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

Supreme Court briefOct 9, 2025

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Nos. 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.

______________________

BRIEF OF AMICUS CURIAE THE NATIONAL

ASSOCIATION OF MANUFACTURERS

IN SUPPORT OF PETITIONERS

_______________

On Petition for a Writ of Certiorari

to the Supreme Court of Colorado

_______________

Linda Kelly

Erica Klenicki

Caroline McAuliffe

THE NAM LEGAL CENTER

733 10th Street, N.W.

Suite 700

Washington, D.C. 20001

October 9, 2025

Philip S. Goldberg

Counsel of Record

SHOOK, HARDY &

BACON L.L.P.

1800 K Street, N.W., 1000

Washington, D.C. 20006

(202) 783-8400

pgoldberg@shb.com

TABLE OF CONTENTS

Page

TABLE OF AUTHORITIES .................................. ii

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

INTRODUCTION AND

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

ARGUMENT .......................................................... 5

THE COURT SHOULD NOT ALLOW

STATES TO CIRCUMVENT ITS

RULING IN AEP THAT CLIMATE

CHANGE CLAIMS INVOKE A

“SPECIAL FEDERL INTEREST” ............. 5

II. REPACKAGING CLAIMS FROM AEP

DOES NOT CHANGE THE FACT THAT

TODAY’S CLIMATE LITIGATION

SEEKS TO REGULATE INTERSTATE

AND INTERNATIONAL EMISSIONS ..... 8

III. MERELY PASTING STATE LAW

LABELS ON FEDERAL LAW CLAIMS

SHOULD NOT BE A MEANS FOR

USURPING FEDERAL AUTHORITY ...... 12

IV. THE COURT SHOULD AFFIRM THAT

CLAIMS ALLEGING HARM FROM

GLOBAL CLIMATE CHANGE RAISE

UNIQUELY FEDERAL INTERESTS....... 15

CONCLUSION ....................................................... 22

TABLE OF AUTHORITIES

Cases

Page

American Electric Power Co. v. Connecticut,

564 U.S. 410 (2011)........ 2, 3, 4, 6, 7, 15, 17, 20, 21

Bucks County v. BP P.L.C., No. 2024-01836

(Pa. Ct. Comm. Pleas May 16, 2025) ................. 14

California v. General Motors Corp.,

No. C06-05755 MJJ, 2007 WL 2726871

(N.D. Cal. Sept. 17, 2007) ...................................... 5

City and County of Honolulu v. Sunoco LP,

537 P.3d 1173 (Haw. 2023) .................................. 13

City of Annapolis v. BP PLC, No. C-020CV21-250 (Md. Cir. Ct. Jan. 23, 2025) ..................... 14

City of Charleston v. Brabham Oil Co.,

No. 2:20-cv-03579 (D.S.C. July 6, 2023) ............. 14

City of Milwaukee v. Illinois,

451 U.S. 304 (1981).............................................. 20

City of New York v. Chevron Corp.,

993 F.3d 81 (2d Cir. 2021) ....... 4, 13, 16, 17, 20, 21

City of New York v. Exxon Mobil Corp., 2025

WL 209843 (N.Y. Sup. Ct. Jan. 14, 2025) .......... 14

Comer v. Murphy Oil USA, Inc.,

718 F.3d 460 (5th Cir. 2013) ............................. 3, 5

Comer v. Murphy Oil USA, Inc.,

839 F. Supp. 2d 849 (S.D. Miss. 2012) .................. 8

iii

Delaware ex rel. Jennings v. BP America Inc.,

2024 WL 98888 (Del. Super. Ct. Jan. 9,

2024) .......................................................... 13-14, 18

Illinois v. City of Milwaukee,

406 U.S. 91 (1972).................................................. 7

International Paper Co. v. Ouellette,

479 U.S. 481 (1987).............................................. 21

Mayor and City Council of Baltimore v. BP

P.L.C., No. 24-C-18-004219

(Md. Cir. Ct. July 10, 2024) ................................. 14

Minnesota v. American Petroleum Inst.,

63 F.4th 703 (8th Cir. 2022) ........................... 10-11

Native Village of Kivalina v. ExxonMobil Corp.,

696 F.3d 849 (9th Cir. 2012) ......................... 3, 5, 8

Platkin v. Exxon Mobil Corp.,

No. 22-cv-06733 (RK)(JBD), 2023

WL 4086353 (D.N.J. June 20, 2023) ................... 14

San Diego Bldg. Trades Council v. Garmon,

359 U.S. 236 (1959).............................................. 17

United States v. Standard Oil Co. of California,

332 U.S. 301 (1947)................................................ 7

Watson v. Philip Morris Cos.,

551 U.S. 142 (2007).............................................. 11

West Virginia v. Environmental Prot. Agency,

597 U.S. 697 (2022)................................................ 3

Other Authorities

Amicus Brief of Alabama and 25 Other States in

Support of Petitioners, Suncor Energy (U.S.A.)

