Bayer faces thousands of Roundup cancer lawsuits. A Supreme Court ruling may make it harder to sue

From Harvest Public Media:

The Supreme Court will soon hear a case that could restrict which legal claims people can bring against chemical companies like Bayer, which produces the popular weedkiller Roundup.

Bayer purchased Roundup’s previous manufacturer, St. Louis-based Monsanto, in 2018. The companies have paid out billions of dollars to settle lawsuits that claim exposure to glyphosate, a key ingredient in Roundup, led to plaintiffs’ cancer.

Earlier this year, the Supreme Court agreed to take up an appeal of one such case: Monsanto v. Durnell.

John Durnell sued Monsanto in St. Louis after developing non-Hodgkin lymphoma. Court filings say he often used Roundup to kill weeds around his neighborhood. In 2023, a Missouri jury awarded him $1.25 million in damages based on his claim that the Roundup label failed to warn of a cancer risk.

But Bayer appealed the ruling, arguing that states cannot set their own labeling standards for herbicides.

When asked for comment on the case, a Bayer representative directed Harvest Public Media to company press releases.

“It is time for the U.S. legal system to establish that companies should not be punished under state laws for complying with federal warning label requirements,” Bayer CEO Bill Anderson said in a statement.

The company’s lawyers say responsibility for pesticide labels belongs only to the Environmental Protection Agency, under the Federal Insecticide, Fungicide, and Rodenticide Act.

“Bayer and Monsanto are arguing…that the federal government intended to take up this entire space when it came to labeling. And so because of that, that preempts states from making any sort of labeling or packaging requirement that differs from the federal law,” said attorney Jennifer Zwagerman, who’s the director of the Agricultural Law Center at Drake University in Des Moines, Iowa. Zwagerman is not directly involved in the litigation.

If the company prevails at the Supreme Court, it may prevent others from suing the company for failing to warn them of a cancer risk, Zwagerman said.

“These types of claims just aren’t going to be possible,” Zwagerman said. “It takes away an entire line of line of litigation of responsibility that plaintiffs had been using for years.”

What’s on the label?

Roundup is a staple chemical for many farmers, particularly those who grow corn or soybeans.

A dozen national agricultural organizations, including the American Farm Bureau Federation and the American Soybean Association, filed a brief in support of Bayer.

“Glyphosate revolutionized farming by providing a highly effective, broad-spectrum, and low-cost weed control solution,” attorneys for the farming groups wrote.

Bayer claims that there is no evidence that the chemical causes cancer when used correctly.

Some research contests this. A 2015 study by the World Health Organization’s International Agency for Research on Cancer concluded that glyphosate is “probably carcinogenic to humans.”

But the Environmental Protection Agency, which regulates pesticides in the U.S., has never found that glyphosate can cause cancer.

Brigit Rollins, an environmental law specialist at the University of Arkansas’ National Agricultural Law Center, said Bayer would argue that it cannot include a cancer warning on the Roundup label without explicit approval from the EPA.

“And I think the plaintiffs would argue the opposite, that it is completely legal,” Rollins said. “That if Bayer truly did fail to warn consumers about a potential health risk of using their products that they should update the label to reflect that.”

Zwagerman of Drake University said that Supreme Court justices may ask Bayer’s attorneys whether the company approached EPA about changing the label to include a cancer risk.

“It is their responsibility to go to the EPA and request the label change and provide all the information and then the support which EPA needs to then evaluate and make a determination,” Zwagerman said.

If Bayer wins, the ruling in this case won’t just affect Roundup, but all kinds of pesticides under the EPA’s purview.

“This is any pesticide or herbicide that falls under the [Federal Insecticide, Fungicide, and Rodenticide Act], and an individual’s ability to seek redress on not being told how dangerous that material was,” said Charlie Stern, a lawyer at Nachawati Law Group in Dallas who represents people suing Bayer.

A win by Bayer would not extinguish all lawsuits filed against the company, however. There are other types of legal claims plaintiffs can bring besides failure to warn, including defective design of the product, negligence and breach of warranty.

“When we file these cases, multiple claims get brought simultaneously,” Stern said. “So within one complaint there’s going to be failure to warn, that might be claim one. Claim two could be the design defect claim.”

The Monsanto v. Durnell ruling will not have a direct effect on a recent $7.25 billion settlement that Bayer reached with a group of plaintiffs. The exact terms of that settlement are still being negotiated.

Working ‘every angle’

This is not the first time Bayer has tried to get the Supreme Court to examine failure-to-warn claims. Some attorneys see Monsanto v. Durnell as part of a larger strategy by Bayer to extricate itself from the Roundup legal morass.

“[Bayer] has been working from a federal legislation, state legislation, every angle, for quite a while now to try to limit the potential scope of damages,” said Zwagerman from the Agricultural Law Center.

Bayer and other agribusiness groups are lobbying state legislatures across the country to pass so-called “shield laws,” which would protect the company from further Roundup-related litigation.

A law in Georgia went into effect this year that keeps people from filing certain lawsuits against pesticide companies like Bayer for failing to warn about cancer risks. It followed a similar law passed in North Dakota last year. Other legislation has been filed unsuccessfully in nearly a dozen other states.

In Congress, a recent spending bill almost included a provision that may have made it harder to bring failure-to-warn claims against pesticide companies and limited how states can regulate them.

The 2026 Farm Bill, as currently drafted, would further protect chemical companies from certain lawsuits, and limit state and local governments’ ability to regulate pesticides.

The Trump administration has backed these efforts. The Department of Justice filed a brief with the Supreme Court supporting Bayer’s arguments in the upcoming Supreme Court hearing. And in February, President Trump signed an executive order to use the Defense Production Act to ensure continued manufacture of glyphosate, as well as phosphorus for fertilizer.

Zwagerman said she was surprised by the administration’s order.

“It does not do anything really to address the concerns about what we’re seeing with fertilizer or pesticide costs and concerns about competitions,” she said. “It was really just directing the limited number of U.S. suppliers to do more.”

This story was produced in partnership with Harvest Public Media, a collaboration of public media newsrooms in the Midwest and Great Plains, including Texas. It reports on food systems, agriculture and rural issues.