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

Supreme Court briefAug 3, 2026

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No. 25-170

IN THE

Supreme Court of the United States

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

Petitioners,

COUNTY COMMISSIONERS OF BOULDER COUNTY, ET AL.,

Respondents.

On Writ of Certiorari

to the Supreme Court of Colorado

BRIEF OF AMICUS CURIAE

AMERICAN ASSOCIATION FOR JUSTICE

IN SUPPORT OF RESPONDENTS

N. John Bey

President

AMERICAN ASSOCIATION

FOR JUSTICE

777 6th Street, NW #300

Washington, DC 20001

(404) 344-4448

john.bey@justice.org

August 3, 2026

Jeffrey R. White

Counsel of Record

AMERICAN ASSOCIATION

FOR JUSTICE

777 6th Street, NW #300

Washington, DC 20001

(202) 617-5620

jeffrey.white@justice.org

TABLE OF CONTENTS

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

TABLE OF AUTHORITIES ................................... iv

INTEREST OF AMICUS CURIAE .......................1

SUMMARY OF THE ARGUMENT .........................2

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

THE CLEAN AIR ACT DOES NOT

PREEMPT RESPONDENTS’ STATE LAW

CAUSES OF ACTION FOR

REIMBURSEMENT OF THEIR

EXPENDITURES TO AMELIORATE THE

EFFECTS OF ALTERED CLIMATE IN

THEIR COMMUNITIES. ...................................6

A. The Localities’ Causes of Action Fall Well

Within Traditional Police Powers. .................. 7

1. Localities’ causes of action seek

reimbursement for their expenditures in

furtherance of their obligations to the

health and safety of their residents. ........... 7

2. Respondents’ state-law causes of action

come well within the states’ traditional

police power. ............................................... 8

B. The Clean Air Act Does Not Preempt

Respondents’ Causes of Action...................... 13

II. THE “STRUCTURE OF THE

CONSTITUTION” DOES NOT PREEMPT

THE MUNICIPALITIES’ STATE-LAW

REMEDIES TO RECOVER EXPENDITURES

TO COMBAT THE EFFECTS OF CLIMATE

ALTERATION IN THEIR COMMUNITIES. 17

A. Petitioners Propose to Preclude State

Remedies for Harms That Can Cross State

Lines Unless Expressly Authorized by

Congress. ........................................................ 17

B. Recovery of Expenditures to Ameliorate the

Public Nuisance Effects of Carbon Emissions

Due in Part to Petitioners’ Fraudulent

Misrepresentations Does Not Amount to

Enforcement of Colorado Law Outside of

Colorado. ........................................................ 19

1. States may regulate activities that cause

harm to persons or property within their

boundaries, even if those activities

originate in other states............................ 19

2. The indirect effects of a state’s regulation

on the decisions of private parties in other

states does not amount to

extraterritoriality. ..................................... 22

C. Application of State Law to Decide Disputes

Between Private Parties Concerning

Interstate Pollution Does Not Offend the

Principle of Equal Sovereignty. .................... 23

D. Petitioners’ Proposed Expansive Federal

Judicial Power to “Displace” State Law

iii

Remedies Itself Violates the Structure of the

Constitution. .................................................. 26

III. THE DIRE WARNINGS VOICED BY

PETITIONERS’ SUPPORTING AMICI ARE

GROUNDLESS AND DO NOT SUPPORT

DENYING RESPONDENTS THE RIGHT TO

RECOUP REASONABLE EXPENDITURES

TO AMELIORATE THE EFFECTS OF

CLIMATE ALTERATION. ..............................27

A. Permitting Respondents’ Causes of

Action to Proceed Will Not Result in

Ruinous Liability. .......................................... 28

B. Fears of a “Carbon Tax” Are Unwarranted. . 30

C. Fears of Undermining National Security or

National Energy Goals Are Unwarranted. ... 31

D. Fears of Difficulties in Obtaining Liability

Insurance to Cover the Local Governments’

State-Law Claims Does Not Warrant

Federal Preemption of Those Claims. .......... 32

CONCLUSION .........................................................33

TABLE OF AUTHORITIES

Cases

American Elec. Power Co. v. Connecticut,

564 U.S. 410 (2011) .................................... 23, 24, 25

American Ins. Ass’n v. Garamendi,

539 U.S. 396 (2003) ................................................ 32

Arizona Pub. Serv. Co. v. EPA,

562 F.3d 1116 (10th Cir. 2009) .............................. 16

Bd. of Cnty. Comm’rs of Cnty. of La Plata v.

Colorado Dep’t of Pub. Health & Env’t,

488 P.3d 1065 (Colo. 2021)..................................... 10

Bd. of Cnty. Comm’rs of Boulder Cnty. v.

Suncor Energy (U.S.A.) Inc.,

25 F.4th 1238 (10th Cir. 2022)............................... 14

Bell v. Cheswick Generating Station,

734 F.3d 188 (3d Cir. 2013).................................... 15

BMW of N. Am., Inc. v. Gore,

517 U.S. 559 (1996) .......................................... 20, 21

Camps Newfound/Owatonna, Inc. v.

Town of Harrison,

520 U.S. 564 (1997) ................................................ 13

Cipollone v. Liggett Grp., Inc.,

505 U.S. 504 (1992) ................................................ 26

Cissna v. Tennessee,

246 U.S. 289 (1918) ................................................ 25

City & Cnty. of San Francisco v.

Purdue Pharma L.P.,

620 F. Supp. 3d 936 (N.D. Cal. 2022) .................... 11

County Comm’rs of Boulder Cnty. v.

Suncor Energy USA, Inc.,

586 P.3d 161 (Colo. 2026)................................... 9, 13

CSX Transp., Inc. v. Easterwood,

507 U.S. 658 (1993) ................................................ 27

Docheff v. City of Broomfield,

623 P.2d 69 (Colo. App. 1980) ................................ 10

Echave v. City of Grand Junction,

193 P.2d 277 (1948) ................................................ 10

Exxon Corp. v. Yarema,

516 A.2d 990 (Md. App. 1986)................................ 12

Farm Raised Salmon Cases,

175 P.3d 1170 (Cal. 2008) ...................................... 12

Florida Lime & Avocado Growers, Inc. v. Paul,

373 U.S. 132 (1963) ................................................ 12

Ford Motor Co. v. Montana Eighth Jud. Dist. Ct.,

592 U.S. 351 (2021) .................................................. 9

Franchise Tax Bd. of California v. Hyatt,

587 U.S. 230 (2019) .......................................... 18, 24

Gade v. Nat’l Solid Wastes Mgmt. Ass’n,

505 U.S. 88 (1992) .................................................. 14

Garcia v. San Antonio Metro. Transit Auth.,

469 U.S. 528 (1985) ................................................ 26

Georgia v. Tennessee Copper Co.,

206 U.S. 230 (1907) ................................................ 25

Goodman v.

