Edwin Hardeman v. Monsanto Company

FOR PUBLICATION

UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

EDWIN HARDEMAN, Nos. 19-16636

Plaintiff-Appellee/ 19-16708

Cross-Appellant,

D.C. Nos.

v. 3:16-cv-00525-VC

3:16-md-02741-VC

MONSANTO COMPANY,

Defendant-Appellant/

Cross-Appellee. OPINION

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.

Roundup is pesticide with the active ingredient

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.

HARDEMAN V. MONSANTO 3

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

4 HARDEMAN V. MONSANTO

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

6 HARDEMAN V. MONSANTO

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 7

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.

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

HARDEMAN V. MONSANTO 9

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

Under FIFRA, the United States Environmental

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

EPA can also institute cancellation proceedings,

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).

Though commonly referred to as an herbicide, Roundup is defined

1

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,

12 HARDEMAN V. MONSANTO

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 13

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.

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

14 HARDEMAN V. MONSANTO

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.

The district court, however, acknowledged that

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 15

experts’ opinions were relevant and reliable, satisfying

Federal Rule of Evidence 702 and Daubert.

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 idiopathy 3 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).

16 HARDEMAN V. MONSANTO

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 17

$5,267,634.10 in compensatory damages and $75 million in

punitive damages.

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

18 HARDEMAN V. MONSANTO

misbranded is consistent with, if not broader than,

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,

HARDEMAN V. MONSANTO 19

California common law requires a manufacturer to warn

either of any health risk 4 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 pesticide registration process, which includes

approval of product labels. And EPA will not register a

pesticide unless it determines that the label “compl[ies]

with” FIFRA’s “requirements.” § 136a(c)(5)(B). But this

argument misses the point for two reasons.

First, EPA’s approval of a label—one step in a larger

registration process—is not conclusive of FIFRA

compliance. FIFRA specifies:

In no event shall registration of an article be

construed as a defense for the commission of

any offense under this subchapter. As long

as no cancellation proceedings are in effect

registration of a pesticide shall be prima facie

evidence that the pesticide, its labeling and

packaging comply with the registration

provisions of the subchapter.

§ 136a(f)(2) (emphasis added). 6 Because EPA has not

instituted any cancellation proceedings against Monsanto,

6

Section 136a(f)(2) distinguishes this case from Riegel v.

Medtronic, Inc., 552 U.S. 312 (2008), which held that the Medical

Device Amendments (“MDA”) to the Federal Food, Drug, and Cosmetic

Act (“FDCA”) expressly preempted claims challenging the safety and

effectiveness of a medical device that received premarket approval from

the Food and Drug Administration (“FDA”). Id. at 315, 330. Like

FIFRA’s preemption provision, the MDA preempts certain state

requirements that are different from, or in addition to, certain federal

HARDEMAN V. MONSANTO 21

EPA’s approval of Roundup’s label is prima facie evidence

of FIFRA compliance. See id. And looking at FIFRA

holistically, this makes sense—if mere EPA approval of a

label were determinative of FIFRA compliance, then

FIFRA’s misbranding provision and regulations imposing a

duty to report “additional factual information regarding

unreasonable adverse effects” would serve no purpose.

§ 136d(a)(2); see also § 136(q)(1) (detailing when a

pesticide is misbranded); 40 C.F.R. § 159.152 (imposing

duty to report additional information on adverse effects). So

even though EPA approved Roundup’s label, a judge or jury

could disagree and find that same label violates FIFRA. And

because EPA’s labeling determinations are not dispositive of

FIFRA compliance, they similarly are not conclusive as to

which common law requirements are “in addition to or

different from” the requirements imposed by FIFRA. See

§ 136v(b); cf. Bates, 544 U.S. at 451 (“Private remedies that

enforce federal misbranding requirements would seem to

aid, rather than hinder, the functioning of FIFRA.”); Indian

Brand Farms, Inc. v. Novartis Crop Prot. Inc., 617 F.3d 207,

222 (3d Cir. 2010) (explaining that Bates “established that

mere inconsistency between the duty imposed by state law

and the content of a manufacturer’s labeling approved by the

EPA at registration did not necessarily mean that the state

law duty was preempted”).

Second, the EPA actions that Monsanto alleges preempt

Hardeman’s claims do not carry the force of law. As noted

in Bates, “[a] requirement is a rule of law that must be

obeyed.” 544 U.S. at 445. To establish requirements that

requirements. See 21 U.S.C. § 360k(a)(1). But the MDA does not

contain a provision like FIFRA’s § 136a(f)(2), which clarifies that the

agency’s approval of a label is not determinative of compliance with the

statute.

22 HARDEMAN V. MONSANTO

can preempt state law under § 136v(b), agency action must

have the force of law. See Wyeth v. Levine, 555 U.S. 555,

576, 580 (2009). In other words, only where there is a

relevant EPA action carrying the force of law are state

failure-to-warn claims prohibited from imposing

requirements inconsistent with that action. 7 Monsanto tries

to circumvent this caveat by arguing that although EPA’s

approval of Roundup’s label was not a rulemaking, it

happened “in the context of [a] registration process” that

“has the hallmarks of formal agency action.” See § 136a;

40 C.F.R. § 155.50(b)–(c). But, as explained above, FIFRA

expressly states that EPA’s decision to approve a label

during the registration process raises only a rebuttable

presumption that the pesticide and its label comply with

FIFRA. § 136a(f)(2). It would defy logic to say a rebuttable

presumption carries the force of law necessary to have

preemptive effect, as doing so would deny any ability to

rebut the presumption.

Nor does EPA’s 2019 letter, sent after the conclusion of

Hardeman’s trial to all registrants of products containing

glyphosate, carry the force of law. Generally, “Congress

contemplates administrative action with the effect of law

when it provides for a relatively formal administrative

procedure tending to foster the fairness and deliberation that

7

Monsanto relies on Bates’s explanation that a failure-to-warn

claim alleging that a label should have stated “DANGER” instead of

“CAUTION” would be preempted “because it is inconsistent with

40 C.F.R. § 156.64 (2004), which specifically assigns these warnings to

particular classes of pesticides based on their toxicity.” 544 U.S. at 453.

But this example deals with agency action that has the force of law—

FIFRA regulation 40 C.F.R. § 156.64. Here, however, neither EPA’s

approval of Roundup’s label during registration nor EPA’s 2019 letter

carries the force of law necessary to preempt Hardeman’s failure-to-warn

claims.

HARDEMAN V. MONSANTO 23

should underlie a pronouncement of such force.” United

States v. Mead Corp., 533 U.S. 218, 230 (2001). But the

2019 letter—stating that EPA believes any pesticide label

with a cancer warning due to the presence of glyphosate will

be misbranded—did not follow any “formal administrative

procedure” that would give the letter the force of law. 8 See

id. The 2019 letter was issued without any written notice,

gave no hearing or opportunity to respond, and lacked any

sort of dispute-resolution process. See Merck Sharp &

Dohme Corp. v. Albrecht, 139 S. Ct. 1668, 1679 (2019).

Instead, the 2019 letter is similar to the letter in Fellner v.

Tri-Union Seafoods, LLC, which lacked preemptive effect

because the FDA “merely expressed an informal policy

opinion in a letter, and it did so only after [the plaintiff’s]

injuries were allegedly suffered.” 539 F.3d 237, 255 (3d Cir.

2008). 9

8

EPA’s 2017 determination that glyphosate is not carcinogenic does

not magically give the “force of law” to this 2019 letter on misbranding.

EPA’s 2017 determination was given in the context of glyphosate

“undergoing Registration Review” after evaluating glyphosate’s

carcinogenic potential. EPA, Revised Glyphosate Issue Paper:

Evaluation of Carcinogenic Potential 12 (Dec. 2017) (“Registration

Review also allows the agency to incorporate new science.”). Even if

the 2017 determination stems from more formal procedures, it is not

necessarily at odds with the future failure-to-warn claim because it was

made as part of EPA’s registration decision, which only supports

presumptive (not conclusive) compliance with FIFRA. See § 136a(f)(2).

9

In contrast, EPA’s cancellation proceedings, for example, may

have the force of law given that § 136d(b) lays out a formal notice and

hearing process, and no comparable prima facie evidence restriction

applies. See § 136a(f)(2) (stating that registration is “prima facie

evidence” of FIFRA compliance “[a]s long as no cancellation

proceedings are in effect”). But no cancellation proceedings were in

effect here.

24 HARDEMAN V. MONSANTO

Thus, we affirm the district court’s conclusion that

Hardeman’s state failure-to-warn claims are “equivalent to”

and “fully consistent with” FIFRA and therefore not

expressly preempted. See Bates, 544 U.S. at 449 (“The long

history of tort litigation against manufacturers of poisonous

substances adds force to the basic presumption against pre-

emption. If Congress had intended to deprive injured parties

of a long available form of compensation, it surely would

have expressed that intent more clearly.”). The Supreme

Court decided Bates over fifteen years ago, and regulatory

preemption in other contexts has developed considerably in

the interim. For FIFRA preemption, however, currently

Bates controls.

B

Because Monsanto could comply with both FIFRA and

California law, FIFRA did not impliedly preempt

Hardeman’s state failure-to-warn claims.

1

A state failure-to-warn claim is impliedly preempted if

the relevant federal and state laws “irreconcilably conflict.”

Merck, 139 S. Ct. at 1679 (quoting Rice v. Norman Williams

Co., 458 U.S. 654, 659 (1982)). “[S]tate and federal law

conflict where it is impossible for a private party to comply

with both state and federal requirements.” PLIVA, Inc. v.

Mensing, 564 U.S. 604, 618 (2011) (internal quotation marks

and citation omitted). To demonstrate an “irreconcilabl[e]

conflict,” Monsanto must present “clear evidence” that

(1) the agency was “fully informed” of “the justifications for

the warning” the plaintiff demands, (2) the agency has

“informed the . . . manufacturer that [it] would not approve

changing the . . . label to include that warning,” and (3) the

agency’s action “carr[ies] the force of law.” Merck, 139 S.

HARDEMAN V. MONSANTO 25

Ct. at 1678–79. However, because EPA’s actions—such as

registering Roundup, approving Roundup’s label, and

issuing the 2019 letter—do not have the force of law,

Monsanto fails part (3) of Merck’s “clear evidence” of

“irreconcilabl[e] conflict” test and cannot show preemption.

See supra Section II.A.

2

Monsanto also argues that Hardeman’s claims are

impliedly preempted because, under EPA’s regulations,

Monsanto could not have unilaterally changed Roundup’s

label, making it impossible for Monsanto to comply with

both FIFRA and California’s common law duty to warn.

Monsanto relies primarily on PLIVA, a case concerning the

federal regulatory scheme governing generic drugs.

564 U.S. 604. But, as explained in PLIVA, “different federal

statutes and regulations may . . . lead to different pre-

emption results.” Id. at 626. Here, FIFRA’s regulatory

regime for pesticides differs meaningfully from the

regulatory scheme governing generic drugs in PLIVA and, as

a result, Monsanto’s implied preemption argument fails.

