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 A WRIT OF CERTIORARI

TO THE SUPREME COURT OF COLORADO

___________

BRIEF OF AMICUS CURIAE

COALITION OF LARGE TRIBES

IN SUPPORT OF PETITIONERS

MICHAEL A. FRAGOSO

CHASE T. HARRINGTON

T. ZACH HORTON

TORRIDON LAW PLLC

801 Seventeenth Street N.W.,

Suite 1100

Washington, DC 20006

(202) 249-6900

JENNIFER H. WEDDLE

Counsel of Record

GREENBERG TRAURIG, LLP

1144 Fifteenth Street,

Suite 3300

Denver, CO 80202

(303) 572-6500

weddlej@gtlaw.com

MAY 21, 2026

Counsel for Amicus Curiae

II

TABLE OF CONTENTS

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

INTRODUCTION AND SUMMARY OF

ARGUMENT .............................................................. 2

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

I. Indian Tribes Are Inherently Sovereign, And

Their Lands’ Energy Resources Are Critical

To Their Sovereignty. ................................................. 5

A. Indian Tribes Retain Inherent Sovereignty

That Long Antedates Our Constitution.............. 6

B. Fossil Energy Reinforces Tribal Sovereignty. .. 7

II. Longstanding Federal Policy Strongly

Supports Tribal Energy Sovereignty. .................... 13

III. State Laws That Impede Federal Indian

Policy Or Interfere With Inherent Tribal

Sovereignty Violate Longstanding Indian

Preemption Doctrine. ............................................... 16

IV. State Attempts To Regulate Energy

Companies’ Contributions To Global

Emissions Are Void Because They Interfere

With Federal Indian Policy And Violate

Inherent Tribal Sovereignty. ................................... 25

CONCLUSION ............................................................... 30

III

TABLE OF AUTHORITIES

Page(s)

Cases

Am. Elec. Power Co. v. Connecticut,

564 U.S. 410 (2011) ....................................................... 28

Arizona v. Navajo Nation,

599 U.S. 555 (2024) (Gorsuch, J.,

dissenting) ....................................................................... 3

Atkinson Trading Co., Inc. v. Shirley,

532 U.S. 645 (2001) ......................................................... 7

Brown v. Fletcher’s Estate,

210 U.S. 82 (1908) ......................................................... 16

California v. Cabazon Band of Mission

Indians,

480 U.S. 202 (1987) ........................................... 21, 26, 27

City of Milwaukee v. Illinois,

451 U.S. 304 313 ............................................................ 28

Cotton Petroleum Corp. v. New Mexico,

490 U.S. 163 (1989) ............................................. 7, 23, 26

Crow Tribe of Indians v. Montana,

819 F.2d 895 (9th Cir. 1987) .................. 5, 26, 27, 28, 29

District of Columbia v. Exxon Mobil,

No. 2020-CA-002892-B (D.C. Sup. Ct.

June 25, 2020) ............................................................... 25

IV

Cases—continued

Fletcher v. United States,

730 F.3d 1206 (10th Cir. 2013) ...................................... 2

Fran. Tax Bd. of Cal. v. Hyatt,

587 U.S. 230 (2019) ................................................. 28, 29

Haaland v. Brackeen,

599 U.S. 255 (2023) ............................................... 4, 6, 17

Int’l Paper Co. v. Ouellette,

479 U.S. 481 (1987) ....................................................... 28

Kiowa Tribe of Oklahoma v. Mfg. Techs.,

523 U.S. 751 (1998) ....................................................... 16

Kodiak Oil & Gas (USA) Inc. v. Burr,

932 F.3d 1125 (8th Cir. 2019) ...................................... 27

Lac du Flambeau Band of Lake Superior

Chippewa Indians v. Coughlin,

599 U.S. 382 (2023) ............................................... 6, 7, 16

McClanahan v. State Tax Comm’n of Ariz.,

411 U.S. 164 (1973) ....................................................... 17

Merrion v. Jicarilla Apache Tribe,

455 U.S. 130 (1982) ................................................... 7, 26

Michigan v. Bay Mills Indian Cmty.,

572 U.S. 782 (2014) ............................. 7, 8, 17, 19, 25, 30

Montana v. Crow Tribe of Indians,

484 U.S. 997 (1988) ................................................... 4, 21

V

Cases—continued

Montana v. Crow Tribe of Indians,

523 U.S. 696 (1998) ....................................................... 23

Montana v. United States,

450 U.S. 544 (1981) ................................................... 5, 17

Nat’l Farmers Union Ins. Cos. v. Crow Tribe,

471 U.S. 845 (1985) ................................................... 6, 16

New Mexico v. Mescalero Apache Tribe,

462 U.S. 324 (1983) ..................................... 18, 19, 21, 28

Oklahoma v. Castro-Huerta,

597 U.S. 629 (2022) ..................................................... 3, 5

Santa Clara Pueblo v. Martinez,

436 U.S. 49 (1978) ......................................................... 16

United States v. Mazurie,

419 U.S. 544 (1975) ......................................................... 6

United States v. U.S. Fid. & Guar. Co.,

309 U.S. 506 (1940) ................................................. 16, 24

United States v. Wheeler,

435 U.S. 313 (1978) ............................................... 5, 6, 28

Upper Skagit Indian Tribe v. Lundgren,

584 U.S. 554 (2018) ....................................................... 13

Ute Indian Tribe of the Uintah & Ouray

Rsrv. v. Utah,

790 F.3d 1000 (10th Cir. 2015) ................................ 4, 16

VI

Cases—continued

Va. Uranium, Inc. v. Warren,

587 U.S. 761 (2019) ....................................................... 18

White Mountain Apache Tribe v. Bracker,

448 U.S. 136 (1980) ..................4, 7, 18, 19, 20, 26, 27, 28

Williams v. Lee,

358 U.S. 217 (1959) ................................................... 6, 17

Ysleta Del Sur Pueblo v. Texas,

596 U.S. 685 (2022) ................................................... 5, 16

Statutes

25 U.S.C. § 396g.................................................................. 26

25 U.S.C. § 2102(a) ............................................................. 27

25 U.S.C. § 2108 .................................................................. 27

Act of Feb. 20, 1893, ch. 148, 27 Stat. 470 ........................ 14

Act of Feb. 28, 1891, ch. 383, § 3, 26 Stat.

794 (codified at 25 U.S.C. § 397) ................................. 14

Act of July 1, 1898, ch. 542, 30 Stat. 567 .......................... 14

Act of June 18, 1934, ch. 576, 48 Stat. 984

(codified at 25 U.S.C. § 5101 et seq.) .......................... 13

Clean Air Act (CAA), 42 U.S.C. § 7401, et

seq. ................................................................................. 27

General Allotment Act, ch. 119, 24 Stat.