South Suburban Park & Recreation Dist.,

No. 24CA1946, 2025 WL 3033756

(Colo. App. Oct. 30, 2025)....................................... 10

Gregory v. Ashcroft,

501 U.S. 452 (1991) ................................................ 18

Hartford Fire Ins. Co. v. California,

509 U.S. 764 (1993) ................................................ 20

Illinois v. Milwaukee,

406 U.S. 91 (1972) .................................................. 25

In re Methyl Tertiary Butyl Ether

(MTBE) Prod. Liab. Litig.,

725 F.3d 65 (2d Cir. 2013)...................................... 12

Int’l Paper Co. v. Ouellette,

479 U.S. 481 (1987) ................................................ 13

Kansas v. Garcia,

589 U.S. 191 (2020) .......................................... 13, 27

Kurns v. R.R. Friction Prods. Corp.,

565 U.S. 625 (2012) ................................................ 14

Martin v. United States,

145 S. Ct. 1689 (2025) ............................................ 15

vii

Medellin v. Texas,

552 U.S. 491 (2008) ................................................ 32

Medtronic, Inc. v. Lohr,

518 U.S. 470 (1996) ...................................... 9, 14, 27

Metropolitan Life Ins. Co. v. Massachusetts,

471 U.S. 724 (1985) .................................................. 9

Missouri v. Illinois,

200 U.S. 496 (1906) ................................................ 25

Monsanto Co. v. Durnell,

146 S. Ct. 2001, 2023 (2026) .................................. 16

Montgomery v. Caribe Transp. II, LLC,

146 S. Ct. 1199 (2026) .............................................. 9

National League of Cities v. Usery,

426 U.S. 833 (1976) ................................................ 26

National Pork Producers Council v. Ross,

598 U.S. 356 (2023) ................................................ 22

New Jersey v. New York,

283 U.S. 473 (1931) ................................................ 25

New York v. New Jersey,

256 U.S. 296 (1921) ................................................ 25

New York v. United States,

505 U.S. 144 (1992) ................................................ 18

North Dakota v. Minnesota,

263 U.S. 365 (1923) ................................................ 25

viii

Parker Drilling Mgmt. Servs., Ltd. v. Newton,

587 U.S. 601 (2019) .......................................... 15, 16

PLIVA, Inc. v. Mensing,

564 U. S. 604 (2011) ............................................... 16

Puerto Rico Dep’t. of Consumer Affs. v.

Isla Petroleum Corp.,

485 U.S. 495 (1988) ................................................ 27

Rice v. Santa Fe Elevator Corp.,

331 U.S. 218 (1947) ................................................ 26

Ross v. Butler,

19 N.J. Eq. 294 (Ch. 1868) ..................................... 10

Simpson v. State,

17 S.E. 984 (Ga. 1893) ...................................... 19, 20

State Farm Mut. Auto. Ins. Co. v. Campbell,

538 U.S. 408 (2003) .......................................... 20, 21

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

451 U.S. 630 (1981) ................................................ 24

United States v. Morrison,

529 U.S. 598 (2000) ................................................ 18

Univ. of Denver v. Doe,

547 P.3d 1129 (Colo. 2024)....................................... 9

Virginia Uranium, Inc. v. Warren,

587 U.S. 761 (2019) ................................................ 27

Watson v. Employers Liab. Assurance Corp.,

348 U.S. 66 (1954) .................................................. 19

Wyeth v. Levine,

555 U.S. 555 (2009) .......................................... 16, 27

Constitutional Provisions

U.S. Const. Art. VI, cl. 2 ............................................ 15

Statutes

Clean Air Act, 42 U.S.C. § 7401 et seq. ........... 2, 14, 15

Other Authorities

Caleb Nelson,

Preemption, 86 VA. L. REV. 225 (2000) .................. 16

David W. Ziegele & Jay A. Evans,

Regulating Underground Storage Tank Systems, 27

TRIAL 34 (Sept. 1991) ............................................. 12

ExxonMobil,

Executive Summary, in ADVANCING CLIMATE

SOLUTIONS: 2026 REPORT (May 2026),

https://corporate.exxonmobil.com/-/media/

global/files/advancing-climate-solutions/2026/

2026-advancing-climate-solutions-report.pdf ......... 7

Frank N. Ikhard,

Meeting the Challenges of 1966, in

45(1) AM. PETROLEUM INST., PROCEEDINGS OF THE

AMERICAN PETROLEUM INSTITUTE, 1965 (1965),

https://www.documentcloud.org/documents/

5348130-1965-API-Proceedings/ .......................... 6, 7

Guido Calabresi,

The Costs of Accidents (1970)................................. 23

James A. Sevinsky,

Public Nuisance: A Common-Law Remedy Among

the Statutes, 5 NAT. RES. & ENV’T 29 (1990).......... 10

Leslie Kendrick,

The Perils and Promise of Public Nuisance,

132 YALE L.J. 702 (2023) ....................................... 10

Michael J. Maher,

Common Law Liability for Leaking Underground

Storage Tanks, 13 N. ILL. U. L. REV. 519 (1993) ... 12

Michael J. Purcell,

Settling High: A Common Law Public

Nuisance Response to the Opioid Epidemic,

52 COLUM. J.L. & SOC. PROBS. 135 (2018) ............. 11

Nora Freeman Engstrom & Robert L. Rabin,

Pursuing Public Health Through Litigation,

73 STAN. L. REV. 285 (2021) ................................... 11

Restatement (Second) of the Foreign Relations

Law of the United States § 18 (1965) .................... 20

Restatement (Second) of Torts § 821B(1) ................. 10

Ronald E. Bornstein & N. Elaine Dugger,

International Regulation of Insider Trading,

1987 COLUM. BUS. L. REV. 375 (1987).................... 20

State Opioid Settlement Spending Decisions,

NAT’L ACAD. FOR STATE HEALTH POL’Y,

http://nashp.org/state-tracker/state-opioidsettlement-spending-decisions/.............................. 11

Susan Emmenegger,

Extraterritorial Economic Sanctions and

Their Foundation in International Law,

33 ARIZ. J. INT’L & COMP. L. 631 (2016) ................. 20

William L. Prosser,

The Assault Upon the Citadel

(Strict Liability to the Consumer),

69 YALE L.J. 1099 (1960) ....................................... 22

INTEREST OF AMICUS CURIAE 1

The American Association for Justice (“AAJ”) is a

national, voluntary bar association established in

1946 to strengthen the civil justice system, preserve

the right to trial by jury, and protect access to the

courts for those who have been wrongfully injured.

With members in the United States, Canada, and

abroad, AAJ is the world’s largest plaintiff trial bar.

AAJ members primarily represent plaintiffs in personal injury actions, employment rights cases, consumer cases, and other civil actions, including claims

for environmental harms and toxic exposures.

Throughout its 80-year history, AAJ has served as a

leading advocate for the right of all Americans to seek

legal recourse for wrongful conduct.

This case is of acute interest to AAJ. AAJ addresses this Court to urge rejection of Petitioners’ radical proposition that judges may set aside traditional

state tort causes of action on the ground that state law

is “incompetent” to remedy harms that are interstate

or international in scope with no indication Congress

so intended. To the contrary, Congress expressly provided in the Clean Air Act that the United State work

cooperatively with state and local governments to address interstate air pollution.

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

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

entity, other than amicus, its members, or its counsel has made

a monetary contribution to its preparation or submission.

SUMMARY OF THE ARGUMENT

1. Climate change is real. Petitioners and Respondents agree. And carbon emissions have harmed and

will continue to harm people and property. Respondents—local governments charged with protecting the

health and safety of their residents—have spent and

will spend tax dollars to ameliorate their impacts, including rising temperatures, drought conditions, wildfires, and insect infestations. They brought this lawsuit under state law, alleging that producers and

sellers of fossil fuels in Colorado, by their fraudulent

misrepresentations and deceptive trade practices,

have contributed to a public nuisance in their localities. Importantly, they do not ask Colorado courts to

ban, limit, or tax the sales of fossil fuels or to impose

caps on carbon emissions. Respondents’ narrowly focused action seeks to recoup their expenditures to address the impact of this public nuisance on their communities.

