Supreme Court blocks state cancer lawsuits over Roundup

In a 7-2 decision on June 25, the Supreme Court ruled that federal pesticide rules prevent state-level lawsuits accusing Bayer’s Roundup of inadequate cancer warnings. The ruling shields Bayer’s Monsanto unit from claims tied to an alleged lack of a cancer war

On June 25, the Supreme Court dealt a swift, punishing blow to thousands of people who believe Roundup caused their cancer.

In a 7-2 decision. the country’s highest court ruled that Bayer—Monsanto’s parent company—can’t be sued at the state level over claims that it failed to sufficiently warn consumers about cancer risks tied to Roundup. the popular brand name for glyphosate. The ruling protects Bayer from lawsuits brought under state law, shifting the playing field toward federal standards.

The case began with a Missouri man. John Durnell alleged that two decades of exposure to Roundup caused his non-Hodgkin’s lymphoma, a form of blood cancer. He filed a state lawsuit in 2019 against Monsanto, arguing the product should carry a warning label addressing cancer risks. After the case was appealed up the courts, the Supreme Court took it and affirmed Monsanto’s position.

Writing for the majority, Justice Brett Kavanaugh said federal regulations preempt Durnell’s state-level claim and that they “expressly pre-empt” Durnell’s lawsuit. The court’s key point was that Bayer and Monsanto must use the pesticide label approved under federal oversight.

“Importantly, EPA’s regulations require a pesticide manufacturer such as Monsanto to use the EPA-approved pesticide label—here, the Roundup label without a cancer warning—unless and until EPA approves or requires a different label,” Kavanaugh wrote.

Federal rules, not state additions

The decision ties the hands of plaintiffs seeking extra warnings through state courts. Because the Environmental Protection Agency does not require products containing glyphosate to be sold with a cancer warning—and because Bayer says it complies with EPA’s guidelines for its top-selling herbicide—the Supreme Court ruled states cannot impose additional or substitute warning labels.

That conclusion rests on how pesticides are governed. The Supreme Court said EPA regulates pesticides under a law known as the Federal Insecticide, Fungicide, and Rodenticide Act, and under that structure, state law cannot add its own labeling requirements for products like Roundup.

The court’s majority sided with Bayer on that preemption argument, while Justices Ketanji Brown Jackson and Neil Gorsuch dissented.

For Bayer, the decision lands at the center of a financial storm.

More than 180,000 claims have been filed involving Roundup, according to the case’s broader record referenced in the reporting. The litigation has helped push Bayer to pull glyphosate out of many products under the Roundup brand, even though the chemical remains widely used in farming.

And while the EPA has deemed glyphosate safe if applied as directed. that view has not closed every argument around cancer risk. More than 10 years ago. the World Health Organization’s cancer agency classified the chemical as a substance likely to cause cancer in humans. though those findings faced scrutiny a few years later over reports that the published version differed from a draft.

Earlier this year. a landmark study determining that glyphosate doesn’t pose a risk to human health was retracted—more than two decades after it was published. The retraction followed emails revealing Monsanto’s influence on the science. a development that has raised doubts about regulations that have relied on key research for decades.

A deal that turned costly

Bayer acquired Roundup maker Monsanto in 2018 for $63 billion, betting that owning a major agriculture supplier would pay off in a booming market. Instead, Monsanto’s litigation over Roundup has dragged the parent company down.

Even as the Supreme Court ruling delivered new protection for Bayer at the state level. the numbers tell a story of financial pressure. Bayer is worth $10 billion less than the price it once paid for Monsanto. Shares jumped sharply following the Supreme Court decision on Thursday. reflecting relief that at least some waves of lawsuits may be blocked going forward.

Still. for plaintiffs like John Durnell—who says two decades of exposure led to his non-Hodgkin’s lymphoma—the decision closes off a specific route to recovery. The Supreme Court’s ruling does not settle every question about glyphosate; it settles a legal question about where and how warning-label claims can be pursued. For those who believed the state system would require a cancer warning. the answer from the nation’s highest court arrived with decisive finality on June 25.

Supreme Court Roundup Bayer Monsanto glyphosate cancer warning preemption Federal Insecticide Fungicide and Rodenticide Act EPA non-Hodgkin’s lymphoma John Durnell