Amicus Curiae Brief — Monsanto Company, Petitioner v. John L. Durnell
Supreme Court briefApr 1, 2026
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No. 24-1068
In the Supreme Court of the United States
________________
MONSANTO COMPANY,
PETITIONER
v.
JOHN L. DURNELL,
RESPONDENT
_______________
ON WRIT OF CERTIORARI TO THE COURT OF
APPEALS OF MISSOURI, EASTERN DISTRICT
_______________
BRIEF OF AMICI CURIAE
NEW MEXICO AND SEVENTEEN OTHER STATES
IN SUPPORT OF RESPONDENT
_________
RAÚL TORREZ
Attorney General of
New Mexico
ALETHEIA V.P. ALLEN
Solicitor General
ALEXANDER W. TUCKER*
Asst. Solicitor General
New Mexico
Department of Justice
201 Third Street NW,
Suite 300
Albuquerque, NM 87102
(505) 948-8244
atucker@nmdoj.gov
*Counsel of Record
(Additional counsel listed inside)
April 1, 2026
KATHLEEN JENNINGS
ATTORNEY GENERAL OF
DELAWARE
ROB BONTA
ATTORNEY GENERAL OF
CALIFORNIA
DANA NESSEL
ATTORNEY GENERAL OF
MICHIGAN
PETER F. NERONHA
ATTORNEY GENERAL OF
RHODE ISLAND
AARON M. FREY
ATTORNEY GENERAL OF
MAINE
CHARITY R. CLARK
ATTORNEY GENERAL OF
VERMONT
LETITIA JAMES
ATTORNEY GENERAL OF
NEW YORK
KWAME RAOUL
ATTORNEY GENERAL OF
ILLINOIS
JENNIFER DAVENPORT
ATTORNEY GENERAL OF
NEW JERSEY
PHILIP J. WEISER
ATTORNEY GENERAL OF
COLORADO
KEITH ELLISON
ATTORNEY GENERAL OF
MINNESOTA
DAN RAYFIELD
ATTORNEY GENERAL OF
OREGON
BRIAN SCHWALB
ATTORNEY GENERAL OF
THE DISTRICT OF
COLUMBIA
ANTHONY G. BROWN
ATTORNEY GENERAL OF
MARYLAND
ANDREA JOY CAMPBELL
ATTORNEY GENERAL OF
MASSACHUSETTS
ERIC J. WILSON
DEPUTY ATTORNEY
GENERAL OF WISCONSIN
KRIS MAYES
ATTORNEY GENERAL OF
ARIZONA
i
TABLE OF CONTENTS
Page
TABLE OF AUTHORITIES.................................... iv
INTERESTS OF AMICI CURIAE ........................... 1
SUMMARY OF ARGUMENT .................................. 2
ARGUMENT ............................................................ 4
I. FIFRA DOES NOT EXPRESSLY
PREEMPT STATE LAW FAILURE TO
WARN CLAIMS............................................. 4
A. Failure to warn theories are
consistent with FIFRA’s
misbranding provision. ......................... 4
B. EPA registration does not create a
“requirement” under FIFRA. ................ 9
C. Monsanto’s positions do not further
uniformity and instead hinder other
objectives of FIFRA.. ........................... 11
D. The Court should defer to the
democratic process. ............................. 13
II. FIFRA DOES NOT IMPLIEDLY
PREEMPT STATE FAILURE TO WARN
CLAIMS. ...................................................... 15
A. Monsanto can comply with both
FIFRA and state duties to warn......... 15
B. Federalism weighs against implied
preemption. ......................................... 17
ii
C. Alternatively, any preemption
should be narrow................................. 18
III.EQUAL SOVEREIGNTY CONCERNS
ARE UNFOUNDED. ................................... 21
CONCLUSION ....................................................... 24
iii
TABLE OF AUTHORITIES
Page(s)
Cases
Baksic v. Ethicon Inc.,
659 F.Supp.3d 763 (W.D. Tx. 2023) ........................5
Bates v. Dow Agrosciences LLC,
544 U.S. 431 (2005) ....2, 4, 5, 7, 9-12, 14, 15, 17, 22-25, 28, 29
Burton v. Am. Cyanamid,
334 F.Supp.3d 949 (E.D. Wisc. 2018) ......................5
Carson v. Monsanto Co.,
92 F.4th 980 (2024) ................................................10
Clark v. Sweeny,
607 U.S. ___ (2025) ................................................16
Corrigan v. Covidien LP,
748 F.Supp.3d 1 (D. Mass. 2024) ............................6
Crosby v. Nat’l Foreign Trade Council,
530 U.S. 363 (2000) ................................................15
Dunn v. Astaris, LLC,
292 Fed.Appx. 525 (8th Cir. 2008) (per curiam) ...20
Ferebee v. Chevron Chem. Co.,
736 F.2d 1529 (D.C. Cir. 1984) ................................8
iv
Gaetano v. Gilead Scis., Inc.,
529 F.Supp.3d 333 (D.N.J. 2021) ..........................20
Gareis v. 3M Co.,
9 F.4th 812 (8th Cir. 2021) ......................................6
Geier v. Am. Honda Motor Co.,
529 U.S. 861 (2000) .......................................... 17, 18
Hardeman v. Monsanto Co.,
997 F.3d 941 (9th Cir. 2021).................. 5, 10, 11, 20
Higgins v. E.I. DuPont de Nemours & Co.,
671 F.Supp.1055 (D. Md. 1987) ...............................5
Hogan v. Novartis Pharms. Corp.,
2011 WL 1533467 (E.D.N.Y. 2011)
(unpublished) .........................................................20
Lingle v. Norge Div. of Magic Chef, Inc.,
486 U.S. 399 (1989) ................................................20
Medtronic, Inc. v. Lohr,
518 U.S. 470 (1996) ............................................ 5, 17
Metro. Life Ins. Co. v. Massachusetts,
471 U.S. 724 (1985) ................................................17
Monsanto Co. v. Durnell,
707 S.W.3d 828 (Mo. Ct. App. 2025) .....................19
v
Motor Coach Indus., Inc. v. Khiabani ex rel. Rigaud,
137 Nev. 416, 493 P.3d 1007 (S. Ct. Nev. 2021) .....6
Nat’l Pork Producers Council v. Ross,
598 U.S. 356 (2023) .......................................... 21, 22
NRDC v. EPA,
38 F.4th 34 (9th Cir. 2022) ....................................10
PLIVA, Inc. v. Mensing,
564 U.S. 604 (2011) ................................................16
Primal Vantage Co., v. O’Bryan,
677 S.W.3d 228 (S. Ct. Ky. 2022) ............................6
Rice v. Santa Fe Elevator Corp.,