Petitioners broadly resist any application of state

law to their activities, first asserting that the Clean

Air Act, 42 U.S.C. § 7401 et seq. (“CAA”), preempts the

entire field of regulation of interstate air pollution.

Failing that, they assert that the “structure of the

Constitution” renders the states not “competent” to

address disputes involving interstate pollution. Neither rationale supports ousting Colorado law. To the

contrary, Congress has clearly intended and provided

for federal-state cooperation in this area.

The entire basis for Petitioners’ rejection of the

municipalities’ claims is the supposition that “ambient” air or water pollution is “inherently federal” and

has never been a legitimate area of state regulation.

In fact, air and water pollution have long been matters

for state regulation by common-law actions for the

abatement of public nuisances. Respondents’ causes of

action fall well within the states’ broad police power.

For example, state and local governments relied

on traditional public nuisance doctrine and their police power to recoup their expenditures to treat health

problems traced to years of producers and sellers misrepresenting and minimizing the dangers associated

with cigarettes and, later, opioid drugs. The public

nuisance doctrine was also a basis for requiring fossil

fuel companies to bear the costs of removing leaking

underground gasoline storage tanks and in requiring

the producers of the gasoline additive MTBE to pay

damages to local governments for contamination of

public drinking water.

The Clean Air Act does not preempt the municipalities’ state tort remedies. Congress did not include

an express preemption provision in the statute, and

there is no basis for implied preemption. Nor can Petitioners support their claim for implied field preemption. The CAA is not so comprehensive as to demonstrate an implied purpose on the part of Congress to

exclude state regulation of greenhouse gases altogether. In fact, Congress provided for state regulation

more stringent than EPA standards and included a

savings clause preserving the right of any state or political subdivision to enforce any standard that is at

least as stringent as the federal one. Importantly, Petitioners can point to no conflict between Respondents’

state-law causes of action and any specific provision of

federal law, as preemption under the Supremacy

Clause demands. The text of the CAA clearly shows

that Congress intended to control and improve the nation’s air quality through a combination of state and

federal regulation.

2. Petitioners then resort to making the extreme argument that this Court’s ordinary preemption principles do not apply: Congressional purpose is not relevant or needed because Petitioners’ air pollution activities are shielded from state regulation not by any federal statute or law, but by the structure of the Constitution itself.

In their view, two principles that are implicit in

the constitutional structure preclude any liability under one state’s law for the climate effects of air pollution that can cross state lines.

First, imposing liability for the costs of addressing

altered climate in Colorado does not amount to enforcing Colorado law or policy on other states. It is widely

accepted that states can regulate or punish harm to

persons or property within their borders, even where

these effects were caused by actions outside the state.

This Court has upheld awards of punitive damages in

such circumstances, for the purpose of deterring tortious misconduct, including by actors in other states.

Adopting Petitioners’ view prohibiting states from

awarding damages that may influence private decision-making in other states would throw wide areas of

state law into chaos.

Second, for Colorado to award damages for addressing altered climate in Colorado does not offend

the “equal sovereignty” of other states. The fact that

other states may suffer similar harms does not diminish Colorado’s or any state’s authority to provide remedies. Nor does it render such disputes inherently federal. Application of state law to “interstate” disputes

is only inappropriate in disputes between states as

parties to the lawsuits, not simply where the subject

of a private lawsuit can cross state lines.

Petitioners’ proposal to authorize federal judges to

set aside state-law remedies without regard to the intent of Congress is itself a threat to the federalism that

underlies the structure of the U.S. Constitution.

3. Amici supporting Petitioners fear the consequences they imagine will follow if Respondents prevail. They expend a great deal of ink and energy to

construct and attack a straw man. But their “strawsuit” is not this case.

First, Respondents’ causes of action will not result

in ruinous liability for the fossil fuel industry. The local governments are not seeking compensation for all

the harm caused by global carbon emissions, only reimbursement for their own expenditures in ameliorating the effects in their communities.

Second, the localities do not seek to limit or impose

caps on emissions that could result in a patchwork of

standards or conflict with foreign policy or national

energy goals.

Third, Respondents are not seeking to levy a “carbon tax” on either producers or consumers of fossil

fuel. Whether energy companies choose to pass on liabilities to customers is a private decision, and it is no

different than any other statutory or tort liability

which is not deemed to be a “tax.”

This Court should affirm the Colorado Supreme

Court’s decision.

ARGUMENT

THE CLEAN AIR ACT DOES NOT PREEMPT

RESPONDENTS’ STATE LAW CAUSES OF

ACTION FOR REIMBURSEMENT OF THEIR

EXPENDITURES TO AMELIORATE THE

EFFECTS OF ALTERED CLIMATE IN

THEIR COMMUNITIES.

“There is still time to save the world’s peoples

from the catastrophic consequence of pollution.” Those

were not the words of anti-fossil fuel activists. They

were delivered in a speech by American Petroleum Institute President Frank Ikard at the oil industry’s annual meeting in 1965. 2

The thrust of the litigation before this Court is

that the fossil fuel industry knew of the dangers that

lay ahead for the American people if they did not alter

their pace of consumption of fossil fuels. But the energy industry failed to meet that challenge. It chose

profits instead, denying that carbon emissions and

greenhouse gases were matters that Americans and

their lawmakers needed to be concerned about.

There may yet be time to avert catastrophe. The

energy industry has changed. For example, this year’s

ExxonMobil report on “Advancing Climate Solutions”

2 Frank N. Ikhard, Meeting the Challenges of 1966, in 45(1) AM.

PETROLEUM INST., PROCEEDINGS OF THE AMERICAN PETROLEUM

INSTITUTE, 1965 12 (1965), https://www.documentcloud.org/documents/5348130-1965-API-Proceedings/.

opens with the declaration that “Climate change is

real” 3 and proceeds to outline efforts to reduce carbon

emissions “now and well into the future.” Id. at 25. In

the meantime, in many areas it has fallen to local governments to take meaningful steps to address the effects of climate alteration that are already impacting

their communities. Respondents here commenced this

litigation to recoup at least some of their expenditures

in this effort.

A. The Localities’ Causes of Action Fall Well

Within Traditional Police Powers.

1. Localities’ causes of action seek reimbursement for their expenditures in furtherance

of their obligations to the health and safety

of their residents.

Respondents’ primary claim is that fossil fuel companies fraudulently misrepresented and minimized

the environmental dangers presented by their products, with the result that they were able to oversell

their products and discourage or delay steps to address environmental impact. As a result, local governments, including Respondents, were obliged to address rising temperatures in Colorado, shifting

drought and wildfire conditions, insect infestations,

ExxonMobil, Executive Summary, in ADVANCING CLIMATE

SOLUTIONS: 2026 REPORT 3 (May 2026), https://corporate.exxon

mobil.com/-/media/global/files/advancing-climate-solutions/2026/

2026-advancing-climate-solutions-report.pdf. See also Brief for

the Petitioners [“Pet. Br.”] 6 (“Like ExxonMobil, Suncor is ‘fully

committed’ to . . . reduc[ing] greenhouse gas emissions.’”).

and other dangers to public safety and health. See

Amended Complaint ⁋⁋ 145–96.