Inc. v. Cnty. Commissioners of Boulder County,

No. 25-170 (U.S., filed Sept. 26, 2025) ................ 14

Beyond the Courtroom, Manufacturers’

Accountability Project, at https://mfgaccountability project.org/beyond-the-courtroom .................. 11

Bill of Complaint, Alabama v. California, No. 158

(Original) (U.S., filed May 22, 2024) ............... 4, 14

Brief for the Tennessee Valley Authority,

American Electric Power Co. v. Connecticut, No. 10-174 (U.S., filed Jan. 31, 2011) ............ 6

Brief for the United States as Amicus

Curiae, Sunoco LP v. City and County of

Honolulu, Nos. 23-947, 23-952, 2024 WL

5095299 (U.S., filed Dec. 10, 2024) ..................... 18

Julia Caulfield, Local Lawsuits Asks Oil and

Gas to Help Pay for Climate Change,

KOTO, Dec. 14, 2020, at https://coloradosun.com/2021/02/01/boulder-climate-lawsuit-opinion/ ........................................................... 9

City of Hoboken Press Release, Hoboken Becomes

First NJ City to Sue Big Oil Companies,

American Petroleum Institute for Climate

Change Damages, Sept. 2, 2020, at

https://www.hobokennj.gov/news/hobokensues-exxon-mobil-american-petroleum-institute-big-oil-companies ......................................... 10

Lesley Clark, Why Oil Companies Are Worried

About Climate Lawsuits From Gas States,

E&E News, Nov. 7, 2023 ..................................... 11

Editorial, Climate Lawsuits Take a Hit,

Wall St. J., May 17, 2021 .................................... 11

Ross Eisenberg, Forget the Green New Deal. Let’s

Get to Work on a Real Climate Bill, Politico,

Mar. 27, 2019 ....................................................... 22

Establishing Accountability for Climate Damages:

Lessons from Tobacco Control, Summary of the

Workshop on Climate Accountability, Public

Opinion, and Legal Strategies, Union of

Concerned Scientists & Climate Accountability

Inst. (Oct. 2012), at https://www.ucs.org/sites/

default/files/attach/2016/04/establishing-accountability-climate-change-damages-lessonstobacco-control.pdf .............................................. 8-9

Kirk Herbertson, Oil Companies vs. Citizens: The

Battle Begins Over Who Will Pay Climate

Costs, EarthRights Int’l, Mar. 21, 2018 ................ 9

Donald Kochan, Supreme Court Should Prevent

Flood of State Climate Change Torts, Bloomberg Law, May 20, 2024 ...................................... 19

Pl.’s Mot. For Entry of Partial Judgment Pursuant

to Rule 54(b), Delaware v. BP Am., Inc., C.A. No.

N20-C-09-097 (Del. Super. Ct. Oct. 21, 2024)..... 19

Dawn Reeves, As Climate Suits Keeps Issue

Alive, Nuisance Cases Reach Key Venue

Rulings, Inside EPA, Jan. 6, 2020, at

https://insideepa.com/outlook/climate-suitskeeps-issue-alive-nuisance-cases-reach-keyvenue-rulings ....................................................... 10

Bill Schuette, Energy, Climate Policy Should be

Guided by Federal Laws, Congress, Not a

Chaotic Patchwork of State Laws, Law.com,

Apr. 25, 2024 ........................................................ 19

Alexa St. John, Justice Department Sues Hawaii,

Michigan, Vermont and New York Over State Climate Actions, Assoc. Press, May 1, 2025, at

https://apnews.com/article/trump-doj-climatestates-policy-lawsuitsa5228e1dd6348f09d2a70f460142531a ................ 14

Jerry Taylor & David Bookbinder, Oil Companies

Should be Held Accountable for Climate Change,

Niskanen Center, Apr. 17, 2018 ....................... 9-10

Danielle Zanzalari, Government Lawsuits Threaten

Consumers’ Pockets and Do Little to Help the Environment, USA Today, Nov. 1, 2023 .................. 17

INTEREST OF AMICUS CURIAE1

Amicus curiae, the National Association of Manufacturers (“NAM”), is the largest manufacturing association in the United States, representing small and

large manufacturers in every industrial sector and in

all 50 states. Manufacturing employs 13 million men

and women, contributes $2.9 trillion to the U.S. economy annually, has the largest economic impact of any

major sector, and accounts for more than half of all

private-sector research and development in the nation. The NAM is the voice of the manufacturing community and leading advocate for a policy agenda that

helps manufacturers compete in the global economy

and create jobs across the United States.

The NAM is dedicated to manufacturing safe, innovative and sustainable products that provide essential benefits to consumers while protecting human

health and the environment. Climate change is one of

the most important public policy issues of our time,

and the NAM supports national efforts to address climate change and improve public health through appropriate laws and regulations. Developing new technologies to reduce greenhouse gas emissions, make

energy more efficient, and modify infrastructures to

deal with the impacts of climate change has become

an international imperative.

1 Pursuant to Rule 37.6, counsel for amicus curiae certifies that

this brief was not authored in whole or in part by counsel for any

party and that no person or entity, other than amicus curiae, its

members, or its counsel made a monetary contribution to the

preparation or submission of the brief. The parties received

timely notice of the intent of amicus curiae to file this brief.

