Amicus Curiae Brief — Suncor Energy (U.S.A.) Inc., et al., Petitioners v. County Commissioners of Boulder County, et al.

No. 25-170

IN THE

Supreme Court of the United States

SUNCOR ENERGY (U.S.A.) INC., ET AL.,

Petitioners,

v.

COUNTY COMMISSIONERS OF BOULDER COUNTY, ET AL.,

Respondents.

On Writ of Certiorari to the

Colorado Supreme Court

BRIEF OF THE LOCAL GOVERNMENT LEGAL

CENTER, NATIONAL ASSOCIATION OF COUNTIES, NATIONAL LEAGUE OF CITIES, AND INTERNATIONAL MUNICIPAL LAWYERS ASSOCIATION AS AMICI CURIAE IN SUPPORT OF

RESPONDENTS

AMANDA KARRAS

ERICH EISELT

INTERNATIONAL

MUNICIPAL LAWYERS

ASSOCIATION

51 Monroe Street, Ste. 404

Rockville, MD 20850

August 3, 2026

ROBERT S. PECK

Counsel of Record

CENTER FOR

CONSTITUTIONAL

LITIGATION, PC

6817 Vianda Court

Carlsbad, CA 92009

(202) 944-2874

robert.peck@cclfirm.com

i

TABLE OF CONTENTS

TABLE OF CONTENTS ............................................. i

TABLE OF AUTHORITIES ...................................... iii

INTEREST OF AMICI CURIAE ................................ 1

INTRODUCTION AND SUMMARY OF

ARGUMENT ......................................................... 3

ARGUMENT ................................................................ 6

I.

THIS CASE SHOULD BE DISMISSED AS

IMPROVIDENTLY GRANTED. ........................... 6

II. FEDERAL LAW DOES NOT PREEMPT THIS

ACTION. .............................................................. 11

A. Federal Law Does Not Sanction Marketing

Misrepresentations. ...................................... 12

B. Federal Law Does Not Preempt Boulder’s

Remaining Claims. ....................................... 16

1. Local government plays a critical role in

society, the economy, and environmental

protection, and the Constitution’s structure

accommodates that role. ........................... 16

2. No federal common law nor any shadowy

remnants of federal common law foreclose

Boulder’s claims. ...................................... 21

ii

3. The Clean Air Act does not foreclose

Boulder’s claims. ...................................... 25

4. No equal sovereignty principle forecloses

Boulder’s claims. ...................................... 27

CONCLUSION .......................................................... 28

iii

TABLE OF AUTHORITIES

Cases

Abney v. United States, 431 U.S. 651 (1977) .............. 8

Am. Elec. Power Co., Inc. v. Connecticut,

564 U.S. 410 (2011) .......................................... 23, 25

Arizonans for Off. Eng. v. Arizona,

520 U.S. 43 (1997) .................................................. 11

ASARCO Inc. v. Kadish, 490 U.S. 605 (1989) ............ 9

Avery v. Midland Cnty., 390 U.S. 474 (1968) ........... 18

Behrens v. Pelletier, 516 U.S. 299 (1996) .................... 8

BMW of N. Am., Inc. v. Gore, 517 U.S. 559 (1996) ... 27

BP P.L.C. v. Mayor & City Council of Baltimore,

593 U.S. 230 (2021) ...................................... 4, 11, 12

Bristol-Myers Squibb Co. v. Superior Ct.,

582 U.S. 255 (2017) ................................................ 27

City of Milwaukee v. Illinois,

451 U.S. 304 (1981). .......................................... 22-24

Cohen v. Beneficial Industrial Loan Corp.,

337 U.S. 541 (1949) .................................................. 7

Cox Broadcasting Corp. v. Cohn,

420 U.S. 469 (1975) .................................................. 9

Doe v. Facebook, Inc., 142 S. Ct. 1087 (2022) ........... 10

Fed. Trade Comm’n v. Standard Educ. Soc’y,

302 U.S. 112 (1937) ................................................ 14

Flast v. Cohen, 392 U.S. 83 (1968) ............................ 10

Helstoski v. Meanor, 442 U.S. 500 (1979) ................... 8

Hillsborough Cnty. v. Automated Med.

Laboratories, Inc., 471 U.S. 707 (1985) ........... 14, 19

Holmes Grp., Inc. v. Vornado Air Circulation

Sys., Inc., 535 U.S. 826 (2002) ............................... 22

In re R. M. J., 455 U.S. 191 (1982)............................ 13

Int’l Paper Co. v. Ouellette,

479 U.S. 481 (1987) .......................................... 23, 25

iv

Mayor & City Council of Baltimore v. BP P.L.C.,

31 F.4th 178 (4th Cir. 2022), cert. denied, 143 S. Ct.

1795 (2023).............................................................. 15

Medtronic, Inc. v. Lohr, 518 U.S. 470 (1996) ...... 14, 24

Metropolitan Life Ins. Co. v. Massachusetts,

471 U.S. 724 (1985) ................................................ 19

Minnesota by Ellison v. Am. Petroleum Inst.,

63 F.4th 703 (8th Cir. 2023) ................................... 24

Mitchell v. Forsyth, 472 U.S. 511 (1985)..................... 7

Nat’l Pork Producers Council v. Ross,

598 U.S. 356 (2023) ................................................ 28

Nixon v. Fitzgerald, 457 U.S. 731 (1982) .................... 8

O’Dell v. Espinoza, 456 U.S. 430 (1982)

(per curiam) .............................................................. 9

Puerto Rico Aqueduct & Sewer Auth. v.