331 U.S. 218 (1947) ................................................17
Roley v. Am. Honda Motor Co.,
259 Mont. 128, 856 P.2d 196 (S. Ct. Mont. 1993) ...6
Schoenhofer v. McClaskey,
861 F.3d 1170 (10th Cir. 2017)..............................10
Sluis v. Ethicon, Inc.,
529 F.Supp.3d 1004 (D. S.D. 2021) .........................5
Town of Bridport v. Sterling Clark Lurton Corp.,
166 Vt. 304, 693 A.2d 701 (S. Ct. Vt. 1997) ............6
United States v. Sineng-Smith,
590 U.S. 371 (2020) ................................................16
vi
Virginia v. Black,
538 U.S. 343 (2003) ................................................10
Whitman v. Am. Trucking Ass’ns,
531 U.S. 457 (2001) ................................................11
Wos v. E.M.A. ex rel. Johnson,
568 U.S. 627 (2013) ................................................13
Wright v. Ryobi Techs., Inc.,
175 F.Supp.3d 439 (E.D. Penn. 2016) .....................6
Wyeth v. Levine,
555 U.S. 555 (2009) .......................................... 18, 20
Ziglar v. Abbasi,
582 U.S. 120 (2017) ................................................13
Statutes
7 U.S.C. § 136 ...................................................... 2, 5, 8
7 U.S.C. § 136a ...................................................... 8, 11
7 U.S.C. § 136v ............................. 2, 4, 5, 10-12, 14-17
7 U.S.C. §§ 136-136y ...................................................2
Cal. Health & Safety Code § 25249.11(f) (2006) ......20
O.C.G.A. § 2-7-171(b) (2025) .....................................15
vii
Other Authorities
About
Us,
MODERN
AG
ALLIANCE,
https://modernagalliance.org/about-us/ (last visited
Mar. 22, 2026) ........................................................14
Allan E. Korpela, Failure to warn as basis of liability
under doctrine of strict scrutiny in tort, 53 A.L.R.3d
239 (Originally published in 1973) .........................6
C. M. Benbrook, Trends in glyphosate herbicide use in
the
United
States
and
globally. 28(1)
ENVIRONMENTAL SCIENCES EUROPE 3 (2016),
https://doi.org/10.1186/s12302-016-0070-0 ...........23
CAL. DEP’T OF PESTICIDE REGUL., Pesticide Use
Annual Report 2023 Data Summary (2025),
https://files.cdpr.ca.gov/pub/outgoing/pur/data/2023
_pur_report_textfiles/annual_report/2023_pur_ann
ual_report.pdf ........................................................23
Data Requirements for Pesticide Registration, U.S.
ENV'T
PROT.
AGENCY,
https://www.epa.gov/pesticide-registration/datarequirements-pesticide-registration (last updated
Jan. 14, 2026) ...........................................................7
Erwin Chemerinsky, Empowering States When It
Matters: A Different Approach to Preemption, 69
BROOKLYN L. REV. 1313 (2004) ..............................18
Farm, Food, and National Security Act of 2026, H.R.
7567, 119th Cong. (2026) .......................................15
viii
H.B. 129, 2025 Leg., Reg. Sess. (Fla.2025) ...............15
H.B. 285, 68th Leg., Gen. Sess. (Wyo. 2025) ............15
H.B. 303, 68th Leg., 1st Reg. Sess. (Idaho 2025).…. 15
H.B. 522, 69th Leg., Reg. Sess. (Mont. 2025) ...........15
H.B. 544, 103rd Gen. Assemb., 1st Reg. Sess.
(Mo. 2025)...............................................................15
H.B. 809, 114th Gen. Assemb., 1st Reg. Sess.
(Tenn. 2025) ...........................................................15
H.B. 1221, 2025 Leg., Reg. Sess. (Miss.2025) ..........15
H.B. 1318, 69th Leg. Assemb., Reg. Sess.
(N.D. 2025) .............................................................15
H.B. 1755, 60th Leg., 1st Reg. Sess. (Okla.2025).....15
Monsanto Co. v. Durnell, No. 24-1068
(U.S. Jan. 16, 2026) ...............................................19
Monsanto Co. v. Durnell, No. 24-1068 (U.S. Mar. 2,
2026), Br. of Amici Curiae Nebraska, Iowa,
Missouri, and 12 Other States in Support of
Petitioner ...............................................................21
Monsanto Co. v. Hardeman, No. 21-241 (U.S. May 10,
2022), Brief for the U.S. as Amicus Curiae ..........17
ix
Montgomery v. Caribe Transport II, LLC., et al., No.
24-1238 (U.S. Dec. 8, 2025), Preemption Scholars
Amicus Br...............................................................18
Political Disclosures, BAYER UNITED STATES (Feb. 20,
2026),
https://www.bayer.com/en/us/politicaldisclosures ..............................................................14
S.B. 144, 158th Gen. Assemb., Reg. Sess. (Ga. 2025)
................................................................................ 15
S.F. 394, 91st Gen. Assemb., 2025 Reg. Sess. (Iowa
2025) ..................................................................... 15
Regulations
40 C.F.R § 156.64 ......................................................10
40 C.F.R. § 156.70 .......................................................6
40 C.F.R. § 158.1 .........................................................7
40 C.F.R. § 158.130 .................................................6, 7
83 Fed. Reg. 27652 (June 13, 2018) ..........................22
1
INTERESTS OF AMICI CURIAE
Private rights of action under state common law
are a form of state police power to protect human and
environmental health. Amici States have a strong
interest in preserving their constitutional police
power and ensuring that principles of federalism are
adequately considered in preemption cases.