388 (1887)....................................................................... 13

VII

Statutes—continued

Indian Appropriations Act of 1871, ch. 120,

16 Stat. 544 (codified at 25 U.S.C. § 71) ..................... 13

Indian Energy Resources Act of 1992, Pub.

L. 102-486, tit. XXVI, 106 Stat. 3113 .......................... 15

Indian Gaming Regulatory Act, 102 Stat.

2467 (1988) (codified at 25 U.S.C. § 2701

et seq.) ............................................................................ 21

Indian Mineral Leasing Act of 1938, ch.

198, 52 Stat. 347 (codified at 25 U.S.C.

§§ 396a–396g) ................................................................ 14

Indian Tribal Energy Development and

Self-Determination Act of 2005, Pub. L.

109-58, tit. V, 119 Stat. 764 (codified at

25 U.S.C. §§ 3501–3506)............................................... 15

Indian Tribal Energy Development and

Self-Determination Act Amendments of

2017, Pub. L. 115-325, 132 Stat. 4445 ......................... 15

Indian Mineral Development Act, Pub. L.

97-382, 96 Stat. 1938 (codified at 25

U.S.C. §§ 2101–2108) ................................................... 14

Treaty with the Sauk and Foxes, Sept. 21,

1832, 7 Stat. 374 ............................................................ 13

Treaty with the Shoshoni-Goship, Oct. 12,

1863, 13 Stat. 681 .......................................................... 13

VIII

Statutes—continued

Surface Mining Control and Reclamation

Act of 1977, 30 U.S.C. § 1201 et seq.

(1982) ............................................................................. 23

Treaty with the Chippewa, Aug. 5, 1826, 7

Stat. 290 ......................................................................... 13

Constitutional Provisions

U.S. CONST. art. I, § 8, cl. 3 ........................................... 6, 17

U.S. CONST. art. I., § 10 ..................................................... 28

Other Authorities

25 C.F.R. § 212.1(a) ............................................................ 27

About Us, RED CEDAR GATHERING CO.,

redcedargathering.com ............................................... 10

About Us, RED WILLOW PRODUCTION CO.,

rwpc.us........................................................................... 10

Andrew Curley, CARBON SOVEREIGNTY:

COAL, DEVELOPMENT, AND ENERGY

TRANSITION IN THE NAVAJO NATION

(Univ. of Ariz. Press 2023) ............................................. 9

BHP Billiton to Sell Mine to Navajo

Nation, MINING ENGINEERING (Dec.

20, 2012), tinyurl.com/NN-Mine ................................. 12

IX

Other Authorities—continued

Business, SOUTHERN UTE INDIAN TRIBE,

tinyurl.com/S-Ute-Biz .................................................... 9

Comment Letter on Tax Treatment of

Tribally-Chartered Corporations and

Other Entities Organized by Tribes

Under Tribal Law (Aug. 18, 2023),

perma.cc/2YEM-KJ35 ................................................... 7

David Williams, THE GEORGIA GOLD

RUSH: TWENTY-NINERS, CHEROKEES,

AND GOLD FEVER (Univ. of S.C. Press

1993) ................................................................................. 3

Economic Development, UTE MOUNTAIN

UTE TRIBE, tinyurl.com/Ute-Mt-EcDev ................... 12

Federalist Soc’y, Can State Courts Set

Global Climate Policy?, YOUTUBE

(Oct. 8, 2025), tinyurl.com/FedSocBookbinder.................................................................... 25

Indian Energy Development: Poor

Management by BIA Has Hindered

Energy Development on Indian Lands

(2015), tinyurl.com/GAO-BIA-Rpt ............................. 24

Matthew L.M. Fletcher, In Pursuit of

Tribal Economic Development as a

Substitute for Reservation Tax

Revenue, 80 N.D. L. Rev. 759 (2004) ............................ 8

X

Other Authorities—continued

U.S. Dep’t of the Interior, Off. of Nat. Res.

Revenue, Natural Resources Revenue

Data (2025), perma.cc/KV9J-7H8W............................. 9

Navajo Transitional Energy Co., 2024

Operational Report (July 2025),

tinyurl.com/NTEC-Rpt-24 .......................................... 12

Phil Davies, Homeland of Opportunity,

Fed Gazette, Fed. Rsrv. Bank of

Minneapolis (Oct. 2014),

tinyurl.com/Fed-Gaz-Bakken ....................................... 9

Rennard Strickland, Osage Oil: Mineral

Law, Murder, Mayhem, and

Manipulation, 10 Nat. Res. & Env’t 39

(1995) ............................................................................... 3

U.S. Dep’t of Health & Human Servs.,

Admin. for Children & Families,

REPORT TO CONGRESS ON THE SOCIAL

AND ECONOMIC CONDITIONS OF

NATIVE AMERICANS: FISCAL YEAR

2019 (Jan. 18, 2023), tinyurl.com/NAPovty ................................................................................ 8

Ronald Reagan, Statement on Indian

Policy, 19 Weekly Comp. of Pres. Doc.

99 (1983), tinyurl.com/ReaganPolicy .......................... 14

XI

Other Authorities—continued

Rudy Montoya, SHIFTING FROM FOSSIL

FUEL RELIANCE TO GREEN ENERGY

SOVEREIGNTY: UTE MOUNTAIN UTE

TRIBE, Sandia Nat’l Lab’ys, No.

SAND2022-16503 (Nov. 2022),

tinyurl.com/sandia-rprt ............................................... 12

Shawn E. Regan & Terry L. Anderson,

The Energy Wealth of Indian Nations,

3 LSU J. Energy L. & Resources 193

(2014) ............................................................................... 8

Sierra Crane-Murdoch, The Other Bakken

Boom, HIGH COUNTRY NEWS (Apr. 23,

2012), tinyurl.com/Bakken-Boom ............................... 11

Southern Utes Take Energy Destiny in

Hands, Become Major Coalbed

Methane Producer in Colorado,

NATURAL GAS INTELLIGENCE (Sept.

