Summary of Monsanto/Bayer Appeal to Ninth Circuit Court (Hardeman)

Michael Stiles
7 min readDec 17, 2019

The following extracts and summarizes from the 105 page appeal of an unfavorable verdict in the federal San Francisco District Court.

Plaintiff Edwin Hardeman sued Monsanto, alleging that his use of glyphosate to treat weeds and other vegetation on his property — which spanned many years and ended in 2012 — led to his diagnosis of non-Hodgkin’s lymphoma (Diffuse Large B-Cell Lymphoma (DLCBL) in early 2015. Non-Hodgkin’s lymphoma is a cancer that affects white blood cells in the immune system. Approximately 70% or more of cases are idiopathic — i.e., they develop for unknown reasons. Id. However, some causes of the cancer — such as hepatitis C — are well established. Hardeman had hepatitis C for 25 to 40 years before developing non-Hodgkin’s lymphoma. At trial, Hardeman pursued a theory based on Monsanto’s failure to warn him of the alleged carcinogenic potential of Roundup. At the time of Hardeman’s exposure, no regulatory or public health body — including IARC — had concluded that glyphosate might cause cancer. Although Hardeman pointed to IARC’s 2015 report as establishing that glyphosate is carcinogenic, he claimed that Monsanto had become aware of glyphosate’s allegedly carcinogenic properties “[a]s early as the 1980’s”.


I. Hardeman’s state-law failure-to-warn case is both expressly and by implication preempted by federal law. FIFRA gives EPA the authority to regulate pesticide labeling and prohibits states from imposing any labeling requirement “in addition to or different from” federal requirements. 7 U.S.C. §136v(b).

Both express preemption and impossibility preemption principles bar this suit. National uniformity of pesticide labeling is a bedrock principle of FIFRA. Bates v. Dow Agrosciences LLC, 544 U.S. 431, 452 n.26 (2005). An applicant intending to register a pesticide for sale must submit for EPA approval any labeling that will accompany the pesticide. 7 U.S.C. §136a(c)(1)©. Once that labeling is approved, the manufacturer generally may not change it without prior EPA approval. 40 C.F.R. §§152.44, 152.46. FIFRA expressly prohibits states from “impos[ing]” any labeling requirement “in addition to or different from” federal requirements. 7 U.S.C. §136v(b). And a pesticide that is sold with any labeling that is “false or misleading in any particular” is misbranded in violation of federal law. [As the Bates Court explained, where EPA determines that a pesticide should be accompanied by one warning (such as “CAUTION”) but a jury concludes under state law that the label should include a more aggressive one (such as “DANGER”), then the state-law rule on which the verdict rests “would be pre-empted” by §136v(b). 544 U.S. at 453. That is so because, by selecting a less aggressive warning, EPA necessarily rejected the more aggressive warning. The same principle applies here. EPA cannot register a pesticide for sale in the United States without determining that it does not pose an unreasonable risk to human health, and in doing so it determines exactly what warnings are required on the pesticide’s labeling — and what warnings are not warranted. EPA has for decades exercised that authority by registering glyphosate without the warning Hardeman seeks, having fully considered the question whether it causes cancer and having analyzed all of the evidence on which Hardeman relied.]

II. The district court made several evidentiary and instructional errors relating to causation, the central issue in the case. Those errors were prejudicial and require reversal:

A. In this case, the district court’s legal error led to the improper admission of unreliable testimony about both general and specific causation. As to general causation, the court allowed testimony that relied on flawed studies and deviated from basic statistical norms. As to specific causation, the court allowed Hardeman’s experts to engage in a unsupported “always glyphosate” approach — deeming exposure to glyphosate above a certain number of days to be a cause of non-Hodgkin’s lymphoma, even though more than 70% of such cases have no known etiology and even though Hardeman had lived with hepatitis C, a well established cause of the cancer, for decades.

Hardeman’s suit should never have gone to the jury because his expert opinions on the central issue in the case — whether glyphosate caused Hardeman’s illness — should not have been admitted. The district court admitted that flawed testimony only because it misread this Circuit’s Daubert decisions and failed to exercise its gatekeeping responsibilities properly.

The district court rightly expressed its “skeptic[ism]” about the methodologies Hardeman’s experts applied at both steps of the inquiry. E.g.,ER33, 38. It said the experts’ opinions were “borderline” and “sometimes cross[ed] into the realm of junk science,” recognizing that they would be inadmissible under the interpretation of Daubert applied by other Circuits. See ER36–39; see also ER50 (underlying scientific evidence was “rather weak” and “too equivocal”).Nonetheless, the district court admitted the experts’ opinions under the theory that “district courts in the Ninth Circuit must be more tolerant of borderline expert opinions than in other circuits.”