Metcalf & Eddy, Inc., 506 U.S. 139 (1993) .............. 8

Retail Clerks v. Schermerhorn,

375 U.S. 96 (1963) .................................................. 24

Rodriguez v. Fed. Deposit Ins. Corp.,

589 U.S. 132 (2020) ................................................ 22

Sorrell v. IMS Health Inc., 564 U.S. 552 (2011) ....... 13

Texas Indus., Inc. v. Radcliff Materials, Inc.,

451 U.S. 630 (1981) ................................................ 22

United Haulers Ass’n, Inc. v. Oneida-Herkimer

Solid Waste Mgmt. Auth., 550 U.S. 330 (2007) ..... 19

W. Virginia Univ. Hosps., Inc. v. Casey,

499 U.S. 83 (1991) .................................................. 26

Wheeldin v. Wheeler, 373 U.S. 647 (1963) ................ 22

Statutes & Rules

Sup. Ct. R. 37.6 ............................................................ 1

13 U.S.C. § 161 .......................................................... 17

28 U.S.C. § 1257 .......................................................... 9

42 U.S.C. § 7401 ........................................................ 25

v

42 U.S.C. § 7416 ........................................................ 26

42 U.S.C. § 7604 ........................................................ 26

Other Authorities

2 M. Keely et al., Ch. 11: Built Environment,

Urban System, and Cities in Impacts, Risks,

and Adaptation in the United States: The

Fourth National Climate Assessment

(D.R. Reidmiller et al. eds., 2018). ......................... 21

C. Wright, Federal Courts 34 (1963) ........................ 10

Daniel B. Rodriguez, Localism and Lawmaking,

32 Rutgers L.J. 627 (2001) ..................................... 18

Fed. Reserve Bank of St. Louis, “Local

Governments in the U.S.: A Breakdown by

Number and Type (Mar. 14, 2024),

https://www.stlouisfed.org/publications/regionaleconomist/2024/march/local-governments-usnumber-type ...................................................... 17-18

J.R. Franke & D.A. Ballum,

New Applications of Consumer Protection

Law: Judicial Activism or Legislative Directive?,

32 Santa Clara L. Rev. 347 (1992) ......................... 13

Lynn A. Baker & Daniel B. Rodriguez,

Constitutional Home Rule and Judicial Scrutiny,

86 Denv. U. L. Rev. 1337 (2009) ............................ 19

National League of Cities, Principles of Home Rule

for the 21st Century, 100 N.C. L. Rev. 1329

(2022) ...................................................................... 18

National League of Cities, State of the Cities 2023

(Jul. 21, 2023),

https://www.nlc.org/resource/state-of-the-cities2023/........................................................................ 20

vi

Nora Freeman Engstrom & Robert L. Rabin,

Pursuing Public Health Through Litigation:

Lessons from Tobacco and Opioids,

73 Stan. L. Rev. 285 (2021) ............................... 14-15

Richard Kluger, Ashes to Ashes: America’s

Hundred-Year Cigarette War, the Public

Health, and the Unabashed Triumph of

Philip Morris (1997) .......................................... 12-13

Robert L. Rabin, The Tobacco Litigation: A Tentative

Assessment, 51 DePaul L. Rev. 331 (2001) ...... 13, 14

Sarah L. Swan, Plaintiff Cities,

71 Vand. L. Rev. 1227 (2017) ................................. 14

The Federalist No. 17 (Alexander Hamilton)

(Clinton Rossiter ed., 1961) ................................... 17

The Federalist No. 39 (James Madison)

(Clinton Rossiter ed., 1961) ................................... 17

The Federalist No. 46 (James Madison)

(Clinton Rossiter ed., 1961) ................................... 17

U.S. Conference of Mayors,

U.S. Metro Economies: Economic Growth

and Full Employment, Annual GMP Report (2018),

http://www.usmayors.org/wp-content/uploads/

2018/06/Metro-Economies-GMP-June-2018.pdf ... 20

1

INTEREST OF AMICI CURIAE1

The Local Government Legal Center (“LGLC”) is a

coalition of government organizations formed in 2023

to provide education to local governments regarding

the Supreme Court and its impact on local governments and officials and to advocate for local government positions at the Supreme Court in appropriate

cases. The National Association of Counties, the National League of Cities, and the International Municipal Lawyers Association are the founding members of

the LGLC.

The National Association of Counties (“NACo”) is

the only national organization that represents county

governments in the United States. Founded in 1935,

NACo provides essential services to the nation’s 3,069

counties through advocacy, education, and research.

The National League of Cities (“NLC”), founded in

1924, is the oldest and largest organization representing U.S. municipal governments. NLC works to

strengthen local leadership, influence federal policy,

and drive innovative solutions. In partnership with 49

state municipal leagues, NLC advocates for over

19,000 cities, towns, and villages where more than 218

million Americans live.

1 Pursuant to Rule 37.6, Amici affirms that no counsel for any

party authored this brief in whole or in part and no person or

entity, other than Amici, its members, or its counsel has made a

monetary contribution to its preparation or submission.

2

The International Municipal Lawyers Association

(“IMLA”) is the nation’s oldest and largest organization devoted solely to local government law. Founded

in 1935, IMLA is a nonpartisan, nonprofit, professional association of counsel encompassing more than

2,500 local government entities (including cities, counties, and subdivisions thereof), represented through

their chief legal officers, state municipal leagues, and

individual attorneys. IMLA advocates for the responsible development of municipal law and presents the

collective viewpoint of local governments around the

country in lawsuits before the United States Supreme

Court, federal courts of appeal, and state supreme and

appellate courts. IMLA regularly files as amicus in

cases affecting the powers and responsibilities of local

governments, including matters concerning the scope

of local authority to protect the health, safety, and welfare of their residents.

