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

Supreme Court briefSep 15, 2025

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Text

No. 25-170

IN THE

Supreme Court of the United States

————

SUNCOR ENERGY (U.S.A.) INC.; SUNCOR ENERGY

SALES INC.; EXXON MOBILE CORPORATION,

Petitioners,

COUNTY COMMISSIONERS OF BOULDER COUNTY;

CITY OF BOULDER,

Respondents.

————

On Petition for a Writ of Certiorari to the

Supreme Court of Colorado

————

BRIEF FOR THE AMERICAN PETROLEUM

INSTITUTE AS AMICUS CURIAE

IN SUPPORT OF PETITIONERS

————

MARK A. PERRY

Counsel of Record

WEIL, GOTSHAL & MANGES LLP

2001 M Street NW

Suite 600

Washington, DC 20036

(202) 682-7000

mark.perry@weil.com

Counsel for Amicus Curiae

American Petroleum Institute

September 15, 2025

WILSON-EPES PRINTING CO., INC. – (202) 789-0096 – WASHINGTON, D.C. 20002

TABLE OF CONTENTS

Page

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

INTERESTS OF THE AMICUS CURIAE .........

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

ARGUMENT ........................................................

I. The essence of Respondents’ action is to

seek redress for alleged injuries arising

from global climate change and to

regulate emissions ....................................

II. The regulation of interstate emissions is

an inherently federal domain ...................

III. Allowing Boulder’s claims to proceed

would have the effect of interfering with

federal regulation of emissions and

setting back the energy transition ...........

CONCLUSION ....................................................

(i)

TABLE OF AUTHORITIES

CASES

Page(s)

Am. Ins. Ass’n v. Garamendi,

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

American Electric Power Co. v. Connecticut,

564 U.S. 410 (2011) ........................... 4, 9, 10, 13

Anne Arundel Cty. v. BP p.l.c.,

No. C-02-CV-21-000565 (Md. Cir. Ct.) .....

Bucks County v. BP p.l.c.,

No. 2024-01836-0000 (Pa. Commw. Ct.).......

California v. Exxon Mobil Corp.,

No. CGC23609134 (Cal. Super. Ct.) .........

Cal. ex rel. Herrera v. BP p.l.c.,

No. CGC-17-561370 (Cal. Super. Ct.) ......

Cal. ex rel. Oakland City Att’y v. BP p.l.c.,

No. RG17875889 (Cal. Super. Ct.) ...........

City and County of Honolulu v. Sunoco LP,

No. CAAP-22-0000429 (Haw. Ct. App.) ........

City and County of Honolulu v.

Chevron Corp.

No. CAAP-22-0000135 (Haw. Ct. App.) ........

City of Annapolis v. BP p.l.c.,

No. C-02-CV-21-000250 (Md. Cir. Ct.) .....

City of Charleston v. Brabham Oil Co.,

No. 2020CP1003975 (S.C. Ct. Com.) ........

City of Chicago v. BP p.l.c.,

No. 2024CH01024 (Ill. Cir. Ct.) ................

City of Hoboken v. Exxon Mobil Corp.,

No. HUD-L-003179-20 (N.J. Super.) ........ 15-16

iii

TABLE OF AUTHORITIES—Continued

Page(s)

City of Imperial Beach v. Chevron Corp.,

No. C17-01227 (Cal. Super. Ct.) ...............

City of Milwaukee v. Illinois & Michigan,

451 U.S. 304 (1981) ................................... 5, 10

City of New York v. Chevron Corp.,

993 F.3d 81 (2d Cir. 2021) ................ 4, 8, 10, 19

City of Richmond v. Chevron Corp.,

No. C18-00055 (Cal. Super. Ct.) ...............

City of Santa Cruz v. Chevron Corp.,

No. 17CV03243 (Cal. Super. Ct.) .............

Cnty. of Marin v. Chevron Corp.,

No. CIV1702586 (Cal. Super. Ct.) ............

Cnty. of Multnomah v. Exxon Mobil Corp.,

No. 23CV25164 (Or. Cir. Ct.) ...................

Cnty. of San Mateo v. Chevron Corp.,

No. 17CIV03222 (Cal. Super. Ct.) ............

Cnty. of Santa Cruz v. Chevron Corp.,

No. 17CV03242 (Cal. Super. Ct.) .............

Connecticut v. Exxon Mobil Corp.,

No. HHDCV206132568S (Conn. Super.

Ct.) .............................................................

Delaware ex rel. Jennings v.

BP America Inc.,

No. N20C-09-097, 2024 WL 98888

(Del. Super. Ct. Jan. 9, 2024), appeal

refused, No. 54, 2024 (Del. May 8, 2024) . 1, 16

TABLE OF AUTHORITIES—Continued

Page(s)

Estado Libre Asociado de Puerto Rico v.

Exxon Mobil Corp.,

No. SJ2024CV06512 (P.R. TPI) .....................

Illinois v. City of Milwaukee,

406 U.S. 91 (1972) .................................. 4, 10-12

Illinois v. City of Milwaukee,

731 F.2d 403 (7th Cir. 1984),

cert. denied, 469 U.S. 1196 (1985) ...........

Int’l Paper Co. v. Ouellette,

479 U.S. 481 (1987) ....................... 10, 11, 14, 16

Leon v. Exxon Mobil Corp.,

No. 25-2-15986-8 (Wash. Super. Ct.) .......

Makah Indian Tribe v. Exxon Mobil Corp.,

No. 23-2-25216-1 (Wash. Super. Ct.) .......

