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

No. 25-170

In the

Supreme Court of the United States

SUNCOR ENERGY (U.S.A.) INC., et al.,

Petitioners,

v.

COUNTY COMMISSIONERS OF

BOULDER COUNTY, et al.,

Respondents.

On Writ of Certiorari to the

Supreme Court of Colorado

BRIEF FOR THE PELICAN INSTITUTE FOR

PUBLIC POLICY AND MICHAEL TOTH AS AMICI

CURIAE IN SUPPORT OF PETITIONERS

Sarah Harbison

Counsel of Record

Pelican Center for Justice

Pelican Institute for

Public Policy

400 Poydras Street, Suite 900

New Orleans, LA 70130

(504) 500-0506

sarah@pelicaninstitute.org

Counsel for Amici Curiae

121069

A

(800) 274-3321 • (800) 359-6859

i

TABLE OF CONTENTS

Page

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

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

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

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

ARGUMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

I.

Municipal climate cases encroach on

the federa l gover n ment ’s exclusive

authority over national security and

foreign policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

A. The cases conf lict w ith express

federal foreign policy . . . . . . . . . . . . . . . . . 10

B. The cases intrude on the federal

gover n ment ’s e xclu sive doma i n

without addressing a traditional state

concern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

ii

TABLE OF CITED AUTHORITIES

Page

Cases

Am. Ins. Ass’n v. Garamendi,

539 U.S. 396 (2003) . . . . . . . . . . . . . . . . . . . . . . . . . 3, 17

American Electric Power Co. (AEP) v. Connecticut,

564 U.S. 410 (2011) . . . . . . . . . . . . . . . . . . . . . . . . 18, 19

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

No. 2024-01836, slip op. at 11 (Pa. Ct. Com. Pl.

Bucks Cnty. May 16, 2025) . . . . . . . . . . . . . . . . . . . . . . 2

City of New York v. Chevron Corp.,

993 F.3d 81 (2d Cir. 2021) . . . . . . . 10, 11, 13, 16, 18, 20

Crosby v. Nat’l Foreign Trade Council,

530 U.S. 363 (2000) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Hines v. Davidowitz,

312 U.S. 52 (1941) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

International Paper Co. v. Ouellette,

479 U.S. 481 (1987) . . . . . . . . . . . . . . . . . . . . . 18, 19, 20

Massachusetts v. EPA,

549 U.S. 497 (2007) . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Movsesian v. Victoria Versicherung AG,

670 F.3d 1067 (9th Cir. 2012) . . . . . . . . . . . . . . . . . . . . 2

Zschernig v. Miller,

389 U.S. 429 (1968) . . . . . . . . . . . . . . . . . . . . . . . . 10, 11

iii

Cited Authorities

Page

Statutes and Other Authorities

15 U.S.C. § 2901 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11, 12

42 U.S.C. § 7415(a) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

42 U.S.C. § 7415(c) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

42 U.S.C. § 7416 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

42 U.S.C. § 7604(e) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

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

Claudia Assis, The World’s Largest NaturalGas Complex Is Now Battered . Here’s

Who Will Benefit, MarketWatch (Mar. 19,

2026), https://www.morningstar.com/news/

marketwatch/20260319214/the-worlds-largestnatural-gas-complex-is-now-battered-hereswho-will-benefit (last visited Mar. 30, 2026) . . . . . 8, 9

By rd-Hagel Resolution, S. Res 9 8 , 10 5th

Cong. (1997) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13, 14

Ca l. Energ y Comm’n, A nnua l Oi l Supply

Sources to California Refineries, https://www.

energy.ca.gov/data-reports/energy-almanac/

californias-petroleum-market/annual-oilsupply-sources-california (last visited Apr. 1, 2026) . . . 9

iv

Cited Authorities

Page

Eugene Chausovsky, Europe Needs to Learn Its

Lesson: Stop Relying on Imported Energy,

Wall St. J. (Mar. 24, 2026), https://www.wsj.

com/business/energy-oil/europe-needs-tolearn-its-lesson-stop-relying-on-importedenergy-63a7349e (last visited Mar. 28, 2026) . . . . . . 7

Declaring a National Energy Emergency, Exec.

Order 14156, § 1, 90 Fed. Reg. 8,433 (Jan. 20, 2025) . . . 15

Chen ie r e Ene r g y, I nc ., 2 0 23 Co r p o r a t e

Responsibility Report (2024), https://www.

cheniere.com/pdf/2023-CR-Report.pdf . . . . . . . . . . . 8

Rebecca F. Elliott, ‘The Old Game Is Back’: Oil

Is a Potent Geopolitical Tool Again, The New

York Times (Mar. 9, 2026), https://www.nytimes.

com/2026/03/09/business/energy-environment/

oil-gas-iran-war.html (last visited Mar. 26, 2026) . . . 5

Establishing the National Energy Dominance

Council, Exec. Order 14213, § 1, 90 Fed.