Amici and its members have a direct interest in

the outcome of this case. For decades, America’s local

governments have relied on state common law — including public nuisance, trespass, and related tort doctrines — to abate harms occurring within their jurisdictions and to recover the costs those harms impose

on their residents and infrastructure. That authority

is not a novel invention of climate litigation; it is the

same traditional police power that has long allowed

cities and counties to hold responsible parties accountable for contamination, pollution, and other harms

first felt at the local level. Local governments are frequently the level of authority best positioned to bring

3

these actions, because it is local budgets that most directly absorb the costs of injury to constituents, damage to infrastructure, and costs of emergency response.

Amici submit this brief to provide the Court with

the perspective of the local governments whose traditional authority to seek redress in their own courts,

under their own states' law, is at stake in the jurisdictional and preemption questions presented. Faced

with deceptive and injurious conduct, local governments have the responsibility to take action despite

the efforts of wrongdoers to divert and delay.

This case presents a paradigmatic example of such

an effort. The local government response should not be

short-circuited, as the Petitioner oil companies ask of

this Court, by a decision that forecloses the day in

court that Boulder County and other local governments across the country seek. The Petitioners' act of

alchemy should not be credited so that provable misrepresentations harming local residents are inaccurately deemed an attempt to regulate automobile

emissions and other claims are stripped of their focus

on the local injuries they seek to remedy.

INTRODUCTION AND

SUMMARY OF ARGUMENT

Amici curiae seriously question whether this case

presents this Court with a proper vehicle to address

the Questions Presented. Without a final judgment

4

and with their liability uncertain, Petitioner oil companies (collectively, hereinafter, Suncor) seek to fit

themselves into a narrow band of cases eligible for interlocutory review that this Court has reserved for certain government actors and, in very limited cases, private litigants where the litigation has effectively and

finally resolved the key federal issue without any opportunity for it to be properly resolved at a later time.

This action does not qualify for such solicitous treatment.

Still, if this Court reaches the merits, it should

find that the Colorado Supreme Court correctly resolved the issue. To the extent that this action is exemplary of other cases brought by local governments

against oil companies like Petitioners, the consistent

overlap is found in the allegation that the companies

have violated the state consumer protection act. See

App. 50a; cf. BP P.L.C. v. Mayor & City Council of Baltimore, 593 U.S. 230, 234 (2021) (describing Baltimore’s similar lawsuit as primarily “centered on the

defendants’ alleged failure to warn about the dangers

of their products—and the injuries the City says it suffered as a result.”).

Suncor asks this Court to preclude cities and counties from suing them when the companies misrepresent what they know about the adverse effects of their

products, even when that tortious conduct is responsible for significant damages and costs to the public fisc.

To make that argument colorable, the companies con-

5

flate a requirement about providing truthful information about their products with an attempt to create

a patchwork regulatory approach to fossil fuels or

some type of cross-border overreach that would dictate

climate rules to other jurisdictions. Yet, no liability

would attach and no changes in their products or their

products’ effects would be required if the companies

did not engage in affirmative misrepresentations

about their products.

That multiple parallel lawsuits exist around the

country does not establish that the issue is federal in

nature, as the oil companies and their amici contend,

but instead highlights the adverse impact on local government and their constituents that results from a

misleading marketing scheme. When other industries

have engaged in similar misrepresentations about the

safety or healthfulness of their products, no preemptive effect has stopped those lawsuits – and none

should here.

Preemption should not block Boulder’s other

claims either. Local government plays an important

and congressionally recognized role under the Clean

Air Act that deserves this Court’s attention and precludes preemption. Not only does the constitutional

structure accommodate the critical part that local government play in safeguarding both the public fisc from

expenses caused by bad actors, but the Framers anticipated that local government would have an outsized

function in assuring its residents health, safety, and

welfare.

6

Even without regard to that recognized function

within our constitutional system and within the Clean

Air Act, nothing in federal law supports Suncor’s fanciful preemption argument. The most relevant common law was displaced by the Clean Air Act, leaving

not even vapors that might signal preemption, as this

Court has already acknowledged. The Clean Air Act

itself contains no text or other indication that local

government lawsuits over the impact oil companies

have on municipal and county expenses, infrastructure, and other functions are preempted. Instead, the

only textual commitment evident from the Act supports the role of local government. And, finally, Suncor’s invocation of an equal-sovereignty principle as a

bar on these lawsuits holds no water. An adjudication

over whether an offender pays for the damage it

causes within the jurisdiction has no impermissible

extraterritorial impact.

ARGUMENT

I.

THIS CASE SHOULD BE DISMISSED AS IMPROVIDENTLY GRANTED.

Petitioner oil companies (collectively, “Suncor”)

have asked this Court to use this case to short-circuit

the litigation process for measurable harms they have

caused, painting a variety of distinct legal theories

brought separately by state and local governments, as

attempts to regulate fossil fuels nationwide, if not

worldwide. The assertion is transparently alarmist

without real basis.

7

Even if the claim had arguable merit, which it assuredly does not, Suncor has chosen an improper vehicle for the exercise of this Court’s jurisdiction. They

failed to prevail in state court on a motion to dismiss

based largely on claims of federal preemption. It is

plainly not a final judgment, and no party claims otherwise. In seeking to cut off litigation at this early

stage, Suncor seeks treatment that is reserved for an

extremely narrow category of specially privileged litigants – and it does not qualify.

