US Supreme Court Holds FIFRA Preempts State-Law Failure-to-Warn Claims

The US Supreme Court recently issued an important decision addressing the relationship between EPA-approved pesticide labeling and state-law product liability claims. In Monsanto Co. v. Durnell, the Court held that the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) expressly preempts state-law failure-to-warn claims that would require pesticide manufacturers to include warnings different from or in addition to those approved by the US Environmental Protection Agency (EPA). The decision resolves a Circuit split regarding the preemptive effect of federal agency labeling decisions.

KEY TAKEAWAYS

• The majority held that state failure-to-warn tort claims are preempted by federal law and cannot be sustained where they would attempt to impose liability based on information different from or absent from EPA-approved pesticide labels under FIFRA.
• Justice Clarence Thomas filed a concurring opinion raising constitutional questions concerning the scope of federal regulatory authority under FIFRA.
• Justice Ketanji Brown Jackson, joined by Justice Neil Gorsuch, dissented, concluding that failure-to-warn tort claims merely paralleled FIFRA’s labeling requirements.

OVERVIEW

FIFRA establishes a comprehensive federal framework governing the registration, labeling, sale, and use of pesticides in the United States.

Before a pesticide can be sold, EPA reviews the manufacturer’s proposed label to determine whether it contains the warnings necessary to protect human health and the environment and complies with the statute’s prohibition against “misbranding.” Once EPA approves a label, manufacturers generally must continue using that label unless EPA requires a modification.

FIFRA also contains an express preemption provision in 7 USC § 136v(b) prohibiting states from imposing labeling requirements “in addition to or different from” those required under federal law.

The case arose from claims that Roundup, Monsanto’s glyphosate-based herbicide, should have included a warning regarding an alleged risk of cancer. EPA has repeatedly reviewed glyphosate and concluded that it is not likely to be carcinogenic to humans. Consistent with those determinations, EPA repeatedly approved Roundup’s labeling without requiring a cancer warning.

Plaintiff John Durnell alleged that he developed non-Hodgkin’s lymphoma after using Roundup over a period of approximately twenty years. A Missouri jury ultimately found in his favor on a failure-to-warn theory and awarded more than $1 million in damages. Monsanto argued that the claim was preempted because EPA had specifically considered whether Roundup required a cancer warning and approved the label without it. After the Missouri courts rejected that argument, the Supreme Court granted review to resolve a conflict among federal and state appellate courts, including the Third Circuit (which found state failure-to-warn claims preempted) and the Ninth and Eleventh Circuits and Oregon and California state courts (which found no preemption).

THE SUPREME COURT’S DECISION

Writing for a seven-Justice majority, Justice Brett Kavanaugh concluded that Durnell’s failure-to-warn claim was expressly preempted because it would require Monsanto to include a warning on its pesticide label different from the warning—or lack of warning—required by EPA.

Although the opinion addresses several statutory arguments, its analysis rests on three principal conclusions.

EPA’s Labeling Determinations Constitute Federal Requirements

The central issue before the Court was whether EPA’s approval of a pesticide label during the registration process constitutes a federal “requirement” under FIFRA’s express preemption provision.

The Court answered that question in the affirmative.

The majority explained that EPA’s role extends well beyond reviewing a manufacturer’s proposed label for general compliance. Under FIFRA, EPA evaluates whether the label contains all warnings necessary to protect human health and the environment and determines whether the proposed labeling satisfies the statute’s requirements. Once EPA approves the label, manufacturers are generally required to continue using that label unless EPA authorizes or directs a change.

Because EPA repeatedly determined that Roundup’s label did not require a cancer warning, the majority concluded that a Missouri jury could not require Monsanto to include one without imposing a labeling requirement “in addition to or different from” federal law.

National Uniformity Was Central to the Court’s Analysis

The majority repeatedly emphasized that the US Congress intended for FIFRA to establish a nationally uniform system of pesticide labeling administered by EPA.

According to the Court, allowing individual states to impose different warning requirements through common-law tort claims would undermine that objective. Manufacturers could face conflicting obligations depending on where a lawsuit was filed, notwithstanding EPA’s determination regarding the appropriate content of a federally approved pesticide label.

The Court also observed that FIFRA provides EPA with continuing authority to monitor pesticide safety after registration. Manufacturers must report new safety information to the agency, EPA may require additional data or revised warnings, registrations are subject to periodic review, and interested parties may petition EPA to modify or cancel a registration based on new scientific information. In the majority’s view, Congress intended for EPA—not state tort litigants—to address evolving scientific evidence concerning pesticide safety.

The Court Clarified Its Prior Preemption Decisions

The Court also addressed two prior Supreme Court decisions that have shaped FIFRA preemption litigation.

First, the Court distinguished Bates v. Dow Agrosciences LLC, explaining that Bates involved product efficacy claims that EPA had not reviewed as part of the registration process. By contrast, EPA had repeatedly evaluated the scientific evidence concerning glyphosate’s potential carcinogenicity and repeatedly determined that a cancer warning was not required. Because EPA had specifically addressed the issue presented by Durnell’s claim, the Court concluded that Bates did not control the outcome.