Under the regulatory scheme at issue in PLIVA, generic

drug manufacturers have an “ongoing federal duty of

sameness,” according to which they must use the same

labeling as the corresponding name-brand drug. Id. at 613

(internal quotation marks and citations omitted). Generic

drug manufacturers do not draft their products’ initial

labeling and do not have the power to revise labeling. See

id. As the Supreme Court explained, “[i]f [the generic drug

manufacturers] had [asked the FDA for help], and if the FDA

decided there was sufficient supporting information, and if

the FDA undertook negotiations with the brand-name

manufacturer, and if adequate label changes were decided on

and implemented, then the [generic drug] [m]anufacturers

26 HARDEMAN V. MONSANTO

would have started a Mouse Trap game that eventually led

to a better label.” Id. at 619. But, in PLIVA, the generic drug

manufacturer could not “independently satisfy . . . state

duties for pre-emption purposes” because it “cannot satisfy

its state duties without the Federal Government’s special

permission and assistance, which is dependent on the

exercise of judgment by a federal agency.” Id. at 623–24

(explaining that “[t]he only action the [generic drug]

[m]anufacturers could independently take” was “asking for

the FDA’s help”).

Unlike the FDCA and FDA regulatory scheme for

generic drug manufacturers, FIFRA and the EPA regulatory

scheme provide that pesticide manufacturers are responsible

for drafting their own product labels, § 136a(c)(1)(C), and

do not need to maintain the same labeling as another

manufacturer. Once a pesticide is registered, the

manufacturer has a “continuing obligation to adhere to

FIFRA’s labeling requirements.” Bates, 544 U.S. at 438

(citations omitted). When a label needs to be changed, the

manufacturer has the responsibility to change the label by

drafting and submitting the label to EPA for approval,

40 C.F.R. § 152.50(e), which EPA “shall” approve if it

determines the change will not violate FIFRA, § 136a(f)(1).

This is a far cry from the “special permission and assistance”

needed from the FDA in PLIVA to change a generic drug

label, a process constrained by a duty of sameness and the

added step of agency deliberations with name-brand

manufacturers. See 564 U.S. at 623–24.

Moreover, EPA permits pesticide manufacturers to make

certain changes to labels without prior approval. See id.

at 623. Specifically, manufacturers can make minor

modifications to labeling without prior EPA approval if EPA

is notified of the change. 40 C.F.R. § 152.46(a); EPA,

HARDEMAN V. MONSANTO 27

Office of Pesticide Programs, Pesticide Registration Notice

98-10 (Oct. 22, 1998) (“PRN 98-10”). Thus, unlike the

generic drug manufacturers in PLIVA, pesticide

manufacturers “can act sufficiently independently under

federal law” when amending a label. See PLIVA, 564 U.S.

at 623.

Though Monsanto contends that “[a]dding a warning

about cancer would hardly qualify as a ‘minor

modification,’” EPA has repeatedly permitted pesticide

manufacturers to use the notification procedure to add

notices related to cancer to their products’ labels. 10

Nevertheless, Monsanto counters that there is no “single

example where EPA has allowed a registrant to use the

notification process” where EPA previously “found the

relevant chemical was not carcinogenic, much less where it

determined a cancer warning would render a label false and

misleading,” referring to the 2019 letter.

But neither EPA’s 2017 finding that glyphosate is not

carcinogenic nor the 2019 letter (which do not carry the force

of law) divert Monsanto to a different process for amending

10

For instance, pursuant to PRN 98-10, pesticide manufacturer

Bayer CropScience notified EPA “of a minor labeling amendment for

LARVIN Technical,” informing EPA that “[a]s required by California

Proposition 65, the following statement has been added to the label, ‘This

product contains a chemical known to the state of California to cause

cancer.’” Letter from Larry R. Hodges, Registration Manager, Bayer

CropScience, to EPA, Office of Pesticide Programs 4 (Nov. 29, 2012),

www3.epa.gov/pesticides/chem_search/ppls/000264-00343-20131217.

pdf. In response, EPA’s Registration Division “conducted a review of

this request for its applicability under PRN 98-10 and finds that the

action(s) requested fall within the scope of PRN 98-10.” Letter from

Jennifer Gaines, EPA, Office of Pesticide Programs, to Larry Hodges,

Bayer CropScience 2 (Dec. 17, 2012), www3.epa.gov/pesticides/chem_

search/ppls/000264-00343-20131217.pdf.

28 HARDEMAN V. MONSANTO

a label beyond those normally followed by pesticide

manufacturers under FIFRA and its regulations, as described

above. Considering the responsibility FIFRA places on

manufacturers to update pesticide labels and that EPA has

allowed pesticide manufacturers to add cancer warnings to

labels through the notification process without prior

approval, it is not impossible for Monsanto to add a cancer

warning to Roundup’s label. See PLIVA, 564 U.S. at 623;

see also Wyeth, 555 U.S. at 573 (explaining that

“[i]mpossibility pre-emption is a demanding defense”).

III

Whether the district court applied the correct legal

standard under Daubert is reviewed de novo, and the district

court’s decision to admit expert testimony is reviewed for

abuse of discretion. Estate of Barabin v. AstenJohnson, Inc.,

740 F.3d 457, 462 (9th Cir. 2014) (en banc), overruled on

other grounds by United States v. Bacon, 979 F.3d 766 (9th

Cir. 2020) (en banc). We hold that the district court

ultimately applied the correct legal standard under Daubert

and did not abuse its discretion by admitting Hardeman’s

general and specific causation expert testimony.

A

Under Federal Rule of Evidence 702, expert testimony

must be reliable to be admissible. Daubert, 509 U.S. at 589.

Scientific evidence is reliable when “the principles and

methodology used by an expert are grounded in the methods

of science.” Clausen v. M/V New Carissa, 339 F.3d 1049,

1056 (9th Cir. 2003). When determining reliability, district

court judges can consider the following non-exclusive

factors: (1) “whether the theory or technique employed by

the expert is generally accepted in the scientific

community;” (2) “whether it’s been subjected to peer review

HARDEMAN V. MONSANTO 29

and publication;” (3) “whether it can be and has been tested;”

and (4) “whether the known or potential rate of error is

acceptable.” Daubert v. Merrell Dow Pharms., Inc., 43 F.3d

1311, 1316 (9th Cir. 1995) (citing Daubert, 509 U.S. at 593–

95). “Th[is] inquiry is ‘flexible,’” Wendell, 858 F.3d at 1232

(quoting Daubert, 509 U.S. at 594), and “should be applied

with a ‘liberal thrust’ favoring admission,” Messick v.

Novartis Pharms. Corp., 747 F.3d 1193, 1196 (9th Cir.

2014) (quoting Daubert, 509 U.S. at 588). 11

Monsanto contends that, by relying on a misguided

reading of Wendell and Messick, the district court

misinterpreted Daubert to be more forgiving of experts’

extrapolations than this circuit allows. But, in reaching its

conclusions, the district court followed this court’s

precedent and thus cannot be faulted for following binding

case law. Monsanto’s specific critiques are addressed

below.

First, according to Monsanto, the district court

erroneously stated there is “slightly more room for deference

to experts” in close cases, In re Roundup, 390 F. Supp. 3d

at 1113, and that courts in this circuit are “more tolerant of

11

This liberal thrust favoring admission is not without limits. “Just

as the district court cannot abdicate its role as gatekeeper, so too must it

avoid delegating that role to the jury.” Estate of Barabin, 740 F.3d at 464

(holding that district court erred by “pass[ing] its greatest concern about

[the expert’s] testimony to the jury to determine” and there was little

“indication that the district court assessed, or made findings regarding,

the scientific validity or methodology of [another expert’s] proposed

testimony”); see also United States v. Valencia-Lopez, 971 F.3d 891, 899

(9th Cir. 2020) (holding that district court erred in admitting expert

testimony without making a reliability determination by dismissing the

expert’s deficiencies as “going to the weight, not admissibility, of [the

expert’s] testimony” (quoting Nease v. Ford Motor Co., 848 F.3d 219,

230 (4th Cir. 2017))).

30 HARDEMAN V. MONSANTO

borderline expert opinions,” In re Roundup, 358 F. Supp. 3d

at 959.

As an initial matter, this court is not an outlier following

a more flexible Daubert approach than other circuits. The

cases on which the district court relied do not establish

otherwise. For instance, in the Fourth Circuit case relied on

by the district court, the expert failed to provide a proper

scientific basis for her differential diagnosis by “focus[ing]

almost exclusively on the fact that [plaintiff] took the drug

and later developed the disease, rather than explaining what

led her to believe that it was a substantial contributing factor

as compared to other possible causes.” In re Lipitor

(Atorvastatin Calcium) Mktg., Sales Pracs. & Prods. Liab.

Litig., 892 F.3d 624, 645 (4th Cir. 2018). But if we compare

the expert in Lipitor to, for instance, the expert in Messick,

the cases are readily distinguishable. Unlike the Lipitor

expert, the expert in Messick provided a scientific basis for

his conclusion by “refer[ing] to his own extensive clinical

experience as the basis for his differential diagnosis, as well

as his examination of [plaintiff’s] records, treatment, and

history.” 747 F.3d at 1198.

Similarly, in the Sixth Circuit case relied on by the

district court, the expert’s causation analysis was insufficient

because literature had only hypothesized but did not find a

link between the chemical and disease. Tamraz v. Lincoln

Elec. Co., 620 F.3d 665, 677–78 (6th Cir. 2010). The

Tamraz court explained, “the problem is not that [the expert]

failed to cite studies about [the chemical] causing [the

disease] . . . or could not quantify how much [of the

chemical] would lead to how much [of the disease]; the

problem is that he failed to cite any non-speculative evidence

for his conclusion.” Id. at 674. In contrast, the experts in

Wendell did not present that deficiency, as they “relied not

HARDEMAN V. MONSANTO 31

just on . . . studies—which not only examined reported cases

but also used statistical analysis to come up with risk rates—

but also on their own wealth of experience and additional

literature.” 858 F.3d at 1236. Thus, the Fourth Circuit and

Sixth Circuit cases on which the district court relied are not

at odds with this court’s Daubert approach.

To the extent the district court relied on In re Zoloft

(Sertraline Hydrochloride) Products Liability Litigation,

858 F.3d 787, 800 (3d Cir. 2017), and McClain v. Metabolife

International, Inc., 401 F.3d 1233, 1244–45 (11th Cir.

2005), to show those courts adopted the any step

principles, 12 those cases do not reveal a more flexible

Daubert approach in this circuit. We have explained that

“expert evidence is inadmissible where the analysis is the

result of a faulty methodology or theory as opposed to

imperfect execution of laboratory techniques whose

theoretical foundation is sufficiently accepted in the

scientific community to pass muster under Daubert.” City

of Pomona v. SQM N. Am. Corp., 750 F.3d 1036, 1047–48

(9th Cir. 2014) (internal quotation marks and citation

omitted). Imperfect application of methodology may not

render expert testimony unreliable because “‘[a] minor flaw

in an expert’s reasoning or a slight modification of an

otherwise reliable method’ does not render expert testimony

inadmissible.” Id. at 1048 (quoting Amorgianos, 303 F.3d

at 267 (adopting the any step principles)) (alteration in

original). The reasoning guiding the any step principles is

12

“The Daubert ‘requirement that the expert testify to scientific

knowledge—conclusions supported by good grounds for each step in the

analysis—means that any step that renders the analysis unreliable under

the Daubert factors renders the expert’s testimony inadmissible.’”

Amorgianos v. Nat’l R.R. Passenger Corp., 303 F.3d 256, 267 (2d Cir.

2002) (quoting In re Paoli R.R. Yard PCB Litig., 35 F.3d 717, 745 (3d

Cir. 1994)); see also Zoloft, 858 F.3d at 797; McClain, 401 F.3d at 1245.

32 HARDEMAN V. MONSANTO

not dissimilar; namely, “[t]he judge should only exclude the

evidence if the flaw is large enough that the expert lacks

‘good grounds’ for his or her conclusions.” Amorgianos,

303 F.3d at 267 (quoting Paoli, 35 F.3d at 746).

Despite its incorrect assumption that this court is 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.

