FOR PUBLICATION
`
`UNITED STATES COURT OF APPEALS
`FOR THE NINTH CIRCUIT
`
`
`
`EDWIN HARDEMAN,
`Plaintiff-Appellee/
`Cross-Appellant,
`
`
`
`
`
`Nos. 19-16636
`
`19-16708
`
`D.C. Nos.
`3:16-cv-00525-VC
`3:16-md-02741-VC
`
`
`OPINION
`
`v.
`
`
`MONSANTO COMPANY,
`Defendant-Appellant/
`Cross-Appellee.
`
`Appeal from the United States District Court
`for the Northern District of California
`Vince G. Chhabria, District Judge, Presiding
`
`Argued and Submitted October 23, 2020
`San Francisco, California
`
`Filed May 14, 2021
`
`Before: Michael D. Hawkins, N. Randy Smith, and
`Ryan D. Nelson, Circuit Judges.
`
`Opinion by Judge R. Nelson;
`Dissent by Judge N.R. Smith
`
`
`
`
`

`

`2
`
`
`HARDEMAN V. MONSANTO
`
`SUMMARY*
`
`Pesticides / Punitive Damages
`
`
`
`
`The panel affirmed the district court’s judgment in favor
`
`of Edwin Hardeman in his action alleging that Monsanto’s
`pesticide, Roundup, caused his non-Hodgkin’s lymphoma.
`
`ingredient
`the active
`is pesticide with
` Roundup
`glyphosate. Since 2015, thousands of cancer victims sued
`Monsanto in state and federal court. This appeal arose out
`of the first bellwether trial for the federal cases consolidated
`in a multidistrict litigation. The jury awarded Hardeman
`$5,267.634.10 in compensatory damages, and $75 million in
`punitive damages. The district court reduced the punitive
`damages award to $20 million.
`
`The panel held that Hardeman’s state failure-to-warn
`
`claims based on Roundup’s labeling were consistent with the
`Federal Insecticide, Fungicide, and Rodenticide Act
`(“FIFRA”) and thus were neither expressly nor impliedly
`preempted. Specifically, the panel affirmed the district
`court’s conclusion that Hardeman’s state failure-to-warn
`claims were “equivalent to” and “fully consistent with”
`FIFRA and therefore not expressly preempted. Bates v. Dow
`Agrosciences LLC, 554 U.S. 431, 449 (2005). In addition,
`because Monsanto could comply with both FIFRA and
`California
`law, FIFRA did not
`impliedly preempt
`Hardeman’s state failure-to-warn claims.
`
`
`
`* This summary constitutes no part of the opinion of the court. It
`has been prepared by court staff for the convenience of the reader.
`
`

`

`3
`
`HARDEMAN V. MONSANTO
`
`
`
`The panel held that the district court ultimately applied
`
`the correct standard from Daubert v. Merrell Dow
`Pharmaceuticals, Inc., 509 U.S. 579 (1993), and did not
`abuse its discretion in admitting Hardeman’s expert
`testimony. Despite its incorrect assumption that this court
`was more permissive than others in admitting Daubert
`testimony, the district court still employed the correct legal
`standard for reliability when it admitted Hardeman’s expert
`testimony. The panel held further that the district court did
`not abuse its discretion in concluding that Hardeman’s
`experts reliably based their general causation opinions on
`epidemiological evidence showing a connection between
`glyphosate and cancer. The panel also held that the district
`court did not abuse its discretion in admitting Hardeman’s
`expert testimony on specific causation to show that
`Hardeman’s cancer was caused by glyphosate, rather than
`some other factor. Here, Hardeman’s experts reliably used
`differential diagnosis because they ruled in glyphosate based
`on the epidemiological evidence supporting the general
`causation opinions and ruled out alternate causes, such as
`idiopathy and Hepatitis C (HCV).
`
`The panel held that the district court did not abuse its
`
`discretion in admitting the International Agency for
`Research on Cancer’s classification of glyphosate as
`probably carcinogenic and three regulatory rejections of that
`classification by excluding evidence from other regulatory
`bodies. The panel held further that even if these evidentiary
`decisions were erroneous, any error was harmless because it
`was more probable than not that the admission of the
`evidence did not affect the jury’s verdict.
`
`The panel held that the district court’s jury instruction on
`
`causation was erroneous because it was inconsistent with the
`
`