27, 2004), tinyurl.com/NGI-Article ............................... 9

U.S. Dep’t of Energy (DOE), Off. of Indian

Energy (OIE), STRENGTHENING

TRIBAL COMMUNITIES, SUSTAINING

FUTURE GENERATIONS, No. DOE/IE0038 (Aug. 2017), tinyurl.com/DOEOIE .................................................................................. 5

U.S. Dep’t of Interior, Bakken Formation

Oil Assessment in North Dakota (May

19, 2011), tinyurl.com/DOI-Bkn-PR ........................... 10

XII

Other Authorities—continued

U.S. Env’t Prot. Agency, Region 6, Federal

Synthetic Minor New Source Review

Permit, No. R6NSR-NM-004 (July 13,

2017), perma.cc/KLG7-ZHFP..................................... 25

INTEREST OF AMICUS CURIAE

Established in 2011, the Coalition of Large Tribes

(COLT),1 represents the interests of more than 50 Indian

tribes with reservations encompassing 100,000 acres or

more, some the size of states like Delaware and West Virginia, including the Navajo Nation, Crow Tribe, Blackfeet

Nation, Shoshone-Bannock Tribes, Spokane Tribe, Sisseton-Wahpeton Sioux Tribe, Mandan, Hidatsa and Arikara

Nations, Rosebud Sioux Tribe, the Northern Arapaho

Tribe, and others. All told, COLT’s members manage

over 50 million acres—over 78,000 square miles—across

dozens of Indian reservations, a cumulative landmass

larger than each of 38 of the 50 states.

COLT’s mission is to defend its member tribes’ inherent sovereign and treaty rights and to promote the health

and welfare of tribal citizens. Many COLT member tribes

own or manage substantial fossil-energy interests on

tribal lands, which collectively contain more than 20% of

U.S. oil and gas reserves and more than 30% of the nation’s coal reserves west of the Mississippi. These valuable energy interests bolster tribal sovereignty through financial and energy independence, and they promise to lift

many tribe members out of poverty. COLT cares about

tribal sovereignty and reducing Indian poverty, and both

interests would be harmed if the decision below were affirmed.

No counsel for any party authored this brief in any part, and no person or entity other than amicus made a monetary contribution to fund

its preparation or submission. See Sup. Ct. R. 37.6.

1

(1)

2

INTRODUCTION AND SUMMARY OF ARGUMENT

This case presents a dramatic example of overweening

state and local attempts to regulate global greenhouse gas

emissions. Petitioners and fellow amici amply explain how

these attempts by Respondents and similar jurisdictions

to bankrupt the national fossil-energy industry trench on

the sovereign power of coequal states and the federal government. But that is not all. Respondents’ aggressive use

of state tort law also interferes with Indian sovereignty

and violates longstanding Indian preemption doctrine.

For these reasons too, the decision below must be reversed.

*

The early history of Indians and their lands’ mineral

wealth is rife with injustice. Over the past century, however, many tribes have finally begun to enjoy the benefits

of their energy resources. These tribes’ substantial reserves of oil, gas, and coal have brought them muchneeded revenue for self-government and the promise of

economic security for their people—in a word, sovereignty. But their sovereignty now faces a new threat from

states and localities hostile to the fossil-energy industry.

The history of the Osage Nation is illustrative. “After

settlers displaced the Osage … from [their] native lands,

the federal government shunted the tribe onto the open

prairie in Indian Territory.” Fletcher v. United States,

730 F.3d 1206, 1207 (10th Cir. 2013) (Gorsuch, J.). “At the

time, the government had no idea those grasslands were

to prove a great deal more fertile than they appeared.

Only years later did the Osages’ mammoth reserves of oil

and gas make themselves known.” Id. And when that

black gold was discovered, mayhem soon followed:

3

Rapacious settlers stole Osage “headrights” to mineral

wealth, murdering as much as three percent of the entire

Osage people in the process—an outrage that “history has

come to call ‘the Osage reign of terror.’” See Rennard

Strickland, Osage Oil: Mineral Law, Murder, Mayhem,

and Manipulation, 10 Nat. Res. & Env’t 39, 42 (1995); see

also Oklahoma v. Castro-Huerta, 597 U.S. 629, 668 (2022)

(Gorsuch, J., dissenting) (noting that “many [Oklahoma]

settlers engaged in schemes to seize Indian lands and

mineral rights by subterfuge”); cf. KILLERS OF THE

FLOWER MOON (Apple Studios 2023).

The gross injustice visited upon the Osage in Oklahoma magnifies the tragic and all-too-common relationship between Indians and their land’s mineral wealth well

into the early twentieth century. When gold was discovered on their ancestral lands in Georgia, the Cherokee

were sent on the infamous Trail of Tears to the seemingly

barren grasslands of Oklahoma. See generally David Williams, THE GEORGIA GOLD RUSH: TWENTY-NINERS,

CHEROKEES, AND GOLD FEVER (Univ. of S.C. Press 1993).

And when “precious as well as other useful metal” was

“said to abound” on their lands, the Navajo were sent on

“the Long Walk” to a “a semiarid, alkaline, fuel-stingy, insect-infested” wasteland. Arizona v. Navajo Nation, 599

U.S. 555, 576 (2024) (Gorsuch, J., dissenting) (quotations

omitted).

The recurring storyline is clear: An Indian tribe had

land; that land had mineral wealth; so the tribe was removed and sent to what was considered worthless wasteland. But worthless it was not. Many of these tribes’ ostensibly barren reservations bore a tremendous wealth of

energy resources beneath the surface. And over the better part of the last century, tribes like those in amicus

COLT have wrested value from lands once dismissed as

4

valueless in the form of coal, oil, and gas. These crucial

natural resources have become the lifeblood of tribal sovereignty, providing tribes with a critical source of income

with which to provide essential government services independent of federal funding.

History now threatens to repeat itself. Tribal mineral

wealth is again under attack. But this time, the attack

comes not from pillaging prospectors who want the tribes’

minerals for themselves. Rather, the threat today comes

from hostile states and localities—like Respondents—

whose aggressive use of state tort and consumer-protection law would severely restrict, if not forbid, tribes and

their energy-industry partners from developing tribal

fossil-fuel resources.

Inherent tribal sovereignty and federal law, however,

interpose “two independent barriers” to these rogue jurisdictions’ overbroad “assertion[s] of state regulatory authority.” White Mountain Apache Tribe v. Bracker, 448

U.S. 136 (1980). A key “corollary of [tribes’ inherent] sovereignty” is that “States have virtually no role to play

when it comes to Indian affairs.” Haaland v. Brackeen,

599 U.S. 255, 304 (2023) (Gorsuch, J., concurring). Moreover, given the “paramount federal policy of ensuring that

Indians do not suffer interference with their efforts to develop strong self-government,” Ute Indian Tribe of the

Uintah & Ouray Rsrv. v. Utah, 790 F.3d 1000, 1007 (10th

Cir. 2015) (Gorsuch, J.) (citation modified), contrary state

policies must yield under longstanding principles of Indian preemption. Respondents and jurisdictions like

them unabashedly aim to bankrupt the fossil-fuel industry

over its alleged contributions to global greenhouse-gas

emissions. But that would interfere with tribes’ sovereignty, and it would thwart overarching federal policy favoring tribal self-government and mineral development.