Reg. 9,945 (Feb. 14, 2025) . . . . . . . . . . . . . . . . . . . . . 15

Eurostat, EU Imports of Energy Products

Decreased Again in 2025, Eurostat News

( M a r. 2 5 , 2 0 2 6), ht t p s: //e c .eu r op a .eu /

eurostat/web/products-eurostat-news/w/

ddn-20260325-3 (last visited Apr. 7, 2026) . . . . . . . . . 7

Exec. Order No. 14,156 § 1 . . . . . . . . . . . . . . . . . . . . . . . 17

v

Cited Authorities

Page

Exec. Order No. 14260, § 1, 90 Fed. Reg. at 15513 . . . . 15

Lisa Friedman, America Officially Leaves

the Par is Climate Agreement . For the

Second Time, N.Y. Times (Jan. 27, 2026),

ht t p s : // w w w. ny t i m e s . c o m / 2 0 2 6 / 01 / 2 7/

climate/par is- climate-ag reementwithdrawal.html (last visited Apr. 4, 2026) . . . . 14, 15

Libby Harg reaves, Which Countr y is the

Largest Exporter of Oil?, Supply Chain Digit.

(Mar. 3, 2026), https://supplychaindigital.

com /news/which- countr y-largestexporter-oil (last visited Apr. 7, 2026) . . . . . . . . . . 5, 6

Mag nus Hen rek son et a l. eds., A G reen

Entrepreneurial State? Exploring the Pitfalls

of Green Deals 137 (Springer Cham 2026),

https://doi.org/10.1007/978-3-032-15512-2 . . . . . . . . . 7

Int’l Energy Agency, Global Energy Review

2025 40 (2025), https://iea.blob.core.windows.

n e t /a s s e t s / 5 b16 9 a a 1- b c 8 8 - 4 c 9 6 - b 8 2 8 aaa50406ba80/GlobalEnergyReview2025.pdf . . . . . . 3

Kyoto Protocol to the United Nations Framework

Convention on Climate Change annex B,

Dec. 11, 1997, 2303 U.N.T.S. 162, https://

unfccc.int/resource/docs/convkp/kpeng.pdf . . . . . . . 13

vi

Cited Authorities

Page

Vali Nasr, Iran Is Playing a Long Game,

Financial Times (Mar. 13. 2026), https://

w w w.ft.com/content/93b7b65d-074b-4e8b807f-5c27c7362213 (last visited Apr. 3, 2026) . . . . . . 8

Par is Ag reement, Dec. 12 , 2 015, T.I.A . S.

No. 16-1104 art. IV . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Press Release, U.S. Dept. of State, On the

U.S. Withdrawal from the Paris Agreement

(Nov. 4, 2019) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

P ress Release, U. S . Dept . of St at e, T he

United States Officially Rejoins the Paris

Agreement (Feb. 19, 2021) . . . . . . . . . . . . . . . . . . . . . 14

P rot ecti ng A mer ican Energ y f rom St at e

Overreach, Exec. Order 14260, § 1, 90 Fed.

Reg. 15515 (Apr. 8, 2025) . . . . . . . . . . . . . . . . . . . . . . 15

Pub. L. No. 100-204, Title XI, § 1103, 101 Stat.

1331 (1987) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Pub. L. No. 100-204, Title XI, § 1103(a)(2)-(4),

101 Stat. at 1408 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Pub. L. No. 100-204, Title XI, § 1103(b)-(c),

101 Stat. at 1408-1409 . . . . . . . . . . . . . . . . . . . . . . . . . 12

Pub. L. No. 100-204, § 1103(a)-(b), 101 Stat. at 1408–09 . . . 16

vii

Cited Authorities

Page

Pub. L. No. 100-204, § 1103(b) . . . . . . . . . . . . . . . . . . . . 17

S. Treaty Doc. No. 102-38, 1771 U.N.T.S. 107, https://

unfccc.int/resource/docs/convkp/conveng.pdf . . . . . 12, 13

Brenda Shaffer, ‘Renewable’ Energy Gives Us

a Crisis, Wall St. J. (Mar. 26, 2026), https://

w w w.wsj.com /opinion /renewable-energygives-us-a-crisis-e8426cd8?mod=opinion_

lead_pos8 (last visited Mar. 26, 2026) . . . . . . . . . . . . 4

Vaclav Smil, How the World Really Works (2022) . . . . . 5

Todd Stern, Special Envoy for Climate Change

(Oct. 28, 2015), https://2009-2017.state.gov/s/

climate/releases/2015/248980.htm . . . . . . . . . . . . . . 13

S t r e n g t h e n i n g Un i t e d S t a t e s Na t i o n a l

Defense with A merica’s Beautiful Clean

Coal Power Generation Fleet, Exec. Order

14386 § 1, 91 Fed. Reg. 7,393 (Feb. 11, 2026) . . . . . . 15

The Federalist No. 42 (Carey & McClellan

eds., 2001) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

T h e W h i t e Ho u s e , Na t i o n a l S e c u r i t y

Strategy of the United States of America

( Nov. 2 0 2 5 ), ht t p s: // w w w.w h it e hou s e .

gov/ w p - cont ent / uploa d s / 2 0 2 5 / 1 2 / 2 0 2 5 National-Security-Strategy.pdf . . . . . . . . . . . . . . 6, 15

viii

Cited Authorities

Page

U.S. Editorial Board, EPA Is Right to Reverse

Obama Overreach, Wash. Post (Feb. 10,

2026), https://w w w.washingtonpost.com /

opinions/2026/02/10/epa-is-right-reverseobama-overreach/ (last visited Mar. 27, 2026) . . . . . 4

