EPA-Approved Pesticide Labels Reign Supreme

Glyphosate, for decades the active ingredient in Monsanto’s Roundup weedkiller, is the most widely used herbicide in the world. There is general agreement that it kills weeds effectively and general disagreement as to whether it also kills people.

Across administrations, the U.S. Environmental Protection Agency (EPA) has consistently determined that glyphosate is not a carcinogen. In February, President Donald J. Trump charged the Secretary of Agriculture with taking all steps necessary to encourage the production and use of glyphosate-based herbicides. But several stakeholders disagree: those marching under the Make America Healthy Again banner, including “Glyphosate Girl,” have called for limits on agricultural glyphosate use; the World Health Organization’s International Agency for Research on Cancer declared glyphosate a probable carcinogen; and California has placed glyphosate on its Proposition 65 list of chemicals “known to the state of California to cause cancer.” And a dozen juries in state court tort actions—the first of which included the now Secretary of the U.S. Department of Health and Human Services, Secretary Robert F. Kennedy, Jr., on the plaintiff’s legal team—have concluded that exposure to Roundup caused the plaintiffs’ cancer and have awarded significant damages against Monsanto for failure to warn of the risks.

The Roundup lawsuits are all state-law claims brought under common-law tort theories—particularly failure-to-warn—or consumer protection laws. Monsanto has settled more than 100,000 of these claims for a total of about $11 billion; some 65,000 state suits are pending, along with 4,000 federal lawsuits based on state-law theories that have been consolidated in a multidistrict litigation. New claims continue to be filed. A global settlement for $7.25 billion in the Missouri class action King v. Monsanto has received the judge’s preliminary approval and is set for a hearing on August 19, 2026.

John Durnell had used Roundup for two decades when he was diagnosed with non-Hodgkin’s lymphoma. He sued Monsanto in Missouri state court alleging that his cancer was caused by exposure to glyphosate. Durnell relied on multiple legal theories, but the key, and successful, one was failure to warn. A jury awarded $1.25 million in damages. The Missouri Court of Appeals affirmed.

In Roundup cases, Monsanto has argued that state-law duty-to-warn requirements are preempted by the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Most but not all lower courts, including the state courts in Monsanto v. Durnell, have rejected the argument. The U.S. Supreme Court declined to hear the issue in Monsanto v. Hardemann but agreed to hear it in Durnell. (An aside: Advocacy in the Supreme Court begins with the framing of the “question presented” in a petition for the Court to hear a case. It is common for the respondent to phrase the question differently than the petitioner; each framing it so as to hint at an answer in their favor. In this case, the petitioner, the respondent , and the United States as amicus each penned very different, and tendentious, versions. In granting cert the Court pointedly wrote its own bare-bones question presented.)

In a 7-2 decision that did not fall along familiar ideological lines, the Court agreed with Monsanto: State courts cannot find a pesticide manufacturer liable for failure to warn of its product’s risks if it has used the label approved by EPA as part of the pesticide’s registration. The state-law claim is preempted by the FIFRA.

Under the Supremacy Clause of the U.S. Constitution, federal law is “supreme, … any Thing in the Constitution or Laws of any State to the Contrary notwithstanding.” A state law “to the contrary” is said to be “preempted.” By definition, then, preemption of state law rests on conflict with federal law.

Some preemption cases are easy, such as where the federal law explicitly prohibits state regulation or it is literally impossible to comply with both federal and state requirements. But the Supreme Court also sometimes finds preemption where the conflict is more abstract, such as when state law “stands as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress” or Congress has sought to “occupy the field.”

A recurring conundrum in preemption cases is what to do when federal and state law have the same valence—they are aiming at the same problem—but state law goes further than the federal. Suppose that federal law requires reducing emissions by 50 percent and New York requires reducing them by 75 percent; the feds require two months of training for inspectors and California requires four. Is the state law “contrary” to the federal? On the one hand, they are aimed at the same problem, and it is easy to comply with both—compliance with the state requirement is compliance with the federal. On the other hand, state and federal policymakers have weighed the relevant considerations differently and reached different decisions; the state law imposes burdens the feds chose not to impose.

At bottom, Durnell was such a case. According to the majority, it was an easy one because FIFRA expressly prohibits any state deviation from federal labeling requirements. According to the dissent, FIFRA does no such thing and the state law was parallel to, rather than a deviation from, the federal.

The general rule under FIFRA is that states can regulate pesticides more strictly than EPA but not less so. That is a common approach to federal environmental regulation—The Clean Air Act takes this approach with regard to stationary sources of air pollution, for example. But the same FIFRA section that sets out that general principle immediately qualifies it: States cannot impose labeling requirements that differ from FIFRA’s, period.