The “collateral order” doctrine of Cohen v. Beneficial Industrial Loan Corp. is available for an extremely narrow class of cases. 337 U.S. 541, 546

(1949), Qualified immunity provides the paradigmatic

example of when such special treatment applies. The

burden on government actors is so great where qualified immunity is denied that the decision becomes “effectively unreviewable on appeal from a final judgment,” exposing the defendant and its government

employer to burdens “conceptually distinct from the

merits of the plaintiff’s claim.” Mitchell v. Forsyth, 472

U.S. 511, 527 (1985). Much of the special solicitude accorded to a defendant in those circumstances arises

from qualified immunity’s existence as “an entitlement not to be forced to litigate the consequences of

official conduct,” a right lost if erroneously permitted

to proceed. Id. (emphasis added). In fact, the protection is so great that a defendant gets two bites at the

same apple, an appeal from denial of a motion to dis-

8

miss and from a subsequent denial of summary judgment. See Behrens v. Pelletier, 516 U.S. 299, 307−09

(1996).

Claims of absolute immunity qualify for interlocutory review based on the same logic. See Nixon v. Fitzgerald, 457 U.S. 731, 743 (1982). The Eleventh

Amendment immunity available to States and arms of

the state also qualifies for immediate appeal under the

“same rationale.” Puerto Rico Aqueduct & Sewer Auth.

v. Metcalf & Eddy, Inc., 506 U.S. 139, 144 (1993). And

members of Congress asserting the protective shield of

the Speech and Debate Clause also enjoy qualification

under the collateral order doctrine for the same reasons. Helstoski v. Meanor, 442 U.S. 500, 507 (1979).

What unites these examples is that the interest in

protection from the rigors of unwarranted litigation is

bestowed upon government defendants, which, among

other things, shows due regard for the impact on the

public fisc. The same solicitude is not normally accorded private defendants, like Suncor here. In fact,

the only private defendants provided similar protection from facing allegations in court are criminal defendants who lost a motion to dismiss on double-jeopardy grounds. Abney v. United States, 431 U.S. 651,

659 (1977). The unique rationale behind that collateral appeal is that the defendant is “contesting the

very authority of the Government to hale him into

court to face trial on the charge against him.” Id.

9

No equivalent basis allows Suncor to add themselves to that tiny list. Instead, for the same reasons

as this Court dismissed for want of jurisdiction, coincidentally from the Colorado Supreme Court in O'Dell

v. Espinoza, 456 U.S. 430 (1982) (per curiam), this

Court should dismiss the case as improvidently

granted. Cases cited by Suncor to broaden the availability of interlocutory review appear to share a distinction that Suncor does not enjoy: a functionally final

judgment. Take, for example, ASARCO Inc. v. Kadish, 490 U.S. 605 (1989), a case upon which Suncor

heavily relies. There, this Court undertook review of

a case that could not be filed in federal court, even if a

state court was free to hear it because the federal bar

on advisory opinions did not apply. It did so because it

held the Arizona Supreme Court’s decision constituted

a disposition of “final judgment altering tangible legal

rights,” id. at 619, that inflicted a “direct, specific,

and concrete injury.” Id. at 623-24.

To be sure, Suncor asserts that it qualifies under

the Cox Broadcasting category available when delayed

review would cause irreparable erosion of a federal

right or policy. Cox Broadcasting Corp. v. Cohn, 420

U.S. 469, 483 (1975). Such an application where a federal defense of a private party was rejected at an interlocutory stage would be an extravagant use of that

limited category. Permitting a Cox Broadcasting review whenever a federal preemption defense is rejected at a preliminary stage would effectively eliminate the finality requirement of Section 1257(a) and

10

invite piecemeal appellate litigation in every case involving a federal preemption defense, not only immeasurably multiply appeals, but will encouraging dilatory tactics by well-heeled private defendants that

will strain the already-limited resources of public

plaintiffs as in these cases.

At the same time, there is little logic to Suncor’s

claim that waiting for a final judgment would erode

federal policy. Suncor can, and undoubtedly will, raise

the federal preclusion defense again after final judgment in the underlying trial court proceedings, and

this Court could review the issue at that point without

any permanent loss to or even adverse effect on the

federal interest. See Doe v. Facebook, Inc., 142 S. Ct.

1087, 1088 (2022) (Thomas, J., respecting denial of

certiorari).

To proceed when liability remains uncertain

would not resolve an actual, live controversy between

adverse parties. This Court has acknowledged that

“‘the oldest and most consistent thread in the federal

law of justiciability is that the federal courts will not

give advisory opinions.’” Flast v. Cohen, 392 U.S. 83,

96 (1968) (quoting C. Wright, Federal Courts 34

(1963)). The need to avoid advisory opinions has particular import in the context of preemption. Where a

state court has not yet determined whether liability

exists, any federal ruling that the cause of action

would be preempted by federal law is purely advisory

— it operates on a legal fiction rather than on an es-

11

tablished legal reality. Without a settled understanding of what liability exists under state law, this Court

will enter upon turf it has long disdained because of

the risk of a friction-generating error with yet-undefined or still somewhat inchoate state law. Cf. Arizonans for Off. Eng. v. Arizona, 520 U.S. 43, 79 (1997).

II. FEDERAL LAW DOES NOT PREEMPT THIS

ACTION.

