Client Alert: When Federal Registration Meets State Tort Law: The Stakes in Monsanto Co. v. Durnell
Date: May 18, 2026
By:
Dale G. Mullen
The factual engine of the case is a divergence among scientific bodies. In 2015, the International Agency for Research on Cancer classified glyphosate as probably carcinogenic to humans. The U.S. Environmental Protection Agency has reached the opposite conclusion, determining that glyphosate is not likely to be carcinogenic and declining to require a cancer warning on Roundup labeling. Durnell asks who, given that divergence, gets to decide what a label must say.
The Statutory Bargain
The Federal Insecticide, Fungicide, and Rodenticide Act (“FIFRA”), 7 U.S.C. §§ 136–136y, divides authority between Washington and the states with deliberate care. Section 136v(a) preserves the states’ power to regulate the sale or use of a registered pesticide. Section 136v(b) withholds something narrower: a state “shall not impose or continue in effect any requirements for labeling or packaging in addition to or different from” those FIFRA requires. The structure is a savings clause paired with a preemption clause — states retain general regulatory authority but lose the power to dictate label content. FIFRA separately defines a pesticide as “misbranded” when its labeling lacks adequate warning or caution statements. 7 U.S.C. § 136(q)(1)(G).
The Court last construed § 136v(b) in Bates v. Dow Agrosciences LLC, 544 U.S. 431 (2005). Bates held that common-law duties can constitute “requirements,” but that a state failure-to-warn rule survives preemption when it is equivalent to FIFRA’s own misbranding standard rather than additional to or different from it. A manufacturer, the Court explained, should not be held liable under a state labeling requirement unless it would also be liable for misbranding under FIFRA. That “parallel requirements” principle is the fulcrum of Durnell.
A Split Over a Single Provision
The lower courts have fractured over how to apply that principle. In Hardeman v. Monsanto Co., 997 F.3d 941 (9th Cir. 2021), cert. denied, 142 S. Ct. 2834 (2022), and Carson v. Monsanto Co., 92 F.4th 980 (11th Cir. 2024), the Ninth and Eleventh Circuits held that FIFRA does not preempt Roundup failure-to-warn claims, reasoning that the relevant state-law duties track FIFRA’s misbranding prohibition. The Third Circuit reached the opposite result in Schaffner v. Monsanto Corp., 113 F.4th 364 (3d Cir. 2024), holding such claims expressly preempted. The Missouri Court of Appeals aligned with the Ninth and Eleventh Circuits when it affirmed a $1.25 million verdict for John Durnell. Durnell v. Monsanto Co., No. ED112410 (Mo. Ct. App. Feb. 11, 2025). The Supreme Court granted certiorari limited to one question: whether FIFRA preempts a label-based failure-to-warn claim where EPA has not required the warning.
Two Theories, Unequal in Strength
Two preemption theories are before the Court, and they are not equally strong.
The first is express preemption under § 136v(b). Monsanto’s position is that a jury verdict premised on the absence of a cancer warning necessarily imposes a labeling requirement different from the federal label EPA approved — and that Bates’s parallel-requirements safe harbor cannot rescue a claim when EPA has affirmatively declined to require the warning. The United States, appearing as amicus in support of Monsanto, advances the same reading, invoking National Meat Ass’n v. Harris, 565 U.S. 452 (2012), where the Court held that a similarly worded preemption clause displaces even nonconflicting state requirements that merely differ from federal ones. Durnell’s answer is textual: FIFRA itself defines misbranding to include the absence of adequate warnings, so a state duty to warn enforces — rather than departs from — the federal standard, and nothing in the statute converts EPA’s registration decision into the exclusive measure of a label’s adequacy.
