Supreme Court Weighs Roundup Cancer Warning Labels in Bayer-Monsanto Case

Since 2018, when German conglomerate Bayer acquired Monsanto, the company has set aside billions to settle legal claims alleging that glyphosate—the active ingredient in Roundup—causes cancer and other health issues. More than 100,000 plaintiffs across the U.S. have filed lawsuits over the weedkiller’s safety.

In February 2024, Bayer agreed to a $7.25 billion settlement for a class-action lawsuit. However, one case advanced to the Supreme Court after failing to reach a settlement. The dispute hinges on whether federal law preempts state-level cancer warnings on Roundup labels.

John Durnell’s Case

John Durnell sued Monsanto in 2019, claiming his non-Hodgkin lymphoma resulted from decades of exposure to glyphosate. He regularly sprayed Roundup in his neighborhood for 20 years. In 2023, a Missouri jury found Monsanto liable for failing to warn users about the cancer risk and awarded Durnell $1.25 million in damages. Monsanto has denied the allegations and appealed the verdict.

Legal Framework: FIFRA and State Law

The case centers on the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), which governs pesticide labeling and sales. Under FIFRA, the Environmental Protection Agency (EPA) approves pesticide labels, and states cannot impose additional warnings beyond federal requirements. Manufacturers must register products with the EPA, which reviews and signs off on labels before sale.

Durnell’s lawsuit relies on a Missouri state law that prohibits selling dangerous products without adequate warnings. Monsanto argues that FIFRA preempts the Missouri law because the EPA had already approved Roundup’s label. The Supreme Court must decide whether the EPA’s approval overrides state-level safety warnings.

Supreme Court Oral Arguments

During oral arguments, the justices appeared divided on the issue. Justice Ketanji Brown Jackson questioned whether preemption would prevent states from responding to new scientific evidence. She asked Monsanto’s lawyer, Paul Clement, whether a product’s label—approved at registration—could become outdated if new research later casts doubt on its safety.

“Could we have a world in which a product that has been registered, the label is consistent with what the agency has said is appropriate at the time of registration, but let’s say a new research study comes out at some point between when the EPA is statutorily required to look at it again that casts doubt on the safety of this product?”

Clement responded that the EPA could address such concerns through amended registrations or cancellation processes subject to judicial review. Justice Amy Coney Barrett further probed the issue, asking whether the agency could penalize manufacturers for failing to update labels with new safety information.