Should this Court take up the preemption issue, it

should affirm the Colorado Supreme Court. That

Court addressed two distinct claims. In one, “Boulder

alleges that, through their advertising, defendants

have for decades intentionally misled the public about

the impacts of climate change and the role that defendants’ fossil fuel products have played in exacerbating those impacts.” Pet. App. 3a. This is the allegation that many state and local governments have advanced. See, e.g., BP P.L.C. v. Mayor & City Council of

Baltimore, 593 U.S. 230, 234 (2021) (Baltimore “sued

various energy companies for promoting fossil fuels

while allegedly concealing their environmental impacts;” most of the City’s causes of action, “centered on

the defendants’ alleged failure to warn about the dangers of their products—and the injuries the City says

it suffered as a result.”).

In a separate set of allegations different from

those raised by Baltimore, Boulder claimed Suncor

“knowingly caused and contributed to the alteration of

12

the climate by producing, promoting, refining, marketing and selling fossil fuels at levels that have caused

and continue to cause climate change.” Pet. App. 2a.

As a result of both allegations of misconduct, Boulder

“alleges that it has incurred and will continue to incur

millions of dollars in costs to protect its property and

residents from the impacts of climate change. Id.

It would be easy to lump Boulder’s causes of action

together and treat them as indistinct, thereby deserving of a single analysis of their relationship to federal

law. But it would be error to do so. The misrepresentation claims provide an easy basis upon which to find

preemption lacking. The remaining claims are also not

preempted, but require a slightly deeper consideration.

A. Federal Law Does Not Sanction Marketing Misrepresentations.

Boulder alleges that oil companies, despite knowing better, hawked the cleanliness of their fuel and the

efforts they made to support the environment. The allegations are reminiscent of those advanced by the tobacco industry when it promoted “safer” cigarettes

based on “advances” in filtering technology, added

menthol flavoring, and the reduction of “noxious

gases,” while its own research confirmed that connection between smoking and cancer that it insisted remained unproven. See, e.g., Richard Kluger, Ashes to

Ashes: America’s Hundred-Year Cigarette War, the

Public Health, and the Unabashed Triumph of Philip

13

Morris 271, 300, 359-64, 371 (1997). The duplicity was

publicly revealed by documents revealed by whistleblowers and archived due to litigation by state and local governments. The papers assembled “told a tale of

industry deceit and indifference to public health considerations.” Robert L. Rabin, The Tobacco Litigation:

A Tentative Assessment, 51 DePaul L. Rev. 331, 339

(2001).

Our commercial speech doctrine explicitly puts

misleading speech outside the protection of the First

Amendment. In re R. M. J., 455 U.S. 191, 203 (1982)

(“Misleading advertising may be prohibited entirely.”);

Sorrell v. IMS Health Inc., 564 U.S. 552, 579 (2011)

(government retains a “legitimate interest in protecting consumers from ‘commercial harms’”). Without

that constitutional protection, misleading commercial

speech is ripe for litigation on behalf of consumers.

Nothing about federal-state relationships limit

that authority. Beginning in the 1960s, recognition

grew that existing tort and contract remedies, as well

as the prevailing authority of the Federal Trade Commission (“FTC”), were inadequate to protect consumers from unfair or deceptive trade practices. The FTC

itself then proposed that States aid the effort by adopting their own “Little FTC Act” to curb unfair or deceptive acts or practices. J.R. Franke & D.A. Ballum, New

Applications of Consumer Protection Law: Judicial Activism or Legislative Directive?, 32 Santa Clara L. Rev.

347, 357 (1992).

14

Cities and counties, like a number of states, have

initiated litigation over a wide variety of consumerprotection concerns that affect the health of their residents and the livability of their environs. They authorize damages for material representations that

tend to deceive or mislead. These laws reflect the ideal

that “honesty should govern competitive enterprises,

and that the rule of caveat emptor should not be relied

upon to reward fraud and deception.” Fed. Trade

Comm’n v. Standard Educ. Soc’y, 302 U.S. 112, 116

(1937). Moreover, these laws reflect an exercise of

States’ “police powers to protect the health and safety

of their citizens,” which “are ‘primarily, and historically, ... matter[s] of local concern.’” Medtronic, Inc. v.

Lohr, 518 U.S. 470, 475 (1996) (quoting Hillsborough

Cnty. v. Automated Med. Laboratories, Inc., 471 U.S.

707, 719 (1985)). They do not single out environmental

concerns for liability, but evenhandedly require truthful marketing.

Local government’s modern use of state-law consumer-protection claims, in both state and federal

courts, to address issues of common (but local) concern

began more than three decades ago, when cities joined

state attorneys general litigating asbestos and tobacco

claims. See Sarah L. Swan, Plaintiff Cities, 71 Vand.

L. Rev. 1227, 1233 (2017). The tobacco litigation relied

heavily on state consumer-protection laws. See Rabin,

51 DePaul L. Rev. at 337. Today, cities are major

claimants in opioid litigation and rely heavily on state

consumer-protection laws in a variety of other matters. See Nora Freeman Engstrom & Robert L. Rabin,

15

Pursuing Public Health Through Litigation: Lessons

from Tobacco and Opioids, 73 Stan. L. Rev. 285, 291,

303 (2021).

Nothing in federal common law or any of the federal environmental statutes touch upon the exercise of

this authority by state or local governments. Instead,

to challenge that authority, Suncor seeks to transmogrify these false marketing causes of action into one

that would establish a patchwork of conflicting state

and local regulations over the contribution of oil companies to climate change. This Court should not adopt

Suncor’s formulation, rejecting it as the Fourth Circuit

did similar claims by the oil companies. It characterized the defendants’ assertions about the gist of these

types of actions, as “rest[ing] on a fundamental confusion” that seeks to treat a “misinformation campaign”

as the equivalent of “emission standards,” which they

plainly were not. Mayor & City Council of Baltimore v.