5

See generally Crow Tribe of Indians v. Montana, 819

F.2d 895 (9th Cir. 1987), summarily aff’d sub nom. Montana v. Crow Tribe of Indians, 484 U.S. 997 (1988). Accordingly, Respondents’ claims cannot stand.

ARGUMENT

I. Indian Tribes Are Inherently Sovereign, And Their

Lands’ Energy Resources Are Critical To Their

Sovereignty.

“Native American Tribes possess inherent sovereign

authority over their members and territories.” Ysleta Del

Sur Pueblo v. Texas, 596 U.S. 685, 689 (2022) (Gorsuch,

J.) (quotation omitted); accord Castro-Huerta, 597 U.S. at

668 (Gorsuch, J., dissenting) (“Tribes are sovereigns.”). A

core aspect of that inherent sovereign authority is to ensure “the economic security … of the tribe.” Montana v.

United States, 450 U.S. 544, 566 (1981). Tribal lands are

exceptionally rich in natural resources, especially fossilenergy resources like oil, gas, and coal. See U.S. Dep’t of

Energy (DOE), Off. of Indian Energy (OIE), STRENGTHENING TRIBAL COMMUNITIES, SUSTAINING FUTURE GENERATIONS 2, No. DOE/IE-0038 (Aug. 2017), tinyurl.com/DOE-OIE (OIE Report).2 This tremendous

natural wealth offers historically impoverished tribes the

opportunity to achieve energy independence and financial

security for self-government—an opportunity that many

tribes have readily embraced. Prudent stewardship and

development of their land’s abundant resources is thus

critical to tribal sovereignty.

2

Many COLT member tribes believe that this report significantly underestimates tribal mineral resources.

6

A. Indian Tribes Retain Inherent Sovereignty

That Long Antedates Our Constitution.

Indigenous peoples have populated the lands of the

present-day United States for at least 23,000 years. See

Nat’l Park Serv., White Sands Nat’l Park, Fossilized

Footprints (last updated Jan. 27, 2026), tinyurl.com/23Myears. Over millennia, these native peoples formed communities and governed themselves as tribes. See United

States v. Wheeler, 435 U.S. 313, 322–23 (1978) (“Before the

coming of the Europeans, the tribes were self-governing

sovereign political communities.”); see Haaland, 599 U.S.

at 309 (Gorsuch, J., concurring) (quotation omitted) (noting that, “years before Jamestown,” tribes “employed sophisticated governmental models, formed confederacies

with one another, and often engaged in decisionmaking by

consensual agreement” (citation modified)). From the beginning, tribes were sovereign political bodies, capable of

and entitled to self-rule.

When British colonists landed on American shores,

they “regarded the Indians as owners of their land.” Id.

at 304 (Gorsuch, J., concurring) (quotation omitted). The

Crown, as the English sovereign, made treaties with the

Indian tribes—sovereign-to-sovereign. Id. at 308–09.

And after the American Revolution, “the new Republic

broadly recognized the sovereignty of Indian Tribes, even

if it did so sometimes grudgingly.” Id. at 309 (citation

modified). The Constitution’s text and the Framers’ early

practice confirm the tribes’ sovereign status. Id. at 310–

11 (citing, e.g., U.S. CONST. art. I, § 8, cl. 3, id. § 2, cl. 3.,

and letters from George Washington’s Secretary of War

Henry Knox and Thomas Jefferson); accord Lac du

Flambeau Band of Lake Superior Chippewa Indians v.

Coughlin, 599 U.S. 382, 407 (2023) (Gorsuch, J., dissenting).

7

Today, Indian tribes continue to “occupy a unique status” in our law. See Nat’l Farmers Union Ins. Cos. v.

Crow Tribe, 471 U.S. 845, 851 (1985). As pre-Constitutional entities that had been “separate nations,” Williams

v. Lee, 358 U.S. 217, 218 (1959), tribes retain a certain sovereignty like that of foreign nations—a sovereignty that

“has never been extinguished.” Wheeler, 435 U.S. at 322

(quoting F. Cohen, Handbook of Federal Indian Law 122

(1945) (emphasis omitted)); see also United States v. Mazurie, 419 U.S. 544, 557 (1975) (“Indian tribes are unique

aggregations possessing attributes of sovereignty over

both their members and their territory.”). But unlike foreign nations, tribes exist within our country’s borders like

states. Yet “Tribal reservations are not States,” Bracker,

448 U.S. at 143, either; they exist within states, although

many straddle state lines. In sum, tribes are “neither politically foreign nor domestic”—they exist in the twilight

zone somewhere in between. Lac du Flambeau, 599 U.S.

at 407 (Gorsuch, J., dissenting).

B. Fossil Energy Reinforces Tribal Sovereignty.

Generating revenue is “an essential attribute of Indian

sovereignty.” See Merrion v. Jicarilla Apache Tribe, 455

U.S. 130, 137 (1982). Each tribe has “general authority,

as sovereign, to control economic activity within its jurisdiction, and to defray the cost of providing governmental

services.” Id. (holding that tribe had inherent power to

tax on-reservation oil-and-gas production).

Yet “Tribes face a number of barriers to raising revenue in traditional ways” like taxing property or income.

Michigan v. Bay Mills Indian Cmty., 572 U.S. 782, 807

(2014) (Sotomayor, J., concurring). For one thing, because states can tax non-Indian business activity on tribal

lands, tribes that tax on top risk deterring business with

double taxation. See Cotton Petroleum Corp. v. New

8

Mexico, 490 U.S. 163, 188–89 (1989); id. at 208–09

(Blackmun, J., dissenting); cf. Atkinson Trading Co., Inc.

v. Shirley, 532 U.S. 645, 659 (2001) (imposing limits on

tribal taxing power).3 For another, tribes have long suffered from endemic poverty and lack of opportunity, so

tribe members typically do not have much taxable income,

if any. See U.S. Dep’t of Health & Human Servs., Admin.

for Children & Families, REPORT TO CONGRESS ON THE

SOCIAL AND ECONOMIC CONDITIONS OF NATIVE AMERICANS: FISCAL YEAR 2019, at 7 (Jan. 18, 2023), tinyurl.com/NA-Povty (historical Indian poverty rate is

double the national average). “As a result, ‘there is no stable tax base on most reservations.’” Bay Mills, 572 U.S.

at 813 (Sotomayor, J., concurring) (quoting Matthew L.M.