Mayor & City Council of Balt. v. BP p.l.c.,

No. 24-C-18-004219 (Md. Cir. Ct.) ...........

Minnesota v. American Petroleum Institute,

No. 62-CV-20-3837, 2025 WL 562630

(Minn. Dist. Ct. Feb. 14, 2015), appeal

docketed on other grounds, No. A250407 (Minn. Ct. App.) ............................... 1, 16

Platkin v. Exxon Mobil Corp.,

No. MER-L-001797-22 (N.J. Super. Ct.) ..

TABLE OF AUTHORITIES—Continued

COURT FILINGS

Page(s)

Rhode Island v. Chevron Corp.,

No. PC-2018-4716 (R.I. Super. Ct.) ..........

State of Texas v. Pankey,

441 F.2d 236 (10th Cir. 1971) ............. 10, 11, 13

West Virginia v. Env’t Prot. Agency,

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

Compl., Cnty. of Multnomah v. Exxon Mobil

Corp, No. 23CV25164 (Or. Cir. Ct. June

22, 2023) ....................................................

NON-PERIODICAL PUBLICATIONS

Energy’s Vital Role in World War II Offers

Lessons For Today, Am. Oil & Gas Rptr.

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ay ...............................................................

Europe and the U.S. Make Ambitious Plans

to Reduce Reliance on Russian Gas, The

New York Times, March 22, 2022,

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iness/energy-environment/biden-eu-liqu

efied-natural-gas-deal-russia.html (last

visited September 2, 2025) .......................

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s/2022-11/1949-National_Oil_Policy_for_

United_States.pdf (last visited September

3, 2025) ......................................................

TABLE OF AUTHORITIES—Continued

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PBS News Hour, California Sues Oil

Companies for Exacerbating Climate

Change (Sept. 20, 2023), https://www.

pbs.org/video/suing-big-oil-1695235855/

(last visited September 3, 2025) ...............

U.S. Dep’t Energy Info. Admin., Natural

gas explained, https://www.eia.gov/energ

yexplained/natural-gas/ (last visited

September 3, 2025) ...................................

U.S. Dep’t Energy Info. Admin., Use of

energy explained, https://www.eia.gov/en

ergyexplained/use-of-energy/ (last visited

September 10, 2025) ................................. 17, 18

U.S. Dep't of Agric., Impacts of Higher

Energy Prices on Agriculture and Rural

Economies (Aug. 18, 2011), https://ers.us

da.gov/sites/default/files/_laserfiche/publ

ications/44894/6806_err123_reportsum

mary.pdf (last visited September 3, 2025)

...................................................................

U.S. Dep’t of Energy, U.S. Oil and Natural

Gas: Providing Energy Security and

Supporting Our Quality of Life (Sept.

2020), https://www.energy.gov/fecm/artic

les/us-oil-and-natural-gas-providingenergy-security-and-supporting-ourquality-life (last visited September 3,

2025) ..........................................................

vii

TABLE OF AUTHORITIES—Continued

Page(s)

U.S. Dep’t of Transp., Bureau of Transp.

Stats., Inflation and Transportation,

https://data.bts.gov/stories/s/Transportat

ion-an d-Inflation/f9jm-cqwe/ (last visited

September 3, 2025) ...................................

U.S. Environmental Protection Agency,

Sources of Greenhouse Gas Emissions, ,

https://www.epa.gov/ghgemissions/sourc

es-green

house-gas-emissions

(last

visited September 3, 2025) .......................

What are the trends in greenhouse gas

emissions and concentrations and their

impacts on human health and the

environment?,

U.S

Environmental

Protection Agency, https://www.epa.gov/r

eport-environment/greenhouse-gases#:~:

text=Greenhouse%20gases%2C%20such

%20as%20carbon%20dioxide%2C%20me

thane%2C,received%20from%20the%20s

un%20and%20emitted%20from

(last

visited September 3, 2025) .......................

OTHER AUTHORITIES

Exec. Order No. 14,260 (Apr. 8, 2025) .........

Restatement (Second) of Torts (1979) .........

INTERESTS OF THE AMICUS CURIAE1

The American Petroleum Institute (“API”) is a

nationwide, non-profit trade association that represents

approximately 600 companies involved in every aspect

of the petroleum and natural-gas industry. Its members

range from the largest integrated companies to the

smallest independent oil and gas producers. API’s

members include producers, refiners, suppliers, marketers, pipeline operators, and marine transporters, as

well as service and supply companies that support the

industry. API is also the worldwide leading body for

establishing standards that govern the oil and

natural-gas industry.

This case is one of many that have been brought

against petroleum and natural-gas companies at the

state and local level. Many of the plaintiffs are

represented by the same counsel. Although API is not

a party to this case, state and local plaintiffs are

pursuing API as a defendant in other cases,

contending that API’s exercise of its First Amendment

rights to advocate for its members and petition the

government is a basis for tort liability. See, e.g.,

Minnesota v. Am. Petroleum Inst., No. 62-CV-20-3837,

2025 WL 562630 (Minn. Dist. Ct. Feb. 14, 2025), appeal

docketed on other grounds, No. A25-0407 (Minn. Ct.

App.); Delaware ex rel. Jennings v. BP Am. Inc., No.

N20C-09-097, 2024 WL 98888 (Del. Super. Ct. Jan. 9,

2024), appeal refused, No. 54, 2024 (Del. May 8, 2024).