For instance, the district court’s slight “deference to experts”

with “borderline . . . opinions” was proper under Daubert:

“[T]he interests of justice favor leaving difficult issues in the

hands of the jury and relying on the safeguards of the

adversary system . . . to ‘attack[] shaky but admissible

evidence.’” Wendell, 858 F.3d at 1237 (quoting Daubert,

509 U.S. at 596) (alteration in original). The Supreme Court

has not directed courts to follow a different rule since it first

decided Daubert almost 28 years ago.

Second, Monsanto takes issue with the district court’s

suggestion that courts in this circuit can admit opinions “that

lean strongly toward the ‘art’ side of the spectrum.” In re

Roundup, 358 F. Supp. 3d at 959 (citation omitted). Though

that may seem strange out of context, the district court was

only reiterating our precedent following Daubert. See

Messick, 747 F.3d at 1198 (“Medicine partakes of art as well

as science . . . .”). The district court did not suggest that

courts in this circuit allow “art” as a separate, standalone

category divorced from logic and science. Rather, in

referencing “art,” the district court followed Wendell and

Messick’s instructions that a testifying expert can rely on his

own extensive clinical experience under Daubert. See

Wendell, 858 F.3d at 1237 (“Where, as here, two doctors

who stand at or near the top of their field and have extensive

clinical experience with the rare disease or class of disease

HARDEMAN V. MONSANTO 33

at issue, are prepared to give expert opinions supporting

causation, we conclude that Daubert poses no bar based on

their principles and methodology.”); Messick, 747 F.3d

at 1198 (allowing “extensive clinical experience” to form

basis of differential diagnosis opinion).

Monsanto attempts to distinguish Wendell by arguing

that it only allows experts to rely on clinical experience in

exceptional circumstances not present here, particularly

cases involving rare diseases with insufficient

epidemiological data. Considering that Wendell drew the

concept of “art” from Messick, a case which did not involve

a rare disease, we do not find that the application of art is

limited to exceptional circumstances.

The district court allowed experts to rely on clinical

experience, or “art,” only when conducting differential

diagnosis to render specific causation opinions. Allowing

experts to rely on clinical experience while conducting

differential diagnosis, as the district court did here, is

consistent with Messick. See 747 F.3d at 1198 (“[T]here is

nothing wrong with a doctor relying on extensive clinical

experience when making a differential diagnosis.”).

Monsanto further tries to distinguish Messick by

emphasizing that the expert there relied on clinical

experience as well as an examination of medical literature

and plaintiff’s records. But Hardeman’s experts did the

same thing here, if not more, by relying on epidemiological,

animal, and cell studies. Acknowledging this, Monsanto

counters that “there are numerous epidemiological studies

on the association between glyphosate and Hardeman’s

subtype of non-Hodgkin’s lymphoma that obviated the need

for any reliance on ‘art.’” But Monsanto contradicts its own

argument, asserting Wendell and Messick “state that

experience can supplement reliable scientific studies and

34 HARDEMAN V. MONSANTO

medical literature.” On this point, Monsanto is right:

Hardeman’s experts’ clinical experience could supplement

the epidemiological studies on which they relied.

Thus, the district court applied the correct legal standard

under Daubert by following our precedent and fulfilling its

“special obligation to determine the reliability of an expert’s

testimony.” Elsayed Mukhtar v. Cal. State Univ., Hayward,

299 F.3d 1053, 1063 (9th Cir. 2002) (internal quotation

marks and citation omitted), overruled on other grounds by

Estate of Barabin, 740 F.3d 457.

B

To establish general causation, Hardeman’s experts

needed to show that glyphosate can cause NHL at exposure

levels people realistically may have experienced. Here,

Hardeman’s general causation experts relied on three types

of studies: epidemiological, 13 animal, and cellular. Animal

studies are relevant evidence of causation where there is a

sound basis for extrapolating conclusions from those studies

to humans in real-world conditions. See Domingo ex rel.

Domingo v. T.K., 289 F.3d 600, 606 (9th Cir. 2002).

Similarly, cell studies can support more substantial evidence

of causation. Therefore, animal and cell studies can help

show causation so long as there is evidence of an association

between glyphosate and NHL in humans within the

epidemiological literature. This means that to be admissible

testimony, the experts must have reliably based their general

causation opinions on epidemiological evidence showing a

13

Epidemiology is “the field of public health and medicine that

studies the incidence, distribution, and etiology of disease in human

populations.” Michael D. Green et al., Reference Guide on

Epidemiology, in Reference Manual on Scientific Evidence 551, 551 (3d

ed. 2011) (“Reference Manual”).

HARDEMAN V. MONSANTO 35

connection between glyphosate and cancer. As discussed

below, the district court did not abuse its discretion in

concluding that Hardeman’s experts satisfied this

requirement.

Monsanto maintains that the experts did not use the

epidemiological evidence reliably because they

(1) dismissed the Agricultural Health Study (“AHS”) and

(2) focused on case-control studies that did not sufficiently

account for confounding factors. These criticisms, however,

are not enough to render the expert opinions unreliable.

First, Monsanto criticizes Hardeman’s experts for

ignoring the AHS, which Monsanto considers to be the most

powerful evidence on the relationship between glyphosate

and NHL. That study was a cohort study conducted by the

National Institutes of Health that considered a range of

pesticide exposures on 57,000 participants over several

years. The AHS found no statistically significant association

between glyphosate and NHL and showed no dose-response

relationship, meaning “no evidence of higher rates of [NHL]

with more days of exposure.”

Nonetheless, Hardeman’s experts had a reasonable basis

for placing less weight on the AHS. For instance, an

epidemiologist employed by Monsanto wrote years before

the AHS results were announced that “the exposure

assessment in the AHS will be inaccurate” because the AHS

will have “spurious exposure-disease findings due to

exposure misclassification.” Similarly, Monsanto’s

toxicologist, Donna Farmer, recognized that “[m]any groups

have been highly critical of the study as being a flawed

study, in fact some have gone so far as to call it junk science

. . . . [T]he bottom line is scary . . . there will be associations

identified . . . just because of the way this study is designed.”

36 HARDEMAN V. MONSANTO

These criticisms from Monsanto employees resemble

those from Hardeman’s experts that the AHS is flawed and

unreliable. Though Monsanto changed its tune on the AHS

because the misclassification concerns were allegedly

addressed using “sensitivity analyses” as the study

progressed, the overlapping criticisms still show that

Hardeman’s expert opinions on the AHS are within “the

range where experts might reasonably differ.” Kumho Tire

Co. v. Carmichael, 526 U.S. 137, 153 (1999). Accordingly,

the district court did not abuse its discretion in concluding

that “the epidemiology evidence is open to different

interpretations” such that “an expert who places more weight

on the case-control studies than the AHS cannot be excluded

as categorically unreliable for doing so.” In re Roundup,

390 F. Supp. 3d at 1126.

Second, Monsanto criticizes Hardeman’s experts for

relying on three case-control studies: De Roos (2003),

McDuffie (2001), and Eriksson (2008), which allegedly

contain serious flaws. Although case-control studies are

“prone to recall bias,” 14 Hardeman’s experts gave the district

court valid reasons to discount this concern. For example,

the experts explained that epidemiology studies overall

found associations only between glyphosate and NHL, but

not between glyphosate and other cancers asked about in the

studies. The experts pointed out that, if participants were

pre-disposed to think glyphosate caused cancer and

consequently exhibited recall bias, the studies would have

reported associations for glyphosate and other cancers.

14

“[R]ecall bias[] occurs where people with a disease . . . are

differently able to recall past exposures than are people who never get

sick; generally, the assumption is that the cases will recall greater levels

of exposure, as those who become ill are more likely to ruminate about

the possible causes of their disease.” Reference Manual at 585–86.

HARDEMAN V. MONSANTO 37

Hardeman’s experts also relied upon studies that sought to

validate self-reports of pesticide exposure and found similar

recall accuracy between controls and cases. Considering this

evidence, the district court did not abuse its discretion in

finding the “possible presence of recall bias” is “not

significant enough to require an expert categorically to

weight [the case-control studies] less heavily than the AHS.”

In re Roundup, 390 F. Supp. 3d at 1133.

Monsanto criticizes the De Roos study specifically for

“not properly account[ing] for [NHL’s] latency period”

because the study analyzed data collected between 1979 and

1986, but NHL takes “at least five to ten years to develop”

and Roundup was put on the market in 1974. As the district

court pointed out, a potential confounding variable 15 is an

important reason a study might show an association between

glyphosate and NHL shortly after glyphosate was put on the

market.

The De Roos study, however, reduced the risk of

confounding by adjusting for many other pesticides. While

Hardeman’s experts acknowledged that it is “always

possible” that the observed association was the result of

confounding not accounted for in De Roos, the adjustment

for many other pesticides in De Roos made it “significantly

less likely” that a pesticide other than glyphosate caused the

observed association. As a result, the district court properly

scrutinized the reliability of De Roos and did not abuse its

discretion in concluding that, “at least for the studies that

adjust for other pesticide exposures [i.e., De Roos], the

relatively short period between glyphosate exposure and

cancer development is not a concern so significant as to

15

Confounding variables are other factors that could explain an

observed association between a substance and the disease.

38 HARDEMAN V. MONSANTO

disqualify an expert who gives significant weight to the case-

control studies in rendering a causation opinion.” In re

Roundup, 390 F. Supp. 3d at 1123.

Nonetheless, Monsanto argues that Hardeman’s experts

still did not sufficiently consider confounding factors while

evaluating epidemiology. According to Monsanto,

“McDuffie did not account for the effect of exposure to

pesticides beyond glyphosate at all” and, “while Eriksson

did provide some results adjusted for the effect of other

pesticides, the adjusted results did not show a statistically

significant link between glyphosate and [NHL].”

But while the district court acknowledged that

“exclusive consideration of numbers unadjusted for other

pesticides, when adjusted numbers are available, would be

disqualifying,” In re Roundup, 390 F. Supp. 3d at 1140,

Hardeman’s experts did not do that here. For instance,

“Dr. Portier addressed the most significant concern—the

possibility that pesticides other than glyphosate caused the

observed cases of NHL—by focusing on data adjusted for

potential confounding by various other pesticides.” In re

Roundup, 390 F. Supp. 3d at 1133; see also id. at 1140–41,

1143 (discussing Dr. Ritz and Dr. Weisenburger). Further,

even where adjustment for other pesticides resulted in loss

of statistical significance, the results still showed a positive

association between glyphosate and NHL. 16 Thus, contrary

16

Monsanto criticizes Dr. Weisenburger for relying on a single

favorable odds ratio from the “earliest iteration” of the North American

Pooled Project. But such reliance is not enough to render

Dr. Weisenburger’s entire testimony unreliable. See, e.g., Wendell,

858 F.3d at 1233 (explaining that district courts should not look “too

narrowly at each individual consideration, without taking into account

the broader picture of the experts’ overall methodology”). The district

HARDEMAN V. MONSANTO 39

to Monsanto’s criticisms, the general causation expert

opinions were sufficiently supported by reliable

epidemiological evidence, so admitting these experts’

testimony was not an abuse of discretion.

C

To establish specific causation, experts needed to show

that Hardeman’s NHL was caused by glyphosate, rather than

some other factor. To do so, Hardeman’s experts—

Dr. Weisenburger, Dr. Shustov, and Dr. Nabhan—used

“differential diagnosis,” which starts with ruling in “all

potential causes, then rul[ing] out the ones as to which there

is no plausible evidence of causation, and then determin[ing]

the most likely cause among those that cannot be excluded.”

