Supreme Court sides with Monsanto in case over cancer risks from weedkiller

Washington — The Supreme Court on Thursday ruled that Monsanto cannot be held liable under state laws for failing to warn consumers about the alleged cancer risks of its weedkiller Roundup on its label.

In a 7-2 decision in the case Monsanto Co. v. Durnell, the high court found that a federal law regulating the sale and labeling of pesticide products bars lawsuits in state courts alleging that Monsanto failed to include a cancer warning on Roundup's labels.

The Environmental Protection Agency has deemed Roundup safe to use and does not require a cancer warning on its label. In its opinion Thursday, the Supreme Court reiterated that federal law requires Monsanto to use an EPA-approved label unless the EPA approves or requires a different label.

The decision was delivered by Justice Brett Kavanaugh, who was joined in the majority opinion by Chief Justice John Roberts as well as Justices Samuel Alito, Sonia Sotomayor, Elena Kagan, Amy Coney Barrett and Clarence Thomas. Justices Ketanji Brown Jackson and Neil Gorsuch dissented.

Monsanto has faced a tidal wave of litigation in recent years over its Roundup product. Thursday's ruling is expected to block thousands of lawsuits from consumers who claimed Monsanto failed to warn them that the product could cause cancer.

Bayer, a German pharmaceutical company, acquired Roundup when it bought Monsanto in 2018.

"The U.S. Supreme Court decision is good for science, farmers, and industries that depend on regulatory clarity for innovation," Bayer said in a statement shared with CBS News. "It should help significantly contain the Roundup litigation after nearly a decade of legal battles."

Bayer added that it will continue to seek final approval of a $7.25 billion class settlement it proposed in February to "contain the Roundup litigation." The proposed settlement, which would resolve current and future claims related to Roundup's use, is now before a Missouri state court. If the plan gets a green light, Monsanto would make annual payments for up to 21 years.

The case before the Supreme Court was brought in 2019 by John Durnell, a gardener from Missouri who is one of more than 100,000 people across the country who have sued Monsanto and alleged that the key ingredient in Roundup, glyphosate, caused them to develop cancer. Durnell said he had been exposed to Roundup for more than 20 years, leading him to develop non-Hodgkin's lymphoma, a type of blood cancer.

Durnell's lawyers did not immediately respond to a request for comment.

At the center of the dispute is a federal law called the Federal Insecticide, Fungicide, and Rodenticide Act, or FIFRA, which was enacted by Congress in 1947. The law regulates the use and sale of pesticides and sets a uniform framework for labeling of the chemicals. It also requires pesticide manufacturers to register their products with the EPA before they can be sold.

The EPA has, for decades, evaluated whether glyphosate-based pesticides pose adverse health risks to humans, including cancer risks, and has deemed Roundup safe to use. As a result, the herbicide's label does not include a cancer warning.

Bayer had argued that FIFRA's rules prohibited it from unilaterally changing its label's "precautionary warnings" to include a cancer warning.

While the EPA has determined that Roundup is safe when used as directed, a working group of the International Agency for Research on Cancer, which is part of the World Health Organization, classified glyphosate as "probably carcinogenic to humans" in 2015.

Following IARC's determinations, the EPA conducted its own examinations of glyphosate's carcinogenic potential and found the "strongest support" for classifying the chemical as "not likely to be carcinogenic to humans." Based on its analyses, the EPA in 2019 and 2020 concluded that a cancer warning for glyphosate was not needed, and it has continued to approve labels of glyphosate-based pesticide products that do not contain cancer warnings.

Still, the classification from IARC sparked a slew of lawsuits from scores of plaintiffs who alleged that their use of Roundup caused their cancers and sought to hold Monsanto liable for failing to warn about the alleged carcinogenic risk.

Among those plaintiffs was Durnell, who sued Monsanto in Missouri state court in 2019.

A jury rejected all but one of Durnell's claims — that Monsanto failed to warn consumers about Roundup's alleged cancer risk — and awarded him $1.25 million in damages in 2023. Bayer says it no longer sells glyphosate-based Roundup products, but does offer other versions of the herbicide through retailers such as Home Depot and Lowe's.

The Missouri Court of Appeals went on to reject Monsanto's arguments that FIFRA preempted Durnell's lawsuit, and the state's supreme court declined to review the decision.

The decision is a victory for the Trump administration, but one that could be tricky politically since allies in the Make America Healthy Again movement want to rein in pesticide use.

The Trump administration backed Monsanto in the case, writing in a filing that federal law gives the EPA the responsibility to determine whether pesticide warnings are needed to protect human health and the environment. The Justice Department argued the EPA had reviewed extensive evidence and conducted its own analysis before determining Roundup's labeling adequately protected users' health.

Separately, President Trump signed an executive order in February that aimed to boost the production of glyphosate-based herbicides, warning that the lack of access to the substance threatened agricultural productivity, putting pressure on the domestic food system.