The damage to persons and property are and will

be severe. Id. at ⁋⁋ 139–44. But Respondents do not

seek compensatory damages for the harm to residents.

Nor do they seek to enjoin or limit carbon emissions. 4

The gist of Respondents’ lawsuit is narrow and focuses

on their local governmental role. The local governments assert that they are duty-bound to protect their

residents’ health and safety, and in their Amended

Complaint they detail the numerous ways they have

expended resources to monitor, mitigate, and adapt to

the effects of altered climate in their communities Id.

at ⁋⁋ 221–321.

The localities allege that those costs “should be

shared by Exxon and the Suncor Defendants because

they knowingly caused and contributed to the alteration of the climate by producing, promoting, refining,

marketing and selling fossil fuels at levels that have

caused and continue to cause climate alteration, while

concealing and/or misrepresenting the dangers associated with fossil fuels’ intended use.” Id. at ⁋ 5.

2. Respondents’ state-law causes of action

come well within the states’ traditional police power.

Petitioners insist that “interstate pollution is an

See id. at ⁋ 542 (“Plaintiffs do not seek to enjoin any oil and gas

operations or sales in the State of Colorado, or elsewhere, or to

enforce emissions controls of any kind.”).

inherently federal area in which state law cannot govern.” Pet. Br. 21; id. at 27 (“States have always lacked

the authority to regulate interstate pollution.”). To the

contrary, as the Colorado Supreme Court correctly

held, “the nuisance abatement issues and the other

torts that Boulder has alleged in this case have been

deemed traditional state law matters implicating important state interests.” County Comm’rs of Boulder

Cnty. v. Suncor Energy USA, Inc., 586 P.3d 161, 170–

71 (Colo. 2026). Respondents’ claims “involve areas of

traditional state responsibility.” Id. at 174.

“Throughout our history,” this Court has observed, “the several States have exercised their police

powers to protect the health and safety of their citizens,” Medtronic, Inc. v. Lohr, 518 U.S. 470, 475

(1996), and “States traditionally have had great latitude under their police powers” to do so. Metropolitan

Life Ins. Co. v. Massachusetts, 471 U.S. 724, 756

(1985). It is well settled, this Court recently noted,

“that common-law duties and standards of care form

part of a State’s authority to regulate safety.” Montgomery v. Caribe Transp. II, LLC, 146 S. Ct. 1199,

1204 (2026). States have a strong interest in providing

a remedy for wrongful harms to their citizens “as well

as enforcing their own safety regulations.” Ford Motor

Co. v. Montana Eighth Jud. Dist. Ct., 592 U.S. 351,

368 (2021).

The public nuisance cause of action is an important element of “[t]he American law of torts [which]

aims to protect all citizens from the risk of physical

harm to their persons or to their property.” Univ. of

Denver v. Doe, 547 P.3d 1129, 1145–46 (Colo. 2024). At

common law in England and in state courts in America

“smoke, or offensive vapors” were widely viewed as actionable public nuisances warranting injunctive relief.

See Ross v. Butler, 19 N.J. Eq. 294, 299–302 (Ch. 1868)

(collecting cases).

The state of Colorado adheres to the widely accepted definition of public nuisance in Restatement

(Second) of Torts § 821B(1), as “an unreasonable interference with a right common to the general public.”

Goodman v. South Suburban Park & Recreation Dist.,

No. 24CA1946, 2025 WL 3033756, at *5 (Colo. App.

Oct. 30, 2025) (quoting Docheff v. City of Broomfield,

623 P.2d 69, 71 (Colo. App. 1980)). An interference is

unreasonable if it injuriously affects the safety or

health of the public. Docheff, 623 P.2d at 71; Echave v.

City of Grand Junction, 193 P.2d 277, 280 (1948).

Traditionally, as the Colorado Supreme Court has

observed, the state-law remedy of remediation of a

public nuisance has been viewed as “essentially an exercise of the police power to protect public health and

safety.” Bd. of Cnty. Comm’rs of Cnty. of La Plata v.

Colorado Dep’t of Pub. Health & Env’t, 488 P.3d 1065,

1074 (Colo. 2021) (quoting James A. Sevinsky, Public

Nuisance: A Common-Law Remedy Among the Statutes, 5 NAT. RES. & ENV’T 29, 29 (1990)).

State and local governments relied on this “centuries-old doctrine” to recoup billions of dollars in public

funds that were spent to combat the effects of tobacco

addiction and opioid addiction. Leslie Kendrick, The

Perils and Promise of Public Nuisance, 132 YALE L.J.

702, 705–06 (2023). In the 1990s state attorneys general filed lawsuits against major tobacco companies

seeking reimbursement for the public funds spent,

mainly through Medicaid, to treat smoking-related illnesses. Not unlike the municipalities in this case, the

states argued that the tobacco companies had known

about and concealed the health risks and addictive nature of nicotine and should bear much of the cost. The

companies ultimately reached a $246 billion agreement with all 50 states to resolve their reimbursement

claims. See Nora Freeman Engstrom & Robert L.

Rabin, Pursuing Public Health Through Litigation, 73

STAN. L. REV. 285, 304–05 (2021).

Throughout the 2010s, states, cities, and counties

across the country filed suits against opioid manufacturers, distributors, and pharmacy chains, arguing

these companies had fueled a public health crisis by

overselling and fraudulently minimizing addiction

risks, requiring governments to spend billions of dollars for additional healthcare, law enforcement, foster

care, and addiction treatment. See, e.g., City & Cnty.

of San Francisco v. Purdue Pharma L.P., 620 F. Supp.

3d 936, 938 (N.D. Cal. 2022). The bulk of the federal

cases were consolidated into one of the largest MDLs

in U.S. history. See Michael J. Purcell, Settling High:

A Common Law Public Nuisance Response to the Opioid Epidemic, 52 COLUM. J.L. & SOC. PROBS. 135, 136

(2018). States are in the process of implementing

structures and plans to distribute at least $50 billion

awarded to states and localities from opioid-related

lawsuits. See State Opioid Settlement Spending Decisions, NAT’L ACAD. FOR STATE HEALTH POL’Y,

http://nashp.org/state-tracker/state-opioid-settlement-spending-decisions/ (last updated Oct. 1, 2025).

The public nuisance doctrine was also central to

early litigation efforts to require former gas station

owners to pay for damage and remediation of public

nuisance caused by leaking, abandoned, underground

gasoline storage tanks. E.g., Exxon Corp. v. Yarema,

516 A.2d 990, 993 (Md. App. 1986). See Michael J. Maher, Common Law Liability for Leaking Underground

Storage Tanks, 13 N. ILL. U. L. REV. 519 (1993); David

W. Ziegele & Jay A. Evans, Regulating Underground

Storage Tank Systems, 27 TRIAL 34 (Sept. 1991).

Protection of consumers from deceptive commercial conduct and misrepresentation of consumer products is also an area in which states are traditionally

authorized to regulate pursuant to their broad sovereign police powers. See, e.g., Florida Lime & Avocado

Growers, Inc. v. Paul, 373 U.S. 132, 150 (1963) (holding states have “traditional power to enforce . . . regulations designed for the protection of consumers”);

Farm Raised Salmon Cases, 175 P.3d 1170, 1176 (Cal.