Almost all states allow common law failure to warn
claims against pesticide manufacturers. Two states,
North Dakota and Georgia, expressly prohibit
manufacturer liability for failure to warn. Most states
have no official policy on glyphosate’s carcinogenicity
but do not prevent municipalities from establishing
their own glyphosate bans or use restrictions. No state
has a uniform ban on glyphosate use or sale.
These views reflect state choices over how best to
regulate glyphosate products like Monsanto’s
Roundup to promote the health and welfare of their
respective people. Though relevant state law—and
jury verdicts in Roundup cases—vary to some extent,
inconvenience to Monsanto is no reason to preempt
state law where federal law allows considerable
latitude.
The Federal Insecticide Fungicide and Rodenticide
Act, 7 U.S.C. §§ 136-136y (FIFRA) is Congress’
attempt to balance the economic benefits of pesticides1
with inherent risks to human and environmental
health. FIFRA’s prohibition of misbranding leaves
Roundup is an herbicide but is classified as a pesticide
under 7 U.S.C. § 136(t) and (u).
1
2
ample room for states to allow recovery from pesticide
manufacturers that do not adequately warn of
dangers that could be caused by their products. It
follows that § 136v(b) of FIFRA—which preempts
certain state label requirements that are “in addition
to or different from” those “required” by FIFRA—
cannot be read as broadly preempting state law claims
for failure to warn, such as Respondent’s. The
Environmental
Protection
Agency’s
(EPA)
registration of glyphosate and approval of Roundup’s
labeling without a cancer warning do not change that
outcome.
Amici States support Respondent John L. Durnell
in his efforts to uphold state law.
SUMMARY OF ARGUMENT
FIFRA does not expressly preempt state failure to
warn claims such as Respondent’s. First, Bates v. Dow
Agrosciences LLC, 544 U.S. 431 (2005), permits
parallel failure to warn claims, and FIFRA’s
prohibition of misbranding is consistent with such
claims, especially considering that EPA’s evaluations
do not consider all evidence material to misbranding.
Second, EPA’s registration decisions do not create a
substantive “requirement” under FIFRA. Indeed,
registration is only prima facie evidence that a
product is not misbranded. Third, Monsanto’s
expansive reading of EPA’s power does not
meaningfully further FIFRA’s purpose of uniformity
but instead hinders FIFRA’s balancing of health and
economy. Fourth, Congress has made an informed
decision not to amend FIFRA to preempt claims such
3
as Respondent’s, and this Court should defer to the
democratic process.
FIFRA also does not impliedly preempt state
failure to warn claims. Monsanto’s impossibility
preemption arguments lack merit because federal law
does not prohibit Monsanto from including a warning
on Roundup that satisfies state common-law
standards. Federalism concerns animating the
presumption against preemption also counsel against
implied preemption. Alternatively, if the Court is
inclined to find preemption, any such ruling should be
narrow and limited only to label-based failure to warn
theories. And either way, the Court should also
consider the extent to which causation and jury
instructions mitigate or cure Monsanto’s grievances.
Finally, Nebraska and fourteen other states
support Monsanto and argue that allowing other
states’ common law to survive preemption will disrupt
their farming industries and thereby undermine
equal state sovereignty. But they identify no evidence
that could even remotely demonstrate a burden on
equal state sovereignty. And their sky-is-falling
arguments are belied by Monsanto’s significant
market share and enduring demand for glyphosate
products despite billions of dollars in Roundup
judgments and settlements to date. In any event,
Bates counsels against considering market reactions
to state tort liability in the preemption analysis, and
Monsanto’s arguments sound in the “inducement test”
this Court has already rejected.
4
ARGUMENT
I.
FIFRA
DOES
NOT
EXPRESSLY
PREEMPT STATE LAW FAILURE TO
WARN CLAIMS.
A.
Failure to warn theories are
consistent with FIFRA’s
misbranding provision.
Bates v. Dow Agrosciences LLC, 544 U.S. 431
(2005), controls. There, this Court recognized
§ 136v(b) as “narrow” and set forth a two-part test to
decide whether a state law claim is expressly
preempted. First, the state law must be a requirement
for “labeling or packaging.” 544 U.S. at 444. Second,
the “state-labeling requirement is not preempted by
§ 136v(b) if it is equivalent to, and fully consistent
with, FIFRA’s misbranding provisions.” Bates, 544
U.S. at 447. In other words, Bates provides that a
manufacturer cannot be held liable for failure to warn
under a state labeling requirement unless the
manufacturer is also liable for misbranding. Id. at
454. In considering whether a failure to warn claim is
preempted by § 136v(b), Bates tells courts to measure
any state requirements against FIFRA’s text or
relevant EPA regulations. Bates, 544 U.S. at 453. But
see Resp. Br. at 4-7. Lower courts have come to
recognize this test as a “parallel claim” requirement.
See, e.g., Hardeman v. Monsanto Co., 997 F.3d 941,
955 (9th Cir. 2021).
In pertinent part, FIFRA provides that a pesticide
is “misbranded” if its label “is false or misleading in
5
any particular” or if the label “does not contain
directions for use which are necessary for effecting the
purpose for which the product is intended and if
complied with . . . are adequate to protect health.”
§ 136(q)(1)(A), (F).