U.S. Energy Information Administration, Annual

U.S. Crude Oil Exports Decrease for First

Time Since 2021 (Mar. 10, 2026), https://www.

eia.gov/todayinenergy/detail.php?id=67324 . . . . . . . 4

U.S. Energy Info. Admin., Ten Years After First

Sabine Pass Cargo, U.S. LNG Exports Are

Still on the Rise (Feb. 24, 2026), https://www.

eia.gov/todayinenergy/detail.php?id=67224 . . . . . . . 5

Curtis Williams, Cheniere Already Operating

at Maximum Capacity, CEO Says, as Asia

Calls for More LNG, Reuters (Mar. 25, 2026),

https://www.reuters.com/business/energy/

ceraweek-cheniere-already-operating-atma x i mum- capacity- ceo - says-asia- ca l lsmore-2026-03-25/ (last visited Mar. 30, 2026) . . . . . . 9

Daniel Yergin et al., Major New U.S. Industry at a

Crossroads: A U.S. LNG Impact Study—Phase 1,

S&P Glob. (Dec. 17, 2024), https://www.spglobal.

com/en/research-insights/special-reports/

major-new-us-industry-at-a-crossroads-us-lngimpact-study-phase-1 (last visited Apr. 4, 2026) . . . . 6

1

INTEREST OF AMICI CURIAE1

The Pelican Institute for Public Policy is a nonprofit,

non-partisan research institute whose mission is to

research and develop policy solutions that promote

individual liberty, free enterprise, and equal opportunity.

Based in New Orleans, Louisiana, the Institute is located

near the epicenter of the American liquified natural gas

(LNG) industry. The LNG terminals in the Gulf Coast are

major suppliers of affordable energy to consumers around

the globe. As an organization committed to constitutional

governance, the Institute is concerned about the damage

to national energy security and the rule of law that would

result from the extraterritorial application of the law

of all 50 states to the use of American energy products

anywhere in the world. Amicus has a strong interest in

this case because the issues presented are inextricably

linked to the principles the Pelican Institute champions:

constitutional federalism, regulatory predictability, and

American energy dominance.

Michael Toth is the Director of Research at the Civitas

Institute, University of Texas at Austin, and a former

justice on the Texas Third District Court of Appeals. He

maintains a unique interest and expertise in ensuring that

courts preserve the proper allocation of authority between

federal and state sovereignty essential to the American

experiment in ordered liberty.

1. Pursuant to Supreme Court Rule 37.6, amici curiae affirm

that that no counsel for a party authored this brief in whole or in

part, and that no person or entity, other than amicus curiae, made

such a monetary contribution to the preparation or submission of

the brief.

2

Amici seek to assist this Court by providing its

research and policy analysis demonstrating the real-world

economic and national security consequences that flow

from permitting state and local governments to regulate

global greenhouse gas emissions, particularly when states

and localities undermine the Nation’s energy diplomacy

and restrict domestic producers from meeting global

energy needs amid rising geopolitical instability.

SUMMARY OF ARGUMENT

In today’s global economy, oil and gas are akin

to international currency. In constant use virtually

everywhere, these energy sources are indispensable to

global supply chain reliability, international commerce, and

the balance of powers between nations. Yet Respondents

seek to trample on the federal government’s exclusive

authority and set global standards for the worldwide use

of American oil and gas.

While Amici agree with the numerous federal and

state courts that have dismissed similar climate lawsuits

(hereinafter, the “municipal climate cases”) on the grounds

that the Clean Air Act preempts the use of state laws to

regulate global greenhouse gas emissions, see, e.g., Bucks

Cnty. v. BP p.l.c., No. 2024-01836, slip op. at 11 (Pa. Ct.

Com. Pl. Bucks Cnty. May 16, 2025) (discussing “growing

chorus” of such rulings), this brief advances a separate

and equally compelling basis for rejecting Respondents’

claims. They violate the Foreign Affairs Doctrine because

they conflict with “express federal foreign policy,” and

“intrude[] on the field of foreign affairs without addressing

a traditional state responsibility.” Movsesian v. Victoria

Versicherung AG, 670 F.3d 1067, 1071-72 (9th Cir. 2012)

3

(en banc) (citing Am. Ins. Ass’n v. Garamendi, 539 U.S.

396, 421 (2003)).

Against a backdrop of mounting international

conflict and geopolitical tension, Respondents’ attempt to

transform municipalities into worldwide emissions czars

collides with the federal government’s exclusive authority

to “speak with one voice” in foreign affairs. Crosby v.

Nat’l Foreign Trade Council, 530 U.S. 363, 381 (2000).

The municipal climate cases stand to open the litigation

floodgates, inviting thousands of local governments to

wield the laws of all 50 states to regulate the worldwide

consumption of fossil fuels—the opposite of a traditional

state responsibility well-suited to the application of local

law. Weaponizing the civil justice system in this manner

threatens national energy security and risks straining

diplomatic relations with countries that rely heavily on

American energy. The resulting legal and compliance

morass would drive up costs for U.S. oil and gas and, in

turn, increase global dependence on energy from unstable

petrostates in violation of standing federal foreign policy.

For these reasons alone, Respondents’ claims should be

rejected under the Foreign Affairs Doctrine.