Wendell, 858 F.3d at 1234; see also Clausen, 339 F.3d

at 1057. 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 alternative causes, such as idiopathy

and HCV.

1

Monsanto argues that Hardeman failed to adequately

rule out idiopathy, considering that 70% or more of NHL

cases have unknown causes. Monsanto acknowledges that

an expert can rule out idiopathy by reliably concluding that

the known factor (here, glyphosate) is a “substantial cause,”

which can be shown when a strong association exists

between the disease and that known risk factor. See Wendell,

858 F.3d at 1235, 1237 (even though expert “was not entirely

court properly considered this issue before concluding

Dr. Weisenburger’s testimony was sufficiently reliable.

40 HARDEMAN V. MONSANTO

able to rule” out idiopathy, he could conclude a “known risk

factor[]” was a substantial cause because “literature

show[ed] that patients exposed to” the drugs in question

were “at an increased risk for” the disease). But here,

Monsanto argues that Hardeman’s experts did not reliably

conclude that glyphosate was a substantial cause because no

strong association existed between glyphosate and NHL,

forcing the experts to rely on two flawed studies and their

own subjective judgment.

Specifically, Monsanto argues that Hardeman’s experts

did not rule in glyphosate as a substantial cause because,

unlike the experts in Wendell, they did not show a sharp

enough increased risk of cancer for those exposed to

glyphosate. Monsanto focuses on Hardeman’s experts’

inability to present a study with an adjusted odds ratio

above 2.0. But we have never suggested that a hardline

increase in a risk statistic, or even an adjusted odds ratio

above 2.0, is necessary for finding a strong association. See

id. at 1234. To the contrary, flexibility is warranted

considering the contextual nature of the Daubert inquiry.

Thus, it was not an abuse of discretion to admit expert

testimony—that glyphosate is a substantial cause—partly

based on the epidemiological studies from the general

causation opinions, where the general causation opinions

showed a “robust connection between glyphosate and NHL.”

In re Roundup, 358 F. Supp. 3d at 960.

Next, Monsanto criticizes Hardeman’s experts for

relying on “two flawed studies”—McDuffie and Eriksson—

linking glyphosate and NHL. Monsanto focuses on the

experts’ two attempted uses for those studies: (1) to assign a

quantified risk to Hardeman based on the studies’

“unadjusted numbers” and (2) to show that Hardeman’s risk

ratio must have exceeded 2.0 because he exceeded the

HARDEMAN V. MONSANTO 41

exposure minimums from the two studies (i.e., two days per

year or ten lifetime days of exposure). But this focus is

misplaced. Though relying on McDuffie and Eriksson for

those propositions may have been problematic, that is not

what happened here. The district court explicitly considered

these issues and properly exercised its gatekeeping function

by precluding the experts from using the studies in those two

ways.

Instead, the district court allowed Hardeman’s experts to

rely on McDuffie and Eriksson to show a dose-response

relationship between glyphosate and NHL. And

Hardeman’s experts presented a sufficient basis for using

these studies (though unadjusted for other pesticides) to

show such a relationship. For instance, Dr. Weisenburger

clarified, if a chemical “shows a dose response, it’s very

likely an etiologic agent because it’s . . . unusual that a

chemical would cause a disease and not have a dose

response. So when you see a dose response, that gives you

some assurance that it really is causing the disease.”

Had the experts relied only on McDuffie and Eriksson to

show glyphosate is a substantial cause of NHL, their specific

causation opinions may have been unreliable. However,

Hardeman’s experts relied not only on McDuffie and

Eriksson but also other epidemiological evidence (like De

Roos) supporting a strong association, as well as their

clinical experience and review of plaintiff’s medical records.

Thus, as a whole, the evidence provided a sufficient basis for

reliably ruling out idiopathy by concluding glyphosate was

a substantial cause of Hardeman’s NHL. See Wendell,

858 F.3d at 1233–34 (ruling out idiopathy for disease with

70% idiopathy rate where expert relied on clinical

experience, literature, and medical records).

42 HARDEMAN V. MONSANTO

2

Monsanto also argues that Hardeman’s experts did not

reliably rule out HCV as an alternate cause. HCV is an

established cause of NHL. Even though Hardeman was

treated for HCV in 2005 and 2006, Monsanto claims that he

was vulnerable to cellular damage caused by the virus for

many years, including NHL. But, as Dr. Weisenburger

explained, to cause cancer, the virus must be active, and

there was no evidence that Hardeman’s HCV had been

active for the decade preceding his NHL diagnosis. And this

conclusion, as determined by the district court, had

significant support in the scientific literature.

Further, Dr. Weisenburger’s underlying methodology

for reaching this conclusion was sound. He relied on

Hardeman’s medical records and his clinical experience and

reviewed scientific literature (including seven studies) as the

basis for ruling out HCV. See Messick, 747 F.3d at 1199

(“[D]ifferential diagnosis grounded in significant clinical

experience and examination of medical records and

literature can certainly aid the trier of fact and cannot be

considered to be offering ‘junk science.’”). Thus,

Dr. Weisenburger reliably ruled out HCV as an alternate

cause of Hardeman’s NHL, and the district court did not

abuse its discretion in admitting Hardeman’s expert

testimony on specific causation.

IV

The district court’s decision to admit IARC’s

glyphosate classification as a “probable carcinogen” but

exclude contrary conclusions from other regulatory bodies is

reviewed for abuse of discretion. Estate of Barabin,

740 F.3d at 462. The district court made that decision to

HARDEMAN V. MONSANTO 43

mitigate prejudice to Hardeman after granting Monsanto’s

request to bifurcate the trial.

Monsanto argues that admitting IARC’s classification

was an error because the classification’s minimal probative

value was outweighed by unfair prejudice and juror

confusion, which was allegedly exacerbated by the district

court’s exclusion of various foreign regulatory agencies’

rejections of IARC’s classification. We disagree.

Under Rule 403, the district court can “exclude relevant

evidence if its probative value is substantially outweighed by

a danger of one or more of the following: unfair prejudice,

confusing the issues, misleading the jury, undue delay,

wasting time, or needlessly presenting cumulative

evidence.” Fed. R. Evid. 403. “A district court’s Rule 403

determination is subject to great deference, because the

considerations arising under Rule 403 are susceptible only

to case-by-case determinations, requiring examination of the

surrounding facts, circumstances, and issues.” United States

v. Hinkson, 585 F.3d 1247, 1267 (9th Cir. 2009) (en banc)

(internal quotation marks and citation omitted).

According to Monsanto, IARC’s classification had

minimal probative value because it did not rely on new data

or gauge cancer risk from real-world glyphosate exposure.

But this misses the point: IARC’s classification was

admitted to mitigate prejudice to Hardeman from the trial’s

bifurcation. Monsanto had specifically requested

bifurcation to preclude evidence of its “attempting to

influence regulatory agencies and manipulate public opinion

regarding glyphosate.” Without IARC’s classification,

“jurors w[ould] be left wondering, during the causation

phase, how glyphosate could possibly be dangerous if it

ha[d] gone largely unregulated for decades.” Further, the

district court minimized the risk of prejudice to Monsanto by

44 HARDEMAN V. MONSANTO

only admitting IARC’s classification, not the underlying

details, and admitting the continued approval of glyphosate

from three other regulators—EPA, EFSA, and ECA.

Importantly, the district court instructed the jury to “not

defer” to the conclusions of any of these regulatory bodies

because they were not a substitute for the jurors’ “own

independent assessment of the evidence.” While other

regulatory agencies had also rejected IARC’s classification,

the district court did not err in concluding that evidence of

additional regulators’ post-IARC conclusions would have

been cumulative. Admitting all foreign regulatory

conclusions would have invited the jury to weigh competing

regulatory findings rather than independently assess the

scientific evidence.

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.” United States v. Ramirez-Robles, 386 F.3d

1234, 1244 (9th Cir. 2004) (internal quotation marks and

citations omitted). Considering the strong limiting

instruction and the expert testimony linking glyphosate to

cancer, the jury would likely have reached the same

causation verdict even without evidence of IARC’s

classification or with more evidence of regulatory agency

rejections of that classification. Therefore, we affirm the

decision to admit the conclusions from IARC, EPA, EFSA,

and ECA, and to exclude evidence from additional

regulatory agencies.

V

Monsanto also challenges the district court’s causation

jury instruction. We review de novo whether that instruction

correctly states the law. Peralta v. Dillard, 744 F.3d 1076,

1082 (9th Cir. 2014) (en banc). We conclude that the district

HARDEMAN V. MONSANTO 45

court’s causation jury instruction was inconsistent with the

Judicial Council of California Civil Jury Instructions

(“CACI”) and California case law. We conclude, however,

that any error was harmless. See Caballero v. City of

Concord, 956 F.2d 204, 206 (9th Cir. 1992).

The district court’s causation jury instruction included a

substantial factor and but-for causation instruction, drawing

from CACI 430, and a concurrent independent causes

instruction. 17 The first paragraph of this instruction (on

substantial factor and but-for causation) adopted the same

17

The jury was instructed as follows:

To prevail on the question of medical causation,

Mr. Hardeman must prove by a preponderance of the

evidence that Roundup was a substantial factor in

causing his non-Hodgkin’s lymphoma. A substantial

factor is a factor that a reasonable person would

consider to have contributed to the harm. It must be

more than a remote or trivial factor. It does not have

to be the only cause of the harm. Subject to the

additional instructions below, conduct is not a

substantial factor in causing harm if the same harm

would have occurred without that conduct.

The following additional instructions apply if you

believe that two or more NHL-causing factors

operated independently on Mr. Hardeman:

If you conclude that Mr. Hardeman has proven that his

exposure to Roundup was sufficient on its own to

cause his NHL, then you must find for Mr. Hardeman

even if you believe that other factors were also

sufficient on their own to cause his NHL. On the other

hand, if you conclude that Mr. Hardeman has not

proven that his exposure to Roundup was sufficient on

its own to cause his NHL, then you must find for

Monsanto.

46 HARDEMAN V. MONSANTO

language as CACI 430, the model “substantial factor”

instruction. The district court’s instruction included

CACI 430’s final optional sentence on but-for causation that

reads, “[c]onduct is not a substantial factor in causing harm

if the same harm would have occurred without that conduct.”

But CACI 430’s “Directions for Use” instruct courts to “not

include the [but-for instruction] in a case involving

concurrent independent causes,” which the district court did

here. As such, “the but-for test is inappropriate in cases

when two forces are actively operating and each is sufficient

to bring about the harm.” Lopez v. The Hillshire Brands Co.,

254 Cal. Rptr. 3d 377, 383–84 (Ct. App. 2019) (quoting

Major v. R.J. Reynolds Tobacco Co., 222 Cal. Rptr. 3d 563,

579 (Ct. App. 2017)). And this makes sense considering that

the two instructions tend to contradict each other when used

together.

Here, the district court’s causation jury instruction

erroneously incorporated the optional final sentence of

CACI 430. The concurrent independent causation

instruction was appropriate—otherwise, the jury might not

have found causation, even if it thought Roundup caused

Hardeman’s cancer, because HCV may have been an

additional cause. See Viner v. Sweet, 70 P.3d 1046, 1051

(Cal. 2003) (explaining there is an exception to but-for cause

for “multiple forces operating at the same time and

independently, each of which would have been sufficient by

itself to bring about the harm”). But because the concurrent

independent causation instruction inherently conflicted with

but-for causation, the district court’s jury instruction did not

state the law entirely correctly. See Peralta, 744 F.3d

at 1082. We recognize the district court tried to alleviate this

conflict by adding the introductory language of “[s]ubject to

the additional instructions below,” before providing the but-

HARDEMAN V. MONSANTO 47

for causation instruction, but we still find that language

confusing, such that the instruction was “misleading.” Id.