2008) (“[C]onsumer protection laws such as . . . false

advertising law . . . are within the states’ historic police powers and therefore are subject to the presumption against preemption.”).

When local governments sued the manufacturers

and distributors of a gasoline additive for contamination of ground water, a subject addressed in the CAA,

the Second Circuit upheld a substantial verdict under

state public nuisance law, stating that the action fell

“well within the state’s historic powers to protect the

health, safety, and property rights of its citizens” so

that in this case “the presumption that Congress did

not intend to preempt state law tort verdicts is particularly strong.” In re Methyl Tertiary Butyl Ether

(MTBE) Prod. Liab. Litig., 725 F.3d 65, 96 (2d Cir.

2013).

This Court should hold that Colorado law continues to govern Respondents’ claims unless Congress

has made its intent to supplant it with federal law

crystal clear

B. The Clean Air Act Does Not Preempt Respondents’ Causes of Action.

Petitioners do not make a supportable argument

that the CAA preempts the localities’ state-law remedies. See Pet. Br. 43–47. Nor can they. The Colorado

Supreme Court correctly held that the CAA neither

expressly nor impliedly preempts Respondents’ statelaw causes of action. 586 P.3d at 170–72.

Petitioners, however, appear to renew their contention that the CAA ousts Colorado law on the basis

of implied field preemption. Specifically, Petitioners

contend, the CAA “sets forth a pervasive statutory

scheme clearly intended to ‘dominate the field’ of interstate pollution regulation.” Pet. Br. 44 (quoting Int’l

Paper Co. v. Ouellette, 479 U.S. 481, 492 (1987)). State

law causes of action are barred because “here, Congress has occupied the entire relevant field of regulation.” Id.

This line of argument fails as well—for at least

three reasons.

First, some members of this Court have become

“skeptical” of claims of field preemption “in the absence of a congressional command.” Kansas v. Garcia,

589 U.S. 191, 214 n.* (2020) (Thomas, J., concurring).

See also Camps Newfound/Owatonna, Inc. v. Town of

Harrison, 520 U.S. 564, 617 (1997) (Thomas, J., dissenting); Kurns v. R.R. Friction Prods. Corp., 565 U.S.

625, 640–41 (2012) (Sotomayor, J., concurring in part

and dissenting in part).

Second, Petitioners pay no heed to this Court’s

repeated command that “the purpose of Congress is

the ultimate touchstone in every pre-emption case.”

Medtronic, 518 U.S. at 485. In this case, Congress gave

no textual signal that its purpose was to occupy the

entire field of interstate air pollution.

Nor did Congress enact a “scheme of federal regulation so pervasive as to make reasonable the inference that Congress left no room for the States to supplement it.” Gade v. Nat’l Solid Wastes Mgmt. Ass’n,

505 U.S. 88, 98 (1992). The CAA explicitly authorizes

emissions standards for stationary and mobile emitters of greenhouse gases, but makes no provision for

the producers or sellers of the petroleum products that

produce the emissions or for liability for misrepresentation of petroleum products or for the creation of a

public nuisance. Even within the field of regulating

emissions, the CAA does not evince an intent to exclude a state role. The Tenth Circuit, in an earlier review of this case, reminded Petitioners that the CAA

“is designed to provide a floor upon which state law

can build, not a ceiling to stunt complementary statelaw actions.” Bd. of Cnty. Comm’rs of Boulder Cnty. v.

Suncor Energy (U.S.A.) Inc., 25 F.4th 1238, 1263 (10th

Cir. 2022) (citing 42 U.S.C. § 7416).

That section, entitled “Retention of State authority,” states:

[N]othing in this chapter shall preclude or deny the right of any State or

political subdivision thereof to adopt

or enforce (1) any standard or limitation respecting emissions of air pollutants or (2) any requirement respecting control or abatement of air pollution; except . . . any emission standard [less stringent than the federal

standard.]

42 U.S.C. § 7416. This provision is often referred to as

the CAA’s “states’ rights savings clause.” Bell v. Cheswick Generating Station, 734 F.3d 188, 191 (3d Cir.

2013).

Third, Petitioners describe no conflict between

any provision of the CAA and Respondents’ causes of

action. As Justice Thomas has explained, federal

preemption of state law is a solution to a problem inherent in our federalist system in which persons are

subject to two sovereigns, and “the overlapping, dual

jurisdiction of the Federal and State Governments

makes it necessary to decide which law takes precedence.” Parker Drilling Mgmt. Servs., Ltd. v. Newton,

587 U.S. 601, 610 (2019). See also Martin v. United

States, 145 S. Ct. 1689, 1700 (2025) (Gorsuch, J.) (“The

Supremacy Clause supplies a rule of decision when

federal and state laws conflict.”) (citing U.S. Const.,

Art. VI, cl. 2) (emphasis added).

The text of the Supremacy Clause itself makes

clear that conflict is its crucial element. 5 Justice

“This Constitution, and the Laws of the United States which

shall be made in Pursuance thereof . . . shall be the supreme Law

of the Land . . . any Thing in the Constitution or Laws of any

State to the Contrary notwithstanding.” U.S. Const., Art. VI, cl.

Thomas has explained, the term “notwithstanding”

denotes the constitutional presumption that “state

law applies unless it conflicts with federal law.” Parker, 587 U.S. at 610 (citing PLIVA, Inc. v. Mensing,

564 U. S. 604, 617–18 (2011)). See also Caleb Nelson,

Preemption, 86 VA. L. REV. 225, 231 (2000) (“Under the

Supremacy Clause, preemption occurs if and only if

state law contradicts a valid rule established by federal law.”) (emphasis added).

In this case, Petitioners can point to no federalstate conflict. As noted earlier, the CAA imposes no

regulations on producers or sellers of emissions-producing products. Moreover, the statute’s emissions

regulations clearly allow states to enforce their own

more stringent emissions standards. This Court has

recognized that, even in fields heavily regulated by

federal law, such provisions reflect the view of state

tort remedies as “complementary,” augmenting the

federal government’s finite resources and adding

greater access to information. Wyeth v. Levine, 555

U.S. 555, 578–79 (2009). Indeed, “[p]arallel state tort

liability is an enforcement tool that can have a salutary information-forcing effect, and that, in turn, helps

ensure the effectiveness of [federal regulation].” Monsanto Co. v. Durnell, 146 S. Ct. 2001, 2023 (2026).

The Tenth Circuit was surely correct in concluding

that “[t]he purpose of the [CAA] is to control and improve the nation’s air quality through a combination

of state and federal regulation.” Arizona Pub. Serv. Co.

v. EPA, 562 F.3d 1116, 1118 (10th Cir. 2009) (emphasis added).

II. THE “STRUCTURE OF THE CONSTITUTION” DOES NOT PREEMPT THE MUNICIPALITIES’ STATE-LAW REMEDIES TO RECOVER EXPENDITURES TO COMBAT THE

EFFECTS OF CLIMATE ALTERATION IN

THEIR COMMUNITIES.

A. Petitioners Propose to Preclude State

Remedies for Harms That Can Cross

State Lines Unless Expressly Authorized

by Congress.

Implicitly acknowledging that this Court’s ordinary preemption jurisprudence does not support setting aside Respondents’ state-law remedies, as the

Colorado Supreme Court squarely held, Petitioners

urge this Court to adopt a radical theory for rejection

of state law without any indicia that Congress so intended or any conflict between federal law and the

state remedy at issue.