The sweeping extraterritorial reach of the municipal

climate cases is evident from the often-overlooked fact

that roughly 90% of global greenhouse gas emissions—and

growing—originate outside the United States. See, e.g.,

Int’l Energy Agency, Global Energy Review 2025 40 (2025),

https://iea.blob.core.windows.net/assets/5b169aa1-bc884c96-b828-aaa50406ba80/GlobalEnergyReview2025.

pdf (listing the U.S. share of total worldwide carbon

emissions). The international share of global emissions

has risen steadily for decades for two main reasons: the

4

shift to low carbon energy consumption inside the U.S.

and surging demand for traditional fossil fuels outside

the U.S. Editorial Board, EPA Is Right to Reverse

Obama Overreach, Wash. Post (Feb. 10, 2026), https://

www.washingtonpost.com/opinions/2026/02/10/epa-isright-reverse-obama-overreach/ (last visited Mar. 27,

2026). To meet rising global demand for oil and gas,

American production of these essential commodities

has soared to record levels in recent years, propelled

by homegrown innovations such as shale fracking. U.S.

Energy Information Administration, Annual U.S. Crude

Oil Exports Decrease for First Time Since 2021 (Mar.

10, 2026), https://www.eia.gov/todayinenergy/detail.

php?id=67324 (finding that American energy exports

jumped by more than sevenfold from 2004 to 2024).

Ever-escalating global energy demand for American

energy makes plain the ultimate effect of deep-sixing

domestic oil and gas production under an unworkable

patchwork of state-by-state liability standards. Foreign

oil and gas producers, including those from unstable

petrostates, will fill the supply gap. Given the robust

expansion of artificial intelligence (AI), advanced

manufacturing, and data centers, the worldwide mandate

for traditional energy is too strong to fade away anytime

soon. Despite the trillions of dollars funneled into

renewable energy investment over decades, fossil fuels

made up the same sizable share of global energy usage

last year—87%—as they did in the 1970s. Brenda Shaffer,

‘Renewable’ Energy Gives Us a Crisis, Wall St. J. (Mar.

26, 2026), https://www.wsj.com/opinion/renewable-energygives-us-a-crisis-e8426cd8?mod=opinion_lead_pos8 (last

visited Mar. 26, 2026). As one former Clinton and Obama

administration official recently acknowledged, “the post-

5

oil world remains far in the future.” Rebecca F. Elliott,

‘The Old Game Is Back’: Oil Is a Potent Geopolitical Tool

Again, The New York Times (Mar. 9, 2026), https://www.

nytimes.com/2026/03/09/business/energy-environment/

oil-gas-iran-war.html (last visited Mar. 26, 2026) (quoting

David Sandalow).

Indeed, for billions across the developing world, fossil

fuels remain the only viable pathway to industrialization.

To put the global energy divide in perspective, 40% of the

world’s population still uses less energy per capita than

a citizen of 1860s Germany or France. Vaclav Smil, How

the World Really Works 5 (2022). For much of humanity,

energy demand isn’t merely about fuel for cars or light

and heat for homes; it is about the physical substance of

modern life. From the steel and cement of rising cities to

the life-saving plastics of hospital wards and the fertilizers

feeding the planet, these and other core infrastructural

materials are currently impossible to produce at scale

without a fossil fuel backbone. Id. at 78-100. To suppose

that demand for the fundamental components needed to

realize broad-based enhancements in living standards

around the world will soon disappear is to operate in a

parallel universe, not this one.

As global energy demand has increased, the world

has become considerably more reliant on American oil

and gas. Once an energy importer, America is now an

energy superpower—the world’s largest exporter of

liquified natural gas (LNG) and its largest producer (and

third largest exporter) of crude oil. U.S. Energy Info.

Admin., Ten Years After First Sabine Pass Cargo, U.S.

LNG Exports Are Still on the Rise (Feb. 24, 2026), https://

www.eia.gov/todayinenergy/detail.php?id=67224; Libby

6

Hargreaves, Which Country is the Largest Exporter

of Oil?, Supply Chain Digit. (Mar. 3, 2026), https://

supplychaindigital.com/news/which-country-largestexporter-oil (last visited Apr. 7, 2026). U.S. businesses

generate more revenue from LNG exports than from

corn and soybean exports and roughly twice as much as

from movie and TV exports. Daniel Yergin et al., Major

New U.S. Industry at a Crossroads: A U.S. LNG Impact

Study—Phase 1, S&P Glob. (Dec. 17, 2024), https://www.

spglobal.com/en/research-insights/special-reports/majornew-us-industry-at-a-crossroads-us-lng-impact-studyphase-1 (last visited Apr. 4, 2026). Further, energy has

become not just a key driver of domestic economic growth,

but a critical component of federal foreign policy as well.

The 2025 National Security Strategy identifies “energy

dominance” as a “top strategic priority” and describes

fuel exports as a tool for “deepen[ing] relationships with

allies,” “curtailing the influence of adversaries,” and

“project[ing] power” abroad. The White House, National

Security Strategy of the United States of America 14

(Nov. 2025), https://www.whitehouse.gov/wp-content/

uploads/2025/12/2025-National-Security-Strategy.pdf.

The growing use of energy as an instrument federal

foreign policy tool makes the municipal climate cases

all the more problematic. The Framers designed the

Constitution to vest the federal government with authority

sufficient to prevent individual states from conducting

their own foreign policy. As James Madison explained,

“If we are to be one nation in any respect, it clearly ought

to be in respect to other nations.” The Federalist No.