Pursuant to Supreme Court Rule 37.2, ten days before this

brief was due, amicus notified counsel of record for the parties of

its intention to file this brief. Pursuant to Supreme Court Rule

37.6, amicus state that no counsel for a party authored this brief

in whole or in part and that no person other than amicus, their

members, or their counsel made any monetary contributions

intended to fund the preparation or submission of this brief.

This case will have broad implications for the entire

petroleum and natural-gas industry, and thus API has

a concrete stake in ensuring that plaintiffs are not

permitted to misuse state tort law to target its members.

Broadly speaking, these suits are an attempt to

remedy the effects of global climate change at the state

and local level. Although Respondents’ complaint

purportedly focuses only on the marketing, sale, and

production of fossil fuels, there is no doubt that this

case necessarily revolves around the effects of interstate greenhouse gas emissions. Interstate emissions

have long been governed exclusively by federal law

because they occupy an inherently federal domain that

states do not have the authority to regulate. The

strained reasoning of the decision below that held

Respondents could advance state-law claims is contrary to a century of this Court’s precedent, and it

should be rejected.

Furthermore, if Respondents’ claims were to

succeed, the results would be disastrous, both for the

energy industry and for any serious effort to address

climate change. API has advocated for considered and

evidence-based policies at the national level that

support research and the ongoing transition to cleaner

energy sources. API knows well that to execute this

transition, policymakers must strike a delicate

balance between reducing greenhouse gas emissions

and maintaining the consistent energy supply on

which the world economy depends.

Respondents’ suit strikes no such balance; to the

contrary, it merely seeks to recover monetary damages

for a city and the surrounding county, while leaving

the work of reducing greenhouse gas emissions to

others. Indeed, Respondents’ suit will make it more

difficult to address climate change at the national level,

because it will invite a patchwork of conflicting

judgments in 50 states, rather than one uniform

standard for the nation.

This suit and similar litigation would also have

impacts beyond the law. Ad hoc sanctioning and

regulation of energy companies will destabilize the

whole sector. API is uniquely situated to explain the

likely effects on the energy sector and the world

economy if billion-dollar judgments pile up and the

threat of future liability under varying state-court

judgments undercuts American energy production. As

API explains below, even small changes to costs and

prices in the energy industry can have ripple effects

throughout the world economy. This Court should stop

these suits in their tracks and allow national

policymakers to address the nationwide issue of

greenhouse gas emissions.

SUMMARY OF ARGUMENT

The Colorado Supreme Court erred in ruling that

Respondents could bring state tort claims to remedy

alleged injuries caused by global climate change. For

over a century, this Court has held that interstate air

and water pollution are inherently federal domains.

Claims alleging that out-of-state emissions caused

injury within a state have always been governed by

federal law. Yet the decision below found that the

Clean Air Act (“CAA”) somehow revived state law

claims that never existed. This was error, and the

overwhelming weight of this Court’s precedent precludes Respondents’ claims. Furthermore, if Respondents

were to succeed on their claims, they would impair

federal efforts to address climate change by creating a

patchwork of different standards and inconsistent

judgments regulating the same underlying conduct.

Respondents’ suit is not a workable means by which to

address climate change, and it would instead unleash

chaos in sectors vital to the American economy.

As an initial matter, Respondents’ framing of their

claims as related only to the marketing, sale, and

production of fossil fuels—rather than the emission of

the greenhouse gases itself—should be rejected.

Respondents’ framing is an attempt to plead around

the exclusivity of federal law. Respondents know that

matters related to air emissions are exclusively

governed by federal law, and that they cannot openly

base their claims on the emission of greenhouse gases.

But all of Respondents’ alleged injuries were

manifestly caused by global climate change, which is

itself caused largely by the emission of greenhouse

gases. To the extent Petitioners’ “upstream” marketing,

sale, and production of fossil fuels are causal at all, they

are twice-removed from Respondents’ alleged injury.

The complaint’s focus on a narrow set of remote

activities is not credible, and it is clear the

Respondents seek to recover for the effects of

interstate greenhouse gas emissions. As the Second

Circuit held in City of New York v. Chevron Corp., 993

F.3d 81, 91 (2d Cir. 2021), “[a]rtful pleading cannot

transform the . . . complaint into anything other than

a suit over global greenhouse gas emissions.”

The regulation of interstate emissions is an

inherently federal domain. American Electric Power

Co. v. Connecticut, 564 U.S. 410, 421, 422 (2011) (“air

and water in their ambient or interstate aspects” are

“meet for federal law governance”). For decades, this

Court applied federal common law to disputes arising

from interstate emissions. See Illinois v. City of

Milwaukee, 406 U.S. 91, 103 (1972) (hereinafter

“Milwaukee I”); see also City of New York, 993 F.3d at

91 (collecting cases). After the CAA was enacted, this

Court held that the statute had displaced federal

common law in the realm of interstate emissions.

City of Milwaukee v. Illinois & Michigan, 451 U.S. 304,

313-14 (1981) (hereinafter “Milwaukee II”). Disputes

arising from interstate emissions were thereafter

governed by the CAA. Id.

The common thread through all of these cases and

changes to the law is that federal law has always

applied to disputes arising from interstate emissions.

Yet the Colorado Supreme Court found that Respondents’

state tort claims were viable because (1) the tortious

conduct was not the emission of greenhouse gases, and

(2) federal common law no longer precludes state-law

claims. Pet. App’x at 18a, 20a. As discussed above,

Respondents do in fact necessarily allege that the

tortious conduct at issue is the emission of greenhouse

gases, and the decision below incorrectly credited

Respondents’ pleading gimmick. As to (2), the decision

below erroneously assumed that when federal common

law is displaced, state-law claims become available.