The NAM has grave concerns about Boulder’s and

similar state and local governments’ attempts to impose state law liability over the worldwide production,

sale, and promotion of energy products. As the Court

found in American Electric Power Co. v. Connecticut,

564 U.S. 410 (2011), climate litigation implicates federal law and complex policymaking. State law claims,

no matter how pleaded, cannot achieve these goals

and are not the appropriate mechanism for deciding

these critical national issues. For these reasons, the

NAM has a substantial interest in attempts by Respondent and local governments to subject its members to unprincipled state liability for harms associated with climate change and impose these costs on

American manufacturers generally, particularly

when doing so will not meaningfully address climate

change and will harm their ability to compete in the

international marketplace.

INTRODUCTION AND

SUMMARY OF ARGUMENT

This lawsuit is part of a coordinated, national litigation campaign over global climate change that is invoking state liability law to impose a worldwide penalty on the sale of fuels sold by certain entities. These

claims have been filed in chosen jurisdictions, packaged to appeal to parochial interests of state courts by

invoking state law and seeking money for local constituencies, and target companies the plaintiffs want

to blame for global climate change. Some courts, led

by the U.S. Court of Appeals for the Second Circuit,

have held that no state law has this reach. Others, including the Colorado Supreme Court, have welcomed

this litigation. The split is deep and significant.

Of additional importance, this case—and the litigation generally—is an unapologetic effort to circumvent this Court’s ruling in American Electric Power

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

“AEP”). In AEP, the Court already addressed litigation over climate change, holding unanimously that

lawsuits over impacts of greenhouse gas (“GHG”)

emissions on the climate “require federal law governance” because of the interstate and international nature of GHGs. Id. at 422. It also held Congress displaced any federal claims in enacting the Clean Air

Act and delegating governance over GHGs to the Environmental Protection Agency (“EPA”). See id. at

424. Given the clarity of this ruling, the Ninth and

Fifth Circuits dismissed climate suits in their courts

even though the cases were brought under state and

federal legal theories, named different types of energy

companies, and sought other remedies including damages and abatement. See Native Village of Kivalina v.

ExxonMobil Corp., 696 F.3d 849 (9th Cir. 2012) and

Comer v. Murphy Oil USA, Inc., 718 F.3d 460 (5th Cir.

2013). The law was settled; there was no “parallel

track” of tort litigation. AEP, 564 U.S. at 425.2

Nevertheless, since 2017, the City and County of

Boulder are among three-dozen local and state governments that have filed comparable climate-related

claims. The lawsuits have been reframed to look different from AEP but have the same national effect.

They invoke state laws, target other aspects of the fuel

industry, and name various combinations of companies—all to find courts that will not apply AEP to

2 The Court reaffirmed AEP in West Virginia v. Environmental

Prot. Agency, 597 U.S. 697, 730-31 (2022); see also id. at 771 (Kagan, J., dissenting).

dismiss the claims. The inescapable fact, though, is

that regardless of how the claims are packaged, the

overwhelming majority of activities causing climate

change cannot be subjected to any one state’s liability

law. These activities have taken place around the

world for more than two hundred years. The Colorado

Supreme Court recognized this fact but allowed the

claims to proceed anyway.

In doing so, the Colorado Supreme Court acknowledged it was directly contradicting the Second Circuit’s holding in New York City’s climate case. See

City of New York v. Chevron Corp., 993 F.3d 81 (2d

Cir. 2021). There, the Second Circuit held climate litigation presents a “sprawling case [that] is simply beyond the limits” of state liability law. Id. at 92. It also

saw through the post-AEP veneer, stating, “[a]rtful

pleading cannot transform the City’s complaint into

anything other than a suit over global greenhouse gas

emissions.” Id. And, this Court already held in AEP

that when it comes to GHG emissions, “borrowing the

law of a particular State would be inappropriate.”

AEP, 564 U.S. at 422. No state can reach outside its

boundaries to determine the rights and responsibilities for global climate change, including who is to

blame and how much they should have to pay. Indeed,

twenty U.S. states have filed briefs opposing this litigation campaign because it infringes on their state’s

sovereignty and hampers their ability to make decisions about these issues within their borders.3

This litigation campaign is highly divisive. With

comparable lawsuits proliferating around the country,

3 See Bill of Complaint, Alabama v. California, No. 158 (Origi-

nal) (U.S., filed May 22, 2024).

the Court should not wait any longer before intervening to reinforce that state law cannot govern claims

over global GHG emissions, irrespective of which activities leading to GHG emissions are targeted and

where in the world they took place. For these reasons,

as detailed below, amicus respectfully requests that

the Court grant the Petition.

ARGUMENT

THE COURT SHOULD NOT ALLOW

STATES TO CIRCUMVENT ITS RULING

IN AEP THAT CLIMATE CHANGE

CLAIMS INVOKE A “SPECIAL

FEDERAL INTEREST”

AEP was the first major case seeking to impose liability over GHG emissions and climate change. The

targets for the litigation were utilities that generated

electricity for much of America. Three lawsuits followed, each testing other ways climate litigation could

be framed. In California v. General Motors Corp., California sued auto manufacturers for making products

that emit GHGs. See No. C06-05755 MJJ, 2007 WL

2726871 (N.D. Cal. Sept. 17, 2007). In Kivalina, a village sued oil and gas producers for damages related to

rising sea levels. See 696 F.3d at 849. As here, the village alleged the defendants were “substantial contributors to global warming” in part caused by

“conspir[ing] to mislead the public about the science

of global warming.” Id. at 854. In Comer, Mississippi

residents filed a class action against energy producers

for Hurricane Katrina losses, arguing defendants

caused emissions that made the hurricane more intense. See 718 F.3d at 460.