`

`HARDEMAN V. MONSANTO
`
`4
`
`Judicial Council of California Civil Jury Instructions and
`California case law, but it was harmless error.
`
`The panel held that the district court properly denied
`
`Monsanto judgment as a matter of law because evidence
`showed the carcinogenic risk of glyphosate was knowable at
`the time of Hardeman’s exposure.
`
`The panel held that evidence supported a punitive
`
`damages award, punitive damages were properly reduced,
`and the reduced award – while close to the outer limit – was
`constitutional. Specifically, the panel held that punitive
`damages were permissible under California law because
`substantial evidence was presented that Monsanto acted with
`malice by, among other things, ignoring Roundup’s
`carcinogenic risks. The panel held that the jury’s $75 million
`punitive damages award was “grossly excessive” given the
`mitigating factors found by the district court. However,
`considering the evidence of Monsanto’s reprehensibility, the
`district court’s reduced $20 million punitive damages award
`(a 3.8 to 1 damages ratio), while at the outer limits of
`constitutional propriety, ultimately comported with due
`process.
`
`The panel cautioned that although this appeal involved a
`
`bellwether trial, many of its holdings were fact-specific, and
`different Roundup
`cases may
`present
`different
`considerations, leading to different results.
`
`Judge N.R. Smith dissented to section VII.B, concerning
`
`punitive damages. He would hold that Monsanto’s low
`degree of reprehensibility cannot constitutionally justify the
`district court’s substantial punitive damages award. The
`facts found by the district court did not support a 3.8:1 ratio
`to compensatory damages.
`
`

`

`
`
`
`HARDEMAN V. MONSANTO
`
`5
`
`COUNSEL
`
`
`Seth P. Waxman (argued) and Paul R.Q. Wolfson, Wilmer
`Cutler Pickering Hale and Dorr LLP, Washington, D.C.;
`Thomas G. Sprankling and Henry J. Becker, Wilmer Cutler
`Pickering Hale and Dorr LLP, Palo Alto, California; Leon T.
`Kenworthy, Clair H. Chung, James Barton, Samuel M.
`Strongin, and Rafael J. Gallardo Hevia, Wilmer Cutler
`Pickering Hale and Dorr LLP, Washington, D.C.; Brian L.
`Stekloff and Rakesh Kilaru, Wilkinson Walsh and Eskovitz
`LLP, Washington, D.C.; Philip J. Perry and Richard P.
`Bress, Latham & Watkins LLP, Washington, D.C.;
`Michael X. Imbroscio and David M. Zionts, Covington &
`Burling LLP, Washington, D.C.; Lee Marshall, Bryan Cave
`Leighton Paisner LLP, San Francisco, California; for
`Defendant-Appellant/Cross-Appellee.
`
`David J. Wool (argued) and Aimee H. Wagstaff, Andrus
`Wagstaff PC, Lakewood, Colorado; Leslie A. Brueckner,
`Public Justice, Oakland, California; Jennifer A. Moore,
`Moore Law Group PLLC, Louiseville, Kentucky; for
`Plaintiff-Appellee/Cross-Appellant.
`
`Jonathan D. Brightbill (argued) and Eric Grant, Deputy
`Assistant Attorneys General; Jennifer Scheller Neumann,
`Varudhini Chilakamarri, and Matthew R. Oakes, Attorneys;
`Environment and Natural Resources Division, United States
`Department of Justice, Washington, D.C.; Erin S. Koch and
`Amber L. Aranda, Attorneys, EPA Office of General
`Counsel, Washington, D.C.; for Amicus Curiae United
`States.
`
`Andrew Wiener (argued), Laura Zuckerman, and Dennis
`Ragen, Deputy Attorneys General; Harrison M. Pollack,
`Supervising Deputy Attorney General; Office of the
`
`

