Key takeaways:
- Durnell may significantly limit Roundup failure-to-warn litigation and provides further clarification on how FIFRA preempts state failure-to-warn claims tied to EPA-approved pesticide labels.
- Plaintiffs who allege bodily injury from pesticide exposure may increasingly turn to other theories of liability (such as design defect and breach of implied warranty) that have historically proven difficult for plaintiffs to establish.
- Congress retains the ability to amend FIFRA, and the ruling is already drawing renewed political attention to its labeling provisions. Coalitions on different sides of the pesticide debate may find shared reasons to revisit the statute, which could lead to meaningful changes in the framework for pesticide liability going forward.
- For casualty insurers, the durable lesson is about how liability moves. Litigation trajectories can shift before they appear in loss experience, and the value of forward-looking analytics lies in identifying the exposures most likely to be affected as the legal landscape changes.
On June 25, 2026, the US Supreme Court ruled 7-2 in Monsanto v. Durnell that federal pesticide law preempts(1) state-law failure-to-warn claims against the makers of Roundup. For casualty insurers, although this decision may reduce certain liabilities, it’s a reminder that litigation can shift quickly and alter the emergence of claims in profound ways. The Durnell decision may significantly curtail outstanding Roundup litigation, but the more important impact is how its reasoning may influence the viability of other ongoing pesticide failure-to-warn litigation.
The potential scale of the ruling’s immediate impact alone makes it notable. Tens of thousands of pending lawsuits are part of a proposed US$7.25 billion settlement not yet approved by the court. The Durnell ruling could change how the parties view the fairness of the proposed settlement. These immediate results are, of course, important, but Supreme Court decisions often carry broader significance in their underlying logic and reasoning, and how they will apply to other cases.
The court’s reasoning in Durnell is broad; the court had several narrower paths available, including those tied to specific Environmental Protection Agency (EPA) actions regarding glyphosate. Instead, its application of the statutory language of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) held that state claims requiring labeling “in addition to or different from” federal requirements are expressly preempted, without articulating significant limiting caveats. In doing so, the court appears to move beyond two decades of more ambiguous interpretation under Bates v. Dow Agrosciences, which, lower courts often ruled, had preserved space for state-law liabilities, including failure-to-warn theories, by reading FIFRA’s preemption clause narrowly.
A significant change to pesticide liability
For much of the past 50 years, claims alleging that a pesticide’s label inadequately warned the user about harms have been a commonly used and often successful legal theory for plaintiffs in product liability litigation. By holding that FIFRA’s express preemption clause completely overrides state failure-to-warn claims, the court significantly narrowed the scope for product liability claims that judges had previously found available under Bates, using another FIFRA clause stating that despite the express preemption clause, pesticide manufacturers had a duty to continually ensure their products were not “misbranded.”
The apparent post-Durnell standard, though, suggests that approval of a pesticide’s label will be treated as conclusive evidence that the pesticide is not misbranded under federal law, thereby preempting any state law requirements to the contrary(2).
It’s not yet clear how the Durnell ruling will affect glyphosate’s liability risk more broadly. Plaintiffs retain other legal theories they’ve been asserting, including design defect and negligence, although in similar contexts those theories have sometimes been found preempted. It appears likely, though, that the EPA’s regulation of pesticides will take on a more central role in assessing the potential for liability, starting with its interpretation of FIFRA’s warning and misbranding requirements alongside its evaluation of the scientific evidence supporting the pesticide’s registration.
Pesticide liability risk can also evolve through other means: Congress retains the ability to amend FIFRA, the EPA continues to control labeling decisions and registration reviews, and states retain the authority to ban a pesticide’s use within their borders. Each of these levers can move independently, and each can change the trajectory of casualty exposure in ways that traditional loss-based analysis doesn’t capture.
An early test of the post-Durnell world is likely to come in pending pesticide litigation involving paraquat and chlorpyrifos, both of which are prominent in current mass-tort activity in US courts. Paraquat is an herbicide that plaintiffs have alleged causes Parkinson’s disease, and it now represents one of the larger active mass torts in the United States.
As of June 2026, Moody’s CoMeta™ platform is tracking roughly 9,920 paraquat cases across 39 federal and 12 state courts, with nearly all centered on bodily injury claims and a defendant base spanning 43 companies across 26 industries.
Chlorpyrifos is an agricultural insecticide with a smaller but evolving litigation footprint; 47 cases across nine federal and five state courts as of the same period, and a more varied mix of allegations spanning bodily injury, property damage, and economic claims. This year, plaintiff law firms began recruiting plaintiffs who allege their exposure to chlorpyrifos caused their Parkinson’s disease, and the first such lawsuit was filed in a Pennsylvania state court just days before the Durnell decision.
Like all pesticides in the United States, paraquat and chlorpyrifos are regulated under FIFRA and have EPA-approved labels, making the Durnell opinion highly relevant to these cases.