State-law claims have never been available for

disputes arising from interstate emissions, because

interstate emissions are an inherently federal domain.

Federal common law was displaced, but this bedrock

principle remains.

If Respondents’ claims were to succeed, many other

judgments in many other states would surely follow.

Petitioners and other participants in the energy

industry would be subject to an impossible web of

disparate judgments and billion-dollar awards for the

same conduct. This would do nothing to advance a

solution to global climate change and would in fact

impair any federal effort toward a nationwide solution.

The resulting deluge of fines, damages awards, and

conflicting decisions would also unleash chaos in the

energy industry and the world economy more broadly.

Respondents fail to recognize that combatting

climate change requires a concerted effort among

businesses, governments, and nations. Currently,

fossil fuels provide the majority of the world’s energy,

and there is not yet a viable replacement at scale. A

solution to global climate change involves balancing

the world’s energy needs with the need to reduce

greenhouse gas emissions. Regulation must be carefully

targeted to avoid destabilizing the energy supply that

underlies the world economy. Congress and the agencies

to which it has delegated authority can perform this

balancing act, taking the interests of the whole nation

into account. In contrast, Respondents’ suit blindly

targets fossil fuel companies and attempts to recover

for injuries in their locality, without any regard to the

effects on the rest of the country or the world.

Combatting climate change requires serious federal

and international action. Respondents’ suit is not a

serious attempt to address climate change, and it

would impair federal action by inviting a complex and

inconsistent web of state-court rules.

In addition to powering the world economy, fossil

fuels are a strategically important resource and a longstanding pillar of U.S. national security. The United

States’ ability to produce and export fossil fuels has

long been used as both a negotiating tool in diplomatic

relations and an instrument of war. The Constitution

is clear that the federal government has exclusive

control over matters related to foreign affairs, and that

state law should not interfere with this exclusive

federal domain. Respondents’ suit threatens to interfere with the United States’ ability to conduct foreign

affairs, because it would shift regulatory power over a

strategically important industry from the federal

government to the states. Furthermore, Respondents’

suit and the likely follow-on suits, if successful, would

destabilize the energy sector and reduce its capacity to

respond to national security imperatives like the war

in Ukraine.

ARGUMENT

This case exemplifies the President’s recent pronouncement that “States have . . . sued energy

companies for supposed ‘climate change’ harm under

nuisance or other tort regimes that could result in

crippling damages. . . . These State laws and policies

try to dictate interstate and international disputes

over air, water, and natural resources; unduly discriminate against out-of-State businesses; contravene the

equality of States; and retroactively impose arbitrary

and excessive fines without legitimate justification. . . .

They should not stand.” Exec. Order No. 14,260 at 1

(Apr. 8, 2025) (emphasis added).

I. The essence of Respondents’ action is to

seek redress for alleged injuries arising

from global climate change and to regulate

emissions.

A threshold matter is whether Respondents’ claims

are premised only on the marketing, sale, and

production of fossil fuels—purportedly bringing their

claims within the ambit of state law—or if Respondents’

claims seek to remedy alleged injuries from interstate

greenhouse gas emissions—bringing them within an

inherently federal domain. The Colorado Supreme

Court accepted Respondents’ claims at face value.

Finding that the complaint’s allegations had everything to do with “tortious conduct that [federal law]

does not address,” and nothing to do with “[greenhouse

gas] emissions by defendants themselves,” the court held

that Respondents’ claims did not implicate the

regulation of interstate emissions.

Respondents’ assertion that their claims relate only

to the marketing, sale, and production of fossil fuels

does not withstand scrutiny, and the Court should not

indulge their sleight of hand pleading. As the Second

Circuit held in City of New York, 993 F.3d at 91,

“[a]rtful pleading cannot transform the . . . complaint

into anything other than a suit over global greenhouse

gas emissions.”

The majority below reasoned that “[Respondents’]

claims do not seek compensation for any GHG

emissions by defendants themselves but rather focus

on [Petitioners’] upstream production activities.” Pet.

App’x at 20a. But the distinction between greenhouse

gas emissions and “upstream activities” is illusory.

Whether Respondents style their complaint as targeting upstream activities or the emissions themselves,

the result is the same: Respondents are demanding

compensation from Petitioners for the effects of

worldwide greenhouse gas emissions. The “upstream

activities” Respondents identify are only relevant to

the extent they allegedly caused the emission of

greenhouse gases. See, e.g., Amended Compl. ¶¶ 12729 (production of fossil fuels resulted in higher levels

of CO2). There is no question that all of Respondents’

injuries are alleged to have been directly caused by the

accumulation of greenhouse gas emissions. See, e.g.,

id. ¶ 129. Despite Respondents’ superficial focus on

upstream activities, the emissions themselves are a

necessary causal link without which Respondents’

claims fall apart. Respondents would have difficulty

establishing, for example, that the Petitioners’

marketing, sale, and production of fossil fuels was an

actual or proximate cause of injuries in Colorado.

Greenhouse gases have been emitted from many

different sources since the beginning of the industrial

revolution. The “upstream activities” of Petitioners

are far too remote to support Respondents’ claims. To

say that this case does not involve the regulation of

interstate greenhouse gas emissions is to ignore that

these emissions are alleged to be the direct cause of

Respondents’ alleged injuries and are a necessary

element of Respondents’ claims.