42. at 215 (Carey & McClellan eds., 2001) The municipal

climate cases would instead deploy state law to constrain

7

a geopolitically vital industry based on parochial policy

preferences.

Strategic alliances have only intensified global

demand for American energy, further amplifying the

federal government’s foreign affairs interest in energy

security. U.S. oil and gas sales to the European Union

(EU), for example, soared in the wake of the Russian

invasion of Ukraine in 2022. By early 2026, the U.S.

solidified its position as the top supplier of LNG and crude

oil to the bloc. America now accounts for 60 percent of

the EU’s LNG imports, providing the critical baseload

once supplied by Russia, whose energy exports to Europe

have fallen sharply since the Ukraine invasion. Eugene

Chausovsky, Europe Needs to Learn Its Lesson: Stop

Relying on Imported Energy, Wall St. J. (Mar. 24, 2026),

https://www.wsj.com/business/energy-oil/europe-needsto-learn-its-lesson-stop-relying-on-imported-energy63a7349e (last visited Mar. 28, 2026); Eurostat, EU

Imports of Energy Products Decreased Again in 2025,

Eurostat News (Mar. 25, 2026), https://ec.europa.eu/

eurostat/web/products-eurostat-news/w/ddn-20260325-3

(last visited Apr. 7, 2026).

Subjecting American oil and gas companies to a

barrage of municipal climate lawsuits risks a restoration

of the pre-invasion, Russian-dominated energy order

in Europe. On the eve of the Ukraine invasion, Russia

supplied Germany with 55% of its natural gas. Magnus

Henrekson et al. eds., A Green Entrepreneurial State?

Exploring the Pitfalls of Green Deals 137 (Springer

Cham 2026), https://doi.org/10.1007/978-3-032-15512-2.

Europe’s rapid shift away from Russian pipeline gas to

American LNG would have been impossible without U.S.-

8

based companies like Cheniere Energy. A decade ago, it

converted a facility in Cameron Parish, Louisiana, into

the nation’s first LNG export terminal. By 2023, Cheniere

had become the top LNG producer in the United States

and number two globally, accounting for roughly 11%

of worldwide supply. In the early stages of the RussiaUkraine war, the company shipped approximately 70%

of its total production—1,000 cargoes in 2022–23—

to Europe. Cheniere Energy, Inc., 2023 Corporate

Responsibility Report (2024), https://www.cheniere.

com/pdf/2023-CR-Report.pdf. If Respondents and other

municipal plaintiffs prevail, companies like Cheniere could

face liability under the laws of all 50 states for providing

U.S. allies with critical energy supplies. This would impair

the Nation’s ability to respond to international crises in

the future.

The military conflict in Iran that began in February

2026 further underscores the close relationship between

American energy abundance and geopolitical stability. In

response to Operation Epic Fury, Iran attacked critical

energy infrastructure across the Middle East in an

effort to cripple the global economy. See, e.g., Vali Nasr,

Iran Is Playing a Long Game, Financial Times (Mar. 13.

2026) (describing Iranian strikes as part of the country’s

strategy of “waging war on the global economy”),

https://www.ft.com/content/93b7b65d-074b-4e8b-807f5c27c7362213 (last visited Apr. 3, 2026). The strikes

forced major LNG suppliers to halt production and caused

global energy prices to soar. Claudia Assis, The World’s

Largest Natural-Gas Complex Is Now Battered. Here’s

Who Will Benefit, MarketWatch (Mar. 19, 2026), https://

www.morningstar.com/news/marketwatch/20260319214/

the-worlds-largest-natural-gas-complex-is-now-battered-

9

heres-who-will-benefit (last visited Mar. 30, 2026). Global

energy markets responded much as Europe did after

Russia’s invasion of Ukraine: they turned to the United

States to fill the supply gap created by the Iranian

strikes. Curtis Williams, Cheniere Already Operating at

Maximum Capacity, CEO Says, as Asia Calls for More

LNG, Reuters (Mar. 25, 2026), https://www.reuters.com/

business/energy/ceraweek-cheniere-already-operating-atmaximum-capacity-ceo-says-asia-calls-more-2026-03-25/

(last visited Mar. 30, 2026).

The lesson from these international conf licts is

straightforward: traditional carbon-emitting energy

sources remain critical to global supply chains and

international commerce. Global consumption of oil, natural

gas, and coal reached record highs last year. Shaffer,

supra.

The real question is where the supply to meet the

world’s surging energy needs will come from. That

depends in significant part on regulatory policy and

the outcome of the municipal climate cases. California

illustrates the regulatory point. After the state tightened

restrictions on in-state fossil-fuel production, residents

did not stop using oil and gas; they sourced it elsewhere.

Despite its substantial reserves, California now imports

roughly 60% of its crude oil from overseas, up from just 5%

in 1992. Cal. Energy Comm’n, Annual Oil Supply Sources

to California Refineries, https://www.energy.ca.gov/datareports/energy-almanac/californias-petroleum-market/

annual-oil-supply-sources-california (last visited Apr. 1,

2026).

10

The municipal climate cases risk placing American oil

and gas producers at a similar competitive disadvantage

vis-à-vis foreign suppliers, including Russia, Saudi Arabia,

Qatar, Iraq, and Iran. They would impose what amounts

to a carbon tax on the global use of American energy to

the detriment of the Nation’s foreign policy goals and

“carefully balanced scheme of international cooperation”

on the topic of global warming. City of New York v.