Petitioners posit that the municipalities seek to

recover damages “caused by the effects of interstate

greenhouse-gas emissions,” which they characterize

as “ambient.” Pet. Br. 21. Because ambient air and water pollution “can readily flow from one State to another,” id. at 27, “interstate pollution is an inherently

federal area in which state law cannot govern.” Id. at

21. Indeed, “State law is not competent to govern those

claims.” Id.

Petitioners’ proposal to displace state law is not

based on conflict with any act of Congress or congressional purpose. Nor do Petitioners assert that the

state-law remedies sought by Respondents offend any

particular provision of the Constitution. Petitioners

rely instead on a judge-made rule that “arises from the

fundamental structure of the Constitution.” Id. Because the subject of this dispute is pollution that can

travel interstate, remedies for injuries are an “inherently federal area.” Id. Petitioners therefore urge this

Court to hold that the local governments’ claims “fall

squarely within the inherently federal area of interstate-pollution disputes that are foreclosed by the

Constitution.” Id. at. 39.

Petitioners turn the federalist scheme on its head.

As Chief Justice Rehnquist made clear, the fundamental idea that “‘[t]he Constitution created a Federal

Government of limited powers,’” while reserving a

generalized police power to the States, is deeply ingrained in our constitutional history.” United States v.

Morrison, 529 U.S. 598, 619 n.8 (2000) (quoting New

York v. United States, 505 U.S. 144, 155 (1992)); Gregory v. Ashcroft, 501 U.S. 452, 457 (1991).

Petitioners candidly admit that this shockingly

broad intrusion into the authority of local governments to protect the health and safety of their communities has no basis in the Constitution’s text. They purport to find judicial authority to oust state law in two

vaguely defined “principles” that are “not spelled out

in the Constitution” but are “nevertheless implicit in

its structure.” Pet. Br. 23 (quoting Franchise Tax Bd.

of California v. Hyatt, 587 U.S. 230, 247 (2019)). They

describe these as the “extraterritoriality principle”

and the “equal sovereignty principle.” Id. at 23–24. Petitioners wildly distort this Court’s precedents in their

effort to persuade this Court to adopt their prescription for judicial lawmaking.

B. Recovery of Expenditures to Ameliorate

the Public Nuisance Effects of Carbon

Emissions Due in Part to Petitioners’

Fraudulent Misrepresentations Does Not

Amount to Enforcement of Colorado Law

Outside of Colorado.

Petitioners contend that imposition of tort liability

in this case would allow Colorado “to exercise ‘extra

territorial jurisdiction,’” that is, to “regulate and control activities wholly beyond its boundaries.” Id. at 24

(quoting Watson v. Employers Liab. Assurance Corp.,

348 U.S. 66, 70 (1954)). Petitioners’ version of the “extraterritoriality doctrine” has no basis in this Court’s

precedents and, if implemented, would be wholly unworkable.

1. States may regulate activities that cause

harm to persons or property within their

boundaries, even if those activities originate in other states.

Petitioners contend that each sovereign state can

regulate or punish conduct within its borders as it sees

fit, but not harmful conduct that crosses state lines.

Id.

In a case that could be a law school hypothetical

come to life, the Supreme Court of Georgia held that a

man standing on the South Carolina shore of the Savannah River and fired a pistol at a man across the

border in Georgia could be indicted under Georgia law.

Simpson v. State, 17 S.E. 984, 986 (Ga. 1893). The

court’s survey of authorities demonstrated “beyond

question that a criminal act begun in one state and

completed in another renders the person who does the

act liable to indictment in the latter.” Id. In fact, the

matter was “too well established for serious controversy.” Id.

That view is reflected in the Restatement (Second)

of the Foreign Relations Law of the United States § 18

(1965), which states:

A state has jurisdiction to prescribe a

rule of law attaching legal consequences to conduct that occurs outside its territory and causes an effect

within its territory, if . . . the conduct

and its effects are . . . constituent elements of a crime or tort.

See also Ronald E. Bornstein & N. Elaine Dugger, International Regulation of Insider Trading, 1987

COLUM. BUS. L. REV. 375, 401–02 (1987).

This “effects” rule is widely accepted by U.S.

courts. Susan Emmenegger, Extraterritorial Economic

Sanctions and Their Foundation in International

Law, 33 ARIZ. J. INT’L & COMP. L. 631, 648 (2016). See,

e.g., Hartford Fire Ins. Co. v. California, 509 U.S. 764,

796 (1993) (“[I]t is well established by now that the

Sherman Act applies to foreign conduct that was

meant to produce and did in fact produce some substantial effect in the United States.”).

Oddly, Petitioners cite as authority for their contrary view two well-known decisions by this Court that

undermine their position. See Pet. Br. 24 (citing BMW

of N. Am., Inc. v. Gore, 517 U.S. 559 (1996), and State

Farm Mut. Auto. Ins. Co. v. Campbell, 538 U.S. 408

(2003)).

In Gore, BMW’s New Jersey subsidiary-distributor repainted cars that had been damaged during

transport from Germany, then shipped them to dealers to be sold to customers as “new.” Plaintiff Gore

purchased his BMW in Alabama and subsequently

sued for fraud under Alabama law. This Court upheld

the jury’s award of compensatory and punitive damages based on the diminution in the car’s value, despite the fact that the subject of the dispute crossed

state lines and the award punished the BMW distributor for its out-of-state conduct. “No one doubts that a

State may protect its citizens by prohibiting deceptive

trade practices and by requiring automobile distributors to disclose presale repairs that affect the value of

a new car.” Gore, 517 U.S. at 568–69. By contrast, the

Court held that Alabama could not award punitive

damages for similar non-disclosures in sales to other

BMW customers in other states “that had no impact

on Alabama or its residents.” Id. at 573.

In State Farm, plaintiffs obtained an award

against their insurer for fraud and bad faith in the insurer’s handling of their auto accident litigation. This

Court reiterated the position it enunciated in Gore: A

state can punish out-of-state conduct that causes instate harm, but that activity “must have a nexus to the

specific harm suffered by the plaintiff.” 538 U.S. at

422.

Colorado’s decision to allow Colorado local governments to pursue recovery of expenses to address climate conditions in Colorado caused in part by Petitioners’ conduct falls well within the scope of Colorado’s sovereign authority to remedy harms to its citizens that originate beyond its borders.

2. The indirect effects of a state’s regulation

on the decisions of private parties in other

states does not amount to extraterritoriality.

An award of damages to Respondents in this case

would not implicate Petitioners’ extraterritoriality

concerns for an additional reason: Although a liability

award may incentivize an out-of-state defendant or

others to alter their conduct, such indirect effects do

not constitute an impermissible attempt to regulate or

control activities wholly beyond Colorado’s borders.

This Court has rejected the idea that state liability rules are impermissibly extraterritorial merely because they influence private decision making and thus

have “a practical effect of controlling commerce outside the state.” National Pork Producers Council v.

Ross, 598 U.S. 356, 371–76 (2023). Such a rule would

cast doubt on “all manner of” widely accepted state

laws, including environmental and tort laws that may

have an impact on the decisions and conduct of companies in other states or other nations. Id. at 374.

Product liability cases, for example, very often

arise out of injury to a consumer by a product that was

designed and manufactured in another state. Damage

awards not only compensate the wrongfully harmed

plaintiff, but also incentivize the defendant and other

manufacturers to alter the unreasonably dangerous

design, add warnings, or otherwise invest in safety.