The underpinnings of all four cases are the same

as those here: climate change is caused by GHG emissions, including global fuel use. See AEP, 564 U.S. at

416. The emissions have accumulated in the atmosphere for more than 150 years and have caused impacts on the Earth. The defendants are in violation of

federal or state liability law based on the way they are

contributing to GHG emissions through their products, operations, or other activities. See id. at 418

(pleading state tort law in the alternative). Therefore,

the defendants are responsible for climate change and

its impacts, and the governments are entitled to the

remedies under their chosen causes of action. See id.

In AEP, the Obama administration’s brief to the

Court underscored the legal deficiencies with allowing

any entity to be liable for climate change, explaining

that claims over GHG emissions are inherently subjective and unprincipled. It stated that there are “almost unimaginably broad categories of both potential

plaintiffs and potential defendants.” Brief for the Tennessee Valley Authority, American Electric Power Co.

v. Connecticut, No. 10-174 (U.S., filed Jan. 31, 2011).

The “[p]laintiffs have elected to sue a handful of defendants from among an almost limitless array of entities that emit greenhouse gases. Moreover, the types

of injuries that [the] plaintiffs seek to redress, even if

concrete, could potentially be suffered by virtually any

landowner, and to an extent, by virtually every person.” Id. at 15. It is “impossible to consider the sort of

focused and more geographically proximate effects”

characteristic of U.S. liability law. Id. at 17.

This Court then unanimously held that Congress,

in enacting the Clean Air Act, displaced any federal

common law cause of action, thereby extinguishing

the viability of these GHG claims. Its reasoning

demonstrates why claims, including those here, over

global climate change cannot be adjudicated under

any state’s law. First, as the Court held in United

States v. Standard Oil Co. of California, certain

claims invoke the “interests, powers and relations of

the Federal Government as to require uniform national disposition rather than diversified state rulings.” 332 U.S. 301, 307 (1947). And, in Illinois v. City

of Milwaukee, it stated that “air and water in their

ambient or interstate aspects” are among those areas

of law where “the basic scheme of the Constitution”

demands that they are governed by federal law. 406

U.S. 91, 103 (1972). Accordingly, the Court stated in

AEP, determining rights and responsibilities for interstate and international GHG emissions are inherently

matters of “special federal interest.” 564 U.S. at 424.

Second, the Court expressed concern about allowing judges to make determinations and impose remedies over these national public policy matters given

the institutional limitations on the tools judges have

available to them. See id. at 428. To adjudicate these

claims, courts would have to regulate GHG emissions

from defendants’ products and conduct “by judicial decree” and on an “ad hoc, case-by-case” basis. Id. at 427,

428. “The appropriate amount of regulation in any

particular greenhouse gas-producing sector cannot be

prescribed in a vacuum: as with other questions of national or international policy, informed assessment of

competing interests is required.” Id. at 427. Courts do

not have the ability to weigh these extrajudicial factors; they can decide only legal disputes on the evidence presented.

Given the Court’s clear direction against this type

of litigation on legal and policy grounds, courts dismissed the remaining climate cases. In Kivalina, the

Ninth Circuit stated that even though the parties,

theories of liability, and remedies differed from AEP,

given the Court’s broad message against climate liability, “it would be incongruous to allow [such litigation] to be revived in another form.” 696 F.3d at 857.

It appreciated that climate suits are the type of “transboundary pollution” claims the Constitution exclusively commits to federal law. Id. at 855. This is true

regardless of how the suits are framed—over energy

use or products, by public or private plaintiffs, under

federal or state law, or for injunctive relief, abatement, or damages. In Comer, a judge held that under

AEP the state law claims were preempted. See 839 F.

Supp. 2d 849 (S.D. Miss. 2012).

Thus, the law is clear: claims over GHG emissions

and climate change are governed exclusively by federal law and the Clean Air Act. The Court should

grant the Petition so Boulder cannot skirt this jurisprudence merely by painting these federal public policy matters with a state liability law brush.

II. REPACKAGING CLAIMS FROM AEP

DOES NOT CHANGE THE FACT THAT

TODAY’S CLIMATE LITIGATION SEEKS

TO REGULATE INTERSTATE AND INTERNATIONAL EMISSIONS

After AEP, the climate litigation campaign was retooled to appear different from AEP but have the same

effect of regulating interstate and international GHG

emissions from the use of certain fuels. See Establishing Accountability for Climate Damages: Lessons from

Tobacco Control, Summary of the Workshop on

Climate Accountability, Public Opinion, and Legal

Strategies, Union of Concerned Scientists & Climate

Accountability Inst. (Oct. 2012), at 28.4 Rather than

asking a court to directly regulate emissions or put a

price on carbon, the campaign would ask for state tort

damages and statutory penalties. See id. at 13 (“Even

if your ultimate goal [is] to shut down a company, you

still might be wise to start out by asking for compensation for injured parties.”).