BP P.L.C., 31 F.4th 178, 217 (4th Cir. 2022), cert. denied, 143 S.Ct. 1795 (2023).

Requiring truthful and non-misleading marketing

cannot be rationally deemed “an attempt to regulate”

greenhouse-gas emissions and plainly does not conflict

with any conduct the federal government seeks to encourage. Because Suncor cannot colorably argue that

misleading marketing somehow promotes an established federal policy or that Boulder’s claims somehow

interfere with federal objectives, its preemption argument falls flat.

16

B. Federal Law Does Not Preempt Boulder’s

Remaining Claims.

Suncor attacks Boulder’s remaining claims as

seeking to regulate climate change. Among its arguments, Suncor asserts that this lawsuit is impliedly

preempted by the “structure of the Constitution.”

Petrs. Br. 21. In making the argument, Suncor purposely fails to acknowledge local government’s appropriate role in our constitutional structure.

1. Local government plays a critical role in

society, the economy, and environmental

protection, and the Constitution’s structure

accommodates that role.

Rather than conflict with the constitutional structure as Suncor and its allies contend, permitting local

government to move forward with these lawsuits

serves the Framers’ vision of government serving the

peoples’ ends. Those that framed the federal Constitution recognized that local governments would form an

essential part of the sovereign nation they were building. For example, James Madison wrote that the government being formed was “neither wholly national

nor wholly federal” and that despite the supremacy accorded decisions of the national government, “communities united for particular purposes” would still rely

on powers vested partially in municipal legislatures,”

and that “local or municipal authorities form distinct

and independent portions of the supremacy, no more

subject, within their respective spheres to the general

authority, than the general authority is subject to

17

them, within its own sphere.” The Federalist No. 39,

at 246, 245 (James Madison) (Clinton Rossiter ed.,

1961).

The Framers believed that local government

would be “more familiarly and minutely conversant”

with the people’s “domestic and personal interests” for

purposes of regulation while also allowing the people

to engage the local government with greater impact on

policy as an exercise in self-government. Id., No. 46, at

294-95 (Madison). Thus, as Alexander Hamilton echoed that sentiment, the “superintendence of local administrations” will form the “immediate and visible

guardian of life and property … to which the sensiblity

of individuals is more immediately awake” and provide the “great cement of society,” when government

diffused among various levels and channels. Id., No.

17, at 120 (Alexander Hamilton).

Today, local government plays a critical role in

every aspect of modern life – and any examination of

the issues in this case, where Congress has not enacted a law that can be said to conflict with what Boulder seeks to settle in court – must account for that role.

Pursuant to 13 U.S.C. § 161, the U.S. Census Bureau

undertakes a census of governments every five years.

In the 2022 survey, we learned that there are 3,031

county governments, 35,705 township and municipal

governments, 12,546 independent school districts, and

39,555 other special-purpose local governments. Fed.

Reserve Bank of St. Louis, “Local Governments in the

U.S.: A Breakdown by Number and Type (Mar. 14,

18

2024),

https://www.stlouisfed.org/publications/regional-economist/2024/march/local-governments-usnumber-type.

As one would expect with these numbers, counties

and municipalities play an incredibly important role

in American society and its governance. This Court

has observed that “virtually every American lives

within what he and his neighbors regard as a unit of

local government with general responsibility and

power for local affairs.” Avery v. Midland Cnty., 390

U.S. 474, 483 (1968). Being closest to the people and

their problems, “States universally leave much policy

and decisionmaking to their governmental subdivisions.” Id. at 481. Therefore, as one scholar recognized,

“many of the most vexing issues of social policy and

legal institutions are found at the local level,” which is

the only place where they can be addressed. Daniel B.

Rodriguez, Localism and Lawmaking, 32 Rutgers L.J.

627, 627 (2001).

Perhaps for that reason, many state constitutions

grant local governments significant home-rule powers

to address “local affairs.” Since Missouri adopted the

first constitutional home-rule provision in 1875,

“[m]ost states grant most of their municipalities home

rule.” National League of Cities, Principles of Home

Rule for the 21st Century, 100 N.C. L. Rev. 1329, 1351,

1354 (2022).

These constitutionally mandated home-rule provisions:

19

creat[e] for municipalities both a power of initiation – that is, a power to act in the absence

of an express state legislative grant – and a

power of immunity – that is, a power to act in

the specified area notwithstanding any conflicting state law.

Lynn A. Baker & Daniel B. Rodriguez, Constitutional

Home Rule and Judicial Scrutiny, 86 Denv. U. L. Rev.

1337, 1341 (2009) (footnote omitted).

In fact, every level of “government is vested with

the responsibility of protecting the health, safety, and

welfare of its citizens.” United Haulers Ass’n, Inc. v.

Oneida-Herkimer Solid Waste Mgmt. Auth., 550 U.S.

330, 342 (2007); see also id. at 343 (noting that public

health, safety, and welfare “responsibilities set state

and local government apart from a typical private

business.”). Localities have long enjoyed primacy in

providing for the health and welfare of its citizens,

which “primarily, and historically, [is] a matter of local concern.” Hillsborough Cnty. v. Automated Medical

Laboratories, Inc., 471 U.S. 707, 719 (1985).

To discharge this solemn duty, state and local governments maintain “great latitude under their police

powers to legislate as to the protection of the lives,

limbs, health, comfort, and quiet of all persons.” Metropolitan Life Ins. Co. v. Massachusetts, 471 U.S. 724,

756 (1985) (cleaned up).