This is a foundational principle of state products liability law, see, e.g., William L. Prosser, The Assault

Upon the Citadel (Strict Liability to the Consumer), 69

YALE L.J. 1099, 1119–20 (1960), and of negligence law

generally. See Guido Calabresi, The Costs of Accidents

68–129 (1970) (contrasting governmental regulatory

mandates with the indirect influence of “general deterrence” exerted by tort law to incentivize safety

measures).

Voluntary adoption of safety measures by a company in State B in response to a tort award in State A

does not amount to State A imposing its law on State

B. Nor would a verdict in Respondents’ favor in this

case, if it led energy companies in other states to invest in lower-emissions alternatives. It is simply the

normal operation of tort liability in our system of federalism.

C. Application of State Law to Decide Disputes Between Private Parties Concerning Interstate Pollution Does Not Offend

the Principle of Equal Sovereignty.

Petitioners also contend that Colorado law is incompetent to impose liability in this case based on the

“fundamental principle of equal sovereignty among

the States,” a limit on state sovereignty that is “implicit” in the structure of the Constitution. Pet. Br. 23.

Petitioners explain that because air pollution respects

no political boundaries, allowing Colorado to apply its

law to this national problem would result in one “State

having more sovereign power than another,” Id. at 22

(quoting American Elec. Power Co. v. Connecticut, 564

U.S. 410, 422 (2011)).

For that reason, Petitioners assert, interstate air

pollution disputes are “meet for federal law governance.” Id. at 22 (quoting American Elec. Power, 564

U.S. at 422), and “inappropriate for state law to control.” Id. at 28 (quoting Texas Indus., Inc. v. Radcliff

Materials, Inc., 451 U.S. 630, 641 (1981)).

Petitioners take precisely the wrong message from

this Court’s decision in Texas Industries. The mere

fact that private activity is within the federal government’s authority to regulate interstate commerce does

not oust state regulation. The full passage cited by Petitioners confirms that state law is inappropriate in

interstate disputes between states as parties:

[N]or does the existence of congressional authority under Art. I mean

that federal courts are free to develop

a common law to govern those areas

until Congress acts. Rather, . . . federal common law exists only in such

narrow areas as those concerned with

the rights and obligations of the

United States, [and] interstate . . . disputes implicating the conflicting

rights of States.

451 U.S. at 641 (emphasis added).

Petitioners’ heavy reliance on Hyatt is significantly inapt. That case did not involve state regulation

of the interstate activities of private parties; it concerned implied constitutional limits on states as parties in litigation. The Hyatt Court held that a state

cannot be sued in the Courts of another state. 587 U.S.

at 233. Other precedents of this Court cited by Petitioners confirm that the “interstate disputes” for

which state law is inappropriate are lawsuits between

states. See Pet. Br. 25 (citing Missouri v. Illinois, 200

U.S. 496 (1906); Georgia v. Tennessee Copper Co., 206

U.S. 230, 236 (1907)6; New York v. New Jersey, 256

U.S. 296, 301–02 (1921); North Dakota v. Minnesota,

263 U.S. 365, 373–74 (1923); New Jersey v. New York,

283 U.S. 473, 483 (1931); Illinois v. Milwaukee, 406

U.S. 91, 107 n.9 (1972)).

The application of state law in such disputes is inappropriate not because of the interstate nature of the

subject of the dispute, but because, in the same way

that federal law applies in suits concerning the location of the border between two states, one state should

not have the advantage of applying its own law.

Cissna v. Tennessee, 246 U.S. 289, 295 (1918).

Nor does this Court’s decision in American Electric Power offer support for the proposition that the

“ambient” nature of air and water pollution render the

states incompetent to adjudicate litigation between

non-state parties. The Court indicated that, to the contrary, state law of public nuisance may provide a remedy for interstate pollution. 564 U.S. at 429. Because

the parties had not briefed the issue, the Court reserved the question of whether plaintiffs could recover

under state law public nuisance causes of action. Id.

This Court should answer that question in the affirmative and reject the invitation to drastically expand the judicial power to jettison state law remedies

where there is no showing that Congress so intended

or that the remedies conflict with federal law.

Justice Holmes pointedly observed for the Court, “This is a suit

by a state for an injury to it in its capacity of quasi-sovereign.”

206 U.S. at 237.

This Court should preserve the federal-state balance it has struck in its ordinary preemption jurisprudence.

D. Petitioners’ Proposed Expansive Federal

Judicial Power to “Displace” State Law

Remedies Itself Violates the Structure of

the Constitution.

The system of federalism that is the key characteristic of our constitutional republic is not enforced by

statute or any specific provision in the Constitution,

nor even by this Court’s judicial authority. See Garcia

v. San Antonio Metro. Transit Auth., 469 U.S. 528

(1985) (overruling National League of Cities v. Usery,

426 U.S. 833 (1976)). Rather, the autonomy of the

states is “properly protected by the procedural safeguards inherent in the structure of the federal system,” which gives the states representation in Congress. Id. at 552. Indeed, the Founders relied on “the

structure of the Federal Government itself” to allow

the states to guard against federal overreach. Id. at

551. The states can protect their interests on the floor

of Congress. But for that safeguard to be effective,

courts must insist “that the historic police powers of

the States” not be set aside “unless that was the clear

and manifest purpose of Congress.” Rice v. Santa Fe

Elevator Corp., 331 U.S. 218, 230 (1947); Cipollone v.

Liggett Grp., Inc., 505 U.S. 504, 516 (1992).

Courts have found preemptive intent in the statutory text or implied where there is direct conflict between state and federal law. But Petitioners look to no

statutory or constitutional text; they invoke only a

vague notion that the federal government has an overriding interest in applying its law when the subject of

the litigation is one that can cross state lines.

This Court has made it clear that calling upon

“some brooding federal interest” or “judicial policy

preference” falls far short of protecting our constitutional federalist structure. Kansas, 589 U.S. at 202

(quoting Virginia Uranium, Inc. v. Warren, 587 U.S.

761, 767 (2019) (Gorsuch, J.)). Petitioners’ proposal

that federal judges set aside state remedies on that

unmoored basis would undermine proper judicial respect for the States as “‘independent sovereigns in our

federal system,’” Wyeth, 555 U.S. at 565 n.3 (quoting

Medtronic, 518 U.S. at 485), and invite “unintended

encroachment on the authority of the States.” CSX

Transp., Inc. v. Easterwood, 507 U.S. 658, 664 (1993).

In sum, “[t]here is no federal preemption in

vacuo,” Kansas, 589 U.S. at 202 (quoting Puerto Rico

Dep’t. of Consumer Affs. v. Isla Petroleum Corp., 485

U.S. 495, 503 (1988)), and this Court should reject Petitioners’ invitation to create it in this case.

III. THE DIRE WARNINGS VOICED BY PETITIONERS’ SUPPORTING AMICI ARE

GROUNDLESS AND DO NOT SUPPORT

DENYING RESPONDENTS THE RIGHT TO

RECOUP REASONABLE EXPENDITURES

TO AMELIORATE THE EFFECTS OF CLIMATE ALTERATION.

Petitioners’ supporting amici offer a variety of arguments why fossil fuel corporations should not be required to reimburse local governments for their expenditures to combat the effects of climate alteration.