Indeed, the lawyers and other advocates orchestrating this litigation have acknowledged outside of

court that the desired effect of the litigation is to impose costs on consumers for the worldwide production,

promotion, sale and use of fuel—what they call its

“true cost.” Kirk Herbertson, Oil Companies vs. Citizens: The Battle Begins Over Who Will Pay Climate

Costs, EarthRights Int’l, Mar. 21, 2018. They want to

force energy companies to raise the price of fuel so “if

they are continuing to sell fossil fuels, that the cost of

[climate change] would ultimately get priced into

them.” Julia Caulfield, Local Lawsuits Asks Oil and

Gas to Help Pay for Climate Change, KOTO, Dec. 14,

2020.5 Some have referred to this dynamic as market

force regulation. They believe “companies are agents

of consumers,” so “holding oil companies responsible is to hold oil consumers responsible.” Jerry Taylor

& David Bookbinder, Oil Companies Should be Held

4_https://www.ucs.org/sites/default/files/attach/2016/04/estab-

lishing-accountability-climate-change-damages-lessons-tobaccocontrol.pdf.

5 https://coloradosun.com/2021/02/01/boulder-climate-lawsuit-

opinion/.

Accountable for Climate Change, Niskanen Ctr., Apr.

17, 2018.6

To mask these goals and make this litigation more

politically palatable, they have partnered with state

and local governments to seek this monetary penalty

to deal with local impacts of climate change. The governments, as here, often disclaim any attempt to regulate or put costs on emissions; they say they just

want money to deal with impacts of climate change in

their jurisdictions. However, artful pleading and disclaimers cannot hide the true federal, public policy nature of this litigation. The lawsuits are being funded

by national and international non-profits because the

litigation would impact federal energy policy. See, e.g.,

City of Hoboken Press Release, Hoboken Becomes

First NJ City to Sue Big Oil Companies, American Petroleum Institute for Climate Change Damages, Sept.

2, 2020 (noting legal fees would be paid by the Institute for Governance and Sustainable Development).7

One jurist poignantly stated that the governments

and backers of this litigation are waging what is truly

a federal energy dispute “through the surrogate of a

private party as the defendant.” Minnesota v.

6 A reporter who follows the litigation has observed the incongru-

ity between the ways the cases are presented in and out of court:

“State and local governments pursuing the litigation argue that

the cases are not about controlling GHG emissions . . . But they

also privately acknowledge that the suits are a tactic to pressure

the industry.” Dawn Reeves, As Climate Suits Keeps Issue Alive,

Nuisance Cases Reach Key Venue Rulings, Inside EPA, Jan. 6,

2020, at https://insideepa.com/outlook/climate-suits-keeps-issuealive-nuisance-cases-reach-key-venue-rulings.

7_https://www.hobokennj.gov/news/hoboken-sues-exxon-mobil-

american-petroleum-institute-big-oil-companies.

American Petroleum Inst., 63 F.4th 703, 719 (8th Cir.

2023) (Stras, J., concurring). To be clear, this litigation seeks to use state law to penalize national energy

use and direct money from energy consumers across

the country to local governments, unbridled by the

checks and balances of Congress’s legislative process.

This Court has expressed concern that in these situations, some state courts “may reflect ‘local prejudice’

against unpopular federal laws” or defendants. Watson v. Philip Morris Cos., 551 U.S. 142, 150 (2007).

In addition, the groups generating these lawsuits

are engaging in political-style tactics to recruit local

governments to bring these cases and to leverage the

litigation to hinder the energy companies politically.

See Lesley Clark, Why Oil Companies Are Worried

About Climate Lawsuits From Gas States, E&E News,

Nov. 7, 2023 (quoting a leader of this effort: “It’s no

secret that we go around and talk to elected officials”

about bringing these lawsuits and “look at the politics” in deciding whom to approach); see generally Beyond the Courtroom, Manufacturers’ Accountability

Project (detailing this litigation campaign).8

Overall, three dozen of these suits have been filed

in carefully chosen jurisdictions in an effort to “sidestep federal courts and [U.S.] Supreme Court precedent” and convince local courts to help them advance

their preferred public policy agenda by awarding

money to state and local jurisdictions. Editorial, Climate Lawsuits Take a Hit, Wall St. J., May 17, 2021.

8 https://mfgaccountabilityproject.org/beyond-the-courtroom.

III. MERELY PASTING STATE LAW

LABELS ON FEDERAL LAW CLAIMS

SHOULD NOT BE A MEANS FOR

USURPING FEDERAL AUTHORITY

The state-law liability theories in this litigation

are mere fig leaves. Even though the global climaterelated claims here have been reframed under state

law, they present the same central concerns identified

in AEP. Further, the Court’s concerns over institutional deficiencies with judges making federal public

policy decisions on an ad hoc basis are magnified when

individual state judges could reach different determinations without federal oversight or uniformity. Liability against whom for whom and how much would

be unprincipled and would vary from court to court.

Also, the narrative of this litigation—that there is

some widespread “campaign of deception”—is undermined by the litigation itself. The complaints recognize the U.S. Government’s knowledge of and public

discourse over climate change starting in the 1960s

and increasing in the past 40 years. And, the government plaintiffs name anywhere from one to dozens of

defendants, including local entities in an effort to keep

the cases in state court. Here, Boulder seeks to subject

only two companies to liability for its climate change

harms. This ever-changing list of defendants that engage in different aspects of the energy industry highlights the fact that imposing liability on any group of

defendants that a city, state, or other local government chooses to name lacks any principled basis.

