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For more than a decade, litigation over glyphosate-based herbicides has sat at the intersection of federal pesticide regulation, state tort law, scientific risk assessment, and broader debates over the role of juries in evaluating product safety. The Supreme Court’s June 25, 2026, decision in Monsanto Company v. Durnell (Durnell) represents the Court’s most significant interpretation of the Federal Insecticide, Fungicide, and Rodenticide Act’s (FIFRA) preemption provision since Bates v. Dow Agrosciences LLC (Bates), and will reshape the litigation landscape for pesticides registered by the U.S. Environmental Protection Agency (EPA). The landmark ruling determined that state-law warnings requiring a specific labeling requirement “in addition to or different from” those approved by EPA are preempted under FIFRA.
At the center of the dispute is glyphosate, the active ingredient in Roundup®. EPA first registered glyphosate in 1974. Roundup is a trade name for glyphosate-containing products used from the initial registration until recently. Currently, products sold under the Roundup name do not contain glyphosate — although glyphosate herbicide formulations are widely available, especially for use on agricultural crops. Over the last five decades, as EPA states on its website for glyphosate, EPA repeatedly reviewed the chemical through registration review, cancer assessments, Scientific Advisory Panel (SAP) consultations, and other scientific evaluations.
In 1985, an EPA review classified glyphosate as a “possible human carcinogen” but the SAP found the data then equivocal, and after an additional animal cancer study, EPA reclassified glyphosate as “evidence of non-carcinogenicity.” Since 1991, each subsequent review by EPA concluded that glyphosate is not likely to be carcinogenic to humans when used according to label directions and continued to approve labeling that does not include a cancer warning. The scientific terminology of the underlying risk assessment categorizations has evolved to better describe the regulatory conclusion but has led to some public confusion about “what the science says” — terminology such as “possible,” “probable,” “non-carcinogenic,” and “not likely to be carcinogenic to humans.”
Additionally, numerous foreign regulatory authorities, including regulators in Canada, Australia, Japan, and the European Union, have reached similar conclusions that glyphosate is “not a human carcinogen,” which is contrary to a 2015 conclusion from the International Agency for Research on Cancer (IARC) that classified glyphosate as “probably carcinogenic to humans” (Group 2A) — creating one of the most well-known scientific disagreements in the assessment of glyphosate.
That disagreement fueled an unprecedented wave of state-law product liability litigation. Thousands of plaintiffs alleged that prolonged exposure to Roundup caused non-Hodgkin lymphoma and that then-producer Monsanto failed to warn consumers of the alleged cancer risk. Although plaintiffs asserted several theories of liability, failure-to-warn claims became one of the ways that plaintiffs could obtain substantial jury verdicts because they argued that Monsanto should have included a cancer warning beyond EPA’s federally approved labeling.
John Durnell brought one such action in Missouri state court after approximately twenty years of Roundup use. A Missouri jury found in his favor on the failure-to-warn claim and awarded approximately $1.25 million in damages. Monsanto argued throughout the litigation that FIFRA expressly preempted the claim because any state-law duty requiring a cancer warning would necessarily impose labeling requirements “in addition to or different from” those approved by EPA under Section 136v(b) of FIFRA. The Missouri Court of Appeals rejected that argument, deepening a split among courts considering similar claims and prompting Supreme Court review.
As discussed in detail in our June 26, 2026, blog, the Court concluded:
With respect to pesticide labels, FIFRA demands “[u]niformity” and expressly preempts state labeling requirements that are “in addition to” or “different from” federal labeling requirements. §136v(b). Durnell’s state-law failure-to-warn claim would require a cancer warning on Roundup’s label—a requirement “in addition to” and “different from” the label required by EPA under FIFRA. FIFRA therefore expressly preempts Durnell’s claim.
The case attracted extraordinary attention from agricultural organizations, state attorneys general, former EPA officials, public health organizations, environmental groups, manufacturers, and trade associations. Beyond its immediate implications for glyphosate, the case is widely viewed as a referendum on the extent to which EPA-approved labels provide national uniformity under FIFRA and whether state tort litigation may effectively impose alternative labeling obligations after EPA has completed its scientific review.
Commentary
The Supreme Court’s decision in Durnell represents one of the most consequential pesticide decisions in decades — it does not resolve the scientific debate surrounding glyphosate, but clarifies who has the authority to determine when pesticide labels must change. The Court did not weigh the evidence regarding glyphosate’s carcinogenicity or determine whether EPA reached the correct scientific conclusion. Rather, it held that when EPA has exercised its authority under FIFRA to approve a pesticide label, state-law failure-to-warn claims seeking to impose additional or different labeling requirements are expressly preempted. In doing so, the Court reaffirmed Congress’s objective of maintaining nationally uniform pesticide labeling while placing EPA’s scientific and regulatory determinations at the center of that framework.