But rather than address the lawsuit detailed in Respondents’ Amended Complaint and upheld by the

Colorado Supreme Court, amici expend a great deal of

ink and effort to construct and then knock down a

straw man lawsuit. But their strenuous refutation of

this “strawsuit” provides no support for Petitioners’

novel preemption theory. Indeed, most of their dire

warnings are simply not this case.

A. Permitting Respondents’ Causes of Action to Proceed Will Not Result in Ruinous Liability.

For example, several amici warn that liability will

impose extreme costs on the fossil fuel industry and

harm on the wider economy. The brief submitted by

the Atlantic Legal Foundation (ALF) states that local

governments “are necessarily seeking damages for

harms attributed to all interstate and international

emissions combined.” Brief of Atlantic Legal Foundation, et al. as Amici Curiae Supporting Petitioners at

11. ALF forecasts “staggering” costs if each of the

90,837 governments in the U.S. can “pursue its own

multimillion-dollar state-court damages suit against

the nation’s largest fossil fuel energy companies” inflicting “crushing burdens and crippling litigation

costs.” Id. at 18.

Similarly, the Washington Legal Foundation

(WLF), joined by small business organizations, echoes

the prediction that 90,837 governmental units will

pursue lawsuits against energy companies, along

with, perhaps, “every person in the Nation.” Brief of

Washington Legal Foundation, et al. as Amici Curiae

Supporting Petitioners at 17. Judgments would “run

into the trillions,” ruining the entire fossil fuel industry and with it the United States and world economies.

Id. at 17–18. See also Brief for the American Petroleum Institute as Amicus Curiae Supporting Petitioners at 26 (“The damages requested by Respondents

and other plaintiffs across the country could severely

impact the energy industry and cause ripple effects

throughout the American economy.”); Brief of General

(Retired) Richard B. Myers, et al. as Amici Curiae

Supporting Petitioners at 5 (“Respondents seek to impose ruinous liability on Petitioners for their production and sale of these essential products.”).

If Respondents were seeking compensation for all

damages caused by climate alteration, the total could

be great indeed. But that is not this case. See Amended

Complaint ⁋ 542 (“Plaintiffs do not seek to enjoin any

oil and gas operations or sales in the State of Colorado,

or elsewhere, or to enforce emissions controls of any

kind.”) (emphasis in original). 7 The local governments

seek reimbursement for amounts that have or will be

spent to mitigate the effects of climate alteration. Id.

at ⁋ 532. These claims do not represent new societal

costs, but rather a shifting of the burden from taxpayers to the entities that played a role in making those

expenditures necessary. Because many units of local

government are small and command limited budgets,

it cannot be assumed that many will be in a position

to seek to recoup large expenses. More importantly, to

the extent that an ounce of expenditure to soften the

impact of climate alteration is successful in preventing

Although Petitioners do seek compensatory damages for harm

to their local-government property, see Amended Complaint ⁋⁋

532–33, neither party addresses this claim.

much greater damage, the U.S. economy will gain a

net benefit.

B. Fears of a “Carbon Tax” Are Unwarranted.

In a related argument, some supporting amici

breathlessly declare that in this litigation and similar

suits across the country, “state and municipal executives are attempting to use the judiciary to impose

what amounts to a carbon (dioxide) tax.” Brief of Government Accountability & Oversight as Amicus Curiae Supporting Petitioners at 11. See also id. at 2

(These suits “represent nothing less than a campaign

to impose the equivalent of taxation.”); Brief of Former

State Solicitors General as Amici Curiae Supporting

Petitioners at 9 (alleging public nuisance litigation is

the result of a well-funded campaign aimed at “imposing a carbon tax.”); Brief of National Association of

Manufacturers as Amicus Curiae Supporting Petitioners at10–12 (similar).

True, the advisability of a carbon tax is a matter

for the legislative branch and not this Court. But that

is not this case. Amici provide no evidence that energy

companies would add the cost of liability awards to the

price of petroleum products or whether the amount

would be more than miniscule. In any event, governments impose taxes on products, not private manufacturers who price their products to include their costs.

The notion that a tort award (or an award for breach

of contract, antitrust violation, or civil rights violation)

may be viewed as an impermissible “tax” on the product or service is a wholly unworkable fiction.

C. Fears of Undermining National Security

or National Energy Goals Are Unwarranted.

Several amici postulate that allowing Respondents to proceed with their state law claims will lead

affected energy companies to reduce their production

of fossil fuels, with adverse effects on American national priorities. For example, the brief filed by retired

General Richard B. Myers and retired Admiral Michael G. Mullen states that damage awards in these

lawsuits would “force reductions” in the production of

fossil fuels and “pose a grave threat to our national security because any future damages award will necessarily restrict fuel supply” and reduce the availability

of fossil fuels to the military. Brief of General (Retired)

Richard B. Myers, et al. at 10–11. See also id. at 12

(arguing Respondents’ complaint risks “making oil

and gas prohibitively costly and scarce.”).

The National Association of Manufacturers’ brief

argues somewhat differently that when American oil

companies cut back, foreign companies in the Middle

East, North Africa and Latin America take advantage

“by cranking up” production. The result is not shortage and high prices, but rather dependence on “authoritarian leaders and politically unstable countries.”

Brief of National Association of Manufacturers at 24.

Again, that is not this case. “Plaintiffs do not seek

to enjoin any oil and gas operations or sales in the

State of Colorado, or elsewhere.” Amended Complaint

⁋ 542. That liability might indirectly influence the oil

market is unremarkable. This Court has explained

that a neutral state law of general applicability is not

invalid even if it exerts effects on decision making in

other countries. Medellin v. Texas, 552 U.S. 491, 531

(2008); cf. American Ins. Ass’n v. Garamendi, 539 U.S.

396, 425–26 (2003) (preempting a California insurance statute targeting European countries, but distinguishing it from “a generally applicable ‘blue sky’

law”). Indeed, the notion that state liability laws must

not be allowed to affect decisions by other nations,

however indirectly, would essentially cripple America’s civil justice system.

D. Fears of Difficulties in Obtaining Liability Insurance to Cover the Local Governments’ State-Law Claims Does Not Warrant Federal Preemption of Those

Claims.

The American Property Casualty Insurance Association and other insurance-related associations complain that insurers cannot rationally set premiums for

policies covering “unbounded and indeterminate . . .

liabilities that states and municipalities across the

country may seek to impose for climate change.” Brief

of American Property Casualty Insurance Association,

et al. as Amici Curiae Supporting Petitioners at 10.

Setting aside that governmental climate alteration expenditures for which they might seek reimbursement should be ascertainable, those expenditures are designed to mitigate the damage that property-casualty insurers also cover. Significantly, the insurers highlight a KPMG article stating that the insurance industry is already facing difficulties covering

climate-change losses due to “[s]evere convective

storms, flooding, wildfires, windstorms, and earthquakes.” Id. at 14–15, n.8. One might safely surmise

that measures designed to mitigate these impacts

would be welcome in many quarters of the propertycasualty insurance industry.

CONCLUSION

For these reasons, the decision by the Colorado

Supreme Court should be affirmed.

August 3, 2026

Respectfully submitted,

Jeffrey R. White

Counsel of Record

N. John Bey

President

AMERICAN ASSOCIATION

FOR JUSTICE

777 6th St. NW, #300

Washington, DC 20001

Counsel for Amicus Curiae

This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.