Federal courts were the first to assess the validity

of this reframing, with the Second Circuit calling it a

false veneer: “we are told that this is merely a local

spat about the City’s eroding shoreline, which will

have no appreciable effect on national energy or environmental policy. We disagree. Artful pleading cannot

transform the City’s complaint into anything other

than a suit over global greenhouse gas emissions.”

City of New York, 993 F.3d at 91. The court then relied

on AEP and Kivalina to conclude that the specific allegations, legal theories, and remedies sought do not

change the outcome because the claims still seek to

impose liability for GHG emissions. See id. at 96.

The Second Circuit also explained that monetary

remedies have “the same practical effect” of regulating

interstate and international GHG emissions as the injunctive relief sought in AEP. Id. “[A] substantial

damages award like the one requested by the City

would effectively regulate the Producers’ behavior far

beyond New York’s borders.” Id. at 92. “Any actions

the Producers take to mitigate their liability, then,

must undoubtedly take effect across every state (and

country). And all without asking what the laws of

those other states (or countries) require.” Id. Thus,

claims seeking “damages for the cumulative impact of

conduct occurring simultaneously across just about

every jurisdiction on the planet,” are “simply beyond

the limits of state law.” Id. at 92.

The Colorado Supreme Court, in a divided opinion,

deepened the national split on this litigation, acknowledging that the Second Circuit and other state

courts “have addressed similar questions [and] have

reached differing conclusions.” 2025 CO 21, ¶24 (contrasting City and County of Honolulu v. Sunoco LP,

537 P.3d 1173 (Haw. 2023) with City of New York).

The other state courts include those in Delaware,

Maryland, New Jersey, New York, Pennsylvania, and

South Carolina. See Delaware ex rel. Jennings v. BP

America Inc., 2024 WL 98888 (Del. Super. Ct. Jan. 9,

2024); Mayor and City Council of Baltimore v. BP

P.L.C., No. 24-C-18-004219 (Md. Cir. Ct. July 10,

2024); City of Annapolis v. BP PLC, No. C-020CV-21250 (Md. Cir. Ct. Jan. 23, 2025); Platkin v. Exxon Mobil Corp., No. 22-cv-06733 (RK)(JBD), 2023 WL

4086353 (D.N.J. June 20, 2023); City of New York v.

Exxon Mobil Corp., 2025 WL 209843 (N.Y. Sup. Ct.

Jan. 14, 2025); Bucks County v. BP P.L.C., No. 202401836 (Pa. Ct. Comm. Pleas May 16, 2025); City of

Charleston v. Brabham Oil Co., No. 2:20-cv-03579

(D.S.C. July 6, 2023).

In addition, more than half of the states have objected to these climate lawsuits. They have expressed

their concerns that this litigation campaign endangers their rights to adopt “their own divergent policies” with respect to energy production and environmental protection. Amicus Brief of Alabama and 25

Other States in Support of Petitioners, Suncor Energy

(U.S.A.) Inc. v. Cnty. Commissioners of Boulder

County, No. 25-170 (U.S., filed Sept. 26, 2025). Twenty

of them took the extraordinary step of filing a Bill of

Complaint to stop this litigation campaign. See Bill of

Complaint, Alabama v. California, No. 158 (Original)

(U.S., filed May 22, 2024). And the current administration has filed lawsuits in Hawaii and Michigan to

prevent their climate suits as “illegitimate impediments” to national energy policy. Alexa St. John, Justice Department Sues Hawaii, Michigan, Vermont and

New York Over State Climate Actions, Assoc. Press,

May 1, 2025 (quoting U.S. Attorney General Bondi).9

9 https://apnews.com/article/trump-doj-climate-states-policy-

lawsuits-a5228e1dd6348f09d2a70f460142531a.

The Court should grant the Petition to settle this

deep national split now, before more judicial resources

are wasted. There is no need to allow the litigation to

percolate further in the lower courts.

IV. THE COURT SHOULD AFFIRM THAT

CLAIMS ALLEGING HARM FROM

GLOBAL CLIMATE CHANGE RAISE

UNIQUELY FEDERAL INTERESTS

In allowing the reframing of this litigation, the

Colorado Supreme Court’s ruling has created multiple

issues that this Court can address in this litigation.

These issues, each of which would be dispositive, are

significant, recurring, and divisive. And, they all

speak to why these cases cannot arise under state law.

(1) The litigation seeks to turn federal interests related to GHG emissions into state law matters by reframing the case on an underlying conduct or product.

This issue goes to the heart of this litigation campaign. As discussed above, the Court in AEP made

clear that determining matters related to GHG emissions is of special federal interest. See 564 U.S. at 424.

So, plaintiffs here and in the other cases reframed

their legal theories to target products and conduct

that contribute to GHG emissions, not emissions

themselves. The Supreme Court of Colorado joined

the Supreme Court of Hawaii in accepting this reframing, asserting Boulder “has not brought an action

against a pollution emitter to abate pollution. Rather,

it seeks damages from upstream producers for harms

stemming from the production and sale of fossil fuels.”