An erroneous instruction does not require reversal,

however, when “the error is more probably than not

harmless.” Caballero, 956 F.2d at 206 (citation omitted).

That standard is “less stringent than review for harmless

error in a criminal case” and “more stringent than review for

sufficiency of the evidence.” Id. at 207. Because the

instruction given likely did not prejudice Monsanto, the

harmlessness standard is met. For instance, if the jury did

not view the but-for instruction as a bar to finding causation,

then it applied the appropriate causation standard. And even

if the jury interpreted the optional but-for sentence from

CACI 430 to mean Hardeman could only prevail if Roundup

was a but-for cause, then it would have also found legal

causation under the more flexible concurrent independent

causation standard. Thus, we affirm because the error in the

causation instruction was likely harmless.

VI

Monsanto argues it was entitled to judgment as a matter

of law on the failure-to-warn claims because it did not know

and could not have known that glyphosate caused cancer in

2012 (when Hardeman stopped using Roundup). But

reviewing de novo and “view[ing] the evidence in the light

most favorable to [Hardeman] . . . and draw[ing] all

reasonable inferences in h[is] favor,” Lakeside-Scott v.

Multnomah Cnty., 556 F.3d 797, 802 (9th Cir. 2009), we

conclude that sufficient scientific evidence was presented to

the jury to support that the association between glyphosate

and cancer was “knowable” by 2012.

To prevail on his failure-to-warn claim, Hardeman was

required to prove that the link between Roundup and cancer

48 HARDEMAN V. MONSANTO

was “known or knowable in light of the generally recognized

and prevailing best scientific and medical knowledge

available at the time of manufacture and distribution.”

Anderson v. Owens–Corning Fiberglas Corp., 810 P.2d 549,

558 (Cal. 1991). While the “scientific landscape” was “more

favorable” to Monsanto before 2012, there was sufficient

scientific evidence presented to the jury that the link between

glyphosate and cancer was “knowable.”

For instance, as early as 1985, EPA classified glyphosate

as a possible human carcinogen after reviewing a mouse

study finding that “[g]lyphosate was oncogenic in male

mice,” causing rare tumors. Even though EPA changed its

designation of glyphosate to non-carcinogenic in 1991,

several studies found an association between glyphosate and

cancer in the 1990s. In the late 1990s, Monsanto hired

Dr. Parry, a genotoxicologist, who found evidence that

glyphosate may be genotoxic and urged Monsanto to

conduct specific tests on Roundup’s genotoxicity. Though

Monsanto never conducted all the tests Dr. Parry

requested, 18 various independent scientific studies linking

glyphosate and cancer were released by 2012. Thus,

sufficient evidence was presented to the jury that the

association between glyphosate and cancer was, at

minimum, “knowable” by 2012, and Monsanto was

therefore not entitled to judgment as a matter of law.

VII

Finally, we address both parties’ challenges to the

punitive damages award. We review whether California law

Years later, in 2009, Monsanto toxicologist Donna Farmer said,

18

“you cannot say that Roundup does not cause cancer . . . [because] we

have not done carcinogenicity studies with ‘Roundup.’”

HARDEMAN V. MONSANTO 49

permits a jury’s decision to award punitive damages for

substantial evidence. Kaffaga v. Estate of Steinbeck,

938 F.3d 1006, 1013 (9th Cir. 2019). We review de novo,

with an “[e]xacting appellate review,” the constitutionality

of a punitive damages award. State Farm Mut. Auto. Ins.

Co. v. Campbell, 538 U.S. 408, 418 (2003) (citing Cooper

Indus., Inc. v. Leatherman Tool Grp., Inc., 532 U.S. 424, 436

(2001)). “[W]e defer to the district court’s ‘findings of fact

unless they are clearly erroneous.’” Arizona v. ASARCO

LLC, 773 F.3d 1050, 1054 (9th Cir. 2014) (quoting Cooper

Indus., 532 U.S. at 440 n.14). Based on this review, we hold

that (1) California law permits a punitive damages award

because substantial evidence was presented to the jury that

Monsanto acted with malice, and (2) though the $75 million

punitive damages award was constitutionally excessive, the

reduced $20 million award comports with the outer limits of

the Due Process Clause.

A

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. See Kaffaga, 938 F.3d

at 1018.

Punitive damages are permissible under California law

when there is “clear and convincing evidence that the

defendant has been guilty of oppression, fraud, or malice.”

Cal. Civ. Code § 3294(a). As relevant here, “malice” means

“despicable conduct which is carried on by the defendant

with a willful and conscious disregard of the rights or safety

of others.” § 3294(c)(1).

That definition of malice requires that we examine what

constitutes “despicable conduct” and “conscious disregard.”

50 HARDEMAN V. MONSANTO

“Despicable conduct” is conduct “so vile, base,

contemptible, miserable, wretched or loathsome that it

would be looked down upon and despised by most ordinary

decent people.” Pac. Gas & Elec. Co. v. Super. Ct., 235 Cal.

Rptr. 3d 228, 236 (Ct. App. 2018) (internal quotation marks

and citation omitted). “Conscious disregard” requires that

the defendant “have actual knowledge of the risk of harm it

is creating and, in the face of that knowledge, fail to take

steps it knows will reduce or eliminate the risk of harm.” Id.

(internal quotation marks and citation omitted). But whether

a “defendant is aware of the probable dangerous

consequences of [its] conduct and [it] willfully fails to avoid

such consequences” can be “proved either expressly through

direct evidence or by implication through indirect evidence

from which the jury draws inferences.” Pfeifer v. John

Crane, Inc., 164 Cal. Rptr. 3d 112, 135 (Ct. App. 2013)

(quoting Angie M. v. Super. Ct., 44 Cal. Rptr. 2d 197, 204

(Ct. App. 1995)).

Substantial evidence of Monsanto’s malice was

presented to the jury, supporting punitive damages under

§ 3294(a). For example, internal emails were presented

supporting that Monsanto was consciously aware of the

potential health risks associated with Roundup. One email,

from Monsanto toxicologist Mark Martens, read, “I don’t

know for sure how suppliers would react—but if somebody

came to me and said they wanted to test Roundup I know

how I would react—with serious concern.” A second email,

from Monsanto toxicologist William Heydens, read,

“[g]lyphosate is OK but the formulated product (and thus the

surfactant) does the damage.” And a third email, from

Monsanto toxicologist Donna Farmer, read, “you cannot say

that Roundup is not a carcinogen . . . [because] we have not

done the necessary testing on the formulation to make that

statement.” These emails provide the substantial evidence

HARDEMAN V. MONSANTO 51

necessary to support punitive damages based on Monsanto’s

awareness that Roundup posed a potential health risk.

There was also substantial evidence sufficient for a jury

to find that Monsanto “fail[ed] to take steps it kn[ew]

w[ould] reduce or eliminate the risk of harm.” Pac. Gas &

Elec. Co., 235 Cal. Rptr. 3d at 236 (internal quotation marks

and citation omitted). For instance, after its own hired

expert, Dr. Parry, found that glyphosate—alone and when

mixed with other chemicals in Roundup—had increased

genotoxic risks, evidence was sufficient to infer that

Monsanto largely failed to perform further studies. Instead,

Monsanto helped author an article downplaying

glyphosate’s health and safety concerns. Even though “it is

also possible to draw a contrary conclusion” that Monsanto

was ignorant or negligent (but not malicious), 19 the “jury’s

verdict must be upheld [because] it is supported by

substantial evidence” that Monsanto consciously

disregarded Roundup’s potential harm. See Pavao v. Pagay,

307 F.3d 915, 918 (9th Cir. 2002).

B

We next turn to the amount of punitive damages that

would still comport with the Due Process Clause. Hardeman

argues that the district court erred by reducing the jury’s

$75 million punitive damages award to $20 million. And

Monsanto contends that even the reduced punitive damages

award was unconstitutional under the Due Process Clause.

19

Monsanto also argues that it cannot be deemed to have acted with

malice because it complied with regulations. But “[a] defendant’s

compliance with, or actions consistent with, governmental regulations or

determinations about a product do not necessarily eviscerate a claim for

punitive damages.” Johnson & Johnson Talcum Powder Cases, 249 Cal.

Rptr. 3d 642, 678 (Ct. App. 2019).

52 HARDEMAN V. MONSANTO

Consistent with our “[e]xacting appellate review,” State

Farm, 538 U.S. at 418 (citing Cooper Indus., 532 U.S.

at 436), we lay out some fundamental principles underlying

the constitutionality of punitive damages awards.

“Compensatory damages and punitive damages serve

different purposes; compensatory damages redress concrete

loss caused by the defendant’s wrongful conduct, while

punitive damages are aimed at deterrence and retribution.”

Planned Parenthood of Columbia/Willamette Inc. v. Am.

Coal. of Life Activists, 422 F.3d 949, 953 (9th Cir. 2005)

(citing State Farm, 538 U.S. at 416; Cooper Indus., 532 U.S.

at 432). Further, “[t]he Supreme Court has instructed us to

go ‘no further’ if a ‘more modest punishment’ for the

‘reprehensible conduct’ at issue ‘could have satisfied the

State’s legitimate objectives’ of punishing and deterring

future misconduct.” Lompe v. Sunridge Partners, LLC,

818 F.3d 1041, 1065 (10th Cir. 2016) (quoting State Farm,

538 U.S. at 419–20). Ultimately, we are mindful that in

applying the Due Process Clause, it is “a constitution we are

expounding.” Tabares v. City of Huntington Beach,

988 F.3d 1119, 1122 (9th Cir. 2021) (quoting McCulloch v.

Maryland, 17 U.S. 316, 407 (1819)).

When punitive damages are “grossly excessive,” they

violate the Due Process Clause. State Farm, 538 U.S. at 416.

Whether punitive damages are “grossly excessive” depends

on three factors: “(1) the degree of reprehensibility of the

defendant’s misconduct; (2) the disparity between the actual

or potential harm suffered by the plaintiff and the punitive

damages award; and (3) the difference between the punitive

damages awarded by the jury and the civil penalties

authorized or imposed in comparable cases.” Id. at 418

(citing BMW of N. Am., Inc. v. Gore, 517 U.S. 559, 575

(1996)).

HARDEMAN V. MONSANTO 53

1

The weightiest factor is “the degree of reprehensibility

of the defendant’s conduct.” Gore, 517 U.S. at 575. The

district court found “Monsanto’s approach to the safety of its

product was indeed reprehensible.” In re Roundup Prods.

Liab. Litig., 385 F. Supp. 3d 1042, 1047 (N.D. Cal. 2019).

The district court’s finding was reasonable and supported by

the facts presented to the jury. Thus, the question is to what

degree Monsanto’s actions were reprehensible. We

determine the reprehensibility of Monsanto’s conduct by

considering the following five factors: whether “[1] the harm

caused was physical as opposed to economic; [2] the tortious

conduct evinced an indifference to or a reckless disregard of

the health or safety of others; [3] the target of the conduct

had financial vulnerability; [4] the conduct involved

repeated actions or was an isolated incident; and [5] the harm

was the result of intentional malice, trickery, or deceit, or

mere accident.” State Farm, 538 U.S. at 419 (citing Gore,

517 U.S. at 576–77).

Several aggravating factors associated with

reprehensible conduct are present based on the evidence at

trial. First, the harm inflicted on Hardeman—cancer—was

physical, not purely economic. Hardeman has already been

well compensated for damages resulting from his physical

injury. Indeed, $5,066,667 of the compensatory damages—

about 96% of the jury’s $5,267,634.10 total compensatory

award—was based on noneconomic harm. See In re

Roundup, 385 F. Supp. 3d at 1045. The district court found

the $2 million in compensatory damages related to future

noneconomic harm were “borderline” high because

Hardeman’s cancer was in remission. Id. And while

remission is “no guarantee,” testimony showed his cancer is

unlikely to return. Id. But, as the district court explained,

54 HARDEMAN V. MONSANTO

this concern was “mitigate[d]” because “the jury likely

intended the future award to compensate a longer period of

suffering.” Id. These factual findings by the district court,

which are reasonable and not clearly erroneous, highlight the

reprehensibility of causing serious physical harm and the

need to deter future harm. While Hardeman was well

compensated for past and future harm, the serious nature of

the harm supports finding that Monsanto’s actions were

reprehensible.