The second theory is implied conflict preemption, and it is where the case is most interesting. Monsanto argues that it could not have added a cancer warning without EPA approval, making compliance with both federal law and a state duty to warn impossible. That argument runs along the fault line between two of the Court’s pharmaceutical-labeling decisions. In Wyeth v. Levine, 555 U.S. 555 (2009), the Court rejected impossibility preemption because the brand-name manufacturer could have strengthened its warning unilaterally, and it required “clear evidence” that the agency would have refused the change. In PLIVA, Inc. v. Mensing, 564 U.S. 604 (2011), the Court found impossibility preemption because a generic manufacturer was bound to copy the brand label and could not deviate. Monsanto contends that a FIFRA registrant resembles the PLIVA generic, locked to an EPA-approved label. Durnell contends that it resembles the Wyeth brand, free to seek a label amendment — as the manufacturer in fact did for another of its products. The Missouri Court of Appeals took the Wyeth view, holding that Monsanto’s prediction that EPA would reject a warning fell short of an irreconcilable conflict, particularly because Monsanto never asked. Which analogy the Court adopts will do more to shape future pesticide litigation than any single sentence about § 136v(b).
Two Variables: A Shifting Federal Position and the End of Deference
Two contextual features deserve attention.
First, the position of the United States has not been static. In earlier Roundup litigation, the federal government took differing views across administrations on whether these claims are preempted; its current merits brief supports Monsanto. A registrant building a compliance or defense strategy around the federal position should treat that position as a variable, not a fixed point.
Second, Loper Bright Enterprises v. Raimondo, 603 U.S. 369 (2024), eliminated the deference courts once extended to agency interpretations of ambiguous statutes. EPA’s scientific judgment about glyphosate may still carry persuasive weight, but EPA’s view of what FIFRA means for preemption purposes now stands on its own footing. That development cuts against treating an EPA-approved label as though it carried the preemptive force of a statute or a duly promulgated regulation.
What the Decision Will Not Settle
A ruling for Monsanto would not sweep as broadly as headlines may suggest. The question presented reaches only label-based failure-to-warn claims. It does not touch § 136v(a), which preserves the states’ authority to regulate pesticide sale and use; a state or locality that restricts where, when or how a product may be applied stands on different statutory ground that Durnell does not address.
Nor would a decision resolve the parallel legislative effort. The House-passed Farm Bill, H.R. 7567, 119th Cong. (2026), originally contained provisions — Sections 10205 through 10207 — that would have codified nationwide label uniformity and curtailed state and local authority over pesticides, before they were removed on the House floor. Whether comparable language reappears in the Senate is independent of how the Court rules. A party tracking only the litigation, or only the bill, is watching half the board.
Implications for Producers and Conservation Stakeholders
For agricultural producers, the practical questions are immediate. How are pesticide-related indemnities, warranties and hold-harmless terms allocated in current supply, purchase and lease agreements? Does a registrant’s documented label-compliance history — including its interactions with EPA — strengthen or weaken a preemption defense that a producer may need to invoke or rely upon downstream?
For conservation organizations and local governments, the questions run the other direction. A ruling for Monsanto would narrow one avenue of accountability but would leave sale-and-use regulation under § 136v(a) intact; the practical value of that retained authority rises if the labeling route closes. Both constituencies have a concrete stake in the Senate’s forthcoming Farm Bill text and, where appropriate, in amicus participation while the judicial and legislative tracks remain open.
The Court is expected to decide Durnell before the Term ends, likely by late June. The prudent course is not to wait for the opinion but to map exposure under each plausible outcome now — because the contractual, regulatory and legislative decisions that turn on the answer come due before the answer arrives.
This Client Alert is part of Whiteford’s broader environmental and regulatory coverage, including our Lexology State Q&As addressing key environmental legislation and compliance frameworks across Virginia, North Carolina, and the District of Columbia.
For questions about this Client Alert or its implications, please contact Dale Mullen to discuss how these issues may apply to your specific circumstances.
The information contained here is not intended to provide legal advice or opinion and should not be acted upon without consulting an attorney. Counsel should not be selected based on advertising materials, and we recommend that you conduct further investigation when seeking legal representation.