Second, the Court relied extensively on Riegel v. Medtronic, which held that US Food and Drug Administration approval of a medical device created federal requirements capable of preempting conflicting state-law claims. Justice Kavanaugh concluded that EPA’s pesticide registration process functions in a materially similar manner and that the same preemption principles apply under FIFRA.

The Court also rejected arguments that EPA had exceeded its statutory authority in requiring manufacturers to continue using EPA-approved labels or that another provision of FIFRA describing registration as only prima facie evidence of compliance altered the preemption analysis. According to the majority, those arguments were inconsistent with FIFRA’s text, structure, and comprehensive regulatory framework.

The upshot of the majority’s decision is a broad understanding of the preemptive effect of FIFRA’s regulatory framework. It will make it difficult or impossible for plaintiffs to raise failure-to-warn or similar labeling challenges when manufacturers have followed FIFRA’s labeling requirements.

CONCURRING OPINION

Justice Thomas joined the Court’s opinion in full but wrote separately to raise broader constitutional questions that were not before the Court and did not affect the outcome of the case.

His concurrence focused on three issues.

First, Justice Thomas questioned whether certain applications of FIFRA exceed Congress’s authority under the Commerce Clause. In his view, the statute regulates not only the interstate sale of pesticides but also their use by consumers, including purely intrastate use, which he suggested may fall outside Congress’s constitutional authority.

Second, he questioned whether Congress delegated excessive legislative authority to EPA. Justice Thomas observed that EPA exercises broad authority over pesticide labeling through regulations that carry civil and criminal consequences, raising concerns about the scope of Congress’s delegation of regulatory power.

Finally, Justice Thomas questioned whether agency action itself may constitutionally preempt state law. He noted that the Supremacy Clause refers to the Constitution, federal statutes, and treaties—not agency action—as the “supreme Law of the Land.” Although he acknowledged that regulated parties ordinarily should not be required to comply with conflicting federal and state directives, he suggested that the constitutional basis for administrative preemption warrants further consideration.

Justice Thomas’s concurrence reflects his continuing interest in reconsidering foundational questions regarding the scope of federal regulatory authority and the modern administrative state.

DISSENTING OPINION

In an unusual alignment, Justice Jackson, joined by Justice Gorsuch, dissented.

The dissent agreed that state law may not impose labeling requirements different from federal law but disagreed fundamentally with the majority’s identification of the relevant federal requirement.

According to the dissent, FIFRA’s operative federal requirement is the statute’s prohibition against selling a “misbranded” pesticide under Section 136j(a)(1)(E). Missouri’s failure-to-warn claim, Justice Jackson reasoned, imposed essentially the same obligation by requiring manufacturers to provide adequate warnings regarding known product risks. Because the state-law duty merely paralleled FIFRA’s own requirements, she concluded that it was not preempted.

Justice Jackson also disagreed that EPA’s registration decision itself creates a federal labeling requirement. She argued that Congress recognized that a pesticide may remain misbranded even after EPA has approved its label. In the dissent’s view, EPA approval therefore should not foreclose a state-law claim alleging that a label omitted a necessary warning.

The dissent also expressed concern that the Court’s decision significantly limits the availability of state-law remedies challenging EPA-approved pesticide labels. Justice Jackson emphasized that scientific understanding may evolve after a pesticide is registered and questioned whether EPA’s administrative processes provide a complete substitute for traditional state tort litigation.

WHY THE DECISION MATTERS

Implications for Glyphosate

The Supreme Court’s decision resolves Mr. Durnell’s claims that Roundup caused his cancer and clarifies that similar claims based on state failure-to-warn theories are preempted by FIFRA. It does not, however, resolve all claims regarding Roundup. Many of those claims still appear likely to be addressed through a proposed $7.25 billion settlement between Monsanto and a group of plaintiffs that is currently pending court approval in Missouri state court.

Broader Implications

Although the decision arose from litigation involving Roundup, its significance extends beyond glyphosate-based products.

The Court confirmed that, under FIFRA, EPA’s product-specific registration and labeling determinations carry preemptive effect. In doing so, the Court reinforced Congress’s decision to centralize pesticide labeling decisions within EPA and to promote national uniformity through a single federal regulatory framework.

The opinion also further aligns FIFRA with the Supreme Court’s broader preemption jurisprudence. By relying extensively on Riegel v. Medtronic, the Court signaled that agency approval decisions may constitute federal requirements where Congress has established a comprehensive regulatory program and directed the agency to make product-specific safety and labeling determinations.

At the same time, the Court carefully limited its analysis to FIFRA’s statutory framework. The opinion repeatedly emphasized the features of the statute that support preemption, including EPA’s comprehensive review of pesticide safety, its authority over product labeling, the requirement that manufacturers continue using EPA-approved labels, and the statute’s express preemption provision. As a result, the decision’s application outside the FIFRA context will depend on the language and structure of other federal regulatory schemes.