Second, the district court’s factual conclusion that

Monsanto ignored safety risks is not clearly erroneous and

also supports reprehensibility. For example, the district

court found that “Monsanto’s behavior betrayed a lack of

concern about the risk that its product might be

carcinogenic.” Id. at 1047. In addition, it found that “the

evidence at trial painted the picture of a company focused on

attacking or undermining the people who raised concerns, to

the exclusion of being an objective arbiter of Roundup’s

safety.” Id. But the district court also found mitigating

evidence. Notwithstanding the jury’s verdict for Hardeman,

the district court explained that “the metaphorical jury is still

out on whether glyphosate causes NHL.” Id. Indeed, “there

is credible evidence on both sides of the scientific debate”

which “surely diminish[es]—to a degree—Monsanto’s

culpability.” Id. Moreover, “[t]he scientific landscape was

even more favorable to Monsanto during the time

Mr. Hardeman was using Roundup.” Id.

We also agree with the district court that no evidence was

presented that Monsanto knew Roundup in fact caused

cancer. Monsanto never conducted studies that may have

indicated (as its scientists suspected) that Roundup was

carcinogenic. And regulators, like EPA, have repeatedly

found glyphosate to not have carcinogenic risks. But, as the

HARDEMAN V. MONSANTO 55

district court found, the evidence supports that Monsanto

knew Roundup might cause cancer, hence its concern and

reluctance to, for instance, conduct Dr. Parry’s

recommended studies. We have no quibble with any of the

district court’s findings of fact. Ultimately, evidence of

Monsanto’s conduct—downplaying concerns and failing to

fully assess Roundup’s safety after being alerted to possible

risks—supports that Monsanto acted with “indifference to or

a reckless disregard of the health or safety of others.” State

Farm, 538 U.S. at 419.

Third, State Farm asks us to look at Hardeman’s

financial vulnerability. Id. It goes without saying that this

is a case of a large corporation and an individual—not two

corporations on equal footing. Having said that, this factor

is not particularly relevant in a mostly noneconomic

damages case like this one. See Lompe, 818 F.3d at 1066

(“But as a practical matter, the financial vulnerability factor

does not have particular relevance . . . where the harm

[plaintiff] suffered was physical rather than a reprehensible

exploitation of financial vulnerability through fraud or other

financial misconduct.”). The district court below did not

analyze this factor. We do not find this factor helpful one

way or another to establish reprehensibility.

Fourth, the district court did not clearly err in finding that

Monsanto’s “conduct involved repeated actions” instead of

“an isolated incident.” See In re Roundup, 385 F. Supp. 3d

at 1047 (quoting State Farm, 538 U.S. at 419). Evidence

was presented that Monsanto repeatedly sold Roundup

without a warning label. Id. Thus, this factor supports

reprehensibility because “repeated misconduct is more

reprehensible than an individual instance of malfeasance.”

Gore, 517 U.S. at 577.

56 HARDEMAN V. MONSANTO

Fifth, the district court recognized Monsanto’s actions

exhibited malice but also made findings of fact that

mitigated this factor. The district court noted there was no

evidence “that Monsanto hid evidence from the EPA or,

alternatively, that it had managed to capture the EPA.” See

In re Roundup, 385 F. Supp. 3d at 1047. There was also no

evidence “that Monsanto was in fact aware that glyphosate

caused cancer but concealed it, thus distinguishing this case

from the many cases adjudicating the conduct of the tobacco

companies.” Id. Nonetheless, there was evidence of

Monsanto’s malice. As the district court found, “[d]espite

years of colorable claims in the scientific community that

Roundup causes NHL,” emails showed “Monsanto

employees crassly attempting to combat, undermine or

explain away challenges to Roundup’s safety.” Id. And “not

once was [the jury] shown an email suggesting that

Monsanto officials were actively committed to conducting

an objective assessment of its product.” Id. We do not find

the district court’s findings of fact clearly erroneous.

Based upon the district court’s findings, four of the five

factors support that Monsanto’s actions were reprehensible.

But in two of those factors, there were significant mitigating

considerations which suggest that Monsanto’s actions, while

reprehensible, were not “particularly egregious.” See Gore,

517 U.S. at 582.

2

We next examine the disparity between harm to

Hardeman and the punitive damages award by looking to the

Supreme Court’s guidelines on appropriate ratios. State

Farm, 538 U.S. at 424. The Supreme Court has explained

that “[s]ingle-digit multipliers are more likely to comport

with due process, while still achieving the State’s goals of

deterrence and retribution.” Id. at 425. “[A]n award of more

HARDEMAN V. MONSANTO 57

than four times the amount of compensatory damages might

be close to the line of constitutional impropriety.” Id. (citing

Pac. Mut. Life Ins. Co. v. Haslip, 499 U.S. 1, 23–24 (1991)).

But there are “no rigid benchmarks that a punitive damages

award may not surpass” and greater ratios might “comport

with due process where ‘a particularly egregious act has

resulted in only a small amount of economic damages.’” Id.

(quoting Gore, 517 U.S. at 582).

Here, the jury awarded $5,267,634.10 in compensatory

damages and $75 million (approximately 14.2 times the

compensatory amount) in punitive damages. But

Monsanto’s conduct—though plausibly viewed as

reprehensible—was not “particularly egregious” as to

warrant a damages ratio above the single-digit range,

especially considering the absence of evidence showing a

known safety risk was intentionally concealed. See id. Thus,

we have little trouble holding that the jury’s 14.2 to 1 ratio

violated due process.

The $5,267,634.10 compensatory damages award was

substantial. See, e.g., Ramirez v. TransUnion LLC, 951 F.3d

1008, 1037 (9th Cir. 2020), cert. granted in part on other

grounds, No. 20-297, 2020 WL 7366280 (U.S. Dec. 16,

2020) (describing $8 million compensatory damages award

as “quite substantial”); Lompe, 818 F.3d at 1069

(“[C]ompensatory damages have often been considered

‘substantial’ when they are over $1,000,000.”). “When

compensatory damages are substantial, then a lesser ratio,

perhaps only equal to compensatory damages, can reach the

outermost limit of the due process guarantee.” State Farm,

538 U.S. at 425. But “State Farm’s 1:1 compensatory to

punitive damages ratio is not binding, no matter how

factually similar the cases may be.” Hangarter v. Provident

Life & Accident Ins. Co., 373 F.3d 998, 1014 (9th Cir. 2004).

58 HARDEMAN V. MONSANTO

Considering these precedents, we have held that “[i]n cases

where there are significant economic damages and punitive

damages are warranted but behavior is not particularly

egregious, a ratio of up to 4 to 1 serves as a good proxy for

the limits of constitutionality.” Planned Parenthood,

422 F.3d at 962.

Even though “substantial” compensatory damages were

awarded here, the evidence justifies a damages ratio higher

than 1 to 1. Monsanto intentionally downplayed and ignored

calls to test Roundup’s carcinogenic risks, and the jury

determined that Roundup caused Hardeman’s cancer.

Coupled with the physical damage—cancer—these factors

suggest a damages ratio up to 4 to 1 “serves as a good proxy

for the limits of constitutionality.” Id.; see State Farm,

538 U.S. at 425 (“The precise award in any case, of course,

must be based upon the facts and circumstances of the

defendant’s conduct and the harm to the plaintiff.”).

3

Third, the district court speculated that fines for failure

to warn of a product’s risk under FIFRA and the California

Health and Safety Code could potentially “over time[]

become quite high” because “both state and federal law

calculate penalties per violation.” In re Roundup, 385 F.

Supp. 3d at 1048; see also 7 U.S.C. § 136j(a)(1)(E);

40 C.F.R. § 19.4; Cal. Health & Safety Code § 25249.7. We

note the need to avoid speculation in analyzing this factor.

See State Farm, 538 U.S. at 428 (rejecting consideration of

speculative future penalties unrelated to plaintiffs’ harm).

The parties failed below, and again on appeal, to explain

what the relevant civil fines are, how they would be

calculated, and even whether they would be warranted. See

In re Roundup, 385 F. Supp. 3d at 1048. Monsanto points

out, however, that no civil or criminal fines have been

HARDEMAN V. MONSANTO 59

imposed, apparently by any federal or any state agency,

including California.

Though California in 2017 categorized glyphosate as a

chemical known to the state to cause cancer, see Glyphosate

Proposition 65, it is also not clear that Monsanto would have

been subject to civil fines under California law in 2012.

Because neither party presents argument or evidence, we

agree with the district court that this guidepost is not

“particularly helpful here.” See id. at 1048 (“[A]bsent an

explanation from either party about how these penalties

would be calculated, it is difficult to use them as a

benchmark.”).

* * *

We hold that the jury’s $75 million punitive damages

award was “grossly excessive” given the mitigating factors

found by the district court. See State Farm, 538 U.S. at 416.

Considering the evidence of reprehensibility, however, we

hold that 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 comports with

due process. Planned Parenthood, 422 F.3d at 962; see also

Ramirez, 951 F.3d at 1037 (upholding 4 to 1 ratio where

$8 million compensatory damages awarded).

Though we uphold the district court’s $20 million

punitive damages award, we emphasize that the award is

“close to the line of constitutional impropriety.” See State

Farm, 538 U.S. at 425. Considering the number of cases

pending in this Roundup multidistrict litigation, we

recognize a smaller punitive damages award in other cases

may safely satisfy due process concerns by still imposing the

appropriate punishment and achieving the goals of

deterrence and retribution. Cf. Lompe, 818 F.3d at 1065

60 HARDEMAN V. MONSANTO

(“The Supreme Court has instructed us to go ‘no further’ if

a ‘more modest punishment’ for the ‘reprehensible conduct’

at issue ‘could have satisfied the State’s legitimate

objectives’ of punishing and deterring future misconduct.”

(quoting State Farm, 538 U.S. at 419–20)); see, e.g.,

Johnson v. Monsanto Co., 266 Cal. Rptr. 3d 111, 129 (Ct.

App. 2020), as modified on denial of reh’g (Aug. 18, 2020),

review denied (Oct. 21, 2020) (reducing punitive damages

award in a Roundup case to a 1 to 1 ratio with compensatory

damages of $10.3 million and where facts of Monsanto’s

reprehensibility were likely stronger than this case).

VIII

We are aware this appeal involves a bellwether trial with

potentially thousands of federal cases to follow. But many

of our holdings are fact-specific. Different Roundup cases

may present different considerations, leading to different

results. For example, were there evidence that EPA took

certain enforcement action against Monsanto after a cancer

warning was added to Roundup’s label, perhaps the

preemption analysis would lead to a different outcome. And

while our holding that expert testimony was admissible here

may be applicable to other Roundup cases, much of this

expert testimony was unique to Hardeman’s specific case.