2025 CO 21, ¶50 (emphasis added).

This statement directly conflicts with the Ninth

Circuit’s ruling in Kivalina and the Second Circuit in

City of New York that imposing liability against upstream producers is a difference without a legal distinction. The Second Circuit explained: “focus[ing] on

[an] ‘earlier moment’ in the global warming lifecycle”

“cannot transform [the lawsuit] into anything other

than a suit over global greenhouse gas emissions.”

City of New York, 993 F.3d at 91, 97. Plaintiffs cannot

“have it both ways”: “disavowing any intent to address

emissions” while “identifying such emissions as the

singular source” of the harm they allege. Id. at 91.

If this reframing is allowed, plaintiffs could sue

over the GHG emissions through the back door. As

here, they would seek liability for climate change by

targeting some aspect of the defendants’ products or

conduct that they claim exacerbated GHG emissions.

The Court should grant review to clarify that allegations based on harms caused by GHG emissions arise

under federal law.

(2) The litigation seeks to regulate through monetary liability what this Court has held cannot be regulated through injunctive relief.

The Court should also grant the Petition to determine whether changing the remedy sought from injunctive relief to monetary recovery creates a legal

distinction allowing states to impose liability over federal law issues. In AEP, the Court held that determining appropriate GHG emissions is a regulatory, not liability matter. There, the states sought injunctive relief over GHG emissions; here Boulder seeks money

over GHG emissions. The Colorado Supreme Court allowed this distinction: “Boulder does not, however,

seek to enjoin any oil and gas operations or sales in

Colorado or elsewhere. Nor does it seek to enforce

emissions controls of any kind.” 2025 CO 21, ¶10.

This Court, however, has long held that monetary

liability is a form of regulation; it is “a potent method

of governing conduct and controlling policy.” San Diego Bldg. Trades Council v. Garmon, 359 U.S. 236,

247 (1959). A core tenet of liability is to define conduct

that is unlawful, require defendants to compensate

those harmed by that unlawful conduct, and instruct

defendants and others not to engage in any such unlawful conduct. Here, “[i]f the Producers want to avoid

all liability, then their only solution would be to cease

global production altogether.” City of New York, 993

F.3d at 93.

Instead, as discussed above, the goal and effect of

this litigation is to use liability to reduce emissions.

They want to force “companies to raise the price of the

energy they don’t like, like fossil fuel energy, [and]

make it too expensive for people and businesses thus

decreasing the amount used.” Danielle Zanzalari,

Government Lawsuits Threaten Consumers’ Pockets

and Do Little to Help the Environment, USA Today,

Nov. 1, 2023. Some people may consider increasing

costs of these fuels the appropriate climate policy, but

it is not the role of state courts to impose it. Deciding

whether to impose these costs, how much, and where

the money should be spent involves the same type of

“complex balancing” of competing interests this Court

identified in AEP, including energy affordability, economic impacts of raising energy costs, and national

energy security, among others. 564 U.S. at 427. The

Court should grant the Petition to settle this dispute.

(3) This litigation violates constitutional limits on

state authority by allowing each state to govern, and

impose liability on, out-of-state GHG emissions and

conduct wherever they occur in the world.

Boulder is seeking to impose Colorado liability law

on Defendants’ production, promotion, sale and use of

energy wherever in the world they took place—even

though the vast majority of conduct it alleges caused

its injuries occurred outside of Colorado, has no nexus

to Colorado, and is not subject to Colorado law. There

is no escaping the fact that global climate change is

not the result of emissions from Defendants’ products

in Colorado. The U.S. Constitution does not permit a

state to govern, let alone impose liability on, conduct

or products in other states and countries without such

a nexus. That is why interstate pollution cases either

require the application of the source state law or arise

under federal law and are decided in federal courts.

By allowing Boulder’s claims to target products that

led to GHG emissions—not the emissions themselves—the Colorado Supreme Court is refusing to be

constrained by its constitutional boundaries.

These limits are so clear that President Biden’s Solicitor General, who opposed certiorari in Honolulu’s

climate case, appreciated that these climate-related

claims may ultimately be foreclosed by the U.S. Constitution “to the extent they are based on emissions or

other conduct outside of” the state. Brief for the

United States as Amicus Curiae, Sunoco LP v. City

and County of Honolulu, Nos. 23-947, 23-952, 2024

WL 5095299, at *7 (U.S., filed Dec. 10, 2024). She

specified that “the Interstate and Foreign Commerce

Clause, the Due Process Clause, and federal constitutional structure” may bar such claims. Id. at *13.

For this reason, a Delaware court limited that

state’s climate change case to only those emissions in

Delaware. See Delaware ex rel. Jennings, 2024 WL

98888, at *9. In a telling response, Delaware moved

for partial final judgment, stating it had no interest in

litigating a case based “solely [on] in-state emissions.”

Pl.’s Mot. For Entry of Partial Judgment Pursuant to

Rule 54(b), Delaware v. BP Am., Inc., C.A. No. N20-C09-097 (Del. Super. Ct. Oct. 21, 2024). The State affirmed that it was seeking relief for conduct that “occurred in and outside of Delaware and that increased

emissions in and outside of Delaware.” Id.