This broad language ensures that claims like
Respondent’s are not preempted. A label that does not
warn of increased cancer risk is inherently “false or
misleading” if chronic use of the product increases
cancer risk, and a product’s directions cannot be
“adequate to protect health” if following them leads to
increased cancer risk. Cf. Bates, 544 U.S. at 447-48
n.23; Hardeman, 997 F.3d at 954-55 (“FIFRA’s
requirement that a pesticide not be misbranded is
consistent with, if not broader than, California’s
common law duty to warn.” (emphasis added));
Medtronic, Inc. v. Lohr, 518 U.S. 470, 495 (1996)
(noting that state requirements that are “narrower”
than federal requirements are not preempted because
they “duplicate the federal rule” (cleaned up)). Given
that the core components of failure to warn claims are
relatively uniform across states,2 it is unremarkable
2 While state law varies to some extent in evidentiary
burdens and available defenses, common law failure to warn
claims generally ask the same question: was a warning
inadequate, and if so, did that cause the plaintiff’s injuries? See,
e.g., Baksic v. Ethicon Inc., 659 F.Supp.3d 763, 769 (W.D. Tx.
2023); Burton v. Am. Cyanamid, 334 F.Supp.3d 949, 962 (E.D.
Wisc. 2018); Higgins v. E.I. DuPont de Nemours & Co., 671
F.Supp. 1055, 1060 (D. Md. 1987); Sluis v. Ethicon, Inc., 529
F.Supp.3d 1004, 1009-10 (D. S.D. 2021); Roley v. Am. Honda
Motor Co., 259 Mont. 128, 129, 856 P.2d 196, 198 (S. Ct. Mont.
6
that Bates’ parallel claim requirement will often be
satisfied.
EPA registration and label approval do not change
that outcome. There are at least two reasons why,
among others covered here and in Respondent’s brief.
First, EPA considers criteria and evidence
narrower than the wide range of real-world evidence
that could otherwise satisfy FIFRA’s broad definition
of “misbranded.” For example, labeling regulations
require a “precautionary statement for human
hazard” when a product presents acute health risks,
but they do not compel such statement when chronic
health risks may still be present. See 40 C.F.R.
§ 156.70; see also 40 C.F.R. § 158.130(d)(1) (“Data
from acute studies serve as a basis for classification
and precautionary labeling.”); Data Requirements for
Pesticide Registration, U.S. ENV’T PROT. AGENCY,
https://www.epa.gov/pesticide-registration/datarequirements-pesticide-registration (last updated
Jan. 14, 2026) (“acute toxicity data are used . . . to
develop precautionary label statements pertaining to
protective clothing requirements for applicators.”).
1993); Wright v. Ryobi Techs., Inc., 175 F.Supp.3d 439, 455 (E.D.
Penn. 2016); Town of Bridport v. Sterling Clark Lurton Corp.,
166 Vt. 304, 307-08, 693 A.2d 701, 704 (S. Ct. Vt. 1997); Motor
Coach Indus., Inc. v. Khiabani ex rel. Rigaud, 137 Nev. 416, 41920, 493 P.3d 1007, 1011-12 (S. Ct. Nev. 2021); Corrigan v.
Covidien LP, 748 F.Supp.3d 1, 11-12 (D. Mass. 2024); Primal
Vantage Co., Inc. v. O’Bryan, 677 S.W.3d 228, 245-46 (S. Ct. Ky.
2022); Gareis v. 3M Co., 9 F.4th 812, 818-19 (8th Cir. 2021). See
generally Allan E. Korpela, Failure to warn as basis of liability
under doctrine of strict scrutiny in tort, 53 A.L.R.3d 239
(Originally published in 1973).
7
Data requirements for registration also may not
guarantee that chronic health risks will be adequately
considered in EPA’s evaluation. Although relevant
regulations perhaps encourage EPA to consider
subchronic and chronic studies to some extent, e.g., 40
C.F.R. § 158.130(d)(2), (3), such regulations do not
mandate any “study protocols, methodology, or
standards for conducting or reporting test results” nor
do they “describe how [EPA] uses or evaluates the
data and information in its risk assessment[.]” 40
C.F.R. § 158.1(b)(3). Finally, registration occurs only
once every fifteen years, leaving room for development
of both scientific and real-world evidence relevant to
misbranding in the interim. § 136a(g)(1)(A).
Given limitations like these, along with the plain,
broad meaning of language defining “misbranded”
(§ 136(q)(1)(A), (F)), a product is naturally
“misbranded” if chronic exposure increases cancer
risk—even where EPA has made some preliminary
judgment suggesting otherwise. It follows that a jury’s
conclusion in cases like Respondent’s are fully
consistent with FIFRA.
Even assuming EPA’s evaluations of glyphosate or
Roundup’s labeling were thorough and completely
accurate,3 EPA does not consider the entire universe
3 As Respondent and other amici observe, the thoroughness
of EPA’s glyphosate evaluation is undermined by the Ninth
Circuit’s vacatur of the human health portion of EPA’s 2022
glyphosate registration decision. See NRDC v. EPA, 38 F.4th 34,
51-52 (9th Cir. 2022) (holding that EPA’s determination that
glyphosate was “not likely to be carcinogenic to humans” was not
8
of information relevant to a pesticide’s impact on
human and environmental health. That is precisely
why EPA determinations cannot foreclose the
possibility of misbranding—FIFRA “contemplates
that pesticide labels will evolve over time, as
manufacturers gain more information about their
products’ performance in diverse settings.” Bates, 544
U.S. at 451 (citing Ferebee v. Chevron Chem. Co., 736
F.2d 1529, 1541-42 (D.C. Cir. 1984)); Hardeman, 997
F.3d at 955-57.
Second, the result in Bates works against
Monsanto’s arguments by showing that a label-based
failure to warn claim can continue despite EPA
registration and approval of a label without that
warning. See Bates, 544 U.S. at 434-35. If registration
precluded misbranding, Bates would not have
resulted in remand because EPA registration would
have simply foreclosed any possibility of liability. Like
the manufacturer in Bates, Monsanto asks the Court
to adopt an overbroad and atextual reading of §
136v(b). See 544 U.S. at 448-49 (describing the
manufacturer’s “amputated” reading of § 136v(b)).
supported by substantial evidence). Further, in 2015, the World
Health Organization’s International Agency for Research on
Cancer (IARC) classified glyphosate as a probable human
carcinogen, and more recent studies also suggest carcinogenicity.