Justice Brett Kavanaugh’s opinion begins by setting out the overall FIFRA regime, with an emphasis on EPA’s central role in ensuring pesticide safety. FIFRA prohibits the distribution or sale of a pesticide that has not been registered by EPA. Registration requires a determination that the pesticide is effective and, when used properly, not unreasonably harmful to human health or the environment. FIFRA also prevents the sale or distribution of a pesticide that is “misbranded,” meaning that its label “is false or misleading in any particular” or “does not contain a warning or caution statement which may be necessary and if complied with . . . is adequate to protect health and the environment.”. EPA must approve the label as part of registration, and the label must include warnings and instructions for use that will protect public health and the environment. It violates FIFRA to use a registered pesticide in a manner inconsistent with the label.

The key provision, headed “Uniformity,” provides that a state that regulates the sale or use of a federally registered pesticide “shall not impose or continue in effect any requirements for labeling or packaging in addition to or different from those required under this subchapter.” For the Court’s majority, this provision expressly preempts state failure-to-warn claims. Such claims seek to impose a “requirement” that manufacturers warn consumers by adding language to the product’s label. But EPA has approved a label without such a warning; the manufacturer must use the approved label and only the approved label; therefore, requiring a cancer warning would be “in addition to or different from” FIFRA’s requirement. End of case.

Justice Ketanji Brown Jackson, joined by Justice Neil Gorsuch, argued that there was no inconsistency. FIFRA and Missouri require exactly the same thing: a label that is adequate to warn of risks from use of the pesticide. Neither the statute nor EPA regulations impose more specific requirements regarding what sort of labels to have for products that pose chronic risks, such as the risk of cancer. In the abstract, FIFRA and Missouri common law both require that a pesticide label warn purchasers and users of health risks; not doing so is “misbranding” under the statute and a “failure to warn” under tort law.

The disagreement, then, is that the majority sees EPA’s approval of a specific label to mean the manufacturer must use that label and only that label, a legal requirement with the same weight as language in the U.S. Code or the Code of Federal Regulations. Justice Jackson, in contrast, thinks EPA approval reflects a judgment, which may be right or may be wrong—or may have been right in light of available information when made but later turn out to be wrong—that a given label satisfies FIFRA’s requirements. That judgment should not preclude a state court from later determining that the label is inadequate as long as it bases that decision on a defect that violates not only state law but also FIFRA.

Thus, the case ultimately turns on a narrow, in-the-weeds disagreement about FIFRA. The respondent, the lower court, most other lower courts, the dissent, and the Biden Administration’s Department of Justice thought that state law was not preempted because EPA’s approval of a label does not amount to a requirement that the manufacturer use that label and only that label, period. That is a plausible but not necessary reading of the statute, and once it was rejected, the outcome was unavoidable.

Writing just for himself, Justice Clarence Thomas concurred. Although he agreed with the majority, Thomas wrote to “call attention to some of the underlying constitutional infirmities in the Act.” Note the self-restraint; he is pointing out only “some” of the apparently countless constitutional defects. Justice Thomas pointed to three: FIFRA exceeds Congress’s commerce power; FIFRA is an unconstitutional delegation of legislative power to the agency; and an agency regulation or other action is not law that is “supreme” under the Supremacy Clause. The concurrence repeats positions Justice Thomas has staked out in the past.

What impact will Durnell have? It is of course hugely important for the glyphosate litigation itself. Monsanto’s bargaining position in the settlement process suddenly became much stronger. But it is important to remember that the lawsuits raise multiple theories; the now-preempted failure-to-warn claims, though so far the most successful, are only one arrow in the plaintiffs’ quiver. The majority opinion explicitly observes that the decision does not bar liability on theories other than failure to warn. Durnell does not make the lawsuits disappear.

Durnell will also prove consequential with regard to pesticide labeling. For example, at first blush it would seem that California’s Proposition 65 warning requirement is doomed as applied to registered pesticides.

But the decision’s impact stops there. Durnell turned on the particulars of one provision of one statute; the opinion was narrowly written; there is not a hidden principle, ideological or otherwise, that explains the justices’ votes. Justice Kavanaugh makes a passing reference to the appropriateness of preemptive federal labeling requirements when manufacturers sell in a national marketplace, but otherwise there is almost nothing in the way of policy or big picture considerations. The majority is not saying that any time a federal agency has determined that a product is “safe,” states are powerless to regulate it or impose liability for harms it causes. It would be a mistake to draw larger inferences about the Supreme Court’s views on preemption or federalism from this decision.

Finally, Congress is paying attention. Prior to Durnell, proposals to more explicitly preempt these claims were taken seriously. But bills to block implementation of the executive order and create a federal cause of action for glyphosate plaintiffs have also been introduced. Immediately after the decision came down, strange bedfellows Chellie Pingree (D-Maine) and Thomas Massie (R-Ky.) introduced legislation to overturn it. Their bill is going nowhere. But down the road congressional action is at least conceivable. And desirable.

Michael Herz is the Arthur Kaplan Professor of Law at the Cardozo School of Law.