19 October 2026, California: The U.S. Supreme Court on October 13, 2026, granted Monsanto’s petition in Monsanto Co. v. Mike Dennis (Docket No. 26-139), vacated a California appellate court’s judgment, and sent the case back for reconsideration in light of the Court’s June 2026 ruling in Monsanto v. Durnell, a decision that found federal law preempts state failure-to-warn claims against Roundup.
The underlying case was brought by Mike Dennis, a Carlsbad, California resident, who sued Monsanto, now owned by Bayer, in San Diego Superior Court. Dennis alleged that two decades of monthly Roundup use caused his non-Hodgkin lymphoma. A jury initially awarded him $332 million. The trial court reduced that award to approximately $28 million, split between $7 million in compensatory damages and $21 million in punitive damages. California’s Fourth Appellate District, Division One, affirmed that reduced verdict in November 2025.
The Supreme Court’s action, known as a GVR (grant, vacate, remand), does not decide the Dennis case on the merits. It directs the California appellate panel to reconsider its ruling using the legal standard set in Durnell, decided June 25, 2026, in a 7-2 opinion written by Justice Kavanaugh. That ruling held that the Federal Insecticide, Fungicide, and Rodenticide Act expressly preempts state-law claims demanding a cancer warning on Roundup labels, reasoning that EPA-approved pesticide labels must be uniform nationwide and that a state-mandated warning would be “in addition to” and “different from” what federal law requires. Justices Jackson and Gorsuch dissented in Durnell.
Monsanto has said it will ask the California appellate court to vacate the Dennis verdict entirely now that the case is back before it, rather than simply revisit the damages calculation. The company has consistently argued that Durnell forecloses failure-to-warn claims of this kind nationwide.
This is not an isolated development. The Durnell ruling in June effectively opened the door for the Supreme Court to send back other pending Roundup verdicts that rested on the same failure-to-warn theory, and Dennis is the case now moving through that process. Bayer has faced thousands of Roundup-related lawsuits in U.S. courts over claims linking glyphosate exposure to cancer, and the company has repeatedly pointed to regulatory findings, including EPA’s own classification of glyphosate as not likely to be carcinogenic to humans, in defending the product.
The practical effect for Bayer is significant but not immediate. The California appellate court must now re-examine the case under Durnell, a process that will take additional months, and Monsanto’s stated goal of a full vacatur rather than a reduced damages figure suggests the company will continue pressing an aggressive litigation strategy in cases still working through the appeals pipeline. Bayer is scheduled to report third-quarter 2026 results on November 3, with analysts already flagging agriculture-segment timing effects ahead of that release, though the company has not linked the Dennis remand to any specific financial guidance.
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