Fletcher, In Pursuit of Tribal Economic Development as

a Substitute for Reservation Tax Revenue, 80 N.D. L.

Rev. 759, 774 (2004)).

So tribes have had to develop new ways to generate

income to “fund a more substantial portion of their own

governmental functions,” and “commercial enterprises”

have proven “a central means of achieving that goal.” Id.

at 807 (Sotomayor, J., concurring). For this reason,

tribes’ commercial enterprises “cannot be understood as

mere profit-making ventures that are wholly separate

from the Tribes’ core governmental functions.” Id. at 810.

Rather, “tribal business operations are critical to the

goals of tribal self-sufficiency,” and indeed, tribal sovereignty. Id.

3

Although beyond the scope of this amicus brief, it is COLT’s position

that much of the body of Indian tax law that has developed is unjust

and unconstitutional. See Coalition of Large Tribes, Comment Letter

on Tax Treatment of Tribally-Chartered Corporations and Other

Entities Organized by Tribes Under Tribal Law (Aug. 18, 2023),

perma.cc/2YEM-KJ35.

9

Development of natural resources on tribal lands—especially fossil-energy resources—are among the most significant of tribes’ sovereign commercial enterprises. The

opportunity is clear: Tribal lands amount to only about 2%

of the United States, but they “contain almost 30% of the

coal reserves west of the Mississippi … and 20% of known

oil and gas reserves”—and likely much more. OIE Report, supra, at 2; see supra n.2. As tribes discovered their

lands’ subterranean wealth over the twentieth century,

many capitalized on the opportunity to bolster their sovereignty. See Shawn E. Regan & Terry L. Anderson, The

Energy Wealth of Indian Nations, 3 LSU J. Energy L. &

Resources 193, 207 & tbl. 1 (2014) (identifying “major energy resource tribes”); Andrew Curley, CARBON SOVEREIGNTY: COAL, DEVELOPMENT, AND ENERGY TRANSITION IN THE NAVAJO NATION 6 (Univ. of Ariz. Press 2023)

(“[I]n the twentieth century … [fossil fuel] industries

emerged as the basis of sovereignty for many Native nations.”).

Fast-forward to today: In 2025 alone, tribal lands produced over 373 million cubic feet of natural gas, 73 million

barrels of oil, and 4 million tons of coal. See U.S. Dep’t of

the Interior (DOI), Off. of Nat. Res. Revenue, Natural

Resources Revenue Data (2025), perma.cc/KV9J-7H8W.

The revenue from this tremendous volume of tribal energy production has redounded to the benefit of the

tribes, which have grown “more sovereign by the barrel.”

Phil Davies, Homeland of Opportunity, at 19, FED GAZETTE, Fed. Rsrv. Bank of Minneapolis (Oct. 2014), tinyurl.com/Fed-Gaz-Bakken (quoting former tribal chairman).

Many of amicus COLT’s member tribes have taken advantage of their lands’ fossil-energy resources to fund

10

their sovereign self-government and to bring their people

economic security. To name just a few:

•

The Southern Ute Indian Tribe—based in Colorado

almost due south of Respondent Boulder—is among

the top oil-and-gas-producing tribes in the country.

See Business, SOUTHERN UTE INDIAN TRIBE, tinyurl.com/S-Ute-Biz (last visited May 18, 2026);

Southern Utes Take Energy Destiny in Hands, Become Major Coalbed Methane Producer in Colorado,

NATURAL GAS INTELLIGENCE (Sept. 27, 2004), tinyurl.com/NGI-Article (“The Southern Ute tribe is

considered the ‘most successful in energy’ of all the

Native American tribes.”). Roughly 60 fossil-fuel producers have operated on Southern Ute lands and paid

the tribe millions in royalties. Id.

The Southern Ute Indian Tribe also owns two production companies. Over three decades ago, the tribe

formed Red Willow Production Company “to take

greater control over the Tribe’s energy resources.”

About Us, RED WILLOW PRODUCTION CO., rwpc.us

(last visited May 18, 2026). Today, Red Willow has interests in more than 1,800 wells across three states

and offshore in the Gulf of Mexico. Id. (home page).

The Southern Ute Indian Tribe also formed and controls Red Cedar Gathering Company, which collects

natural gas from over 1,200 wells on tribal lands.

About Us, RED CEDAR GATHERING CO., redcedargathering.com (last visited May 18, 2026).

•

The Mandan, Hidatsa, and Arikara (MHA) Nation,

also known as the Three Affiliated Tribes, is located in

the heart of the Bakken Formation, a region containing a “world-class accumulation” of recoverable oil—

the “largest continuous oil accumulation ever assessed

by the [U.S. Geological Survey].” U.S. DOI, Bakken

11

Formation Oil Assessment in North Dakota (May 19,

2011), tinyurl.com/DOI-Bkn-PR. The MHA Nation

embraced its fossil-energy wealth: The Fort Berthold

Reservation produces about 100 million barrels of

crude oil per year, yielding more than $1.5 billion for

the Nation. See Boom in Native American Oil Complicates Biden Climate Push, FLATHEAD BEACON,

Associated Press (June 25, 2021), tinyurl.com/FlthdBcn. This much-needed income has enabled the Nation to invest in “infrastructure development, including $24 million to reconstruct a key road artery; $30

million for housing, streets and utilities; … $6 million

for sewer systems,” and “$14 million [for a] K-12

school.” Davies, supra, at 18–19.

The MHA Nation regards its oil as critical to tribal

sovereignty. Before the North Dakota Legislature,

for instance, former MHA Nation Chairman Tex Hall

professed Nation’s “firm belief [that] we will become

more sovereign by the barrel.” Id. at 19. And the Nation’s wholly-owned energy company, Missouri River

Resources—“dedicated to developing oil and gas resources for the benefit of the Three Affiliated Tribes

membership”—proclaims as its motto: “Sovereignty

by the barrel.” MISSOURI RIVER RESOURCES, missouririverresources.com (last visited May 19, 2026); see

also Sierra Crane-Murdoch, The Other Bakken Boom,

HIGH COUNTRY NEWS (Apr. 23, 2012), tinyurl.com/Bakken-Boom.

