Dennis v. Monsanto Co.

CourtCalifornia Court of Appeal
DecidedNovember 24, 2025
DocketD084130
StatusPublished

This text of Dennis v. Monsanto Co. (Dennis v. Monsanto Co.) is published on Counsel Stack Legal Research, covering California Court of Appeal primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Dennis v. Monsanto Co., (Cal. Ct. App. 2025).

Opinion

Filed 11/24/25 CERTIFIED FOR PUBLICATION

COURT OF APPEAL, FOURTH APPELLATE DISTRICT

DIVISION ONE

STATE OF CALIFORNIA

MIKE DENNIS, D084130

Plaintiff and Respondent,

v. (Super. Ct. No. 37-2021- 00047326-CU-PO-NC) MONSANTO COMPANY,

Defendant and Appellant.

APPEAL from a judgment of the Superior Court of San Diego County, Kevin A. Enright, Judge. Affirmed. Bryan Cave Leighton Paisner, K. Lee Marshall, Jean-Claude André and Andrew E. Tauber for Defendant and Appellant. Kiesel Law, Paul R. Kiesel and Melanie M. Palmer; Ehrlich Law Firm and Jeffrey I. Ehrlich; Law Offices of Clinton Ehrlich and Clinton E. Ehrlich; Clark, Love & Hutson, Scott A. Love, Adam Peavy and Jason M. Milne for Plaintiff and Respondent. Mike Dennis was diagnosed with mycosis fungoides, a form of non- Hodgkin’s lymphoma (NHL), after using Roundup, an herbicide manufactured and sold by Monsanto Company (Monsanto), monthly for approximately 20 years. Dennis sued Monsanto and alleged, among other claims, that they failed to warn consumers that using Roundup in accordance with widespread and common practice presented a substantial danger. The jury found Monsanto liable and awarded Dennis $7 million in economic damages and $325 million in punitive damages. The trial court granted Monsanto’s motion for judgment notwithstanding the verdict (JNOV) in part and reduced the punitive damages to $21 million. Monsanto appeals and asserts the trial court erred by failing to conclude Dennis’s failure to warn claims were preempted by the Federal Insecticide, Fungicide, and Rodenticide Act (7 U.S.C. § 136 et seq.) (FIFRA), and by failing to conclude that the punitive damages award violated due process by punishing Monsanto multiple times for the same conduct. We find no error and affirm the judgment. I. FACTUAL AND PROCEDURAL BACKGROUND In the operative first amended complaint, Dennis alleged that he applied Roundup around his home property on a monthly basis, throughout the year, every year from 2000 until 2020. Roundup is a “non-selective herbicide used to kill weeds.” Its main ingredient is glyphosate, which was discovered by Monsanto in 1970. In 2015, the International Agency for Research on Cancer, an agency of the World Health Organization, classified glyphosate as a Group 2A herbicide, meaning that it is probably carcinogenic to humans. The agency found that NHL is among the cancers most associated with exposure to glyphosate. Roundup also contains other ingredients that increases absorption of the active ingredient, glyphosate, into both plant leaves and human skin. Dennis was diagnosed with mycosis fungoides, a form of NHL, in June 2020. Dennis alleged that his diagnosis was the direct and proximate result of his exposure to Roundup. He alleged further that Monsanto continued marketing and selling the product despite knowing that it carried a risk of causing NHL and without providing adequate warning to consumers.

2 Dennis asserted causes of action for design defect, failure to warn (negligent and strict liability), and negligence against Monsanto. As to the failure to warn causes of action, the jury made the following findings on a directed verdict form: − Roundup has a risk of causing NHL that was known or knowable in light of scientific and medical knowledge that was generally accepted in the scientific community at the time of Monsanto’s manufacture, distribution, or sale.

− The potential risks of Roundup present a substantial danger to persons when used in accordance with widespread and commonly recognized practice.

− Ordinary customers would not have recognized that potential risk.

− Monsanto knew or should reasonably have known that Roundup can cause or was likely to cause NHL when used in accordance with widespread and commonly recognized practice.

− Monsanto knew or should reasonably have known that users would not realize that danger.

− Monsanto failed to adequately warn of the potential risks or danger and failed to adequately instruct on the safe use of Roundup.

− A reasonable manufacturer, distributor, or seller under the same or similar circumstances would have warned of the danger or instructed on the safe use of Roundup.

− The lack of sufficient warnings was a substantial factor in causing Mike Dennis’s mycosis fungoides.

In addition, the jury found that Monsanto “engage[d] in conduct with malice, oppression or fraud committed by one or more officers, directors or managing agents of Monsanto acting on behalf of Monsanto.”

3 Based on those findings, the jury awarded Dennis $2 million in past noneconomic losses, $5 million in future noneconomic losses, and $325 million in punitive damages. Monsanto filed motions for a new trial and JNOV. As relevant to the present appeal, Monsanto asserted that FIFRA expressly and impliedly preempted Dennis’s failure to warn claims, and that the punitive damages award must be set aside because it violated due process by punishing Monsanto multiple times for the same conduct and because the ratio of the punitive to compensatory damages was excessive. The trial court found that the award of $325 million in punitive damages lacked a sufficiently reasonable relationship to the compensatory damages of $7 million. Accordingly, the court reduced the punitive damages award to $21 million. The court rejected Monsanto’s remaining arguments and entered an amended judgment adjusting the punitive damages award. Monsanto filed a timely notice of appeal. II. DISCUSSION Monsanto does not dispute the jury’s verdict or its associated findings in this appeal. Monsanto raises two distinct legal arguments: 1) FIFRA preempts Dennis’s failure to warn claims brought under California law; and 2) the punitive damages award, as adjusted, still violates due process by punishing Monsanto multiple times for the same conduct. We address each in turn. A. FIFRA Does Not Preempt Dennis’s Failure to Warn Claims

We first consider whether FIFRA preempts California state failure to warn claims arising from allegedly inadequate warnings regarding health risks associated with pesticides registered and labeled under FIFRA.

4 1. Federal Preemption A state law, based either in statute or common law, can be preempted by the supremacy clause of the United States Constitution in one of two ways: by express preemption or implied preemption. (Pilliod v. Monsanto Co. (2021) 67 Cal.App.5th 591, 613 (Pilliod); American Meat Institute v. Leeman (2009) 180 Cal.App.4th 728, 745–746 (Leeman).) Express preemption occurs “ ‘when Congress “define[s] explicitly the extent to which its enactments pre-empt state law;” ’ ” for example, by including express language in the federal statute. (Pilliod, supra, 67 Cal.App.5th at p. 613.) Implied preemption occurs “when state law ‘regulates conduct in a field that Congress intended the Federal Government to occupy exclusively,’ ” and when state law “ ‘ “actually conflicts with federal law,” ’ ” either because “ ‘ “it is impossible to comply with both state and federal law” ’ ” or because “ ‘ “the state law stands as an obstacle to the accomplishment of the full purposes and objectives of Congress.” ’ ” (Leeman, supra, 180 Cal.App.4th at p. 746.) Preemption that arises because it is impossible to comply with both state and federal law is sometimes referred to as “ ‘impossibility preemption.’ ” (Pilliod, supra, 67 Cal.App.5th at p. 613.) “Federal preemption of state law is a question of law that we review de novo.” (Pilliod, supra, 67 Cal.App.5th at p. 614.) 2. Bates v. Dow Agrosciences LLC In Bates v. Dow Agrosciences LLC (2005) 544 U.S. 431

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