`

`HARDEMAN V. MONSANTO
`
`6
`
`Attorney General, Oakland, California; for Amicus Curiae
`State of California.
`
`Shannen W. Coffin and Sara Beth Watson, Steptoe &
`Johnson LLP, Washington, D.C., for Amicus Curiae
`CropLife America.
`
`Laura W. Brill, Nicholas F. Daum, and Sharon S. Song,
`Kendall Brill & Kelly LLP, Los Angeles, California, for
`Amicus Curiae Genentech Inc.
`
`Douglas J. Peterson, Attorney General; Justin D. Lavene,
`Maegan L. Woita, and Joshua E. Dethlefsen, Assistant
`Attorneys General; Office of the Attorney General, Lincoln,
`Nebraska; Lawrence G. Wasden, Attorney General of Idaho;
`Jeff Landry, Attorney General of Louisiana; Wayne
`Stenehjem, Attorney General of North Dakota; Jason
`Ravnsborg, Attorney General of South Dakota; Ken Paxton,
`Attorney General of Texas; and Sean D. Reyes, Attorney
`General of Utah; for Amici Curiae States of Nebraska,
`Idaho, Louisiana, North Dakota, South Dakota, Texas, and
`Utah.
`
`Curtis A. Cole, Cassidy C. Davenport, and Scott M.
`Klausner, Cole Pedroza LLP, San Marino, California, for
`Amici Curiae California Medical Association, California
`Dental Association, and California Hospital Association.
`
`William R. Stein, Eric S. Parnes, Stephen R. Halpin III, and
`J. Chesley Burruss, Hughes Hubbard & Reed LLP,
`Washington, D.C.; Theodore V.H. Mayer, Hughes Hubbard
`& Reed LLP, New York, New York; Steven P. Lehotsky and
`Michael B. Schon, U.S. Chamber Litigation Center,
`Washington, D.C.; James C. Stansel and Melissa B. Kimmel,
`Pharmaceutical Research and Manufacturers of America,
`
`

`

`HARDEMAN V. MONSANTO
`
`
`
`Washington, D.C.; for Amici Curiae Chamber of Commerce
`of the United States of America, and Pharmaceutical
`Research and Manufacturers of America.
`
`Adina H. Rosenbaum and Allison M. Zieve, Public Citizen
`Litigation Group, Washington, D.C., for Amicus Curiae
`Public Citizen.
`
`Matthew W.H. Wessler and Larkin Turner, Gupta Wessler
`PLLC, Washington, D.C.; Bruce Stern, President, American
`Association for Justice, Washington, D.C.; for Amicus
`Curiae American Association for Justice.
`
`Ashley Keller, Travis Lenker, and Warren Postman, Keller
`Lenkner LLC, Chicago, Illinois; Ernest A. Young, Apex,
`North Carolina; for Amici Curiae Public Law Scholars.
`
`Ryan D. Talbott, Center for Food Safety, Portland, Oregon,
`for Amici Curiae Center for Food Safety and Center for
`Biological Diversity.
`
`Carrie Apfel, Earthjustice, Washington, D.C.; Alexis
`Andiman and Peter Lehner, Earthjustice, New York, New
`York; Patti Goldman, Earthjustice, Seattle, Washington; for
`Amici Curiae California Rural Legal Assistance Foundation,
`Farmworker Association of Florida, Farmworker Justice,
`Migrant Clinicians Network, Pesticide Action Network,
`United Farm Workers, and UFW Foundation.
`
`Melanie Benesh and Caroline Leary, Environmental
`Working Group, Washington, D.C., for Amicus Curiae
`Environmental Working Group.
`
`
`
`7
`
`
`
`

`

`8
`
`
`HARDEMAN V. MONSANTO
`
`OPINION
`
`R. NELSON, Circuit Judge:
`
`Monsanto Company manufactures Roundup, a pesticide
`with the active ingredient glyphosate. Since 2015, thousands
`of cancer victims have sued Monsanto in state and federal
`court, alleging that Roundup caused their non-Hodgkin’s
`lymphoma. This appeal arises out of the first bellwether trial
`for the federal cases consolidated in a multidistrict litigation.
`
`The jury returned a verdict in favor of plaintiff Edwin
`Hardeman, awarding him $5,267,634.10 in compensatory
`damages and $75 million in punitive damages. The district
`court reduced the jury’s punitive damages award to
`$20 million.
`
`Monsanto appeals, arguing the Federal Insecticide,
`Fungicide, and Rodenticide Act (“FIFRA”) preempts
`Hardeman’s failure-to-warn claims; the district court made a
`series of evidentiary and jury instruction errors; the district
`court erred in denying judgment as a matter of law; and the
`punitive damages award violates California law and the Due
`Process Clause. Hardeman cross-appeals, arguing the jury’s
`$75 million punitive damages award was constitutional.
`
`We affirm the district court and hold that (1) Hardeman’s
`state failure-to-warn claims are not preempted by FIFRA;
`(2) the district court ultimately applied the correct standard
`from Daubert v. Merrell Dow Pharmaceuticals, Inc.,
`509 U.S. 579 (1993), and did not abuse its discretion in
`admitting Hardeman’s expert testimony; (3) the district court
`did not abuse its discretion in admitting the International
`Agency for Research on Cancer’s classification of
`glyphosate as probably carcinogenic and three regulatory
`rejections of that classification but excluding evidence from
`
`