Chevron Corp., 993 F.3d 81, 103 (2d Cir. 2021). By taking

aim at global greenhouse gas emissions, the municipal

climate cases reach beyond state law “into the field of

foreign affairs which the Constitution entrusts to the

President and the Congress.” Zschernig v. Miller, 389 U.S.

429, 432 (1968). Such a blatant intrusion into the federal

government’s exclusive domain is incompatible with the

Foreign Affairs Doctrine and must be preempted.

ARGUMENT

I.

Municipal climate cases encroach on the federal

government’s exclusive authority over national

security and foreign policy.

The municipal climate cases run afoul of the Foreign

Affairs Doctrine for two reasons. They conflict with the

federal government’s express foreign policy and intrude

on the federal government’s exclusive domain without

addressing a traditional concern reserved to state and

local governments.

A.

The cases conflict with express federal foreign

policy.

The Constitution entrusts the conduct of foreign

affairs to the “to the President and the Congress.”

11

Zschernig, 389 U.S. at 432. The municipal climate cases

conflict with the express policies of both.

Federal law on international emissions is directed

toward reciprocity, multilateralism, and international

cooperation on emissions controls. The municipal climate

targets the global emissions from U.S. fossil fuel producers

without seeking reciprocal obligations from foreign energy

producers in violation of Congress’s express policies.

In the Clean Air Act, Congress authorizes the

Environmental Protection Agency (“EPA”) to address

domestic air pollutants that “cause or contribute to air

pollution which may reasonably be anticipated to endanger

public health or welfare in a foreign country.” 42 U.S.C.

§ 7415(a). Crucially, Congress limited the EPA’s authority

to mitigate cross-border air pollution in a critical respect.

The law prevents it from acting unless the affected foreign

nation has afforded the United States “the same rights

with respect to the prevention or control of air pollution

occurring in that country.” Id. § 7415(c). Absent such

reciprocity, the Clean Air Act’s regulatory reach is limited

to domestic emissions only. City of New York., 993 F.3d at

95 n.7, 100-01 (concluding that the Clean Air Act “plainly”

regulates only domestic emissions except when a foreign

state provides reciprocity).

Enacted in 1987, the Global Climate Protection Act

further reflects Congress’s judgment that climate policy

should not be formulated in a local vacuum, but instead

through a coordinated, multilateral process that accounts

for the Nation’s interests in the international arena. See

Pub. L. No. 100-204, Title XI, § 1103, 101 Stat. 1331, 1407–

09 (1987) (reprinted at 15 U.S.C. § 2901 note). The Act

12

articulates a federal policy of international cooperation to

understand and limit the adverse effects of greenhouse

gas emissions. It provides that the Nation should endeavor

to foster “cooperation among nations to develop more

extensive and coordinated scientific research efforts,”

identify technological solutions, and pursue “multilateral

agreements” to address greenhouse gas emissions. Id.

§ 1103(a)(2)-(4), 101 Stat. at 1408. Congress divided the

development of climate policy between the EPA and State

Department, with the former taking the lead on “national

policy” and the later spearheading international efforts

relating to climate. Id. § 1103(b)-(c), 101 Stat. at 1408-1409;

Massachusetts v. EPA, 549 U.S. 497, 534 (2007) (noting

that Congress tasked “the State Department—not [the

EPA]—to formulate United States foreign policy with

reference to environmental matters relating to climate”).

Since the passage of the Act, the federal executive

branch has been engaged in shaping foreign policy on

climate. In 1992, the President ratified, after advice and

consent from the Senate, the United Nations Framework

Convention on Climate Change of 1992 (“UNFCCC”).

S. Treaty Doc. No. 102-38, 1771 U.N.T.S. 107, https://

unfccc.int/resource/docs/convkp/conveng.pdf. Consistent

with the U.S. policy objectives set forth in the 1987 Act,

the UNFCCC established a cooperative regime under

which participating nations agreed to inventory their

greenhouse gas emissions and develop measures to limit

them. Id. art. 4. It likewise emphasized that climate policy

should be balanced against broader social and economic

objectives, rather than displacing other sound public

policies. As the treaty explains, “economic development

is essential for adopting measures to address climate

change.” Id. art. 3. It further provides that climate

13

measures should not “constitute a means of arbitrary or

unjustifiable discrimination or a disguised restriction on

international trade.” Id.

The UNFCCC calls for developed countries to

provide financial resources and technology to support

climate mitigation measures in developing countries.

UNFCCC, art 4.3. But the federal government has

resisted “the idea of compensation and liability” for

climate change impact. Todd Stern, Special Envoy for

Climate Change (Oct. 28, 2015), https://2009-2017.state.

gov/s/climate/releases/2015/248980.htm. In international

climate-change negotiations, the federal government has

maintained a longstanding position in opposition “to the

establishment of liability and compensation schemes” in

international climate-change negotiations. City of New

York, 993 F.3d at 103 n.11.

The United States did not ratify the Kyoto Protocol

of 1997 (the “Protocol”), which would have subjected it

to legally binding greenhouse gas emission limits. Kyoto

Protocol to the United Nations Framework Convention

on Climate Change annex B, Dec. 11, 1997, 2303 U.N.T.S.