20

Municipalities, by themselves, also provide an outsized contribution to the health of State economies. In

2017, municipalities accounted for 90 percent of the

Gross State Product (GSP) in 21 states and 80 percent

of GSP in 32 states. U.S. Conference of Mayors, U.S.

Metro Economies: Economic Growth and Full Employment, Annual GMP Report 1 (2018), http://www.usmayors.org/wp-content/uploads/2018/06/Metro-Economies-GMP-June-2018.pdf.

Economic development and infrastructure improvements, both of which are closely related to residents’ financial and social well-being, remain key urban planning and policymaking issues, as is housing,

homelessness, and housing insecurity. National

League of Cities, State of the Cities 2023, at 2, 5-6 (Jul.

21, 2023), https://www.nlc.org/resource/state-of-thecities-2023/. Municipalities are where public safety is

most usefully addressed Id. at 4. Regardless of commonality of these issues throughout the nation, all

problems are truly local.

That same concentration of people, activity, and

infrastructure make cities and populous counties

uniquely vulnerable to the adverse impacts of a host

of climatic changes, including sea-level rise; increasingly frequent and severe storms that pose immediate

threats to human life and critical infrastructure; damaged and disappearing coastlines; degraded ecosystems and reduced ecosystem services function; increases in heat-related deaths; poor air quality and ex-

21

acerbated health problems; longer droughts that combine with increased temperatures and water evaporation rates to strain water supplies; and heightened

wildfire risk. See 2 M. Keely et al., Ch. 11: Built Environment, Urban System, and Cities in Impacts, Risks,

and Adaptation in the United States: The Fourth National Climate Assessment 444-47 (D.R. Reidmiller et

al. eds., 2018).

It is little wonder, then, that local governments

bear an enormous burden when their efforts to address the harms they experience resemble a Sisyphean task due to the fossil fuel industry’s allegedly

repeating misconduct. This Court should not stop this

process of seeking accountability for the industry’s

role in causing the damage local government must remediate.

2. No federal common law nor any shadowy

remnants of federal common law foreclose

Boulder’s claims.

Suncor asserts that, despite the passage of the

Clean Air Act, some residual federal common law remains in the ethers of constitutional structure and

somehow occupies the field to exclude this lawsuit because its impact will have extraterritorial effect. This

inventive argument is nothing less than fanciful.

Unlike state courts with respect to state common

law, federal common law occupies a narrow spectrum

limited largely to what Congress authorizes in order

22

“to formulate substantive rules of decision.” Texas Indus., Inc. v. Radcliff Materials, Inc., 451 U.S. 630, 641

(1981). That authority generally exists with respect to

the “rights and obligations of United States, interstate

and international disputes implicating conflicting

rights of States or relations with foreign nations, and

admiralty cases.” Id. at 640-41 (footnotes omitted). As

a result, “[j]udicial lawmaking in the form of federal

common law plays a necessarily modest role under a

Constitution that vests the federal government’s ‘legislative Powers’ in Congress and reserves most other

regulatory authority to the States.” Rodriguez v. Fed.

Deposit Ins. Corp., 589 U.S. 132, 136 (2020). For that

reason, the “instances where [federal courts] have created federal common law are few and restricted.”

Wheeldin v. Wheeler, 373 U.S. 647, 651 (1963). That

power is also conditioned on an identified need “to protect uniquely federal interests.” Rodriguez, 589 U.S. at

136. None of these areas of law and no uniquely federal interest are implicated by this lawsuit.

Critically, this Court has also noted that instances

where federal common law is recognized traditionally

respects federalism. Where that occurs, there is little

risk of intruding upon the “independence of state governments” because those carefully delineated areas of

exclusive federal interest necessarily fall outside state

authority. Holmes Grp., Inc. v. Vornado Air Circulation Sys., Inc., 535 U.S. 826, 832 (2002). Therefore, “[i]f

state law can be applied, there is no need for federal

common law; if federal common law exists, it is because state law cannot be used.” City of Milwaukee v.

23

Illinois, 451 U.S. 304, 313 n.7 (1981). The choices do

not admit of a need for a federal common law bar to

Boulder’s action.

A useful lesson can be drawn from the time when

interstate water pollution was the subject of federal

common law. Congress ended any need for federal

common law by enacting the Clean Water Act and

thereby supplanted that body of judge-made law. See

Int’l Paper Co. v. Ouellette, 479 U.S. 481, 487-90 (1987)

(describing the judicial and legislative history). The

Ouellette Court explained that state public nuisance

laws survived the law’s enactment as a valid basis for

lawsuits seeking to abate cross-border pollution. Id. at

498-99. The applicable state laws here deserve no

lesser respect as a valid basis for liability.

The same pattern of prior federal common law being supplanted by federal statute occurred with respect to interstate air pollution. In Am. Elec. Power

Co., Inc. v. Connecticut, 564 U.S. 410, 424 (2011)

(“AEP”), this Court explained that “the Clean Air Act

and the EPA actions it authorizes displace any federal

common-law right to seek abatement” of emissions.

For that reason, “‘the need for such an unusual exercise of law-making by federal courts [has] disappear[ed].’” Id. at 423 (quoting City of Milwaukee, 451

U.S. at 314). That statement utterly undermines the

type of spectral presence Suncor still seeks to attribute

to the preexisting federal common law.