`

`9
`
`HARDEMAN V. MONSANTO
`
`
`
`other regulatory bodies; (4) the district court’s jury
`instruction on causation, though erroneous, was harmless;
`(5) Monsanto was properly denied judgment as a matter of
`law because evidence shows the carcinogenic risk of
`glyphosate was knowable at the time of Hardeman’s
`exposure; and (6) evidence supports a punitive damages
`award, punitive damages were properly reduced, and the
`reduced award—while close
`to
`the outer
`limits—is
`constitutional.
`
`I
`
`A
`
`the United States Environmental
`Under FIFRA,
`Protection Agency (“EPA”) enforces “the use, . . . sale[,] and
`labeling[] of pesticides.” Bates v. Dow Agrosciences LLC,
`544 U.S. 431, 437 (2005) (citation omitted). A state may
`“not impose or continue in effect any requirements for
`labeling or packaging in addition to or different from those”
`required by FIFRA. 7 U.S.C. § 136v(b).
`
`FIFRA requires pesticide manufacturers to register their
`products with EPA. 7 U.S.C. § 136a(a). EPA makes
`registration determinations after considering available
`scientific data, § 136a(c)(1)(F), (c)(2)(A); 40 C.F.R.
`§ 158.500, and FIFRA requires EPA to re-review a
`pesticide’s registration, including its effects on human
`health, every fifteen years, § 136a(g)(1)(A). FIFRA states,
`however, that “[i]n no event shall registration of an article be
`construed as a defense for the commission of any offense
`under this subchapter.” § 136a(f)(2). Rather, “[a]s long as
`no cancellation proceedings are in effect,” registration of a
`pesticide is merely “prima facie evidence that the pesticide,
`its labeling and packaging comply with the registration
`provisions of the subchapter.” Id.
`
`

`

`10
`
`
`HARDEMAN V. MONSANTO
`
`institute cancellation proceedings,
`EPA can also
`7 U.S.C. § 136d(b), or take other enforcement action against
`the manufacturer of a registered pesticide if the agency
`determines the product is “misbranded.” Bates, 544 U.S.
`at 439. Remedies for misbranding include civil and criminal
`penalties. Id. at 439 n.11 (citing 7 U.S.C. § 136l). A duly
`registered pesticide can be misbranded if the label “does not
`contain adequate instructions for use, or if its label omits
`necessary warnings or cautionary statements.” Bates,
`544 U.S. at 438 (citation omitted). “Because it is unlawful
`under the statute to sell a pesticide that is registered but
`nevertheless misbranded, manufacturers have a continuing
`obligation to adhere to FIFRA’s labeling requirements.” Id.
`(citations omitted). This obligation includes a duty to seek
`approval to amend a label that does not contain all
`“necessary warnings or cautionary statements.” Id. (citation
`omitted).
`
`Starting in 1974, EPA registered pesticides containing
`glyphosate, the active ingredient in Roundup.1 EPA,
`Glyphosate Proposed Interim Registration Review Decision
`4 (Apr. 2019) (“Proposed Interim Registration Review”). In
`1985, an EPA review of a mouse study found “[g]lyphosate
`was oncogenic in male mice,” causing rare tumors. EPA
`classified glyphosate as a possible human carcinogen. Since
`then, however, EPA has repeatedly approved the use of
`glyphosate as a pesticide, each time concluding that it is not
`likely to be carcinogenic to humans. See Nat’l Fam. Farm
`Coal. v. EPA, 966 F.3d 893, 905 (9th Cir. 2020).
`
`
`1 Though commonly referred to as an herbicide, Roundup is defined
`as a pesticide under 7 U.S.C. § 136(t), (u). Roundup contains
`glyphosate, water, and other ingredients called “surfactants.”
`
`