162, https://unfccc.int/resource/docs/convkp/kpeng.pdf.

Instead, the Senate voted 95–0 to adopt a resolution

rejecting the Protocol as an unfair and counterproductive

approach to addressing global climate change. S. Res 98,

105th Cong. (1997). Known as the Byrd–Hagel Resolution

after its cosponsors—West Virginia Democrat Robert

Byrd and Nebraska Republican Chuck Hagel—the

measure criticized the Kyoto Protocol for departing

from the principles of international comity reflected in

the Global Climate Protection Act and the Framework

Convention. In particular, the Resolution objected that

14

the Protocol exempted “Developing Country Parties”—

including major emerging economies such as China and

India—even as their emissions were “rapidly increasing

and expected to surpass” those of the United States

and other developed nations. Id. The Resolution further

declared that the United States should not enter into any

future international climate agreement unless certain

conditions were met. Any such agreement, it stated, must

include “specific” emissions limitations for developing

countries, avoid “serious harm to the economy of the

United States,” and be accompanied by a “detailed”

assessment of the financial costs and economic impacts

of implementation. Id.

In 2016, Secretary of State John Kerry signed the

Paris Agreement, which required developed economies

such as the U.S. to “tak[e] the lead by undertaking

economy-wide absolute emission reduction targets.” Paris

Agreement, Dec. 12, 2015, T.I.A.S. No. 16-1104 art. IV.

Participating countries could adjust their emissions limits

but only in the direction of making them more strident.

Id. (providing that parties may adjust their targets “with

a view to enhancing [their] level of ambition”). The U.S.

withdrew from the agreement during the first term of

the Trump administration, then rejoined the agreement

during the Biden administration, only to withdraw from

it again during the Trump administration’s second

term. Press Release, U.S. Dept. of State, On the U.S.

Withdrawal from the Paris Agreement (Nov. 4, 2019);

Press Release, U.S. Dept. of State, The United States

Officially Rejoins the Paris Agreement (Feb. 19, 2021);

Lisa Friedman, America Officially Leaves the Paris

Climate Agreement. For the Second Time, N.Y. Times

(Jan. 27, 2026), https://www.nytimes.com/2026/01/27/

15

climate/paris-climate-agreement-withdrawal.html (last

visited Apr. 4, 2026).

Current U.S. foreign policy emphasizes the “strategic

value” of the U.S. energy sector as a means of enhancing

the nation’s international clout and limiting the influence

of adversaries abroad. Nat’l Sec. Strategy, supra. Apart

from withdrawing from the Paris Agreement, President

Trump has declared an affordable and reliable energy

supply “a fundamental requirement for the national and

economic security of any nation” and “essential to the

national and economic security of the United States, as

well as our foreign policy.” Declaring a National Energy

Emergency, Exec. Order 14156, § 1, 90 Fed. Reg. 8,433

(Jan. 20, 2025); Protecting American Energy from State

Overreach, Exec. Order 14260, § 1, 90 Fed. Reg. 15515

(Apr. 8, 2025). The president has appointed the Secretary

of State to the National Energy Dominance Council, a

newly formed group tasked with highlighting the “national

security concerns with removing reliable and affordable

energ y sources,” announced the administration’s

opposition to state-level climate measures that “dictate

interstate and international” air, water, and natural

resource policies, and stressed that fossil fuels, including

coal, are essential to protecting the electric grid and

protecting the homeland. Establishing the National

Energy Dominance Council, Exec. Order 14213, § 1, 90

Fed. Reg. 9,945 (Feb. 14, 2025); Exec. Order No. 14260,

§ 1, 90 Fed. Reg. at 15513; Strengthening United States

National Defense with America’s Beautiful Clean Coal

Power Generation Fleet, Exec. Order 14386 § 1, 91 Fed.

Reg. 7,393 (Feb. 11, 2026).

16

The municipal climate cases are impossible to

reconcile with the express foreign policy commitments

from Congress and the Executive Branch. Congress

opted against applying the Clean Air Act outside of

the U.S. with a lone exception for instances where the

cross-border pollution affects a country with a reciprocal

protections for the U.S. The municipal climate cases seek

recovery for international emissions without regard for the

principles of reciprocity set forth in the Clean Air Act and

“circumvent Congress’s own expectations and carefully

balanced scheme of international cooperation on a topic

of global concern.” City of New York, 993 F.3d at 103. The

cases conflict with the Global Climate Protection Act’s

stated goals for international climate policy, which commit

the federal government to pursuing “cooperation among

nations,” “multilateral agreements,” and “coordinated

national policy” on greenhouse gas emissions. Pub. L. No.

100-204, § 1103(a)-(b), 101 Stat. at 1408–09. They ignore

the Senate’s unanimous vote against the restrictive Kyoto

Protocol and the Byrd-Hegel Resolution’s policy against

international emissions controls that unfairly target the

U.S. or threaten to cause serious harm on the Nation’s

economy.