See Resp. Br. at 14-15; see also Simona Panzacchi et al.,
Carcinogenic Effects of Long-Term Exposure from Prenatal Life
to Glyphosate and Glyphosate-Based Herbicides in Sprague–
Dawley
Rats,
24
ENV’T
HEALTH
1187
(2025),
https://doi.org/10.1186/s12940-025-01187-2 (finding “robust
evidence” supporting IARC’s 2015 conclusion).
9
By submitting that EPA’s determinations
automatically preempt state law, Monsanto’s
arguments depart from Bates and constructively
narrow FIFRA’s definition of “misbranded.” The Court
should reject such arguments.
B.
EPA registration does not create a
“requirement” under FIFRA.
Bates provides that a “requirement” under FIFRA
is a “rule of law that must be obeyed.” 544 U.S. at 445.
Here, Monsanto and the federal government4 argue
that EPA’s decision to register glyphosate and
approve Roundup without a cancer warning create a
“requirement” under FIFRA that has preemptive
effect under § 136v(b).
That cannot be right. Nothing in FIFRA’s plain
text or EPA’s current regulations bridge the gap
between preemption under § 136v(b) and EPA’s
determinations. See Hardeman, 997 F.3d at 957-58.
There is no “rule of law” that could preempt state law
here. Bates, 544 U.S. at 445.
4 Given the federal government’s historic inconsistency on
§ 136v(b)’s preemptive breadth, its arguments here are entitled
to little weight. See Monsanto Co. v. Hardeman, No. 21-241 (U.S.
May 10, 2022), Br. for the United States as Amicus Curiae; Bates,
544 U.S. at 449 (“[The United States’ preemption arguments are]
particularly dubious given that just five years ago the United
States advocated the interpretation that we adopt today.”); cf.
Wyeth v. Levine, 555 U.S. 555, 580 n.13 (2009) (giving little
weight to the United States’ brief because of inconsistent
positions).
10
In rejecting the same arguments Monsanto makes
here, the Ninth and Eleventh Circuits persuasively
reasoned that EPA’s determinations regarding
glyphosate did not carry “force of law” and thus
created no “requirement” under FIFRA because those
actions were not subject to rulemaking process
required by the Administrative Procedures Act (APA).
Hardeman, 997 F.3d at 957-58; Carson v. Monsanto
Co., 92 F.4th 980, 993-94 (2024); Schoenhofer v.
McClaskey, 861 F.3d 1170, 1175 n.4 (10th Cir. 2017).
That is also dispositive in this case. See Bates, 544
U.S. at 453 (citing 40 C.F.R § 156.64 (2004) as an
example of a rule with preemptive effect). But see
Resp. Br. at 4-7, 20-26 (arguing that even some EPA
rules may not have preemptive effect). While
Monsanto relies on EPA letters, publications, and a
vacated interim decision5 to support its arguments,
Bates requires more.
Even discounting the “force of law” analysis,
FIFRA’s plain text provides that registration is
merely prima facie evidence that a product is not
misbranded. Bates, 544 U.S. at 438-39 (citing
§ 136a(f)(2)). Like any prima facie evidence, it can be
rebutted. See Virginia v. Black, 538 U.S. 343, 369-70
(2003). The jury’s verdict in Respondent’s case is but
one of many showing that EPA’s determinations are
often not conclusive of misbranding.
5 See BIO at 24-25 (citing NRDC v. EPA, 38 F.4th 34, 51 (9th
Cir. 2022) (vacating EPA’s 2020 finding that glyphosate is not
carcinogenic)).
11
§ 136v(b) cannot be read to vest in EPA the power
to decide that manufacturers are immunized from
certain forms of state tort liability. Cf. Whitman v.
Am. Trucking Ass’ns, 531 U.S. 457, 468 (2001)
(“Congress does not hide elephants in mouseholes”
(cleaned up)). EPA does not make its own substantive
law. That is Congress’ job.
C.
Monsanto’s positions do not further
uniformity and instead hinder other
objectives of FIFRA.
Monsanto, the federal government, and supporting
amici insist that preemption would further FIFRA’s
purpose of uniformity by creating a national standard
that manufacturers, farmers, and consumers can rely
on. That is not true, and the ruling Monsanto asks for
would undermine other objectives of FIFRA.
If EPA’s registration and label approval
themselves
create
substantive
statutory
“requirements,” then national policy on glyphosate,
and any impacts it could have on state tort law,
agriculture practices, food prices, or manufacturer
risk profiles, could easily change from one
administration to another—or even within an
administration that changes its mind on registration
decisions—all without any input from Congress or
state legislatures. Monsanto’s uniformity arguments
are overstated.
Indeed, the status quo does not materially impede
uniformity. Monsanto argues that varying jury
verdicts impose a patchwork of duties to warn and
12
thereby undermine FIFRA’s purpose of uniformity.
But that argument cannot carry the day because this
Court recognizes that varying outcomes in jury trials
do not impose difficulties “beyond those regularly
experienced by manufacturers of other products that
every day bear the risk of conflicting jury verdicts.” Id.
at 452.
State common law furthers FIFRA’s objective of
balancing health and economy by allowing tort suits
to serve as a “catalyst” for new information relevant
to the “health” side of that equation. 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.”). Ruling for
Monsanto would significantly frustrate FIFRA’s
balancing purposes while providing no meaningful
uniformity gains.
Finally, Monsanto suggests that state duties to
warn create a “crazy-quilt” of standards that go
against Congress’ intent in passing § 136v(b) with
FIFRA’s 1972 amendments. Pet. Br. at 2-3. But
Monsanto’s
“crazy-quilt”
characterization
is
exaggerated—common law duties to warn are more or
less the same across states, as all share the same roots
in basic negligence principles. See supra n.2.
Moreover, FIFRA’s 1972 amendments were not
intended to preempt state tort law; they were
intended to make labeling easier with respect to
logistics like the color of “lettering,” the size of labels,
and more general state label requirements such as
whether the product is referred to as “flammable” or
13
“inflammable.” Bates, 544 U.S. at 452 n.26. “[T]he
lengthy legislative history is barren of any indication
that Congress meant to abrogate most of the commonlaw duties long owed by pesticide manufacturers.” Id.