`

`
`
`
`HARDEMAN V. MONSANTO
`
`11
`
`In the early 1990s, EPA reevaluated glyphosate’s effects
`on human health as part of its regular review of glyphosate’s
`registration. After considering numerous carcinogenicity
`studies in rats and mice—including new evidence submitted
`by Monsanto—EPA changed its designation of glyphosate
`to a “Group E carcinogen” signifying “evidence of non-
`carcinogenicity in humans.”
`
`In 2015, a working group at the International Agency for
`Research on Cancer (“IARC”), an agency of the World
`Health Organization, issued a report classifying glyphosate
`as a “Group 2A” agent, meaning it is “probably carcinogenic
`to humans” based on glyphosate’s “limited evidence” of
`cancer in humans and “sufficient evidence” of cancer in
`experimental animals. IARC’s classification was a “hazard
`identification,” the first step of a public health assessment
`designed
`to
`identify cancer hazards.
` That hazard
`determination asked whether glyphosate “is capable of
`causing cancer under some circumstances,” but did not
`include a “risk assessment” gauging the carcinogenic effects
`from
`real-world human exposure.
` Since
`IARC’s
`classification, other national and international agencies
`charged with reviewing pesticides—such as the European
`Union’s European Chemicals Agency (“ECA”), European
`Food Safety Authority (“EFSA”), and the national health
`authorities of Australia, Canada, Germany, and New
`Zealand—have reported that scientific evidence does not
`show glyphosate causes cancer.
`
`When the IARC report was released, EPA was
`conducting its registration review of glyphosate, during
`which it examined various scientific studies, including those
`IARC considered. In 2017, EPA published its proposed
`conclusion: Glyphosate was not likely to be carcinogenic to
`humans. But, that same year, pursuant to Proposition 65,
`
`

`

`HARDEMAN V. MONSANTO
`
`12
`
`California law categorized glyphosate as a chemical known
`to the state to cause cancer. Cal. Off. of Env’t Health Hazard
`Assessment, Glyphosate, (“Glyphosate Proposition 65”),
`https://oehha.ca.gov/proposition-65/chemicals/glyphosate.
`That classification triggered a state law requirement to attach
`a warning label to glyphosate products. See id.; Cal. Health
`& Safety Code § 25249.6.
`
`In April 2019—one month after the jury verdict in this
`case—EPA noted that commenters “expressed concerns that
`glyphosate formulations are more toxic than glyphosate
`alone.” Proposed Interim Registration Review at 10. EPA
`explained that “there are few research projects that have
`attempted to directly compare technical grade glyphosate to
`the formulations under the same experimental design,” but
`“[i]f at any time, information becomes available that
`indicates adverse human health effects of concern for
`exposure to glyphosate or its formulations, EPA intends to
`review it and determine the appropriate regulatory action.”
`Id. at 11.
`
`About five months after the jury verdict, EPA issued a
`letter to all registrants of glyphosate-containing products.
`Letter from Michael L. Goodis, EPA, Office of Pesticide
`Programs (Aug. 7, 2019) (“2019 letter”). The 2019 letter
`was not the product of any formal proceeding, was not
`published in the Federal Register, did not cite any new
`scientific findings, and took no position on whether
`Roundup causes cancer. Instead, this letter challenged
`California’s inclusion of glyphosate in Proposition 65 as
`contrary to “EPA’s determination that glyphosate is ‘not
`likely to be carcinogenic to humans.’” Id. at 1. Given this
`determination, EPA “considers the Proposition 65 warning
`language” that glyphosate is carcinogenic “to constitute a
`false and misleading statement” that violates FIFRA’s
`
`