The decision below, however, elided the central issue

in the complaint by concluding that Respondents’

claims do not “involve uniquely federal areas of

regulation” because “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.” Pet. App’x at

15a (emphasis omitted).

The court failed to

acknowledge, however, that the “nuisance abatement

issues” are not the typical local disputes that these

terms imply, but in fact arise from atmospheric

changes of planetary proportions. Putting state-law

labels on plainly interstate activities does not suffice

to sustain state-law claims in the inherently federal

domain of interstate emissions.

II. The regulation of interstate emissions is

an inherently federal domain.

This Court has recognized that “air and water in

their ambient or interstate aspects” are “meet for

federal law governance.” American Electric Power, 564

U.S. at 421, 422. “[A] mostly unbroken string of cases”

going back more than a century “has applied federal

law to disputes involving” claims arising out of

interstate emissions. City of New York, 993 F.3d at 91

(collecting cases); see Milwaukee I, 406 U.S. at 103.

It is because of the inherently federal nature of

interstate emissions and discharges that this Court

long held that suits related to air and water pollution

were governed by federal common law. See American

Electric Power, 564 U.S. at 420-23; Milwaukee I, 406

U.S. at 103. After the enactment of the CAA and Clean

Water Act (“CWA”), this Court held that the federal

statutory schemes had displaced federal common law.

Milwaukee II, 451 U.S. at 313-14; Int’l Paper Co. v.

Ouellette, 479 U.S. 481, 492 (1987). In holding that the

CWA preempted most state-law claims, this Court

relied not only on the statute itself, but also on “the

fact that the control of interstate pollution is primarily

a matter of federal law.” Ouellette, 479 U.S. at 492.

Although the federal common law of air and water

pollution has been displaced, the reasons that it

was first applied remain. In a 1972 case, this Court

explained that interstate pollution required the

application of federal common law because it “touches

basic interests of federalism” and implicates an

“overriding federal interest in the need for a uniform

rule of decision” in the field of interstate emissions.

Milwaukee I, 406 U.S. at 105 n.6. This Court agreed

with a Tenth Circuit decision elaborating on the

reasons that “[f]ederal common law and not the

varying common law of the individual States” must

apply when a controversy invokes “the environmental

rights of a State against improper impairment by

sources outside its domain.” Id. at 107 n.9 (citing State

of Tex. v. Pankey, 441 F.2d 236 (10th Cir. 1971)). The

Tenth Circuit had explained that if state law was

permitted to resolve such disputes, “more conflicting

disputes, increasing assertions and proliferating con-

tentions would seem to be inevitable.” Pankey, 441

F.2d at 241.

The justifications for precluding state-law claims in

emissions cases were not “undermine[d]” by the CAA

or the CWA, Illinois v. City of Milwaukee, 731 F.2d 403,

410 (7th Cir. 1984), cert. denied, 469 U.S. 1196 (1985),

and they are certainly no less applicable to the

emissions that cause global climate change. In fact,

that global climate change inherently requires a

federal solution is perhaps more evident than with

respect to the other forms of pollution that this Court

has previously addressed. In particular, this Court’s

decisions emphasize that the location of the source of

an emission or discharge is a dispositive factor in

determining whether federal law provides the exclusive remedy. See e.g., Milwaukee I, 406 U.S. at 93

(federal common law applied to pollution in Wisconsin

caused by sewage discharge originating in Illinois);

Ouellette, 479 U.S. at 488-89 (state-law claims

permitted only where water pollution is caused by an

in-state source). Although Respondents carefully

avoid admitting it in their complaint, it cannot be

seriously disputed that climate change is caused by

emissions throughout the United States and the

world, and that CO2, methane, and other greenhouse

gases from countless sources intermix in the

atmosphere. See What are the trends in greenhouse gas

emissions and concentrations and their impacts on

human health and the environment?, U.S.

Environmental Protection Agency.2 Importantly, not

all of these emissions originate in petroleum products,

https://www.epa.gov/report-environment/greenhouse-gases

#:~:text=Greenhouse%20gases%2C%20such%20as%20carbon%2

0dioxide%2C%20methane%2C,received%20from%20the%20sun

%20and%20emitted%20from (last visited September 3, 2025).

or indeed from energy consumption at all. Sources of

Greenhouse Gas Emissions, U.S. Environmental

Protection Agency.3 Given the breadth and scale of the

causes of climate change, any solutions that are to be

effective must be uniform and comprehensive,

necessarily making them solutions that only federal

policymakers can provide.

State-law tort claims that aim to regulate emissions

not only violate the “overriding federal interest in the

need for a uniform rule of decision,” Milwaukee I, 406

U.S. at 105 n.6, they also impinge on the rights of other

states by making determinations that will have an

impact well beyond the borders of the state in which

the claims are brought. By asking a Colorado court to

determine whether fossil fuel production “unreasonably

interfere[s]” with a public right such that it amounts

to a public nuisance, Restatement (Second) of Torts §

821B (1979), Respondents are necessarily asking the

court to determine whether fuel producers’ conduct

was reasonable. Making that determination requires

considering not only the risks of fossil fuel use to the

planet, but also how well those risks have been

weighed against the world’s gargantuan need for

energy and the difficulty of developing an alternative

at scale. Furthermore, the Colorado court would need

to apportion blame for climate change as a whole, not

merely alleged harms felt in Colorado, which cannot

possibly be traced to a single source. The court would

thus take on the role of quantifying the contribution of

whole industries to global climate change, including

the many fuel producers and unrelated industries not

before the court. Other states, then, would also make

these same sweeping determinations for claims

https://www.epa.gov/ghgemissions/sources-greenhouse-gasemissions (last visited September 3, 2025).

brought under their own laws. In this untenable

contest between state courts over global emissions,

“more conflicting disputes, increasing assertions and

proliferating contentions would seem to be inevitable,”

Pankey, 441 F.2d at 241.