This history confirms that § 136v(b) does preempt
certain state rules, reinforcing that Respondent’s
arguments against preemption have reasonable
limits. See Resp. Br. at 26.
D.
The Court should defer to the
democratic process.
If Congress in any way disagreed with Bates’
parallel claim requirement, Bates’ treatment of EPA’s
registration power, or how Bates has been applied by
all but one court since, Congress could have amended
FIFRA to preempt all state requirements concerning
labeling. See 544 U.S. at 449. Congress also could have
narrowed the definition of “misbranding,” declared
EPA’s registration and labeling approval as
preempting state common law duties to warn, or
perhaps made express findings regarding glyphosate’s
carcinogenicity. But Congress has not done so. That
inaction is “worth something” where Congress is
“clearly aware” that states traditionally control
private recovery. See Wos v. E.M.A. ex rel. Johnson,
568 U.S. 627, 652-53 (2013) (Roberts, C.J.,
dissenting); see also Ziglar v. Abbasi, 582 U.S. 120,
123 (2017).
To that end, this Court can also infer from recent
events that Congress’ inaction is well-informed.
14
First, Monsanto has extensively lobbied both
Congress and state legislatures to amend or enact
statutes that would shield it from liability. In 2025
alone, Monsanto spent over nine million dollars
lobbying Congress, two million of which was spent in
the last quarter of 2025 while the petition was
pending.6 See also Resp. Br. at 27-28. Despite
Monsanto’s invitations, Congress has thus far
declined to amend FIFRA to preempt claims like
Respondent’s.7
Second, recent state choices also undermine
Monsanto’s reading of § 136v(b) and counsel deference
to the democratic process.
States like North Dakota and Georgia have passed
legislation to cut off both label-based and off-label
failure to warn liability.8 Georgia’s legislative findings
provide that its statute was enacted to “clarify[]
regulatory authority of pesticide labeling[.]” Supra
n.8. That would be unnecessary if FIFRA already did
that work. And the Georgia statute’s text exemplifies
what Congress could have done, but chose not to, any
6Political Disclosures, BAYER UNITED STATES (Feb. 20, 2026),
https://www.bayer.com/en/us/political-disclosures.
BayerMonsanto also founded and sponsors the Modern Ag Alliance,
which funds advocacy across federal and state legislatures. See
About
Us,
MODERN
AG
ALLIANCE,
https://modernagalliance.org/about-us/ (last visited Mar. 22,
2026).
7 There is pending legislation to amend § 136v(b), reinforcing
that Congress knows how to preempt state failure to warn claims
but has chosen not to. See Farm, Food, and National Security Act
of 2026, H.R. 7567, 119th Cong. (2026).
8 SB144 (Georgia) and HB1318 (North Dakota)
15
time after Bates. See O.C.G.A. § 2-7-171(b) (2025)
(providing that any label approved by EPA “shall be
deemed a sufficient warning label . . . under any
provision of state law concerning the duty to warn or
label, or any other common law duty to warn”).
Most states have thus far declined to enact
statutes that would shield Monsanto from liability.9
That Monsanto has been mostly unsuccessful in
obtaining relief through democratic means—even in
many agrarian states—is telling. The Court should
decline Monsanto’s invitation to undermine the policy
choices of Congress and state legislatures.
II.
FIFRA
DOES
NOT
IMPLIEDLY
PREEMPT STATE FAILURE TO WARN
CLAIMS.
A.
Monsanto can comply with both
FIFRA and state duties to warn.
Federal law impliedly preempts state law when “it
is impossible for a private party to comply with both
state and federal law” or when state law “stands as an
obstacle to the accomplishment and execution of the
full purposes and objectives of Congress.” Crosby v.
Nat’l Foreign Trade Council, 530 U.S. 363, 372-73
(2000) (cleaned up).
9 In 2025, the legislatures of Iowa (SB394), Florida (HB129),
Idaho (HB303), Mississippi (HB1221), Missouri (HB544),
Montana (HB522), Oklahoma (HB1755), Tennessee (HB809),
and Wyoming (HB285) rejected bills that would shield Monsanto,
in whole or in part, from failure to warn liability. Other state
legislatures did not even consider such legislation.
16
Monsanto makes no obstacle or field preemption
arguments (Pet. Br. at 43-50), so the Court should not
consider any implied preemption theory other than
impossibility. See Clark v. Sweeny, 607 U.S. ___ (2025)
(per curiam) (citing United States v. Sineng-Smith,
590 U.S. 371, 375 (2020)).
The burden to show impossibility is daunting and
cannot be met by showing the mere “possibility” of
impossibility. PLIVA, Inc. v. Mensing, 564 U.S. 604,
625 n.8 (2011).
First, Monsanto’s impossibility arguments lack
merit. Monsanto relies on a 2019 EPA letter and
EPA’s 1993 glyphosate registration. Pet. Br. at 48-49.
The 2019 letter does not “carry force of law,” and in
any event, EPA backed off its 2019 position in its April
2022 letter, saying that a proposed label identifying
IARC’s 2015 glyphosate classification “could be
approved[.]” See BIO at 32-33. Further, even if the
1993 registration were not outdated, it is only prima
facie evidence against misbranding. See Resp. Br. at
29-31. In short, Monsanto’s implied preemption
arguments fail for the same reasons its express
preemption arguments do.
Second, it is possible to comply with federal and
state law because FIFRA does not prevent Monsanto
from submitting, or EPA from approving, a label
consistent with both EPA’s decisions and state duties
to warn. But Monsanto has not even gotten that far,
as it has never formally submitted a cancer warning
label to EPA for approval. See BIO at 4. That itself is
dispositive to impossibility. However, even if EPA
17
rejected a proposed cancer warning label in the future,
that still would not necessarily prove impossibility
because EPA could instead approve a more qualified
or informative warning that nevertheless satisfies
state duties to warn. See, e.g., Monsanto Co. v.