The conflict is even starker when the municipal

climate cases are considered against the Executive

Branch’s express foreign policy on energy under President

Trump. While previous administrations opposed “liability

and compensation schemes” to address international

emissions, City of New York, 993 F.3d at 103 n.11, the

Trump administration has elevated the strategic value of

energy in U.S. foreign policy. The municipal climate cases

undercut President Trump’s commitment to using the

Nation’s fossil fuel supply to strengthen foreign alliances

17

and project U.S. power abroad. These suits attempt to hold

American companies liable for worldwide usage of their

products and, therefore, threaten to increase the cost of a

resource that President Trump has deemed “essential to

the national and economic security of the United States,

as well as our foreign policy.” Exec. Order No. 14,156 § 1.

The Foreign Affairs Doctrine applies when there

is a “likelihood” that the actions of state “will produce

something more than incidental effect in conflict with

express foreign policy.” Garamendi, 539 U.S at 420.

Here, there a clear conflict that directly effects U.S.

foreign policy. The municipal climate cases eschew

the principles of international comity and multilateral

cooperation that have animated U.S. foreign policy on

climate for decades. Instead, they seek to regulate global

emissions through litigation a state-by-state patchwork

of conflicting emissions standards—the opposite of the

“coordinated national policy” that Congress envisioned

and the Executive Branch is actively implementing. See

Pub. L. No. 100-204, § 1103(b).

B. The cases intrude on the federal government’s

exclusive domain without addressing a

traditional state concern.

The municipal climate cases also fail because they

encroach on the federal government’s exclusive domain

over foreign affairs while addressing no traditional state

or local concern. The Framers assigned “foreign policy

exclusively to the National Government.” Garamendi,

539 U.S. at 419 n.11; Hines v. Davidowitz, 312 U.S.

52, 63 (1941) (providing that the federal government

possesses “full and exclusive responsibility” over foreign

18

affairs). The municipal climate cases address “a uniquely

international problem of national concern.” City of New

York, 993 F.3d at 85. And the sweeping relief that they

seek—damages for global emissions—is “simply beyond

the limit of state law.” Id. at 92.

In the Clean Air Act, Congress vested the EPA with

the authority to weigh the appropriate factors and set

national pollution standards. American Electric Power Co.

(AEP) v. Connecticut, 564 U.S. 410, 426 (2011) (explaining

that the Act authorizes the EPA to determine “whether

and how to regulate carbon-dioxide emissions”). The

Act entrusts the “complex balancing” needed for sound

emissions standards “to EPA in the first instance, in

combination with state regulators.” Id. at 427. While states

have a traditional role in implementing EPA standards,

they have no role under the Act in regulating interstate

or international emissions. Instead, state regulators

are authorized under the Act to collaborate with federal

regulators and adjust the generally applicable standards

set by EPA to align with local circumstances. Thus, each

state may “take the first cut at determining how best to

achieve EPA emissions standards within its domain.”

AEP, 564 U.S. at 438 (emphasis added).

Nor do the Act’s savings clauses permit the use

of state statutory or common law to regulate global

emissions. See 42 § 7604(e); id. § 7416. In International

Paper Co. v. Ouellette, the Court addressed the scope of

a similar savings clause in the context of an interstate

pollution dispute under the Clean Water Act. Ouellette

recognized a narrow exception to the Clean Air Act’s

complete preemption of state law. The Court permitted

state lawsuits under “the law of the [pollution]’s source [s]

19

tate,” allowing individuals injured by out-of-state pollution

to bring a lawsuit under state law. Ouellette, 479 U.S. 481,

497 (1987); see also AEP, 564 U.S. at 429. But the state

law invoked must be the law of the source state, not the

state where the alleged injury occurred. Id.

The municipal climate cases try to recover under

precisely the very type of state law claim that Ouellette

forecloses. Rather than sue under the law in effect at the

“source” of the carbon emissions—basically, every state

and country in the world—they proceed under the law of

their home states, the site of the alleged injuries occurred.

But in Ouellette, the Court squarely rejected the use of

the law where the alleged injury occurred on the grounds

that it would subject a single out-of-state “discharge” that

reached several states to multiple, potentially conflicting

state laws, generating a an “irrational” and “chaotic”

regulatory regime. Ouellette, U.S. 479 at 496-97. Further,

Ouellette also rejected the application of the law of the site

of the alleged injury because it allows that state to impose

its laws on the entire rest of the country and therefore “do

indirectly what [it] could not do directly—regulate the

conduct of out-of-state sources.” Id. at 495. If the law from

the state of the alleged injuries were used in the municipal

climate cases, as the plaintiffs propose, the irrationality

and chaos would be exponentially more extreme than in

Ouelette. The same carbon emissions could face liability

under the laws of all 50 states and individual states could

impose their state laws on emissions from the rest of the

Nation and world.

20

The municipal climate cases bear no resemblance

to the small carve out of state law cases that Ouellette

permitted under the Clean Air Act’s savings clause. Nor

are there any other cases that remotely suggest that

regulating “emissions emanating simultaneously from all

50 states and the nations of the world” is a responsibility

traditionally exercised by the states. City of New York, 993

F.3d at 100. Accordingly, these cases must be preempted.

CONCLUSION

For these reasons, this Court should reverse the

Colorado Supreme Court’s decision and maintain the

exclusive domain over foreign policy that the Constitution

assigns to the federal government.

Respectfully submitted,

Sarah Harbison

Counsel of Record

Pelican Center for Justice

Pelican Institute for

Public Policy

400 Poydras Street, Suite 900

New Orleans, LA 70130

(504) 500-0506

sarah@pelicaninstitute.org

Counsel for Amici Curiae