The Court should grant the Petition to resolve this

dispute over whether each state can impose its

“own climate standards” on other states. Bill

Schuette, Energy, Climate Policy Should be Guided by

Federal Laws, Congress, Not a Chaotic Patchwork of

State Laws, Law.com, Apr. 25, 2024 (Schuette was

Michigan Attorney General from 2011-2019). Allowing the Colorado ruling to stand would result in “a

chaotic mix of state approaches [that] risks interfering

with an effective, unified process to solve the climate

problems the plaintiffs seek to abate.” Donald Kochan,

Supreme Court Should Prevent Flood of State Climate

Change Torts, Bloomberg Law, May 20, 2024.

(4) The litigation is based on the illogical assertion

that when Congress displaces a federal cause of action

that would have governed an interstate dispute, a state

may now impose its own law to that interstate dispute.

One of the most perplexing disputes permeating

this litigation is the impact this Court’s ruling in AEP,

that Congress displaced federal common law over interstate GHG emissions, has on the ability of states to

impose their own law on out-of-state emissions.

In AEP, the Court held that climate litigation (like

all interstate and international pollution cases) is governed by federal law and, if a cause of action is

allowed, the dispute would be determined by federal

common law. However, the Court continued that

when Congress gave the EPA the authority to make

determinations with respect to interstate GHG emissions in the Clean Air Act, it displaced such federal

causes of action. Plaintiffs’ contention is that the

Court’s displacement ruling means that disputes over

interstate GHG emissions, which required federal law

governance and have been assigned to the EPA, can

now suddenly be decided by any state.

The Second Circuit called this theory “too strange

to seriously contemplate.” City of New York, 993 F.3d

at 99. It said this “position is difficult to square with

the fact that federal common law governed this issue

in the first place” because “where ‘federal common law

exists, it is because state law cannot be used.’” Id. at

98 (quoting City of Milwaukee v. Illinois, 451 U.S. 304,

313 n.7 (1981)). “[S]tate law does not suddenly become

presumptively competent to address issues because

Congress saw fit to displace a federal court-made

standard with a legislative one.” Id. The Court should

grant the Petition to settle this split in authority over

this strained interpretation of state law jurisdiction.

(5) This litigation misinterprets AEP that the availability of a state lawsuit over GHG emissions depends

on the “preemptive effect” of the Clean Air Act as discarding the constitutional limits that bar states from

imposing their own laws on out-of-state emissions.

The Court should also grant the Petition to clarify

its statement in AEP that the “availability vel non of

a state lawsuit depends, inter alia, on the preemptive

effect” of the Clean Air Act. 564 U.S. at 429. This

statement has caused substantial confusion.

The Supreme Courts of Colorado and Hawaii,

among others, have misread this statement to suggest

that Congress must have preempted the application of

their state’s law to out-of-state emissions in the Clean

Air Act or such claims are now viable. These courts,

though, ignore the parenthetical following this statement, which properly cabined the availability of state

law in these cases to those potentially allowed by the

U.S. Constitution. Specifically, the Court cited to International Paper Co. v. Ouellette, 479 U.S. 481, 489,

491, 497 (1987) for the proposition that courts should

look to the federal statute to see if it precluded “aggrieved individuals from bringing a ‘nuisance claim

pursuant to the law of the source State.’” AEP, 564

U.S. at 429 (emphasis in original). The Court in AEP

did not, in any way, authorize applying Colorado law

to GHG emissions in other states and countries.

Further, the dissent below states that “the appropriate inquiry with respect to the interstate aspect of

Boulder’s claims is whether the CAA affirmatively authorizes” Colorado to apply its law to out-of-state

emissions. 2025 CO 21, ¶78 (Samour, J., dissenting).

When a question is “previously governed by federal

common law,” state law “is permissible only to the extent authorized by federal statute.” City of New York,

993 F.3d at 99 (cleaned up). Here, the Clean Air Act

permits only those actions brought under law of the

source state and these cases do not proceed under this

“slim reservoir of state common law.” Id. at 100.

Finally, the Court should not be dissuaded from

granting the Petition based on the arguments made in

Honolulu that the court lacks jurisdiction to review

the decision below under 28 U.S.C. 1257(a)’s final

judgment rule. This Court has jurisdiction for the

reasons stated in the Petition and Solicitor General’s

brief. In addition, giving into this argument would allow the lawyers and advocates behind this litigation

campaign to continue gaming the U.S. legal system.

Their game plan is now clear. File cases in multiple

states where they believe the legal climate is favorable to them, do not appeal their losses where they are

not confident in the appellate courts (see, e.g., the Second Circuit ruling, the second New York City case,

and the trial court dismissal in Charleston), and argue

this and other high courts have no jurisdiction over

their wins so they can avoid meaningful review.

***

Ultimately, amicus believes the best way to address the impact of energy on the climate is for federal

and local governments to work with manufacturers

and others to develop public policies and technologies

that can reduce emissions and mitigate damages. See

Ross Eisenberg, Forget the Green New Deal. Let’s Get

to Work on a Real Climate Bill, Politico, Mar. 27, 2019.

CONCLUSION

For these reasons, amicus curiae respectfully requests that this Court grant the Petition and determine that the state law claims are not viable.

Respectfully submitted,