•

The Navajo Nation has developed uranium, oil and

gas, and coal across six Western states. Oil production

on Navajo lands dates to the 1920s and has been central to the Nation’s independence and sense of identity

ever since. History, Navajo Nation, tinyurl.com/NNHstry (last visited May 19, 2026). Indeed, oil is so

12

central to modern Navajo sovereignty that the Nation’s flag features “an oil derrick symbolizing the resource potential of the Tribe.” Id. Today, the Nation

owns and operates two energy companies: (1) Navajo

Nation Oil and Gas Co. (NNOG), the “mission” of

which is “[m]aximizing resources for the benefit of the

Navajo Nation,” NAVAJO NATION OIL & GAS CO.,

nnogc.com (last visited May 19, 2026) (NNOG Website); and (2) Navajo Transitional Energy Co. (NTEC),

which the tribe expressly “established … to exercise

sovereignty over its abundant natural resources,”

NAVAJO TRANSITIONAL ENERGY CO., navenergy.com

(last visited May 19, 2026) (NTEC Website).

NNOG has engaged in upstream, midstream, and

downstream oil-and-gas operations in Colorado, New

Mexico, and Utah for nearly thirty years. NNOG

Website, supra, at “Home” & “What We Do.” Approximately 428 million barrels have been pumped from

577 wells in the Navajo Nation. Id. at “Company History.” Meanwhile, in 2013, NTEC bought Navajo

Mine, a 33,000-acre coal mine on tribal land in New

Mexico that serves the Four Corners Power Plant (in

which NTEC also has an interest). A spokesman for

the Navajo President characterized this deal as “about

Navajo Nation sovereignty, we’re talking about owning our assets.” BHP Billiton to Sell Mine to Navajo

Nation, MINING ENGINEERING (Dec. 20, 2012), tinyurl.com/NN-Mine; see Curley, supra, at 73–74 (explaining that “Navajo sovereignty was built on fossil

fuels”). Between the Navajo Mine and other coal mining operations in Wyoming and Montana, NTEC contributed almost $130 million in royalties, taxes, wages,

and community-building funds to the Nation in 2024

alone. NTEC, 2024 OPERATIONAL REPORT 6 (July

2025), tinyurl.com/NTEC-Rpt-24.

13

•

The Crow Tribe is a historic coal producer in Montana.

It owns coal rights on more than 150,000 acres held in

federal trust and an estimated 1.4 billion tons of coal

beneath its reservation. Empowering Indian Country: Coal, Jobs, and Self-Determination: Field Hearing Before the S. Comm. on Indian Affairs, S. Hrg.

No. 114-42, 114th Cong. 11 (2015) (statement of Crow

Nation Chairman Darrin Old Coyote). The Crow Nation has publicly championed coal mining and export

abroad. See id.

•

The Ute Mountain Ute Tribe extracts oil, gas, and coal

across Utah, Colorado and New Mexico. See Ute

Mountain Tribe – 2012 Project, U.S. DOE, OIE Pol’y

& Programs, tinyurl.com/Ute-DOE (June 2012). The

tribe has relied on oil and natural gas for critical economic support for over 70 years. Rudy Montoya,

SHIFTING FROM FOSSIL FUEL RELIANCE TO GREEN

ENERGY SOVEREIGNTY: UTE MOUNTAIN UTE TRIBE

11, Sandia Nat’l Lab’ys, No. SAND2022-16503 (Nov.

2022), tinyurl.com/sandia-rprt. Besides funding essential government services, the tribe’s oil and gas

royalties and severance taxes have seeded six new enterprises to diversify the tribe’s income and to expand

the job market for tribe members. Id.; see Economic

Development, UTE MOUNTAIN UTE TRIBE, tinyurl.com/Ute-Mt-EcDev (last visited May 18, 2026).

II. Longstanding Federal Policy Strongly Supports

Tribal Energy Sovereignty.

Federal Indian mineral and energy policy has long

recognized tribal energy sovereignty.

From the earliest years of the Republic, the federal

government generally recognized tribes’ sovereignty over

valuable mineral resources. Indeed, from 1826 to 1871,

14

the United States entered into a series of treaties that explicitly addressed tribal mineral interests. See, e.g.,

Treaty with the Chippewa, Aug. 5, 1826, 7 Stat. 290, Art.

III; Treaty with the Sauk and Foxes, Sept. 21, 1832, 7

Stat. 374, Art. XI; Treaty with the Shoshoni-Goship, Oct.

12, 1863, 13 Stat. 681, Art. IV; Indian Appropriations Act

of 1871, ch. 120, § 1, 16 Stat. 544, 566 (codified at 25 U.S.C.

§ 71) (ending the treaty era).

The following six decades were marked by the disastrous federal policy of “allotment,” under which tribal

lands were parceled out to individual Indians in an attempt “to extinguish tribal sovereignty, erase reservation

boundaries, and force the assimilation of Indians into the

society at large.”

Upper Skagit Indian Tribe v.

Lundgren, 584 U.S. 554, 558 (2018) (Gorsuch, J.) (quotation omitted) (discussing the General Allotment Act, ch.

119, 24 Stat. 388 (1887)). But “[i]n 1934, Congress reversed course,” enacting “the Indian Reorganization Act

to restore the principles of tribal self-determination and

self-governance that prevailed before the General Allotment Act,”—principles that animate federal Indian law to

this day. Id.; see Act of June 18, 1934, ch. 576, 48 Stat. 984

(codified at 25 U.S.C. § 5101 et seq.).

Even amid the failed policy of allotment, Congress periodically acted to protect or formalize tribal mineral interests. See, e.g., Act of Feb. 28, 1891, ch. 383, § 3, 26 Stat.

794, 795 (codified at 25 U.S.C. § 397) (first statute providing for Indian mineral leasing); Act of Feb. 20, 1893, ch.

148, 27 Stat. 470 (ratifying agreements authorizing oil and

gas exploration on Seneca reservation); Act of July 1,

1898, ch. 542, 30 Stat. 567 (similar, with Seminole Nation).

And shortly after allotment ended, Congress enacted the

Indian Mineral Leasing Act of 1938 (IMLA), which created a uniform framework for mineral leasing on tribal

15

trust lands, albeit subject to federal approval. Act of May

11, 1938, ch. 198, 52 Stat. 347 (codified at 25 U.S.C. §§

396a–396g).

Fast-forward to 1982: Indian energy production accelerated swiftly with Congress’s passage of the Indian Mineral Development Act (IMDA), which authorized tribes to

negotiate and enter into mineral agreements with greater

autonomy. Pub. L. 97-382, 96 Stat. 1938 (codified at 25

U.S.C. §§ 2101–2108). The following year, President

Reagan underscored the underlying policy of the IMDA

with his canonical statement on modern federal Indian

policy.