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The Eighth Circuit’s cautious approach to the issue merits consideration here. It held that “[e]ven if

federal common law still exists in this space and provides a cause of action to govern transboundary pollution cases, that remedy doesn’t occupy the same substantive realm as state-law fraud, negligence, products liability, or consumer protection claims.” Minnesota by Ellison v. Am. Petroleum Inst., 63 F.4th 703,

710 (8th Cir. 2023). That court concluded that where,

as here, “Congress has not acted to displace the statelaw claims, and federal common law does not supply a

substitute cause of action, the state-law claims are not

completely preempted.” Id. at 710−11. Moreover, congressional inaction “does not express Congressional

intent of any kind—much less intent to completely displace any particular state-law claim.” Id. at 710.

Because federal statutory law displaced federal

common law, the only relevant question in the current

dispute becomes one of ordinary preemption. See City

of Milwaukee, 451 U.S. at 327−29. This Court has long

recognized that “‘[t]he purpose of Congress is the ultimate touchstone’ in every pre-emption case.” Lohr,

518 U.S. at 485 (quoting Retail Clerks v. Schermerhorn, 375 U.S. 96, 103 (1963)). Here, however, Congress has not expressed an intent despite ample opportunity to do so in light of this long-running litigation. The common law, reflecting what Congress did in

abrogating it without replacing it, then, supplies no

basis for preemption.

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3. The Clean Air Act does not foreclose Boulder’s claims.

When this Court recognized that the Clean Air Act

displaced federal common law, it stated that “the

availability vel non of a state lawsuit depends, inter

alia, on the preemptive effect of the federal Act.” AEP,

564 U.S. at 429. As in Ouellette, this Court should hold

that the Clean Air Act provides no basis to preempt

Boulder’s action.

Congress, in passing the Clean Air Act, declared

that “air pollution prevention (that is, the reduction or

elimination, through any measures, of the amount of

pollutants produced or created at the source) and air

pollution control at its source is the primary responsibility of States and local governments.” 42 U.S.C. §

7401(a)(3) (emphasis added). That forthright declaration of a role for state and local government hardly

sounds like the stuff of preemption.

The Act further declared that a “primary goal of

this chapter is to encourage or otherwise promote reasonable Federal, State, and local governmental actions, consistent with the provisions of this chapter,

for pollution prevention.” Id. at § 7401(c). That type of

cooperative federalism is served by actions like the one

brought here by Boulder. And it is good public policy:

state and local governments need not wait for federal

action before undertaking their own initiatives to protect their citizens from hazardous pollutants.

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In fact, the Clean Air Act specifies that “[n]othing

in this section shall restrict any right which any person ... may have under any statute or common law to

seek enforcement of any emission standard or limitation or to seek any other relief[.]” 42 U.S.C. § 7604(e)

(emphases added). The “any other relief” standard certainly provides the best indicia that Congress placed

no limits on what a lawsuit might accomplish. See W.

Virginia Univ. Hosps., Inc. v. Casey, 499 U.S. 83, 98

(1991) (a statute’s text provides the best evidence of

congressional intent).

A second savings clause assures that “any State or

political subdivision thereof” may adopt or enforce

emission standards as long as it is not less stringent

than the federal government sets and, additionally,

permits States and their political subdivisions to establish control or abatement requirements. 42 U.S.C.

§ 7416. None of the relief sought by Boulder surmounts this acknowledgement of authority.

These savings clauses reflect Congress’s judgment

that it wants to preserve state and local authority in

this space. Local governments play an enormously

important role in addressing problems associated with

increased air pollution and remedying their effects.

Funding that effort should not fall on taxpayers alone

if a case like Boulder’s can satisfy state law on where

liability lies.

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4. No equal sovereignty principle forecloses

Boulder’s claims.

Suncor advances another creative argument when

it says “federal law necessarily and exclusively governs interstate-pollution disputes” because allowing

any state’s law to apply would violate the “equal

sovereignty” of other states. Petr. Br. 26- 27. It is true

that this Court has recognized some limits on the extraterritorial reach of state law. For example, the Due

Process Clause, “acting as an instrument of interstate

federalism, may sometimes act to divest the State of

its power to render a valid judgment” by denying personal jurisdiction, “even if the forum State has a

strong interest in applying its law to the controversy.”

Bristol-Myers Squibb Co. v. Superior Ct., 582 U.S. 255,

263 (2017). Due process also limits the punishment

and deterrence a State may mete out through punitive

damages by withholding authority to assess the damages for its extraterritorial effects. BMW of N. Am.,

Inc. v. Gore, 517 U.S. 559, 572–73 (1996).

However, the type of limit that Suncor and its

amici presuppose invade another State’s equal sovereignty does not count as such an invasion. A distinct

difference exists between adjudicating a claim

and displacing another state's substantive law. State

court judgments in a wide variety of areas, such as

products liability, often affect liability in other states,

as Boulder has explained in its brief. See Resp't Br.

36−37. After all, “many (maybe most) state laws have

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the ‘practical effect of controlling’ extraterritorial behavior.” Nat’l Pork Producers Council v. Ross, 598 U.S.

356, 374 (2023). To deny a locality authority to pursue

liability under those laws would “cast a shadow over

laws long understood to represent valid exercises of

the States’ constitutionally reserved powers.” Id. at

375. This Court should reject that invitation.

CONCLUSION

For the foregoing reasons, Amici Curiae respectfully ask this Court to either dismiss this matter as

improvidently granted or, should it reach the merits,

affirm the judgment of the Colorado Supreme Court in

this case.

August 3, 2026

Respectfully submitted,

Robert S. Peck

Counsel of Record

CENTER FOR CONSTITUTIONAL LITIGATION, P.C.

6817 Vianda Court

Carlsbad, CA 92009

Phone: (202) 944-2874

robert.peck@cclfirm.com

Counsel for Amici Curiae