The scale and structure of these two litigations differ, but the underlying legal questions are similar to those in the Roundup litigation. Each involves EPA-approved labels, relies heavily on failure-to-warn theories, and has generally proceeded under the assumption that state juries can evaluate the adequacy of those warnings. Durnell does not automatically resolve either mass litigation, but it changes the analytical starting point by potentially preempting the failure-to-warn cause of action.
Plaintiffs’ other legal theories are likely to be examined to see if they conflict with the emerging preemption framework articulated in Durnell based on the regulatory record and pesticide manufacturers’ ability to comply with state law without running afoul of federal law.
Tracking these developments in close to real time becomes more than a descriptive exercise. This type of analysis can help insurers identify which theories, venues, defendants, and industries may be among the first to absorb the impact.
Beyond pesticides: Where the reasoning may apply next
Although Durnell is a pesticide case, the broader relevance of the court’s reasoning will likely depend on the evolving jurisprudence around federal preemption of state law. The court’s analysis focused on the section of FIFRA that says state law may not impose labeling requirements “in addition to or different from” those required by the EPA.
That preemptive language is not unique to pesticides. Similar or nearly identical preemption provisions appear in other federal statutes governing several regulatory regimes: the Medical Device Amendments; the Food, Drug, and Cosmetic Act (governing pharmaceuticals); the Federal Aviation Administration Authorization Act; the Federal Meat Inspection Act; and more.
In Durnell, the court relied on a medical device preemption case, Riegel v. Medtronic, and observed that FIFRA’s preemption clause was identical in function to the Medical Device Amendments’ preemption clause. Although the decision turns on FIFRA’s specific text, product liability defendants for products regulated by similar laws are likely to cite Durnell, in an attempt to apply preemption to their products as well.
That does not mean every federally regulated product is suddenly insulated from failure-to-warn claims. Many statutes governing regulated products do not have strong express preemption clauses, and other statutes’ regulatory schemes can bring other types of preemption into the equation.
Because each statute has its own structure, purpose, and legislative history, each typically yields statute-specific case law as courts evaluate the issues presented in individual cases. But Durnell offers defendants a strong precedent that similar express preemption clauses may be read more broadly by the courts, particularly where they prevent states from applying requirements “different from or in addition to” those determined by the relevant federal agency. Statutes that provide for more nuanced regulatory schemes, such as pharmaceuticals, are likely to be evaluated accordingly, especially when Congress has declared its desire for national labelling uniformity for regulated products.
What this means for insurers
Durnell is less a single event and more a reminder of how casualty exposure can behave in practice. Liability often does not move in a straight line, and a single court decision at any point in its evolution, whether from the trial court, an appellate court, or the Supreme Court, can alter the trajectory of one of the largest mass torts in recent memory(3). Sometimes those decisions can have implications that extend beyond the individual product at issue, whether that’s across pesticides, federally regulated products, or even the broader interpretation of state-level liability.
The value of forward-looking analytics lies in helping identify the claims, defendants, jurisdictions, and portfolios that may be affected as the legal landscape evolves and in supporting more timely interpretation of developments. Reserve adequacy, pricing assumptions, and portfolio composition can all be adjusted before traditional lagging indicators reflect the change.
As always, an insurer’s task includes identifying accounts with potential mass-tort exposure and managing accumulations related to potential mass-tort risk. This also includes reviewing the assumptions embedded in reserves, pricing, and accumulation management.
Although the ruling may reduce litigation alleging pesticide makers failed to warn their customers of health risks, it may also redirect plaintiffs toward alternative theories, different defendants, or to petition Congress to amend the law in ways that could affect the scope or accessibility of pesticide-related harms.
For casualty risk, the takeaway is not that exposure has become smaller or simpler. It appears to be becoming more interconnected. Science, regulation, litigation, and policy do not operate in sequence. They move in parallel, influence one another in ways that are not always straightforward, and, in some cases, can result in step changes to how the system functions. Durnell is one example of how quickly that system can shift and why recognizing those shifts may help inform insurers’ assessment of emerging risks before they are reflected in loss experience.
References:
[1] Preemption is based on the Supremacy Clause (Article VI) of the US Constitution that says that the “Laws of the United States…shall be the supreme Law of the Land…any Thing in the Constitution of Laws of any State to the Contrary notwithstanding.” Loosely speaking, it means that state laws that contravene federal law are nullified.
[2] The court’s language is particularly clear on this point: “As a matter of law, state tort law may not impose labeling requirements “in addition to” or “different from” federal requirements imposed under FIFRA.” Pp. 21-22 of the Durnell slip opinion.
[3] For example, a Delaware Supreme Court decision in July 2025 overturned a lower court’s decision to admit scientific evidence about the heartburn drug Zantac, leading to the immediate dismissal of 80,000 product liability cases alleging the drug caused cancer by degrading into a chemical called NDMA.