Hardeman, No. 21-241 (U.S. May 10, 2022), Brief for
the United States as Amicus Curiae at 10-13, 15-16
(discussing potential alternatives to overt cancer
warnings and relevant law); see also Resp. Br. at 3943 (arguing that Monsanto could unilaterally change
its label to comply with state law).
Instead of finding ways to comply with federal and
state law, Monsanto decided to live with the risk of
state tort liability. That risk management decision
does not show impossibility, and it certainly does not
justify a bailout from this Court.
B.
Federalism weighs against implied
preemption.
As this Court has long recognized, federalism is an
important factor in preemption cases, especially those
implicating “the historic primacy of state regulation of
matters of health and safety.” Lohr, 518 U.S. at 475
(citing Metro. Life Ins. Co. v. Massachusetts, 471 U.S.
724, 756 (1985)); Rice v. Santa Fe Elevator Corp., 331
U.S. 218, 230 (1947). And in cases where regulations
are relied on for preemption, state interests matter
even more. See Geier v. Am. Honda Motor Co., 529
U.S. 861, 907-08 (2000) (Stevens, J., dissenting).
Thus, where Monsanto argues that state law
requirements are impliedly preempted, the
presumption against preemption ensures that
18
federalism is adequately considered in the preemption
analysis. See id.; Erwin Chemerinsky, Empowering
States When It Matters: A Different Approach to
Preemption, 69 BROOKLYN L. REV. 1313 (2004)
(discussing the importance of federalism in
preemption disputes and collecting cases).
Indeed, this Court starts its implied preemption
analysis “with the assumption that the historic police
powers of the States were not to be superseded . . .
unless that was the clear and manifest purpose of
Congress.” Wyeth v. Levine, 555 U.S. 555, 565 (2009).
And it is not inconsistent with any mode of statutory
interpretation to employ the presumption where state
tort law is at issue. See Montgomery v. Caribe Transp.
II, LLC., et al., No. 24-1238 (U.S. Dec. 8, 2025),
Preemption Scholars Amicus Br. at 20-29.
To be sure, Bates itself provides that federalism
has a part to play in the FIFRA preemption analysis.
544 U.S. at 449-50. Although Monsanto falls far short
of showing implied preemption, if the Court disagrees
and sees the issue as a close call, then federalism
easily tips the scales.
C.
Alternatively,
any
should be narrow.
preemption
If the Court is persuaded by Monsanto’s
arguments, the scope of preemption should be narrow
because the question presented implicates only
aspects of a failure to warn claim that are based on a
product’s label. See Monsanto Co. v. Durnell, No. 24-
19
1068 (U.S. Jan. 16, 2026) (granting certiorari but
narrowing the issue to “label-based” conduct).
Respondent’s case demonstrates why a narrow
ruling would be an appropriate alternative.
Respondent alleged that Monsanto’s glyphosate
products are “unreasonably dangerous to consumers
. . . because they do not contain adequate warnings or
instructions.” Monsanto Co. v. Durnell, 707 S.W.3d
828, 832 n.3 (Mo. Ct. App. 2025). It is common sense
that “adequate warning or instruction” can come from
more than just a product’s label—if that were not the
case, Bates’ two-part test would not include its first
half. 544 U.S. at 444. Instructions or warnings on a
manufacturer’s website, shelf signs at a store, or fine
text in television or print marketing, are all examples
of off-label opportunities to comply with state law
duties to warn.10 To the extent state common law
imposes such duties, they are not inconsistent with
FIFRA.
The Court should also consider the extent to which
a broad ruling would invade the jury’s province to
decide causation. Indeed, many of Monsanto’s
arguments sound in causation rather than
preemption. See, e.g., Pet. Br. at 13, 17, 20, 52.
Causation protects against the purportedly unjust
Monsanto is incorrect that “California’s Proposition 65
required manufacturers to include a warning that glyphosate is
known ‘to cause cancer’ on their labels.” Br. at 17. Proposition 65
identifies several non-labeling mechanisms through which a
required warning may be provided. Cal. Health & Safety Code
§ 25249.11(f) (2006).
10
20
verdicts Monsanto complains of because it gives
manufacturers an opportunity to prove that even an
inadequate warning did not cause the harm at issue.
See supra n.2. And depending on what a product’s
label allegedly fails to warn of (i.e., efficacy,
carcinogenicity, etc.), there may not always be onpoint EPA regulations or FIFRA provisions to
“measure” any state duty against. See Bates, 544 U.S.
at 453. In other words, there is often no need to reach
for preemption where an issue may be resolved on
causation. See, e.g., Dunn v. Astaris, LLC, 292
Fed.Appx. 525, 526-27 (8th Cir. 2008) (per curiam)
(citing Lingle v. Norge Div. of Magic Chef, Inc., 486
U.S. 399, 405-06 (1989)); Gaetano v. Gilead Scis., Inc.,
529 F.Supp.3d 333, 343 (D.N.J. 2021) (speculation
about FDA approval of a safer drug “go[es] primarily
to causation; the specific connection to preemption is
less clear”); Hogan v. Novartis Pharms. Corp., 2011
WL 1533467 (E.D.N.Y. 2011) (unpublished) (“[The
manufacturer’s] defenses . . . are based on causation
rather than any contention that the FDA regulations
forced defendant to discharge its common law duty in
a way that made it impossible to comply with state
law” (citing Wyeth, 555 U.S. at 555)).
Monsanto’s concerns could also be mitigated (if not
cured) by jury instructions distinguishing between
any preempted on-label conduct and any off-label
conduct, or instructions describing the EPA’s
registration and label approval decisions and
processes. See Bates, 544 U.S. at 454 (discussing jury
instructions that give effect to the parallel claim
requirement).
21
If the Court is inclined to preempt state law, it
should do so carefully and with an eye to these
concerns.
III.
EQUAL SOVEREIGNTY CONCERNS ARE
UNFOUNDED.