This Court has affirmed on multiple occasions that

weighty determinations affecting the entire nation

must be made by Congress or its designated federal

agency. W. Virginia v. Env’t Prot. Agency, 597 U.S. 697

(2022) (“Capping carbon dioxide emissions at a level

that will force a nationwide transition . . . . [but] [a]

decision of such magnitude and consequence rests

with Congress itself, or an agency acting pursuant to

a clear delegation from that representative body.”);

American Electric Power, 564 U.S. at 428 (noting that

Congress “designated an expert agency, here, EPA, as

best suited to serve as primary regulator of

greenhouse gas emissions”).

In an attempt to distinguish the repeated declarations of this Court regarding the inherently federal

nature of claims premised on interstate emissions, the

decision below asserted that the enactment of the CAA

rendered the Court’s prior holdings inapplicable.

Specifically, the Colorado Supreme Court reasoned

that “the CAA displaced federal common law governing interstate pollution damages suits and, thereafter,

federal common law did not preempt state law.” Pet.

App’x at 16a. The court thus appeared to posit that if

federal common law no longer applies, state law must

apply.

As an initial matter, the decision below rests on the

dubious suggestion that the enactment of a broad

federal air pollution and emissions scheme reduced the

scope of federal authority in that very field. The

decision below noted that Petitioners had cited

“no applicable authority supporting the proposition

that once federal common law exists, the structure of

the Constitution precludes the application of state law

even when that common law no longer exists.” Id. at

17a. However, in the cases in which this Court has

considered the CWA’s or CAA’s displacement of federal

common law, it has held that the statutes leave no

room for the types of state-law claims at issue here.

See e.g., Ouellette, 479 U.S. at 488-89. Furthermore,

even assuming that the displacement of federal

common law by a federal statute could theoretically

resurrect state-law claims, the court’s reasoning would

nevertheless run up against the basic fact that

interstate emissions have never been governed by

state law. Thus, the CAA’s displacement of federal

common law could not have resurrected state-law

claims that never existed.

III. Allowing Respondents’ claims to proceed

would interfere with federal regulation of

emissions and set back the energy

transition.

The inherently federal nature of emissions

regulation is grounded not only in abstract Constitutional

principles of federalism, but also in the practical

impossibility of effectively regulating nationwide environmental matters at the state level. Allowing state

law to regulate interstate emissions would compromise any attempt at a uniform scheme or concerted

effort toward combatting climate change. It would also

risk serious disruption to the national economy and

undermine the United States’ ability to conduct

foreign affairs.

A. This practical reality is well known to API and

its members, who operate across the world and comply

with the laws of many different jurisdictions. Because

of the need to standardize fuel production methods,

changes in the law of one jurisdiction affect API’s

members’ behavior in other jurisdictions. Furthermore,

climate change is undisputedly a global phenomenon

that requires a coordinated response at the national

and international level. It is widely understood that

combatting climate change is one of the great

challenges of our age, and the solutions require

significant research, scientific innovation, and carefully

targeted regulation. Any solution also requires coordination with other sovereign nations.

Federal

authorities—the President, Congress, and the expert

agency to which it has delegated authority (the EPA)—

are the bodies capable of undertaking this task.

In contrast, state courts are not in a position to

effectively regulate global greenhouse gas emissions

and would in fact harm any effort to do so. Regulating

greenhouse gas emissions via a litany of state-law tort

actions would create a sprawling patchwork of regulations across all 50 states that would undermine any

attempt at uniform, federal regulation. If Respondents’ state-law claims are allowed to proceed, many

will follow in other states. Dozens of lawsuits bringing

state-law tort claims have already been filed in

different state jurisdictions.4 Inevitably, different

Leon v. Exxon Mobil Corp., No. 25-2-15986-8 (Wash.

Super. Ct.); City of Chicago v. BP p.l.c., No. 2024CH01024 (Ill. Cir.

Ct.); Cnty. of Multnomah v. Exxon Mobil Corp., No. 23CV25164

(Or. Cir. Ct.); California v. Exxon Mobil Corp., No. CGC23609134

(Cal. Super. Ct.); Makah Indian Tribe v. Exxon Mobil Corp., No.

23-2-25216-1 (Wash. Super. Ct.); Platkin v. Exxon Mobil Corp., No.

MER-L-001797-22 (N.J. Super. Ct.); City of Annapolis v. BP p.l.c.,

No. C-02-CV-21-000250 (Md. Cir. Ct.); Anne Arundel Cty. v. BP

p.l.c., No. C-02-CV-21-000565 (Md. Cir. Ct.); Connecticut v. Exxon

Mobil Corp., No. HHDCV206132568S (Conn. Super. Ct.); City of

Hoboken v. Exxon Mobil Corp., No. HUD-L-003179-20 (N.J.

states’ courts will come to different decisions, and

API’s members could well be subject to inconsistent

laws and judgments. Ouellette, 479 U.S. at 496

(allowing “a number of different states to have

independent and plenary regulatory authority over a

single discharge would lead to chaotic confrontation

between sovereign states.” (citation omitted)).

In sum, the use of tort law to regulate emissions

takes a hammer to a problem that requires a scalpel.

