Supreme Court Blocks Roundup Cancer Lawsuits Against Bayer
The U.S. Supreme Court ruled 7-2 on Thursday that federal law preempts state-level failure-to-warn lawsuits against Bayer’s Monsanto over its Roundup weedkiller, delivering a landmark victory for the company and effectively blocking thousands of pending claims from people who allege the herbicide’s active ingredient, glyphosate, caused their cancers.
Writing for the majority, Justice Brett Kavanaugh held that the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) expressly preempts state tort claims that would require Monsanto to add a cancer warning to Roundup’s label — a warning the Environmental Protection Agency has repeatedly declined to mandate, according to USA Today. Justice Ketanji Brown Jackson wrote the dissent, joined by Justice Neil Gorsuch, arguing the ruling “leaves Durnell without a remedy for the significant harms he has suffered.”
The Case and the Plaintiff
The case, Monsanto Company v. Durnell, centered on John Durnell, a Missouri resident who used Roundup for more than two decades as the “spray guy” for his neighborhood association in a historic St. Louis neighborhood. After developing non-Hodgkin lymphoma, Durnell sued Monsanto for failing to warn consumers of the cancer risks associated with glyphosate. In 2023, a Missouri jury agreed and awarded him $1.25 million in damages, as reported by SCOTUSblog.
Monsanto appealed, arguing that because the EPA has repeatedly approved Roundup’s label without a cancer warning — concluding that glyphosate is “not likely to cause cancer” — state-law claims demanding additional warnings are preempted by FIFRA’s uniformity requirement, which prohibits states from imposing labeling requirements “in addition to or different from” those required by federal law.
The Supreme Court’s Reasoning
Justice Kavanaugh wrote that federal law requires Monsanto to sell Roundup with the label the EPA approved at initial registration and has subsequently re-approved on multiple occasions — a label without a cancer warning. Durnell’s state tort claim, by contrast, would require Monsanto to add a cancer warning, running afoul of FIFRA’s uniformity provision.
“Therefore, as a matter of federal law,” Kavanaugh wrote, “Monsanto legally must use a label without a cancer warning unless and until EPA approves or requires a change.”
The majority included Chief Justice Roberts and Justices Thomas, Alito, Sotomayor, Kagan, Kavanaugh, and Barrett, according to the Supreme Court opinion.
The Dissent
In a 24-page dissent, Justice Jackson argued that 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.” She noted the decision “departs from the near unanimous view of the many state and federal courts” that had previously rejected Monsanto’s preemption argument, as NPR reported.
Justice Gorsuch joined Jackson’s dissent.
A Major Victory for Bayer
Bayer, which acquired Monsanto in 2018 for $63 billion, has faced a deluge of Roundup-related litigation. The company has already paid billions in damages and settlements while simultaneously negotiating a proposed class action settlement and pushing for federal legislation to shield it from further liability.
Bayer CEO Bill Anderson welcomed the ruling, saying: “The decision brings overdue justice on an issue that should have been clarified much earlier. It’s time to put it behind us.” Though Bayer has stopped using glyphosate in Roundup products sold for residential use, it continues to sell to farmers.
Paul Clement, the former U.S. Solicitor General who argued the case for Bayer, told the justices during oral arguments that “Congress plainly wanted uniformity when it came to the safety warnings on a pesticide’s label.”
Reaction and Broader Implications
Public health and environmental groups condemned the decision, warning its impact extends far beyond Roundup. Ken Cook, president of the Environmental Working Group, said: “This case was never just about Bayer. It was about whether states retain the authority to provide stronger protections for their residents when federal regulations fall short.”
Ricky A. LeBlanc, an attorney at Sokolove Law who has filed successful Roundup suits, argued the court “has essentially handed Bayer a shield and told victims they have no recourse, simply because a federal agency approved a label. But the EPA never said Roundup was safe. They said it was ‘not likely’ carcinogenic. That is not the same thing.”
The Trump administration backed Bayer in the case, filing a brief supporting Monsanto’s position. In February 2026, President Trump signed an executive order to boost domestic production of glyphosate, citing national defense needs — a move that created a rift with the Make America Healthy Again (MAHA) movement, which has been a vocal critic of the herbicide.
The Unresolved Science
The ruling places significant weight on the EPA’s safety determinations, but the agency’s formal glyphosate safety review remains years overdue. In 2022, a federal court ruled the EPA had not adequately considered whether glyphosate causes cancer when it reached an interim decision during the first Trump administration, ordering the agency to reassess its findings, as Mother Jones reported.
The divergence between the EPA’s conclusion that glyphosate is “not likely to cause cancer” and the World Health Organization’s International Agency for Research on Cancer (IARC), which classified glyphosate as “probably carcinogenic to humans” in 2015, remains unresolved.
What’s Next
With the Supreme Court ruling effectively ending the vast majority of pending Roundup failure-to-warn lawsuits, Bayer’s legal liability has been significantly reduced. The company continues to push for federal legislation to codify its liability protections, with the farm bill mentioned as a potential vehicle. Meanwhile, the EPA’s overdue safety review — and the underlying scientific debate over glyphosate’s safety — remains an open question that could shape the next chapter of this long-running controversy.