B. The jury’s causation inquiry was further warped by the court’s erroneous admission of IARC’s idiosyncratic classification of glyphosate as a probable cause of cancer. IARC’s conclusion was admitted even though the jury was not likely to understand the limited meaning of that classification and even though that conclusion added nothing to the underlying studies on which it was based except to lend them an inappropriate air of authority. The district court compounded the error by refusing to mitigate that prejudice by allowing Monsanto to admit evidence of the worldwide regulatory consensus rejecting IARC’s conclusion — thus leaving the jury with the mistaken impression that IARC’s and EPA’s conclusions were equally valid and in equipoise.

“[T]he overwhelming majority of” national and international health authorities charged with approving pesticides “have determined [glyphosate] is not a cancer risk.” National Ass’n of Wheat Growers v. Zeise, 2018 WL 3000488, at *2 (E.D. Cal. June 12, 2018); supra pp. 8–9. Against that consensus, a single working group at IARC classified glyphosate as a “probable carcinogen” in 2015. Admission of IARC’s conclusion was error by itself, because the minimal probative value of IARC’s conclusion was far outweighed by the unfair prejudice and juror confusion it caused. See Fed. R. Evid. 403. And the district court rendered that error even more prejudicial by excluding evidence of the regulatory consensus that glyphosate does not cause cancer, which left the jury with a false sense of the importance of IARC’s conclusion.

C. The causation determination rests on yet another legal flaw. The district court erroneously instructed the jury on both a theory of “but-for causation” and a theory of “concurrent independent causes.” The district court issued that instruction even though California courts, recognizing the theories are inherently contradictory, do not allow jurors to be instructed on the two theories in the same case, and even though Hardeman forswore reliance on the second theory. The inevitable result was prejudicial confusion.

Under California law, a plaintiff must prove that a defendant’s negligence was “a substantial factor in bringing about the injury.” Rutherford v. Owens-Ill., Inc., 941 P.2d 1203, 1214 (Cal. 1997); see also Cal. Civ. Jury Instruction (“CACI”) 430 (California pattern substantial-factor instruction). This “substantial factor” test requires the plaintiff to prove that but for the defendant’s conduct, the harm would not have occurred. See Viner v. Sweet, 70 P.3d 1046, 1051 (Cal. 2003). It applies in all cases except the “exceptional situation” where the injury may have resulted from concurrent independent causes.

III. In any event, the jury had no basis to conclude that Monsanto violated a duty to warn Hardeman. A duty to warn of a particular risk arises under California law only if the risk was known or knowable in light of the generally recognized and prevailing best scientific and medical knowledge at the relevant time. The evidence at trial established the opposite point — that, under the prevailing knowledge at the time of Hardeman’s exposure (and now), glyphosate does not cause cancer.

This is because a “manufacturer is not under a duty to warn of ‘every report of a possible risk, no matter how speculative, conjectural, or tentative,’” and “reports of isolated or speculative injuries do not constitute generally accepted [scientific] knowledge.” Rosa, 684 F.3d at 946–947 (quoting Finn v. G.D. Searle & Co., 677 P.2d 1147, 1153 (Cal. 1984)); see also CACI №1205, Directions for Use (Dec. 2011) (duty to warn arises only where the risk is recognized as “prevailing in the relevant scientific community” and “represents the best scholarship available”; a “minority view,” even if “advanced by one body of scientific thought and experiment,” is not “prevailing”). This Court should therefore direct judgment for Monsanto as a matter of law on Hardeman’s failure-to-warn claims.

IV. Finally, the district court erroneously concluded that Monsanto was eligible for punitive damages. A defendant that markets without a cancer warning a product that the vast majority of regulators and scientists have concluded is non-carcinogenic does not engage in the kind of egregious behavior that warrants punishment akin to a criminal fine. And in any event, quadruple punitive damages are unwarranted, given the strong evidence of Monsanto’s good faith and the substantial compensatory damages awarded.C


The district court upheld a massive verdict sanctioning Monsanto for selling glyphosate without a cancer warning even though (a) regulatory agencies worldwide, including EPA, have repeatedly concluded that glyphosate does not cause cancer, (b) EPA has concluded that such a cancer warning would be unlawful under federal law, and © reliable scientific studies have found no association between glyphosate and non-Hodgkin’s lymphoma. That result was only possible because of the district court’s serious legal errors — especially its misunderstanding of the relationship between federal and state law governing pesticide labels and its failure to exercise its proper authority to ensure that expert testimony is based on reliable scientific methodologies rather than speculation and conclusory assertions. If the judgment is allowed to stand, those errors will spread to thousands of other Roundup cases. This Court should reverse and direct judgment for Monsanto.