`

`HARDEMAN V. MONSANTO
`
`
`
`prohibition against “misbranded” substances. Id. 1–2 (citing
`§ 136(q)(1)(A)). The letter concluded with EPA instructing
`registrants to remove such warning statements from labels of
`glyphosate-based pesticides. Id. at 2.
`
`13
`
`B
`
`In 2016, Hardeman sued Monsanto alleging that his use
`of Roundup—which started in the 1980s and ended in
`2012—led to his diagnosis of non-Hodgkin’s lymphoma
`(“NHL”) in early 2015. Hardeman’s case is one of
`approximately 5,000 in federal court alleging that Roundup
`causes NHL. The Judicial Panel on Multidistrict Litigation
`consolidated those cases for pretrial proceedings in the
`Northern District of California. Hardeman’s case was the
`first of these consolidated cases to go to trial.
`
`NHL is a cancer that affects white blood cells in the
`immune system. Approximately 70% or more of NHL cases
`are idiopathic, meaning they develop for unknown reasons.
`However, some causes of NHL—such as hepatitis C
`(“HCV”)—are well established. Hardeman had HCV for
`25 to 40 years before developing NHL.
`
`Hardeman alleged Monsanto’s failure to warn him of the
`carcinogenic risks of Roundup caused his NHL. Monsanto
`moved to dismiss, arguing that Hardeman’s claims were
`preempted by FIFRA given EPA’s
`registration of
`glyphosate, approval of
`the Roundup
`label, and
`classification of glyphosate as non-carcinogenic. The
`district court denied Monsanto’s motion. Monsanto raised
`preemption again in a motion for summary judgment, which
`the district court likewise denied.
`
`The district court bifurcated the pretrial proceedings.
`The first phase addressed “general causation”—whether
`
`

`

`HARDEMAN V. MONSANTO
`
`14
`
`glyphosate can cause NHL at exposure levels humans might
`experience.
` The second phase addressed “specific
`causation”—whether Hardeman’s exposure to Roundup
`caused his NHL.
`
`The district court granted in part and denied in part
`Monsanto’s motion
`to exclude Hardeman’s general
`causation experts, allowing three of Hardeman’s experts to
`testify—Dr. Portier, Dr. Ritz, and Dr. Weisenburger. These
`experts introduced their general causation opinions with
`scientific evidence from epidemiology (study of disease in
`human populations), toxicology (animal studies), and
`genotoxicology (cell studies); applied the Bradford Hill
`criteria;2 and used meta-analyses that combined and
`analyzed the results of case-control studies.
`
`that
`The district court, however, acknowledged
`significant problems with Hardeman’s experts’ analyses
`made it a “very close question” whether their testimony was
`admissible to support general causation. In re Roundup
`Prods. Liab. Litig., 390 F. Supp. 3d 1102, 1108 (N.D. Cal.
`2018). The district court interpreted the Ninth Circuit’s
`approach to Daubert as requiring “slightly more room for
`deference to experts in close cases than might be appropriate
`in some other Circuits.” Id. at 1113 (citations omitted).
`Ultimately, the district court concluded Hardeman’s three
`
`2 The Bradford Hill criteria are nine factors generally accepted as
`relevant to assessing causation, such as: (1) the strength of the
`association;
`(2) consistency;
`(3)
`specificity;
`(4)
`temporality;
`(5) biological gradient or dose response; (6) biological plausibility;
`(7) coherence with other scientific knowledge; (8) experimental
`evidence; and (9) analogy. See In re Roundup Prods. Liab. Litig., 390 F.
`Supp. 3d 1102, 1116 (N.D. Cal. 2018) (citing Austin Bradford Hill, The
`Environment and Disease: Association or Causation?, 58 Proceedings
`of the Royal Society of Medicine 295 (1965)).
`
`

`

`HARDEMAN V. MONSANTO
`
`
`
`experts’ opinions were relevant and reliable, satisfying
`Federal Rule of Evidence 702 and Daubert.
`
`15
`
`The district court later denied Monsanto’s motion to
`exclude Hardeman’s
`specific
`causation
`experts.
`Hardeman’s experts performed differential diagnosis, a
`methodology by which a physician “rules in” all potential
`causes of a disease, “rules out” those for “which there is no
`plausible evidence of causation, and then determines the
`most likely cause among those that cannot be excluded.”
`Wendell v. GlaxoSmithKline LLC, 858 F.3d 1227, 1234 (9th
`Cir. 2017). Hardeman’s experts considered various risk
`factors beyond Roundup exposure that could explain his
`disease, including age, race, obesity, hepatitis B (“HBV”),
`and HCV, as well as idiopathic origin—i.e., no known cause.
`They concluded Roundup caused Hardeman’s NHL by
`ruling in Roundup based on general causation expert
`opinions and ruling out HCV and idiopathy3 as causes of
`Hardeman’s NHL. The district court admitted the experts’
`opinions, noting this circuit affords experts “wide latitude in
`how they practice their art when offering causation
`opinions.” In re Roundup, 358 F. Supp. 3d at 960 (citing
`Wendell, 858 F.3d at 1237).
`
`Monsanto requested a bifurcated trial, with the first
`phase addressing whether Roundup caused Hardeman’s
`cancer (without reference to any regulatory decisions
`regarding glyphosate or Roundup) and the second phase
`
`3 As to idiopathy, the district court held that “[i]t is sufficient for a
`qualified expert, in reliance on his clinical experience, review of a
`plaintiff[’s] medical records, and evaluation of the general causation
`evidence, to conclude that an ‘obvious and known risk factor[]’ is the
`cause of that plaintiff’s disease.” In re Roundup Prods. Liab. Litig.,
`358 F. Supp. 3d 956, 960 (N.D. Cal. 2019) (quoting Wendell, 858 F.3d
`at 1235).
`
`

