Supreme Court Sides With Monsanto, Limits Lawsuits Over Pesticide Warning Claims

The Supreme Court on Thursday delivered a major victory for pesticide manufacturers, ruling that federal law blocks certain lawsuits claiming companies failed to warn consumers about alleged health risks not recognized by federal regulators.
In a 7-2 decision, the justices concluded that state-law claims seeking additional warning labels beyond those approved under federal law cannot move forward, narrowing the ability of Americans to sue pesticide makers over alleged health harms tied to their products.
The case centered on John Durnell, a cancer patient who sued Monsanto, alleging the company failed to provide an adequate warning that its Roundup weedkiller could increase the risk of cancer. A Missouri court previously awarded Durnell $1.25 million under state law after finding in his favor.
Monsanto, which is owned by Bayer, challenged that verdict, arguing that Durnell's lawsuit conflicted with federal pesticide regulations. The company maintained that Roundup's labeling is approved by the Environmental Protection Agency (EPA), which does not require a cancer warning because it has concluded that glyphosate, the weedkiller's key ingredient, is "unlikely to be a human carcinogen."
At the heart of the dispute was whether individuals can bring state-law failure-to-warn claims against pesticide manufacturers when those claims would effectively require warning labels that go beyond the health risks formally recognized by the EPA.
The Supreme Court determined that such claims are preempted by federal law.
Writing for the majority, Justice Brett Kavanaugh explained that federal law requires Monsanto to market Roundup using the label approved by the EPA during its initial registration and reaffirmed through subsequent reviews. That federally approved label does not include a cancer warning.
According to Kavanaugh, Missouri's failure-to-warn claim would require Monsanto to add a warning beyond what federal law mandates, creating a state labeling requirement that is both "in addition to" and "different from" the company's federal obligations.
The ruling relied on the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), which states that individual states may not impose labeling or packaging requirements that differ from those established under federal law.
The majority opinion drew support from justices across the ideological spectrum. Joining Kavanaugh were Chief Justice John Roberts and Justices Clarence Thomas, Samuel Alito, Sonia Sotomayor, Elena Kagan, and Amy Coney Barrett.
Justices Neil Gorsuch and Ketanji Brown Jackson dissented.
Jackson authored the dissent, arguing that the majority misread both FIFRA's requirements and the scope of its preemption. She contended that the EPA's approval of a pesticide label does not itself create a labeling requirement under the statute.
Jackson also wrote that Durnell's claim did not conflict with federal law and argued that the Court's decision leaves him without a legal remedy for what she described as the significant harms he suffered.
Beyond the immediate dispute involving Bayer and Monsanto, the decision represents a broader victory for the pesticide industry, which has faced numerous lawsuits over Roundup and similar products.
At the same time, the ruling marks a setback for plaintiffs seeking to hold pesticide manufacturers liable for alleged health risks that they believe were not adequately disclosed. It is also a blow to the Make America Healthy Again (MAHA) movement, which has argued that pesticide companies should not be shielded from legal liability over claims involving the health effects of their products.