Idaho Judge Reads Supreme Court’s Roundup Ruling Narrowly

A federal judge in Idaho has allowed a lawsuit alleging that Roundup causes cancer to go to trial, holding that the Supreme Court’s June 2026 ruling in Monsanto v. Durnell only precludes label-based theories against the weedkiller’s manufacturer. The case is an early indication that state-law tort claims may remain viable after Durnell if they do not depend on Roundup’s label.

Issued October 1, 2026, the order denies Monsanto’s motion for summary judgment on the plaintiff’s negligence and design defect claims. Although the court granted summary judgment on the plaintiff’s failure-to-warn claim, the court stressed that such a claim could succeed on different facts.

The case is one of thousands alleging that glyphosate, the active ingredient in past formulations of Roundup, causes cancer. Initially transferred to a multi-district litigation panel, the case was remanded to the District of Idaho for trial.

Meanwhile, the first state-court Roundup trial since Durnell is currently underway in St. Louis County, Missouri, which includes negligence and design-defect claims. That court found failure-to-warn allegations preempted, however.

EPA is also in the midst of reevaluating glyphosate’s human health risks, and recently requested scientific input on its review.

Legal Background

Many of the lawsuits against Monsanto have included claims that the manufacturer did not provide adequate warnings about Roundup’s alleged carcinogenicity. These “failure-to-warn” claims often focused on the absence of warning language on Roundup’s label.

On June 25, 2026, in Durnell, the Supreme Court held that the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) preempts certain Roundup failure-to-warn claims. As discussed in a previous post, the court found that FIFRA and its implementing regulations require manufacturers to use EPA’s approved pesticide label. EPA has not determined that glyphosate causes cancer, and its approved Roundup label carries no cancer warning.

Because the state tort claim would require Monsanto to add a cancer warning, the Court reasoned that the claim would impose a labeling requirement “in addition to or different from” EPA’s approved label. FIFRA expressly prohibits such state-law requirements, so the Court found the claim expressly preempted.

Impossibility Preemption Inapplicable

Before the District of Idaho, Monsanto argued that all of the plaintiff’s claims should be barred by impossibility preemption. The court was unpersuaded, finding the doctrine inapplicable.

Impossibility preemption occurs when it is impossible to comply with state and federal requirements simultaneously. In Durnell, the Supreme Court did not reach impossibility preemption, finding express preemption sufficient to decide the case. But Monsanto pointed to a Durnell footnote observing that FIFRA bars selling a pesticide whose composition differs from the one described at registration. That made it impossible for Monsanto to change its formula, the company argued.

The court disagreed. “Monsanto cannot hide behind impossibility preemption when there is no evidence indicating it could not have pursued changing Roundup’s formula with the EPA had it wanted to,” the decision states. Monsanto knew of alternatives and ultimately changed the formula, the court noted, adding that “it was not impossible to ask EPA to change the formula.”

Non-Label Claims Survive Durnell

The plaintiff brings three claims: negligence, failure-to-warn, and design defect. Because of Durnell, the court held that the plaintiff cannot put on evidence about Roundup’s labeling. However, to the extent that they do not rest on the label, the court determined that none of the three claims are precluded by Durnell.

Addressing negligence, the court held that “nothing in Durnell” suggests “its holding should be read so broadly as to encompass negligence claims that are not based on labeling.” The court rejected Monsanto’s arguments that it was “prohibited” from making any claims differing from those approved by EPA. The plaintiff “is not necessarily saying Monsanto should have warned him that Roundup caused cancer; just that [Roundup] was potentially dangerous for his health,” the decision states.

However, the court noted that the distinction between negligence and failure-to-warn claims would be “a tough line for both parties to tow,” emphasizing that the parties should “hew closely to the negligence framework.”

The court likewise recognized that a failure-to-warn claim could theoretically survive on materials other than the product label, stating that such a claim ‘can still be pleaded in this type of case if facts exist to support it.’”

Finally, the court determined that the plaintiff’s design defect claim was not a disguised failure-to-warn claim and could proceed. The “allegation is that Roundup’s chemical formulation is unsafe. Full stop,” the decision states. The court noted that causation, hotly disputed on competing expert evidence, is for the jury.

The court also cited the Supreme Court’s 2005 decision in Bates v. Dow Agrosciences LLC, which notes that common-law rules requiring manufacturers to design reasonably safe products free of defects do not require manufacturers to label or package products in a particular way.

Facts Preclude Failure-to-Warn Claim

Although the court determined that a failure-to-warn claim could theoretically survive Durnell, the court found evidentiary deficiencies in this case that were fatal to the claim here.

Besides product labeling, the only failure-to-warn theory that was not “severely under-developed” was based on advertising, the court held. But according to the court, the plaintiff admitted that he could not recall seeing Roundup advertisements during deposition. While the plaintiff later tried to recharacterize those statements, the court doubted that it cured the problem.

“Simply put, the Court is concerned that, were it to allow this claim to proceed to trial, Hoge would essentially be arguing a failure to warn labeling claim just without the word ‘label,’” the decision states. “This cuts against the Durnell decision.”

The case is Hoge v. Monsanto Co., No. 4:25-cv-277 (D. Idaho). Trial is set for February 2027.