Respondents seek to short-circuit the ongoing energy

transition to their exclusive benefit, at the expense of

every other state and locality in the nation—all of which

are affected by climate change.

Furthermore, the damages requested by Respondents

and other plaintiffs across the country are enough to

cripple the energy industry and cause ripple effects

throughout the American economy. Respondents seek

Super.); Delaware v. BP America Inc., No. N20C-09-097 (Del.

Super. Ct.); City of Charleston v. Brabham Oil Co., No.

2020CP1003975 (S.C. Ct. Com.); Minnesota v. American

Petroleum Institute, No. 62-CV-20-3837 (Minn. Dist. Ct.); Rhode

Island v. Chevron Corp., No. PC-2018-4716 (R.I. Super. Ct.); City

of Richmond v. Chevron Corp., No. C18-00055 (Cal. Super. Ct.);

Mayor & City Council of Balt. v. BP p.l.c., No. 24-C-18-004219

(Md. Cir. Ct.); City of Imperial Beach v. Chevron Corp., No. C1701227 (Cal. Super. Ct.); Cnty. of Marin v. Chevron Corp., No.

CIV1702586 (Cal. Super. Ct.); Cnty. of San Mateo v. Chevron

Corp., No. 17CIV03222 (Cal. Super. Ct.); City of Santa Cruz v.

Chevron Corp., No. 17CV03243 (Cal. Super. Ct.); Cnty. of Santa

Cruz v. Chevron Corp., No. 17CV03242 (Cal. Super. Ct.); Cal. ex

rel. Herrera v. BP p.l.c., No. CGC-17-561370 (Cal. Super. Ct.); Cal.

ex rel. Oakland City Att’y v. BP p.l.c., No. RG17875889 (Cal. Super. Ct.);

City and County of Honolulu v. Sunoco LP, et al, No. CAAP-22-0000429

(Haw. Ct. App.); City and County of Honolulu v. Chevron Corp. et al, No.

CAAP-22-0000135 (Haw. Ct. App.); Bucks County v. BP p.l.c., No. 202401836-0000 (Pa. Commw. Ct.); Estado Libre Asociado de Puerto Rico v.

Exxon Mobil Corp. et al, No. SJ2024CV06512 (P.R. TPI).

extensive monetary relief to compensate for alleged

property damage and to maintain basic municipal

functions, such as repairing bridges and containing

wildfires. Amended Compl. ¶ 532. Other states have

signaled that they will seek damages on an even larger

scale. For example, California is seeking “tens of

billions to hundreds of billions in ongoing damages going

forward.” PBS News Hour, California Sues Oil

Companies for Exacerbating Climate Change (Sept. 20,

2023).5 Multnomah, Oregon is seeking over $1.5

billion in damages and an abatement fund of over $50

billion paid for by the defendants. Compl. at 174-75,

Cnty. of Multnomah, No. 23CV25164 (Or. Cir. Ct. June 22,

2023).

In these self-interested suits, states and municipalities disregard the national interest in maintaining the

supply of low-cost energy that powers the American

economy. If these suits succeed in obtaining billiondollar judgments for particular states and localities,

the costs will inevitably impact the energy supply

chain. The inflationary effect of increased energy costs

could have sweeping effects on the U.S. economy and

international trade. About 60% of U.S. households rely

on natural gas as their primary source of

energy. U.S. Dep’t Energy Info. Admin., Natural gas

explained6; U.S. Dep’t Energy Info. Admin., Use of

energy explained.7 Nearly the entire transportation

sector depends on energy derived from fossil fuels.

This affects not only the cost of gas for individuals, but

https://www.pbs.org/video/suing-big-oil-1695235855/ (last visited September 3, 2025).

https://www.eia.gov/energyexplained/natural-gas/ (last visited September 3, 2025).

https://www.eia.gov/energyexplained/use-of-energy/ (last

visited September 10, 2025).

also the cost of logistics and shipping. U.S. Dep’t

Energy Info. Admin., Use of energy explained.8 Studies

have shown that, because these sectors are so vital,

even modest increases in core energy prices can have

ripple effects that disrupt the entire economy. Dep’t of

Transp., Bureau of Transp. Stats., Inflation and

Transportation.9

The value of petroleum to the economy also extends

well beyond fuel. Petroleum-based products such as

plastic are ubiquitous in basic consumer products and

essential to nearly every major industry. For example,

an increase in the cost of petroleum-based products

would be immediately felt in the agricultural industry,

U.S. Dep't of Agric., Impacts of Higher Energy Prices

on Agriculture and Rural Economies (Aug. 18, 2011),10

the manufacturing industry, U.S. Dep’t Energy Info.

Admin., Use of energy explained,11 and the healthcare

industry, U.S. Dep’t of Energy, U.S. Oil and Natural

Gas: Providing Energy Security and Supporting Our

Quality of Life (Sept. 2020).12

The potential consequences of Respondents’ suit

have serious implications for the national economy. It

https://www.eia.gov/energyexplained/use-of-energy/ (last

visited September 10, 2025).

https://data.bts.gov/stories/s/Transportation-and-Inflatio

n/f9jm-cqwe/ (last visited September 3, 2025).

https://ers.usda.gov/sites/default/files/_laserfiche/publica

tions/44894/6806_err123_reportsummary.pdf (last visited September 3, 2025).

https://www.eia.gov/energyexplained/use-of-energy/ (last

visited September 10, 2025).

https://www.energy.gov/fecm/articles/us-oil-and-naturalgas-providing-energy-security-and-supporting-our-quality-life

(last visited September 3, 2025).

is for that reason that federal policymakers, and not

individual states, have the exclusive authority to

regulate nationwide emissions. Allowing states to

bypass federal supremacy would impose ad hoc,

localized solutions on a problem that requires a broad

and careful review in which all interested parties are

represented.