Although the decision arose from litigation involving glyphosate, its implications extend well beyond Roundup. The Court’s reasoning reinforces the principle that FIFRA’s labeling scheme is intended to provide consistency across jurisdictions and that, under certain circumstances, registrants should not be forced to navigate conflicting warning obligations imposed through state tort litigation. Going forward, the decision is likely to influence litigation involving numerous EPA-registered pesticides and could reshape the strategic landscape for registrants facing claims based primarily on alleged labeling deficiencies.
Importantly, Durnell should not be viewed as eliminating pesticide litigation altogether. The decision addresses a specific category of claims — state-law failure-to-warn actions premised on the assertion that EPA-approved labels should have contained additional warnings. Other theories of liability, including certain design defect, manufacturing defect, negligent testing, fraud, or warranty claims, may continue to be asserted depending on the facts of individual cases and applicable state law. Plaintiffs’ attorneys will almost certainly explore alternative legal theories that attempt to avoid FIFRA preemption, and courts will likely be asked to define the boundaries of the Supreme Court’s holding over the coming years.
Justice Jackson’s Dissent
Although the Court concluded that FIFRA expressly preempts state-law failure-to-warn claims seeking labeling requirements different from those approved by EPA, Justice Ketanji Brown Jackson’s dissent, joined by Justice Neil Gorsuch, underscores that the broader policy debate surrounding federal preemption is far from settled. Justice Jackson argued that the majority interpreted FIFRA’s preemption provision too broadly by equating common-law damages actions with affirmative state labeling requirements. In the dissent’s view, state tort law does not compel manufacturers to alter federally approved labels; rather, it provides manufacturers with a choice between maintaining existing labeling and accepting potential liability or voluntarily strengthening warnings. Because tort verdicts do not directly regulate labeling in the same manner as statutes or regulations, Justice Jackson concluded that they should not necessarily constitute requirements “in addition to or different from” those imposed under FIFRA. The dissent also reflects a fundamentally different view of the relationship between federal regulation and state common law. Whereas the majority emphasized Congress’s desire for national labeling uniformity and EPA’s expertise in evaluating pesticide risks, Justice Jackson viewed state tort litigation as an important complementary mechanism that encourages manufacturers to reassess product safety as scientific understanding evolves, stating:
At the end of the day, then, the majority’s theory of express preemption rests on a misinterpretation of FIFRA. The EPA’s approval of a pesticide’s label does not create a labeling requirement under FIFRA. Instead, FIFRA’s key labeling requirement—the statutory prohibition on misbranding—continues to apply to registered pesticides even though the EPA has approved their labels. State-law claims that parallel the misbranding prohibition are not preempted, even if the claim requires a warning that was absent from the EPA-approved label.
The argument supporting “parallel” state-law claims is one that prevailed in another Supreme Court case, Bates. The Bates decision was distinguished from the facts in Durnell in the majority opinion because the failure-to-warn claim in Bates was an efficacy-based claim and a pesticide’s efficacy is not reviewed by EPA during the registration process, while the safety-based claim in Durnell is one that is thoroughly reviewed by EPA during registration.
Although the dissent did not prevail, it provides insight into how future plaintiffs may attempt to distinguish Durnell or encourage Congress to revisit FIFRA’s preemption provisions. More broadly, the dissent illustrates that the underlying policy questions surrounding pesticide regulation remain active even if one significant legal question has now been resolved.
Proposition 65 And Other Potential Impacts
One area where tensions may become particularly evident is California’s Proposition 65 (Prop 65) program. The history of glyphosate and Prop 65 has been fraught with challenges since the Office of Environmental Health Hazard Assessment (OEHHA) first listed glyphosate as a substance known to cause cancer in 2017. These challenges included direct intervention by EPA, culminating in EPA taking an unusual step in 2019 by issuing guidance stating that it would not approve product labels claiming glyphosate is known to cause cancer when EPA had repeatedly concluded that glyphosate is unlikely to cause cancer. There also was a successful legal challenge resulting in the U.S. Court of Appeals for the Ninth Circuit on November 7, 2023, finding the Prop 65 warning requirement was unconstitutional as a violation of First Amendment commercial free speech rights since the warning language was not “purely factual and uncontroversial.” That case is discussed in detail in our November 14, 2023, memorandum.
Now, the Durnell decision adds additional grounds to invalidate a Prop 65 warning by holding that the warning is unconstitutional because the Prop 65 warning language is preempted by FIFRA. Just as glyphosate is not the only Prop 65 warning to be held to be unconstitutional under the First Amendment, so too might Prop 65 warning requirements for pesticides other than glyphosate be preempted based on the Durnell decision. Specifically, Prop 65 warnings that exposure to a particular pesticide can cause cancer, birth defects, or other reproductive harm would seemingly be in jeopardy when the EPA-approved label does not include any such language. If there are pesticides where EPA’s reviews and assessments are not clearly unequivocal as to its decision of risks of cancer, birth defects, or other reproductive harm, there may be questions in future litigation as to whether the Durnell decision applies.