President Reagan announced that “[t]he Federal role

is to encourage the production of energy resources” on Indian lands, because “both the Indian tribes and the Nation

stand to gain from the prudent development and management of the vast coal, oil, [and] gas … resources found”

there. Ronald Reagan, Statement on Indian Policy, 19

Weekly Comp. of Pres. Doc. 99 (1983), tinyurl.com/ReaganPolicy. Energy resource development

“is important to the concept of [Indian] self-government,”

he explained, because it enables tribes to “reduce their dependence on Federal funds,” and it promotes “sound reservation economies,” without which, “the concept of selfgovernment has little meaning.” Id.

From the 1980s to the present, Congress built out a

statutory framework on the bedrock principle of Indian

energy sovereignty. See Indian Energy Resources Act of

1992, Pub. L. 102-486, tit. XXVI, 106 Stat. 3113 (promoting tribes’ vertical integration of energy development, enabling them not only to extract resources but to process

and market them too); Indian Tribal Energy Development and Self-Determination Act of 2005, Pub. L. 109-58,

tit. V, 119 Stat. 764 (codified at 25 U.S.C. §§ 3501–3506)

16

(authorizing “Tribal Energy Resource Agreements”

(TERAs), which enable tribes to advance energy development without federal approval—a dramatic departure

from over a century of paternalistic federal oversight); Indian Tribal Energy Development and Self-Determination

Act Amendments of 2017, Pub. L. 115-325, 132 Stat. 4445

(streamlining the TERA process).

In short, over the last century, Congress has progressively and deliberately dismantled the paternalistic controls that once kept tribes from fully exercising sovereignty over their own energy resources. And since President Reagan’s watershed 1983 statement, executive policy has strongly supported Indian self-government and

energy sovereignty. See, e.g., Remarks by President

Trump and Secretary of Energy Rick Perry at Tribal,

State, and Local Energy Roundtable (June 28, 2017), tinyurl.com/DJT-Indian-NRG (“[R]estrictions and regulations that put [tribal] energy wealth out of reach” are “infringements on tribal sovereignty [that] are deeply unfair

to … Native American communities who are being denied

access to the energy and wealth that they have on their

own lands.”).

III. State Laws That Impede Federal Indian Policy Or

Interfere With Inherent Tribal Sovereignty Violate Longstanding Indian Preemption Doctrine.

Tribal sovereignty limits state power. It does so in

three important ways, which mirror tribes’ unique status

as neither foreign nations nor states in the union, but rather as separate, “self-governing political communities”

under the protection of the federal government. Nat’l

Farmers, 471 U.S. at 851; cf. Lac du Flambeau, 599 U.S.

at 410 (Gorsuch, J., dissenting) (“[T]his Court’s Indianlaw jurisprudence … has consistently treated Tribes as a

17

constitutional hybrid, resembling States in certain respects and foreign nations in others.” (citation modified)).

First, as “separate sovereigns pre-existing the Constitution,” tribes—like foreign nations—“have long been

recognized as possessing the common-law immunity from

suit traditionally enjoyed by sovereign powers.” Santa

Clara Pueblo v. Martinez, 436 U.S. 49, 56, 58 (1978); see

also Kiowa Tribe of Oklahoma v. Mfg. Techs., Inc., 523

U.S. 751 (1998) (comparing tribal immunity to foreign sovereign immunity). This means that “Indian tribes have

immunity even when a suit arises from off-reservation

commercial activity,” unless Congress—not a state— “unequivocally” abrogates that immunity. Michigan v. Bay

Mills Indian Cmty., 572 U.S. 782, 785, 790 (2014) (Kagan,

J.) (quotation omitted); accord Utah, 790 F.3d at 1009

(Gorsuch, J.) (principle of tribal sovereign immunity “applies with just as much force to claims … brought by

states as by anyone else”); see also, e.g., United States v.

U.S. Fid. & Guar. Co., 309 U.S. 506, 512 (1940) (tribal sovereign immunity for coal leasing).

Second, like states, tribes share in the split sovereignty of our federal system. Tribes, much like states, are

sovereign over their people and territory. Compare, e.g.,

Ysleta, 596 U.S. at 689 (“Native American Tribes possess

inherent sovereign authority over their members and territories.” (quotation omitted)), with Brown v. Fletcher’s

Estate, 210 U.S. 82, 89 (1908) (“[E]very state possesses

exclusive jurisdiction and sovereignty over persons and

property within its territory.” (quotation omitted)). And

split sovereignty within our constitutional system implies

limits on each sovereign’s power vis-à-vis the others. See

Petitioners’ Br. 23–24 (explaining that structural limitations flow from the states’ “equal sovereignty” in our federal system). So just as states cannot violate others’

18

sovereignty by regulating beyond their own borders, neither can they violate tribes’ sovereign spheres by regulating conduct affecting the tribes’ “political integrity, the[ir]

economic security, or the[ir] health or welfare.” Montana, 450 U.S. at 566; see also Williams v. Lee, 358 U.S.

217, 220 (1959) (“States have no power to regulate the affairs of Indians on a reservation.”); Haaland, 599 U.S. at

307–08 (Gorsuch, J., concurring) (noting the same “[a]s a

corollary of [tribes’] sovereignty”).

Third, because of tribes’ distinct relationship with the

federal government under the Constitution, tribes enjoy

the protection of a uniquely strong form of federal

preemption against state authority. The Constitution

vests Congress and the President with authority over relations with the Indian tribes. See U.S. CONST. art. I, § 8,

cl. 3 (Indian Commerce Clause); id. art. II, § 2, cl. 2 (President’s treaty power). Using these powers, the federal

government has “demonstrat[ed] a firm federal policy of

promoting tribal self-sufficiency and economic development.” Bracker, 448 U.S. at 143; see Sec. II., supra. This

policy, set against the “crucial backdrop” of Indians’ preConstitutional inherent sovereignty, shields tribes from

state interference with federal supremacy. New Mexico

v. Mescalero Apache Tribe, 462 U.S. 324, 334 (1983) (quotation omitted); see also McClanahan v. State Tax

Comm’n of Ariz., 411 U.S. 164, 172 (1973) (similar).

Importantly, this Indian preemption doctrine is more

muscular than normal federal preemption. Ordinarily,

“[i]nvoking some brooding federal interest … [is not]

enough to win preemption of a state law; a litigant must

point specifically to a constitutional text or a federal statute that does the displacing or conflicts with state law.”