Thus, it would not be unreasonable for the district court to

revisit the admissibility of expert testimony based upon the

facts raised in future cases. Similarly, despite the punitive

damages upheld here, a smaller punitive damages award in

future cases may better comport with due process.

Ultimately, we agree that the district court in this case either

reached the correct result or need not be reversed.

AFFIRMED.

HARDEMAN V. MONSANTO 61

N.R. SMITH, Circuit Judge, dissenting to section VII.B.

After a mandated de novo review of the district court’s

punitive damages award, determining if the amount was

constitutionally excessive (not simply determining whether

the award was acceptable or reasonable), I must dissent. Let

me explain.

Punitive damages are “‘quasi-criminal,’ operat[ing] as

‘private fines’ intended to punish the defendant and to deter

future wrongdoing.” Cooper Indus., Inc. v. Leatherman

Tool Grp., Inc., 532 U.S. 424, 432 (2001) (quoting Pacific

Mut. Life Ins. Co. v. Haslip, 499 U.S. 1, 19 (1991)).

“Exacting appellate review ensures that an award of punitive

damages is based upon an ‘application of law, rather than a

decisionmaker’s caprice.’” State Farm Mut. Auto. Ins. Co.

v. Campbell, 538 U.S. 408, 418 (2003). As the majority has

stated, “the Supreme Court has instructed us to go ‘no

further’ if a ‘more modest punishment’ for the ‘reprehensible

conduct’ at issue ‘could have satisfied the State’s legitimate

objectives’ of punishing and deterring future misconduct.”

Lompe v. Sunridge Partners, LLC, 818 F.3d 1041, 1065

(10th Cir. 2016) (quoting State Farm, 538 U.S. at 419–20).

In order to determine de novo whether the punishment is

“grossly excessive,” the Supreme Court requires us “to

consider three guideposts: (1) the degree of reprehensibility

of the defendant’s misconduct; (2) the disparity between the

actual or potential harm suffered by the plaintiff and the

punitive damages award; and (3) the difference between the

punitive damages awarded by the jury and the civil penalties

authorized or imposed in comparable cases.” State Farm,

538 U.S. at 417–18. Of course, we always defer to the

district court’s findings of fact unless they are clearly

erroneous. Cooper Indus., 532 U.S. at 440 n.14.

62 HARDEMAN V. MONSANTO

The district court made the following findings of fact,

upon which one must make the analysis:

a. The jury found it was more likely than not

that Roundup (the glyphosate therein)

was a “substantial factor” in causing

Hardeman’s NHL. In order to evidence

that Roundup was a substantial factor in

this cause, Hardeman’s experts only

performed a differential diagnosis.

Differential diagnosis is 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.”

b. NHL is a cancer that affects white blood

cells in the immune system.

Approximately 70% or more of the 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.

c. Hardeman was diagnosed with NHL in

early 2015. He started using Roundup in

the 1980s but ended his use in 2012.

During the time Hardeman was using

Roundup, the scientific landscape (of

whether it could cause cancer) was more

favorable to Monsanto than at the time of

trial. In 2012, EPA had little to no

HARDEMAN V. MONSANTO 63

evidence that glyphosate was at all

carcinogenic in humans. Not until 2015

did the International Agency for Research

on Cancer (“IARC”) suggest that

glyphosate was probably carcinogenic to

humans.

d. Even today, there is credible evidence on

both sides with regard to whether

glyphosate causes NHL as documented

by the repeated approvals of glyphosate

by EPA, the European Chemicals

Agency, Health Canada, and other

worldwide regulatory agencies.

e. There is no evidence that Monsanto was

in fact aware that glyphosate caused

cancer; that Monsanto concealed it from

EPA; or that Monsanto somehow had

“captured” those in EPA, such that EPA

would not take a position contrary to

Monsanto.

f. The record at best shows that Monsanto

knew Roundup might cause cancer but

made minimal efforts to determine

whether the scientific evidence (finding

glyphosate may cause NHL) was

accurate.

g. However, Monsanto did attack or

undermine those who raised concerns for

Roundup’s safety.

64 HARDEMAN V. MONSANTO

h. Monsanto has sold Roundup without a

warning label. 1

i. The award of future noneconomic

damages was not based on physical pain

or impairment but was limited to

“anxiety, mental suffering, loss of

enjoyment of life, emotional distress, and

inconvenience.”

j. Hardeman’s NHL is now in remission,

his prognosis is “very good” and it is

“extremely unlikely” that his NHL will

return.

See In re Roundup Prod. Liab. Litig., 385 F. Supp. 3d 1042,

1047 (N.D. Cal. 2019).

1. The degree of reprehensibility of Monsanto’s

conduct.

Considering each of the three guideposts, the degree of

reprehensibility is “[t]he most important indicium of the

reasonableness of a punitive damages award.” See State

Farm, 538 U.S. at 419. The degree of reprehensibility is

determined by considering (1) “the harm caused was

physical as opposed to economic”; (2) “the tortious conduct

evinced an indifference to or a reckless disregard of the

health or safety of others”; (3) the target of the conduct had

financial vulnerability”; (4) “the conduct involved repeated

actions or was an isolated incident”; and (5) “the harm was

1

The district court noted that Monsanto continues to sell Roundup

without a warning label. However, “the conduct that harmed [plaintiff]

is the only conduct relevant to the reprehensibility analysis.” State Farm,

538 U.S. at 424.

HARDEMAN V. MONSANTO 65

the result of intentional malice, trickery, or deceit, or mere

accident.” Id. Applying the facts (as determined by the

district court) de novo to these five considerations,

Monsanto’s conduct from the 1980s to 2012 did not

constitute the degree of “reprehensible conduct” that would

warrant an award of punitive damages at a 3.8:1 ratio. See

id. Reviewing these five considerations instead

demonstrates a low degree of reprehensibility.

First, while Hardeman suffered from physical harm

(NHL), he was well compensated for it by the jury.

Importantly, the physical harm suffered was not based on

acts or threats of violence, see Florez v. Delbovo, 939 F.

Supp. 1341, 1348 (N.D. Ill. 1996) (explaining that “acts of

violence or threats of bodily harm” are “the most

reprehensible” (citing BMW of N. Am., Inc. v. Gore, 517 U.S.

559, 575 (1996)), or “from some physical assault or trauma,”

see State Farm, 538 U.S. at 426. Further, (as demonstrated

below) Monsanto did not engage in deliberate conduct to

exploit Hardeman and expose him to a risk of cancer. Cf.

Bullock v. Philip Morris USA, Inc., 131 Cal. Rptr. 3d 382,

396 (Ct. App. 2011) (concluding “that in a case involving

physical harm, the physical or physiological vulnerability of

the target of the defendant’s conduct is an appropriate factor

to consider in determining the degree of reprehensibility,

particularly if the defendant deliberately exploited that

vulnerability”).

Second, one must determine whether Monsanto’s

conduct evinced “indifference to or a reckless disregard of

the health or safety of others.” State Farm, 538 U.S. at 419.

In California, Hardeman had to demonstrate that Monsanto

“had been guilty of oppression, fraud, or malice,” in order to

be awarded punitive damages from Monsanto. Cal. Civ.

Code § 3294(a). Section 3294(c)(1) outlines that

66 HARDEMAN V. MONSANTO

Monsanto’s conduct must have been undertaken “with a

willful and conscious disregard of the rights or safety of

others.” A conscious disregard “requires that the defendant

have actual knowledge of the risk of harm it is creating and,

in the face of that knowledge, fail[ed] to take steps it kn[ew

would] reduce or eliminate the risk of harm.” Ehrhardt v.

Brunswick, Inc., 231 Cal. Rptr. 60, 65 (Ct. App. 1986).

Given this standard, although ignoring evidence that

Roundup might cause cancer could be substantial evidence

to establish punitive damages against Monsanto, there was

and still exists “credible evidence on both sides of the

debate” about whether Roundup actually does cause cancer.

During the time that Hardeman used Roundup, the evidence

was scant that Roundup may cause cancer, but Monsanto did

disregard it. However, its conduct does not demonstrate (nor

did the court find) that Monsanto intentionally targeted

Hardeman.

Third, there is no evidence in the record that the target of

the conduct (Hardeman) had financial vulnerability. See

Clark v. Chrysler Corp., 436 F.3d 594, 604 (6th Cir. 2006)

(“The financial vulnerability of a target is particularly

relevant when the harm inflicted is economic in nature.”).

The wealth of Monsanto cannot justify an award of punitive

damages absent a connection of its “financial resources and

the physical injury suffered” by Hardeman. See id.

Fourth, Monsanto’s failure to place a warning on

Roundup’s label does not constitute “repeated actions.” 2 See

Gore, 517 U.S. at 577. “[E]vidence that a defendant has

repeatedly engaged in prohibited conduct while knowing or

suspecting that it was unlawful would provide relevant

2

As previously noted, the district court seems to rely on conduct

that occurred post 2012 in determining the reprehensibility.

HARDEMAN V. MONSANTO 67

support for an argument that strong medicine is required to

cure the defendant’s disrespect for the law.” Id. at 576–77.

At the time Hardeman used the product, Monsanto was not

engaging in unlawful conduct. At that time, EPA had little

to no evidence that glyphosate was carcinogenic in humans.

In fact (again), there is credible evidence (to this day) on

both sides with regard to whether glyphosate causes NHL.

Notably, IARC did not decide to classify glyphosate as

“probably carcinogenic to humans” until 2015 (three years

after Hardeman stopped using Roundup). See In re Roundup

Prod. Liab. Litig., 385 F. Supp. 3d at 1047. Further, after

California’s passage of Proposition 65 (requiring a warning

label for glyphosate), Michael L. Goodis, EPA, Office of

Pesticide Programs, sent a letter to registrants (like

Monsanto) challenging Proposition 65 as contrary to “EPA’s

determination that glyphosate is ‘not likely to be

carcinogenic to humans.’” Proposed Interim Registration

Review at 11. The letter charged that the Proposition 65

warning was a “false and misleading statement” and violated

the Federal Insecticide, Fungicide, and Rodenticide Act

(“FIFRA”).

Fifth, Monsanto did not act with “intentional malice,

trickery, or deceit.” See State Farm, 538 U.S. at 419. As the

district court found, Monsanto acted with indifference, but

Monsanto did not engage in intentional acts, trickery, or

deceit. 3 See Williams v. First Advantage LNS Screening

3

Even the majority does not conclude that Monsanto acted with

“intentional malice, trickery, or deceit.” See Maj. Op. 53. Rather, it

describes Monsanto’s conduct as “malice.” Id. at 56. However,

“malice,” as found by the district court, means a “conscious disregard of

the rights or safety of others.” See In re Roundup Prod. Liab. Litig.,

385 F. Supp. 3d at 1046 (quoting Cal. Civ. Code § 3294(c)(1)). Thus,

there is no evidence that the harm suffered by Hardeman was the “result

of intentional malice”; Monsanto did not “intend[] to cause injury” to

68 HARDEMAN V. MONSANTO

Sols. Inc, 947 F.3d 735, 754 (11th Cir. 2020) (concluding

that “[a]t worst, Defendant acted recklessly, but without any

intent to harm Plaintiff”). In fact, Monsanto’s actions were

not contrary to “government regulations.” See Johnson &

Johnson Talcum Powder Cases, 249 Cal. Rptr. 3d 642, 678

(Ct. App. 2019), review denied (Oct. 23, 2019). Although

compliance with regulations cannot “eviscerate a claim for

punitive damages,” id., it does evidence that the harm “was

[not] the result of intentional malice, trickery, or deceit,”

State Farm, 538 U.S. at 419. As the district court found, the

association between Roundup and NHL “remains under

scientific investigation” and there was no evidence of

intentional acts on the part of Monsanto. Id.; cf. Satcher v.