`

`HARDEMAN V. MONSANTO
`
`16
`
`addressing liability and damages (where the jury could see
`some of that evidence). Monsanto moved to exclude all
`evidence regarding IARC’s report, which detailed the
`agency’s classification of glyphosate as probably
`carcinogenic, as irrelevant and likely to confuse and distract
`the jury. But if IARC evidence were admitted, Monsanto
`argued, the district court should admit evidence that
`numerous regulatory agencies around the world concluded
`that glyphosate is safe.
`
`Ultimately, the district court excluded IARC’s report but
`admitted IARC’s classification of glyphosate as probably
`carcinogenic to mitigate the prejudice caused to Hardeman
`due to bifurcation of the trial. The district court also
`admitted conclusions from EPA, EFSA, and ECA that
`glyphosate was safe but excluded conclusions from other
`regulatory bodies as cumulative.
`
`At trial, Hardeman’s experts testified that his exposure
`to glyphosate caused his NHL. Monsanto’s experts testified
`that little evidence links glyphosate to cancer in humans and
`that Hardeman’s HCV most likely caused his cancer or his
`cancer was idiopathic.
`
`The district court issued a “substantial factor” causation
`instruction. The jury was instructed that, to rule for
`Hardeman, it must find that glyphosate exposure was a but-
`for cause of his cancer or one of two or more factors that
`independently could have caused his cancer.
`
`After Phase One (on causation), the jury returned a
`verdict that Roundup exposure was a “substantial factor” in
`causing Hardeman’s NHL. After Phase Two (on liability
`and damages), the jury found that Monsanto failed to warn
`about Roundup’s NHL risk and Hardeman was entitled to
`punitive damages.
` The
`jury awarded Hardeman
`
`

`

`HARDEMAN V. MONSANTO
`
`
`
`$5,267,634.10 in compensatory damages and $75 million in
`punitive damages.
`
`17
`
`In post-trial motions, Monsanto argued that the district
`court improperly excluded evidence of foreign regulatory
`approvals of glyphosate, which allegedly deprived the jury
`of the scope of evidence reinforcing Monsanto’s view of the
`science. The district court explained that such evidence
`about foreign regulators would have been cumulative under
`Federal Rule of Evidence 403 and denied Monsanto’s
`motion to overturn the verdict and for judgment as a matter
`of law. But the district court reduced the punitive damages
`award of $75 million to $20 million. These appeals
`followed.
`
`II
`
`Whether Hardeman’s state claims are preempted is
`reviewed de novo. Nathan Kimmel, Inc. v. DowElanco,
`275 F.3d 1199, 1203 (9th Cir. 2002). Monsanto argues that
`Hardeman’s failure-to-warn claims are preempted by
`FIFRA, under which states cannot “impose
`. . . any
`requirements for labeling or packaging in addition to or
`different from” the requirements in FIFRA itself. § 136v(b)
`(emphasis added); see also U.S. Const. art. VI, cl. 2 (federal
`law “shall be the supreme Law of the Land . . . any Thing in
`the Constitution or Laws of any State to the Contrary
`notwithstanding”). We conclude that Hardeman’s failure-
`to-warn claims based on Roundup’s labeling are consistent
`with FIFRA and thus are neither expressly nor impliedly
`preempted.
`
`A
`
`FIFRA does not expressly preempt Hardeman’s claims
`because FIFRA’s requirement that a pesticide not be
`
`

