Supreme Court Rejects Claims Over Pesticide Cancer Warning

In Monsanto Co. v. Durnell, 609 U.S. ___ (2026), the U.S. Supreme Court held that the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) expressly preempts state-law failure-to-warn claims targeting pesticide labels approved by the Environmental Protection Agency (EPA).

Facts of the Case

Monsanto Company manufactures and distributes Roundup, a glyphosate-based herbicide designed to control weeds. Under authority granted by the Federal Insecticide, Fungicide, and Rodenticide Act, the Environmental Protection Agency regulates pesticides, including pesticide labels.

The EPA has repeatedly evaluated glyphosate and repeatedly concluded that glyphosate is not likely to cause cancer. Many other regulatory bodies around the world share the EPA’s assessment. In accordance with EPA’s view that glyphosate is not likely to cause cancer in humans, EPA has not required labels on glyphosate-based pesticides like Roundup to include a cancer warning.

As relevant to this case, the 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. Moreover, to ensure “[u]niformity” in labeling, FIFRA’s preemption clause prohibits States from imposing any pesticide labeling requirements that are “in addition to or different from” the federal labeling requirements “under” FIFRA.

In 2019, John Durnell sued Monsanto in Missouri state court, alleging that he had used Monsanto’s Roundup products for about 20 years and that they had caused his non-Hodgkin’s lymphoma. As relevant here, Durnell brought a failure-to-warn tort claim, asserting that Monsanto should have included a cancer warning on Roundup’s label. A jury agreed and awarded Durnell more than $1 million on the failure-to-warn theory. On appeal, the Missouri Court of Appeals affirmed. It reasoned that Missouri failure-to-warn claims are “fully consistent with” FIFRA’s misbranding provisions because “both require a pesticide manufacturer to adequately warn users of the potential dangers of using its product.”

Supreme Court’s Decision

The Supreme Court reversed 7-2. The majority held that FIFRA expressly preempts state law failure-to-warn claims that would require a pesticide manufacturer to add or alter a warning on a label that EPA has reviewed and approved. Justice Brett Kavanaugh wrote on behalf of the majority.

In reaching its decision, the Supreme Court emphasized that FIFRA’s preemption clause, entitled “Uniformity,” provides that a “State shall not impose or continue in effect any requirements for labeling or packaging in addition to or different from those required” under the law. “FIFRA therefore preempts a state-law labeling requirement that differs from the federal labeling requirements imposed under FIFRA,” Justice Kavanaugh wrote. “‘Uniformity’ in labeling—the textually stated objective of FIFRA’s preemption clause—would otherwise be impossible to achieve.”

The majority further noted that to register a pesticide, EPA must approve the pesticide’s label by determining that the label contains all warnings “necessary and . . .adequate to protect health and the environment” and that the label does not include any “false or misleading” statements. After EPA approves a pesticide’s label at registration, manufacturers are legally required to use that label unless and until EPA approves or requires a label change and amends the pesticide’s registration. Accordingly, “as a matter of federal law, Monsanto legally must use a label without a cancer warning unless and until EPA approves or requires a change,” Justice Kavanaugh wrote. Additionally, Durnell’s state tort claim would require Monsanto to add a cancer warning to its labels, which is “in addition to” and “different from” Monsanto’s federal-law labeling obligations.

The majority rejected the argument that a state failure-to-warn claim does not violate the uniformity requirement because the goal of both the claim and FIFRA is to ensure that manufacturers “include adequate warnings to protect human health.” According to Justice Kavanaugh, the argument “operates at far too high a level of generality and disregards the central and comprehensive role that EPA performs in making labeling determinations.”

The majority also distinguished failure-to-warn claims based on safety from claims targeting efficacy. Citing Bates v. Dow Agrosciences LLC, 544 U.S. 431 (2005), Justice Kavanaugh explained that efficacy-based failure-to-warn claims would not be preempted because EPA does not review a pesticide’s efficacy during the registration process.

Dissent

Justice Ketanji Brown-Jackson authored a dissent, which Justice Neil Gorsuch joined. Justice Jackson argued that “[t]he majority reads into FIFRA a labeling requirement that does not exist, and it reads out of FIFRA the statute’s ongoing prohibition on misbranding.” Accordingly, it “unjustifiably closes the courthouse doors to state tort plaintiffs like Durnell.”