It also would seem there are areas ripe for testing the breadth of the Durnell decision, as preemption issues have been raised in other contexts, like products under the Federal Food, Drug, and Cosmetic Act (FFDCA) or consumer products regulated under the Federal Hazardous Substances Act. Such arguments will be stronger where preemption language and the review process by the particular agency parallel that of FIFRA. For example, FFDCA (21 U.S.C. § 360k) sets forth language that no state can establish a requirement for certain medical devices that is “different from, or in addition to” requirements established by the U.S. Food and Drug Administration (FDA). But is the relevant medical device review process similar enough to EPA’s pesticide label review process? Existing case law on these preemption issues and how they compare to and contrast with the Durnell decision also must be considered. These are the types of arguments we could see in future challenges.
The Supreme Court’s decision does not eliminate California’s broader authority to regulate chemicals through state law, but it does highlight the increasingly difficult relationship between federal labeling uniformity under FIFRA and state initiatives that seek to require additional warnings concerning pesticide products.
Political Tensions
The Court’s decision also arrives during a period of unusual political alignment surrounding pesticide policy. Historically, debates over pesticide regulation largely followed familiar partisan lines, with industry groups — supported generally by Republican members — advocating for reliance on EPA’s scientific determinations, and environmental organizations — supported generally by Democratic members — favoring more precautionary regulatory approaches. Recent political developments suggest that those traditional alignments are becoming less predictable.
The emergence of the Make America Healthy Again (MAHA) movement has introduced additional voices considered a major part of the Republican voter base into discussions surrounding pesticide regulation, food safety, and chemical exposures. While MAHA encompasses a broad range of policy priorities, many of its advocates have questioned existing federal approaches to pesticide regulation and have called for greater scrutiny of glyphosate and other agricultural chemicals. As a result, some policymakers who otherwise support reduced regulatory burdens have simultaneously advocated for increased examination of pesticide safety.
This creates an interesting dynamic following Durnell. By significantly limiting one of the principal avenues through which glyphosate has been challenged over the past decade (state-law failure-to-warn litigation), the decision may shift attention toward EPA registration review proceedings, congressional oversight, public health initiatives, and state legislative efforts as part of the MAHA agenda. In other words, the controversy surrounding glyphosate is unlikely to disappear simply because the litigation landscape has changed. Rather, it may increasingly play out in administrative and political forums instead of courtrooms, especially if the MAHA movement continues to heavily influence policy decisions at the state and federal level.
Executive Branch Policies
The Administration’s recent Executive Order promoting domestic glyphosate production adds yet another layer to this evolving landscape. The Order reflects a broader policy objective of strengthening domestic agricultural supply chains and ensuring reliable access to crop protection products viewed as important to food production and national security.
Although the Supreme Court’s opinion does not reference the Executive Order, regulated entities will likely view these developments together. On one hand, the Administration has signaled support for maintaining access to glyphosate as an important agricultural input. On the other hand, aspects of the MAHA movement have expressed skepticism regarding continued reliance on glyphosate despite broader political alignment on other issues. These competing priorities illustrate that pesticide policy increasingly transcends traditional partisan divisions and instead reflects competing objectives relating to agricultural productivity, public health, environmental protection, and domestic manufacturing.
For registrants, this means that legal certainty following Durnell does not necessarily translate into broader policy certainty. Perhaps more unpredictable is the effect of MAHA movement priorities on the Republican response in Congress and the Administration. EPA registration review, executive branch priorities, congressional oversight, and state initiatives may continue to evolve even as failure-to-warn litigation becomes more constrained.
Conclusion
Perhaps the most significant lesson from Durnell is that the decision is fundamentally about institutional authority rather than toxicology. The Court did not determine whether glyphosate causes cancer or whether EPA’s scientific conclusions are beyond debate. Instead, it determined that Congress assigned EPA, not fifty different state tort systems, the responsibility of establishing nationally uniform pesticide labeling under FIFRA.
That distinction is likely to have implications well beyond glyphosate that will continue to impact administrative law decisions, especially in a post-Loper Bright landscape. Registrants should expect plaintiffs to pursue alternative litigation theories, states to continue exploring regulatory initiatives outside the traditional failure-to-warn context, and advocacy organizations to focus increasing attention on EPA registration reviews and related administrative proceedings. California’s Prop 65 program, MAHA-related policy initiatives, and future executive branch actions will likely remain important drivers of the national conversation surrounding pesticide regulation.
Accordingly, while Durnell substantially reshapes one aspect of pesticide litigation, it will not end the broader regulatory debate. Instead, the decision marks the beginning of a new phase in which disputes over pesticide safety are likely to shift from jury trials toward administrative proceedings, state regulatory programs, executive branch policymaking, and congressional oversight. For regulated entities, active engagement with EPA’s registration process and continued monitoring of state and federal policy developments will be just as important as litigation strategy in the years ahead.