`

`HARDEMAN V. MONSANTO
`
`18
`
`than,
`if not broader
`is consistent with,
`misbranded
`California’s common law duty to warn. Bates employs a
`two-part test to determine whether FIFRA preempts a state
`law claim. 544 U.S. at 444. First, the state law must be a
`requirement “for labeling or packaging.” Id. (quoting
`§ 136v(b)). Second, the state law must impose a labeling or
`packaging requirement that is “in addition to or different
`from” those required under FIFRA. Id. (quoting § 136v(b)).
`Because Hardeman’s complaint is based on Monsanto’s
`failure to provide an adequate warning on a label under
`California law, part one of this test is satisfied.
`
`As to part two of the Bates test, “a state-law labeling
`requirement is not pre-empted by § 136v(b) if it is equivalent
`to, and fully consistent with, FIFRA’s misbranding
`provisions.” 544 U.S. at 447. State law is “equivalent to”
`and “fully consistent with” FIFRA where both impose
`“parallel requirements,” meaning that a violation of the state
`law is also a violation of FIFRA. Id.; see also id. at 454
`(“[A] manufacturer should not be held liable under a state
`labeling requirement subject to § 136v(b) unless the
`manufacturer is also liable for misbranding as defined by
`FIFRA.”). Thus, if a violation of California’s duty to warn
`would also be a violation of FIFRA’s misbranding provision,
`then they impose parallel requirements fully consistent with
`each other. Id. at 454 (“To survive pre-emption, the state-
`law requirement need not be phrased in the identical
`language as its corresponding FIFRA requirement . . . .”).
`To that end, elements of California’s duty to warn and
`FIFRA’s misbranding provision are compared below.
`
`FIFRA’s misbranding provision requires a pesticide
`label “contain a warning or caution statement which may be
`necessary and if complied with . . . is adequate to protect
`health and the environment.” § 136(q)(1)(G). Similarly,
`
`

`

`19
`
`HARDEMAN V. MONSANTO
`
`
`
`California common law requires a manufacturer to warn
`either of any health risk4 that is “known or knowable” (in
`strict liability) or those risks “a reasonably prudent
`manufacturer would have known and warned about” (in
`negligence). Conte v. Wyeth, Inc., 85 Cal. Rptr. 3d 299, 310
`(Ct. App. 2008). Thus, FIFRA—which requires a warning
`“necessary” and “adequate to protect health”—is broader
`than California’s requirement under negligence (no warning
`needed if unreasonable to do so)5 and is, at minimum,
`consistent with California’s requirement under strict liability
`(no warning needed if risk not known or knowable). See id.;
`§ 136(q)(1)(G).
` Because
`FIFRA’s misbranding
`requirements parallel those of California’s common law
`duty, Hardeman’s failure-to-warn claims effectively enforce
`FIFRA’s requirement against misbranding and are thus not
`expressly preempted. See § 136(q)(1)(G); Bates, 544 U.S.
`at 447–48 (citing favorably Justice O’Connor’s explanation
`in Medtronic, 518 U.S. 470, that “a state cause of action that
`seeks to enforce a federal requirement ‘does not impose a
`requirement that is “different from, or in addition to,”
`requirements under federal law’”).
`
`
`4 Because a risk of cancer is a risk contemplated by FIFRA as
`“necessary” and “adequate to protect health,” § 136(q)(1)(G), (x), (bb),
`we need not address the possibility that California common law may
`require a manufacturer to warn of a risk not contemplated by FIFRA’s
`misbranding provision.
`
`5 Though “it may be necessary as a matter of [state] law to prove
`that th[e] violations were the result of negligent conduct . . . such
`additional elements of the state-law cause of action would make the state
`requirements narrower, not broader, than the federal requirement. While
`such a narrower requirement might be ‘different from’ the federal rules
`in a literal sense, such a difference would surely provide a strange reason
`for finding pre-emption of a state rule insofar as it duplicates the federal
`rule.” Medtronic, Inc. v. Lohr, 518 U.S. 470, 495 (1996).
`
`

`

`20
`
`
`HARDEMAN V. MONSANTO
`
`Monsanto, however, argues that because EPA repeatedly
`registered Roundup for sale without a cancer warning on the
`label, a jury’s decision that Roundup should include such a
`warning would effectively impose a requirement “in
`addition to or different from” that required by FIFRA, and
`so the state law is preempted. Granted, EPA is highly
`involved in the pestici