U.S. Supreme Court Blocks Roundup Lawsuits Over Non-Hodgkin’s Lymphoma Warnings

Bayer and its Monsanto subsidiary are immune from liability for failing to warn users about the link between Roundup and cancer, according to landmark ruling.

The U.S. Supreme Court has granted Bayer and Monsanto immunity in all Roundup lawsuits involving allegations that the companies failed to warn about the cancer risks associated with exposure to their controversial glyphosate-based weedkiller.

In a 7-2 opinion (PDF) handed down today, the highest court in the U.S. reversed a Missouri jury’s $1.25 million verdict in favor of John Durnell, a man who said Roundup exposure caused him to develop non-Hodgkin’s lymphoma.

The Supreme Court majority decided that the repeated determinations by the U.S. Environmental Protection Agency (EPA) that glyphosate contained in Roundup is safe protects the manufacturers from all state law-based failure to warn claims, effectively ending one of the largest mass tort litigations over the past decade.

Roundup Cancer Litigation

Since 2015, Bayer and its Monsanto subsidiary have faced more than 120,000 Roundup lawsuits brought in federal and state courts nationwide, each involving former users who developed non-Hodgkin’s lymphoma. The lawsuits raise similar allegations, indicating that the manufacturers knew or should have known that Roundup exposure increased the risk of cancer, yet concealed those risks to protect profit.

Although the company has paid more than $10 billion in Roundup settlements over the past few years, Bayer and Monsanto continue to face thousands of active claims being pursued throughout the U.S. court system, and new claims continue to be brought as former users of the weedkiller develop non-Hodgkin’s lymphoma.

Several trials have been held through the years, many ending in massive verdicts against Bayer and Monsanto, spurring the manufacturers to petition various states and the U.S. Supreme Court for immunity from the litigation.

In April 2025, Bayer filed a Writ of Certiorari, asking the high court to dismiss all Roundup failure to warn claims, arguing that they should be preempted by federal law. The petition indicated that the EPA has reviewed glyphosate multiple times and has determined that it does not cause cancer, despite numerous studies and evidence to the contrary, including a 2015 assessment by the World Health Organization’s International Agency for Research on Cancer (IARC) which indicated that exposure to glyphosate-based herbicides may cause cancer.

The move came in connection with efforts to secure immunity from the lawsuits in several individual states as well, which has seen some limited success. This was the company’s third attempt to get the Supreme Court to agree to consider the issue.

The Supreme Court previously rejected an appeal to review another Roundup trial defeat in June 2022, involving an $87 million verdict awarded to a California couple, Alva and Alberta Pilliod in May 2019.  

This followed a previous refusal to review another Roundup appeal in March 2019. The Court provided no comment about the reasons why the petitions were rejected in either case, which is not uncommon.

However, this time numerous parties, including the federal government and more than a dozen state attorneys general, filed briefs in support of Bayer’s call for immunity, following an intense, multi-state lobbying campaign.

Immunity Granted in Roundup Failure to Warn Claims

In a decision issued on June 25, the Supreme Court sided with the manufacturers, determining that state failure-to-warn claims were preempted by federal law. The ruling states that Bayer and Monsanto cannot be reasonably asked to put cancer label warnings on Roundup if the EPA says it does not cause cancer.

The court noted that the EPA did additional reviews after the IARC warning and did not change its opinion or require new cancer label warnings. The majority of justices decided that meant Monsanto could not change the label to add a cancer warning even if it wanted to.

“Monsanto is not invoking the mere fact of ‘registration’ as a complete defense to state tort suits. Rather, Monsanto is relying on EPA’s specific determination that cancer warnings are not required for glyphosate-based pesticide labels.”

– U.S. Supreme Court Justice Brett Kavanaugh, writing for the majority

Bayer previously indicated that it would remove glyphosate from Roundup products sold in the U.S. However, in February the White House announced plans to encourage ramped up production, claiming the need for the weedkiller was a matter of national security.

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