B. Allowing state tort law to govern emissions

would also intrude on the federal government’s

exclusive control over foreign affairs. Am. Ins. Ass’n v.

Garamendi, 539 U.S. 396, 421 (2003) (“[t]he exercise of

the federal executive authority,” particularly in the

area of foreign affairs, “means that state law must give

way where, as here, there is evidence of clear conflict

between the policies adopted by the two”). As noted

above, no solution to the climate crisis is possible

without international cooperation. The federal government must be able to negotiate on behalf of the

nation as a whole and make agreements regarding

greenhouse gas emissions with other sovereign nations.

The federal government cannot effectively do so if the

states have already imposed their own standards that

may conflict with those under negotiation. In essence,

the federal government cannot negotiate the regulation

of nationwide emissions if it does not have the

exclusive authority to regulate such emissions. City of

New York, 993 F.3d at 103 (State-law tort suit “would

not only risk jeopardizing our nation’s foreign policy

goals but would also seem to circumvent Congress’s

own expectations and carefully balanced scheme of

international cooperation on a topic of global concern.”).

More generally, the strategic importance of fossil

fuels means that they have always played a crucial

role in foreign affairs. During World War II, the United

States’ reserves of oil became “[a] prime weapon of

victory in two world wars” and “a bulwark of our

national security.”

Nat’l Petroleum Council, A

National Oil Policy for the United States 1 (1949).13 At

the time the United States entered the war, it had

more petroleum reserves than any other country in the

world, and President Franklin Roosevelt wielded the

industry as an instrument of foreign affairs. Energy’s

Vital Role in World War II Offers Lessons For Today,

Am. Oil & Gas Rptr. (Oct. 2023).14 In 1941, the United

States embargoed oil shipments to Japan, dramatically altering the course of the war in the Pacific. Id.

On the other hand, President Roosevelt accelerated

shipments of high-octane fuel for aircraft, as well as oil

for ships, lubricants, and synthetic rubber to the Allies.

Id. During the span of the conflict, the oil industry

increased production by nearly 30% to meet the

enormous demand. Id. U.S. oil and petroleum-based

products were necessary for the Allies to continue

fighting, and the United States’ wealth of petroleum

resources emerged as one of its most powerful tools in

foreign affairs.

Id.; Nat’l Petroleum Council, A

National Oil Policy for the United States 1.15

The petroleum industry is no less a part of foreign

affairs today. In 2022, following Russia’s invasion of

Ukraine, the European Union sought to reduce its

dependence on natural gas from Russia. President Joe

https://www.energy.gov/sites/default/files/2022-11/1949National_Oil_Policy_for_United_States.pdf (last visited September 3, 2025).

https://www.aogr.com/web-exclusives/exclusive-story/ene

rgys-vital-role-in-world-war-ii-offers-lessons-for-today (last visited September 3, 2025).

https://www.energy.gov/sites/default/files/2022-11/1949National_Oil_Policy_for_United_States.pdf (last visited September 3, 2025).

Biden agreed to increase shipments of natural gas and

dramatically increase the United States’ export

capacity. Europe and the U.S. Make Ambitious Plans

to Reduce Reliance on Russian Gas, The New York

Times, March 22, 2022.16 The agreement envisions the

United States increasing its exports to the EU from 15

billion cubic meters of liquefied natural gas to 50

billion cubic meters by 2030. Id. The executive

agreement called on the energy industry to respond

with massive investments to increase production of

fossil fuels. Id.

Given the vital role that fossil fuels continue to play

in foreign affairs and national security, the need to

reduce emissions and combat climate change must be

carefully weighed against the need to increase

production when it is in the interest of national

security. State courts are clearly not the proper

authority to conduct this balancing of environmental

and national security interests, and their attempt to

do so would violate the federal government’s exclusive

control over foreign affairs. State-court suits like

Respondents’ and their attendant risk of future

liability for climate-related damages could well impact

fuel production. This would severely hinder the

federal government’s ability to use the United States’

natural resources as a tool to advance the nation’s

strategic interests. State interference with any of

these interests is untenable and only reinforces why

the conduct at issue in this case falls within an

inherently federal domain.

* * *

https://www.nytimes.com/2022/03/25/business/energy-en

vironment/biden-eu-liquefied-natural-gas-deal-russia.html (last visited September 2, 2025).

Global climate change is a serious issue that

deserves serious action. API firmly believes that the

only viable solutions to climate change exist at the

national level and as a uniform, nationwide standard.

Americans depend on a stable energy supply and the

economy that it powers, and these energy needs must

be carefully balanced against the need to reduce

greenhouse gas emissions. However, policymakers

representing the interests of all 50 states must

address this issue. The basic principles of federalism

hold that it is improper for one state court addressing

one county’s claims to render decisions that affect the

citizens of every other state.

CONCLUSION

The petition for a writ of certiorari should be granted.

Respectfully submitted,

MARK A. PERRY

Counsel of Record

WEIL, GOTSHAL & MANGES LLP

2001 M Street NW

Suite 600

Washington, DC 20036

(202) 682-7000

mark.perry@weil.com

Counsel for Amicus Curiae

American Petroleum Institute

September 15, 2025

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.