this included some judgments worth billions against global agrochemical manufacturer Bayer, a Germany-based company that acquired Roundup when it bought its original manufacturer, Monsanto, in 2018.
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The decision is a victory for US President Donald Trump’s administration, but one that could be politically sensitive as allies in the “Make America Healthy AgainThe movement wants to curb the use of pesticides.
The Supreme Court concluded in a 7-2 ruling that the company cannot face failure-to-warn lawsuits in state court because federal regulations have deemed a link to cancer unlikely and no warning is required.
Justices overturned a jury verdict in Missouri that awarded $1.25 million to a man named John Durnell who said he was diagnosed with non-Hodgkin’s lymphoma after years of exposure to glyphosate in Roundup. The Supreme Court agreed with Bayer that a U.S. law regulating pesticides bars failure-to-warn claims brought under state law from going to trial.
Bayer shares rose almost 18 percent after the verdict.
The Trump administration had supported Bayer in the case.
Conservative Justice Brett Kavanaugh, who wrote the ruling, said the U.S. Environmental Protection Agency (EPA) concluded that glyphosate does not cause cancer and did not require Roundup to have a cancer warning.
The law preempts Durnell’s claim because it “would require Monsanto to add a cancer warning to Roundup’s label, even though federal law requires Monsanto to use the EPA-approved label without a cancer warning,” Kavanaugh wrote.
Liberal Justice Ketanji Brown Jackson, in a dissent joined by conservative Justice Neil Gorsuch, said Durnell’s claim would impose the same labeling requirements on Monsanto as federal law and therefore should not be preempted.
Jackson called the ruling “remarkable and unfortunate because it unjustifiably closes the courthouse doors to state tort plaintiffs like Durnell.”
Bayer acquired Roundup as part of its $63 billion purchase of agrochemical company Monsanto in 2018. More than 100,000 plaintiffs have filed cancer-related lawsuits in U.S. federal and state courts, and the German drug and crop research company had said the lawsuits could jeopardize its ability to supply the herbicide to farmers.
The spate of litigation has already led Bayer to remove glyphosate from its consumer version of Roundup. Bayer said before the Supreme Court’s decision that a ruling in its favor could largely end the Roundup litigation.
“The U.S. Supreme Court’s decision is good for science, farmers and industries that rely on clear regulations to innovate. It should help significantly curb the Roundup litigation after nearly a decade of litigation. The ruling should result in the dismissal of current suits based on a warning notice and bar future suits based on a failure to warn,” Bayer spokesman Tino Andresen said in a statement.
The company emphasized throughout the litigation that the EPA has repeatedly found that glyphosate does not cause cancer and approved its product labels without warning.
Facing billions of dollars in potential liability, Bayer in February announced a planned $7.25 billion settlement to resolve tens of thousands of current and future lawsuits. According to the company, the settlement would not affect claims arising from pending appeals or outside the agreement. These amount to almost a billion US dollars, it was said.
“Public health disaster”
Environmental activists and others criticized the court’s ruling on Thursday.
“Once again, the Supreme Court has sided with big business over people and the environment. Today’s ruling is a public health disaster,” said Tarah Heinzen, legal director for the advocacy group Food and Water Watch.
“The damage caused by this decision will perpetuate our cancer, infertility and general chronic disease epidemics for generations,” said Kelly Ryerson, co-executive director of the advocacy group American Regeneration and a Make America Healthy Again activist who posts on social media under the moniker “The Glyphosate Girl.”
The wide-ranging dispute centers on a U.S. law called the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), which regulates the sale and labeling of pesticides and prevents states from imposing different or additional requirements.
The measure bans pesticides that carry labels that lack sufficient warning to protect health and the environment.
Bayer has argued that Durnell’s claims are barred by this law. The EPA has repeatedly approved labels without such a cancer warning, proving that these products are not mislabeled, the company said, adding that labels cannot be significantly changed without the agency’s approval.
Durnell’s lawyers said that despite Roundup’s registration by the EPA, the label could still be challenged as mislabeled. They also said Durnell’s claims are not barred because Missouri state law requiring products to adequately warn of hazards imposes the same requirements as FIFRA’s ban on false branding.
“A new era”
Union Investment fund manager Markus Manns called Thursday’s ruling an important milestone for Bayer, adding that the company is “entering a new era” a decade after the Monsanto takeover.
“Future lawsuits are not completely off the table, but they will become significantly more difficult. A final breakthrough would be possible if the settlement was accepted by the plaintiffs and approved by the responsible court in July. This would finally close Bayer’s glyphosate litigation chapter and management could concentrate fully on operational and strategic matters again,” said Manns.
Durnell sued Monsanto in Missouri state court in 2019, saying the company failed to warn users about the dangers associated with Roundup and glyphosate.
He was diagnosed with a rare and often aggressive form of non-Hodgkin’s lymphoma, a cancer that begins in the white blood cells, and attributed the disease to his exposure to Roundup beginning in 1996. According to court documents, he was the “spray guy” for a neighborhood association in St. Louis for about 20 years, killing weeds in local parks without protective equipment.
In 2023, a jury sided with Durnell, and in 2025, a state appeals court upheld that verdict.