Nebraska and fourteen other states (Nebraska et
al.) support Monsanto and argue that states that
allow failure to warn claims impose some
extraterritorial detriment on their farming industries
and thereby undermine equal state sovereignty. See
Monsanto Co. v. Durnell, No. 24-1068 (U.S. Mar. 2,
2026), Br. of Amici Curiae Nebraska, Iowa, Missouri,
and 12 Other States in Support of Petitioner. They are
wrong for two reasons.
First, Nebraska et al. identify no evidence that
demonstrates a causal (or even correlational) nexus
between failure to warn claims in other states and any
economic detriment in their states. But even if they
could, that still would be unlikely to prove any
material burden on equal state sovereignty. As this
Court has recognized, there are many “state laws with
extraterritorial effects.” Nat’l Pork Producers Council
v. Ross, 598 U.S. 356, 388 (2023). It would not make
sense for the Constitution to grant the judiciary “a
roving license to reassess the wisdom of state [law] in
light of any conceivable out-of-state interest, economic
or otherwise.” Id. at 388-89 (cleaned up).
If anything, Nebraska et al.’s contentions are
antithetical to equal state sovereignty because they
suggest that some states should have a say in other
22
states’ tort law anytime they vaguely allege “far flung”
implications. See id. at 388. If the bar were that low,
a single aggrieved state could impose de facto tort
reform on forty-nine other states that had not chosen
such reform democratically.
Second, even if relevant, the economic havoc
Nebraska et al. warn of has yet to occur despite
Roundup judgments and settlements to date.
Monsanto continues to enjoy a significant share of the
domestic foundational herbicide market,11 and
glyphosate use has only increased despite Roundup
judgments and settlements. According to the federal
government, glyphosate’s global and domestic use
increased fifteen-fold between 1996 and 2014.12 In
California, the latest data show that glyphosate use
increased through 2023, and glyphosate was the top
applied ingredient per acres treated.13 These
examples suggest there is no credible evidence that
glyphosate demand or production will slow or cease—
let alone that a mere warning label could have that
effect.
11 According to the Department of Justice in 2018, and prior
to the Bayer-Monsanto merger, Monsanto controlled 53% of the
domestic foundational herbicide market (which includes both
glyphosate and glufosinate products). See 83 Fed. Reg. 27652
(June 13, 2018).
12 C. M. Benbrook, Trends in glyphosate herbicide use in the
United States and globally. 28(1) ENVIRONMENTAL SCIENCES
EUROPE 3 (2016), https://doi.org/10.1186/s12302-016-0070-0
13 CAL. DEP’T OF PESTICIDE REGUL., Pesticide Use Annual
Report
2023
Data
Summary
(2025),
https://files.cdpr.ca.gov/pub/outgoing/pur/data/2023_pur_report
_textfiles/annual_report/2023_pur_annual_report.pdf
23
Nebraska et al. (and other amici supporting
Monsanto) may be concerned that any losses or
operational challenges Monsanto might experience as
a result of Roundup litigation will be passed on to
farmers or consumers. But those amici fail to consider
that normal market conditions like increased
competition, not Roundup suits, are a likely culprit of
Monsanto’s purported troubles (among more obvious
causes like poor risk management). Indeed, increased
competition is a natural byproduct of Monsanto’s
relevant patents expiring in 2000 (glyphosate) and
2014 (Roundup Ready seeds), respectively. And it is
axiomatic that competition is a good thing for
consumers in the long term, especially in a market
that has historically been (and may still be)
significantly noncompetitive. See supra n.11.
In any event, Bates counsels against considering
market speculation or how companies might react to
legal risk in the preemption analysis. 544 U.S. at 44448. The sky-is-falling arguments submitted by
Monsanto and supporting amici bear striking
resemblance to the “inducement test” this Court
rejected in Bates. Id. at 445-46. There, this Court
declined to adopt the lower court’s reasoning that
preemption could be inferred where state tort law
could induce a manufacturer to alter its label. Id.
Here, arguments alleging downstream effects of
litigation have no place in the preemption analysis
because they are not “supported by either the text or
the structure” of FIFRA. Id.
24
CONCLUSION
The Missouri Court of Appeals’ judgment should
be affirmed.
Respectfully submitted,
RAÚL TORREZ
Attorney General of
New Mexico
ALETHEIA V.P. ALLEN
Solicitor General
ALEXANDER W. TUCKER*
Asst. Solicitor General
201 Third Street NW,
Suite 300
Albuquerque, NM 87102
(505) 948-8244
atucker@nmdoj.gov
*Counsel of Record
April 1, 2026
25
KATHLEEN JENNINGS
ATTORNEY GENERAL OF
DELAWARE
ROB BONTA
ATTORNEY GENERAL OF
CALIFORNIA
DANA NESSEL
ATTORNEY GENERAL OF
MICHIGAN
PETER F. NERONHA
ATTORNEY GENERAL OF
RHODE ISLAND
AARON M. FREY
ATTORNEY GENERAL OF
MAINE
CHARITY R. CLARK
ATTORNEY GENERAL OF
VERMONT
LETITIA JAMES
ATTORNEY GENERAL OF
NEW YORK
KWAME RAOUL
ATTORNEY GENERAL OF
ILLINOIS
JENNIFER DAVENPORT
ATTORNEY GENERAL OF
NEW JERSEY
PHILIP J. WEISER
ATTORNEY GENERAL OF
COLORADO
KEITH ELLISON
ATTORNEY GENERAL OF
MINNESOTA
DAN RAYFIELD
ATTORNEY GENERAL OF
OREGON
BRIAN SCHWALB
ATTORNEY GENERAL OF
THE DISTRICT OF
COLUMBIA
ANTHONY G. BROWN
ATTORNEY GENERAL OF
MARYLAND
ANDREA JOY CAMPBELL
ATTORNEY GENERAL OF
MASSACHUSETTS
ERIC J. WILSON
DEPUTY ATTORNEY
GENERAL OF WISCONSIN
KRIS MAYES
ATTORNEY GENERAL OF
ARIZONA
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