Honda Motor Co., 52 F.3d 1311, 1316–17 (5th Cir. 1995)

(precluding punitive damages when there was a genuine

dispute in the scientific community).

Lastly, in reviewing these considerations, “some wrongs

are more blameworthy than others,” such as “violence,”

“trickery and deceit,” or “intentional malice” and are more

deserving of a higher punitive damages ratio. See Gore,

517 U.S. at 575. We have suggested that this “hierarchy of

reprehensibility” starts “with acts and threats of violence

. . . , followed by acts taken in reckless disregard for others’

health and safety, affirmative acts of trickery and deceit, and

finally, acts of omission and mere negligence.” Swinton v.

Potomac Corp., 270 F.3d 794, 818 (9th Cir. 2001) (citation

Hardeman. See Gober v. Ralphs Grocery Co., 40 Cal. Rptr. 3d 92, 106

(Ct. App. 2006). Nevertheless, despite a lack of evidence of this

“important criterion,” the majority still concludes that a punitive

damages award at outer constitutional boundaries for this case of

significant compensatory damages was appropriate. See Rhone-Poulenc

Agro, S.A. v. DeKalb Genetics Corp., 345 F.3d 1366, 1371 (Fed. Cir.

2003) (noting that this “factor has become an important criterion of what

the Constitution accepts as reprehensible conduct”).

HARDEMAN V. MONSANTO 69

and quotation marks omitted). Thus, “[i]n order to justify a

substantial punitive damage award, a plaintiff ordinarily

must prove that the defendants’ conduct falls at the upper

end of the blameworthiness continuum, or, put another way,

that the conduct reflects a high level of culpability.”

Zimmerman v. Direct Fed. Credit Union, 262 F.3d 70, 82

(1st Cir. 2001).

No review of these considerations reflects “a high level

of culpability.” Id. Thus, Monsanto’s low degree of

reprehensibility cannot constitutionally justify the district

court’s substantial punitive damages award.

2. The disparity between harm suffered and

punitive damages award.

“The second and perhaps most commonly cited indicium

of an unreasonable or excessive punitive damages award is

its ratio to the actual harm inflicted on the plaintiff.” Gore,

517 U.S. at 580. In determining punitive damages for each

case, the Supreme Court has outlined that “the precise

award” of such damages “must be based upon the facts and

circumstances of the defendant’s conduct and the harm to the

plaintiff.” State Farm, 538 U.S. at 425. Although the Court

has not drawn a “bright-line ratio” for punitive damages, the

Court’s jurisprudence suggests “that, in practice, few awards

exceeding a single digit-ratio between punitive and

compensatory damages, to a significant degree, will satisfy

due process.” Id. “A higher ratio may . . . be justified in

cases” where (1) “the injury is hard to detect,” (2) “the

monetary value of noneconomic harm might have been

difficult to determine,” or (3) “a particularly egregious act

has resulted in only a small amount of [compensatory]

damages.” Gore, 517 U.S. at 582. The Court then clarified

the outer boundaries for such an award: “an award of more

than four times the amount of compensatory damages might

70 HARDEMAN V. MONSANTO

be close to the line of constitutional impropriety.” Id.

However, it also emphasized an outermost limit in making

such an award, stating “when compensatory damages are

substantial, then a lesser ratio [less than 4:1], perhaps only

equal to compensatory damages, can reach the outermost

limit of the due process guarantee.” Id. (emphasis added).

The compensatory damages in this case are substantial

($5,267,634.10) and the reasons to justify a higher ratio do

not exist. Thus, a punitive damages amount equal to

compensatory damages reaches the Supreme Court’s

outermost limit for punitive damages.

The California Supreme Court provides further

guidance, especially focusing on a case where there is a

relatively low reprehensibility. It said that “a ratio of one to

one might be the federal constitutional maximum in a case

involving . . . relatively low reprehensibility and a

substantial award of noneconomic damages: ‘When

compensatory damages are substantial, then a lesser ratio,

perhaps only equal to compensatory damages, can reach the

outermost limit of the due process guarantee.’” Roby v.

McKesson Corp., 219 P.3d 749, 769 (Cal. 2009) (quoting

State Farm, 538 U.S. at 425). In this case, the district court

reduced the jury’s 14.2:1 punitive damages award to nearly

a 4:1 ratio, which is generally reserved for a higher degree

of reprehensible conduct. Id. Monsanto’s conduct here did

not include (1) acts or threats of violence; or (2) acts of

trickery or deceit, evidencing a low degree of

reprehensibility.

Even in a case that involved conduct that was highly

reprehensible, the California Court of Appeal concluded that

“the permissible ratio of punitive to compensatory damages”

should be reduced when the noneconomic damages

“appear[ed] to include a punitive component.” See

HARDEMAN V. MONSANTO 71

Bankhead v. ArvinMeritor, Inc., 139 Cal. Rptr. 3d 849, 866–

67 (Ct. App. 2012) (allowing punitive damages award at a

2.4:1 ratio). The Supreme Court agrees. See State Farm,

538 U.S. at 425–26, 429 (explaining that “in light of the

substantial compensatory damages awarded (a portion of

which contained a punitive element), a punitive damages

award at or near the amount of compensatory damages” was

justified).

The jury awarded substantial past and future

noneconomic damages totaling $5,066,667, which contain a

punitive element. The district court recognized this fact

when it noted that the $2,000,000 in future noneconomic

damages was “borderline,” because it was “somewhat

difficult to rationalize the conclusion that the suffering he

will face is, effectively, two-thirds of the suffering he has

already endured.” In re Roundup Prod. Liab. Litig. 385 F.

Supp. 3d. at 1045. Thus, a punitive damages award of 3.8:1

exceeded the constitutionally permissible limits. See State

Farm, 538 U.S. at 425; Roby, 219 P.3d at 769. The ratio of

punitive damages should be reduced to a 1:1 ratio. See id.

3. The difference between the punitive damages

awarded and the civil penalties authorized or

imposed in similar cases.

The third guidepost also supports punitive damages

equal to the compensatory damages award. Sanctions for

comparable misconduct can be determined by either the

“civil or criminal penalties that could be imposed for

comparable misconduct,” Gore, 517 U.S. at 583, or “the

existence of other civil awards against the defendant for the

same conduct,” Haslip, 499 U.S. at 22; see also Ismail v.

Cohen, 899 F.2d 183, 186 (2d Cir. 1990) (“Reference to

other awards in similar cases is proper.”).

72 HARDEMAN V. MONSANTO

One has difficulty comparing civil or criminal penalties

with this punitive damages award. During the time

Hardeman used Roundup, there were no federal or state

criminal or civil penalties for Monsanto’s conduct. Neither

the federal government nor the State of California had

imposed any penalties for the possibility that glyphosate may

cause cancer. 4 Although Monsanto’s conduct following the

harm can be considered in setting the punitive damages

award, see Johnson & Johnson Talcum Powder Cases,

249 Cal. Rptr. 3d at 678, California did not list glyphosate as

a chemical known to cause cancer until 2017. 5 It is similarly

difficult to determine how the federal government or

California would apply or calculate fines (which is probably

one of the reasons neither party really addressed this issue).

Comparing this case to the only other litigated case

against Monsanto regarding the sale of Roundup supports a

1:1 ratio. See Johnson v. Monsanto Co., 266 Cal. Rptr. 3d

111, 135 (Ct. App. 2020). In Johnson, the plaintiff

developed cancer in 2014 after using Roundup. Id. at 116–

17. Johnson sought damages, based on Monsanto’s

knowledge regarding Roundup’s carcinogenicity. Id. at 117.

4

Criminal and civil penalties may be imposed under federal and

state law. See 7 U.S.C. §§ 136j(a)(1)(E), 136l(a)(1); 40 C.F.R. § 19.4;

Cal. Health & Safety Code §§ 25249.6, 25249.7(a). Under federal law,

civil penalties may be assessed up to $5,000 for each offense. 7 U.S.C.

§ 136l(a)(1); see also 40 C.F.R. § 19.4 (2012). Criminal penalties may

result in either imprisonment of one year, a $50,000 fine, or both. Id.

§ 136l(b)(1). California law imposes a civil penalty up to $2,500 per day

for each violation. Cal. Health & Safety Code § 25249.7(a).

5

California Health & Safety Code section 25249.6 prohibits any

“person in the course of doing business [from] knowingly and

intentionally expos[ing] any individual to a chemical known to the state

to cause cancer or reproductive toxicity without first giving clear and

reasonable warning to such individual.”

HARDEMAN V. MONSANTO 73

Reviewing the evidence, the district court reduced

compensatory damages to $10,253,309.32 and awarded

punitive damages at a 1:1 ratio. Id. at 129. The damages

awarded (for essentially “the same conduct”) in Johnson

provide a worthy comparison in assessing the

constitutionality of this punitive damages award. See

Haslip, 499 U.S. at 22; see also Restatement (Second) of

Torts § 908 cmt. e (1979) (noting that “[i]t seems appropriate

to take into consideration both the punitive damages that

have been awarded in prior suits and those that may be

granted in the future, with greater weight being given to the

prior awards”).

Finally, our sister circuits have come to similar

conclusions when dealing with substantial compensatory

damages (even when the conduct is highly reprehensible).

For example, in Boerner v. Brown & Williamson Tobacco

Co., the Eighth Circuit concluded that, despite American

Tobacco’s “highly reprehensible” conduct, the “punitive

damages award [of $15,000,000] [wa]s excessive when

measured against the substantial compensatory damages

award [of $4,025,000].” 394 F.3d 594, 603 (8th Cir. 2005).

Thus, it “conclude[d] that a ratio of approximately 1:1 would

comport with the requirements of due process.” Id.;

Saccameno v. U.S. Bank Nat’l Ass’n, 943 F.3d 1071, 1090

(7th Cir. 2019), cert. denied sub nom. Saccameno v. Ocwen

Loan Servicing, LLC, 140 S. Ct. 2674 (2020) (holding that

“a considerable compensatory award for the indifferent, not

malicious, mistreatment” and evidence that the “award

reflects emotional distress damages that ‘already contain [a]

punitive element’” “should not exceed 1:1”); Bridgeport

Music, Inc. v. Justin Combs Pub., 507 F.3d 470, 490 (6th

Cir. 2007) (“Given the large compensatory damages award

of $366,939, a substantial portion of which contained a

punitive element, and the low level of reprehensibility of

74 HARDEMAN V. MONSANTO

defendants’ conduct, a ratio of closer to 1:1 or 2:1 is all that

due process can tolerate in this case.”); see also Clark,

436 F.3d at 607 (holding that “because the compensatory

damage award here is not particularly large, a 1:1 ratio is

inappropriate. But due to the lack of several of

reprehensibility factors, any ratio higher than 2:1 is

unwarranted”).

4. Conclusion:

I start where I began. Because we are mandated to

review de novo the district court’s award of punitive

damages, one must undertake the review. In light of the

three guideposts, the district court’s $20,000,000 punitive

damages award exceeds the line of constitutionality. The

facts found by the district court do not support a 3.8:1 ratio

to compensatory damages. Most notably, Monsanto’s

conduct is not particularly reprehensible in light of the

ongoing scientific debate. The compensatory damages are

substantial; thus, punitive damages in an amount equal to

compensatory damages reaches the outermost limit of the

due process guarantee. Criminal and civil penalties and

punitive damages awarded in other cases do not suggest a

higher award. We then should go no further; this

punishment will satisfy the State’s legitimate objectives for

imposing such damages.