Va. Uranium, Inc. v. Warren, 587 U.S. 761, 767–68 (2019)

(Gorsuch, J.) (citation modified). But with Indian

19

preemption, “[t]hat is simply not the law.” Bracker, 448

U.S. at 150–51. As this Court has explained, “[t]he unique

historical origins of tribal sovereignty make it generally

unhelpful to apply to federal enactments regulating Indian tribes those standards of pre-emption that have

emerged in other areas of the law.” Id. at 143. Instead,

in the Indian context, “to find a particular state law to

have been preempted by operation of federal law, an express congressional statement to that effect is [not] required.” Id. at 144; see Mescalero, 462 U.S. at 334 (“[O]ur

[Indian preemption] cases have rejected a narrow focus

on congressional intent to preempt State law as the sole

touchstone.”). Given “both the broad policies that underlie [federal Indian law] and the notions of sovereignty that

have developed from historical traditions of tribal independence,” federal preemption applies with singular force

to protect tribes’ prerogative of self-government, as reinforced by Congress and the President under their constitutional powers. Bracker, 448 U.S. at 144–45; see Sec. II.,

supra.

In these three ways, then, tribes enjoy robust protection against state interference: States cannot sue them—

even for off-reservation commercial conduct—unless

Congress expressly abrogates (or they unequivocally

waive) their immunity. Bay Mills, 572 U.S. at 785. States

cannot meddle with tribes’ inherent sovereign power to

govern themselves and provide for their members’ economic security, health, and welfare. Bracker, 448 U.S. at

142–43. And states cannot hinder federal policy—instantiated in countless Congressional acts and Presidential

policies—of promoting Indian independence and sovereign self-government. Id. at 143–44. Any one of these “independent but related barriers,” “standing alone,” “can

be a sufficient basis” to preclude “the assertion of state

20

regulatory authority over tribal reservations and members.” Id. at 142.

Applying these principles, this Court has held, in case

after case, that states cannot interfere with tribes’ commercial activities that support tribal sovereignty, especially tribes’ development of their lands’ abundant natural

resources.

1. In White Mountain Apache Tribe v. Bracker, 448

U.S. 136 (1980), for example, this Court held that federal

Indian preemption and inherent tribal sovereignty foreclosed two Arizona taxes on an Apache tribe’s non-Indian

timber-harvesting contractor. Federal law had “expressly authorized” Indian tribes “to establish commercial enterprises for the harvesting and logging of tribal

timber.” Id. at 147. The White Mountain Apache tribe

did so. It formed a company and contracted with a nonIndian enterprise to harvest timber on tribal land—an operation that the tribe itself “could not carry out as economically on its own.” Id. at 139. Arizona imposed taxes

on this non-Indian contractor, and the Apache sued. Id.

at 139–40.

The Court ruled for the Apache. Observing that the

“economic burden” of Arizona’s taxes on the non-Indian

contractor would “ultimately fall on the Tribe,” the Court

explained that the taxes hindered the federal “policy of

assuring that the profits derived from timber sales will inure to the benefit of the Tribe.” Id. at 149, 151. The state’s

taxes “would threaten the overriding federal objective of

guaranteeing Indians that they will receive the benefit of

whatever profit the forest is capable of yielding.” Id. at

149 (citation modified). “That objective,” the Court

added, “is part of the general federal policy of encouraging tribes to revitalize their self-government and to assume control over their business and economic affairs.”

21

Id. (quotations omitted). Arizona’s taxes also constituted

unwarranted “additional burdens” atop a “comprehensive

federal regulatory scheme” that, among other things, required the Bureau of Indian Affairs (BIA) to approve the

tribe’s timber-harvesting contracts with non-Indian companies. Although federal law did not expressly preempt

Arizona law, its “purpose of promoting self-sustaining [Indian] communities” and its substantial “supervision over

the harvesting and management of tribal timber” implicitly preempted the state’s taxes.

2. In New Mexico v. Mescalero Apache Tribe, 462 U.S.

324 (1983), this Court rejected another state attempt to

regulate a tribe’s management of its natural resources for

the benefit of its people. “Anticipating a decline in the sale

of lumber which ha[d] been the largest income-producing

activity within the reservation,” the Mescalero Apache

Tribe—a member of amicus COLT—sought to develop

“other sources of income.” Id. at 327. The tribe undertook

“a substantial development of the reservation’s hunting

and fishing resources,” which “generate[d] income …

used to maintain the Tribal government and provide services to tribe members.” Id. But New Mexico got in the

way. The state sought to regulate hunting and fishing on

the tribe’s reservation concurrently and asserted the

power “to impose conditions more restrictive than the

Tribe’s own regulations, including an outright prohibition.” Id. at 330.

The Court roundly rejected New Mexico’s invasion of

tribal sovereignty: “It is beyond doubt that the … Tribe

lawfully exercises substantial control over the lands and

resources of its reservation,” an “aspect of tribal sovereignty … expressly confirmed by numerous federal statutes.” Id. at 337; see also id. at 334–35 & n.17. New Mexico’s hunting and fishing laws, meanwhile, were “based on

22

[statewide] considerations not necessarily relevant to, and

possibly hostile to, the needs of the reservation.” Id. at

339. The state laws could not stand: They impeded tribal

resource development that “generate[d] funds for essential tribal services and provide[d] employment for members who reside[d] on the reservation.” Id. at 341. And

that “threaten[ed] Congress’ overriding objective of encouraging tribal self-government and economic development.” Id.

3. California v. Cabazon Band of Mission Indians,

480 U.S. 202 (1987) addressed a state’s attempt to regulate a different kind of Indian commercial activity: gaming.4 Because their “Reservations contained no natural

resources which c[ould] be exploited,” the Cabazon and

Morongo Bands of Mission Indians had resorted to bingo.

Id. at 218. California tried to impose its strict state gambling regulations on the tribe—regulations that imperiled

the commercial viability of tribal gaming. Id. at 205 & n.3.

These regulations were not compatible with “Indian sovereignty” and the “important federal interests” of promoting “Indian self-government,” and “encouraging

tribal self-sufficiency and economic development.” Id. at

216–18. Writing for a unanimous Court, Justice White explained that “[s]elf-determination and economic development are not within reach if the Tribes cannot raise revenues and provide employment for their members.” Id. at

219. Despite California’s “legitimate concern” that “tribal

games” would “attract[ ] organized crime” to the state, its

4

Congress later superseded Cabazon with its enactment of the Indian

Gaming Regulatory Act (IGRA), 102 Stat. 2467 (1988) (codified at 25

U.S.C. § 2701 et seq.), which comprehensively regulated the field of

Indian gaming. The Indian preemption principles enunciated in

Cabazon remain good law.

23

regulations could not “escape the pre-emptive force of

federal and tribal interests.” Id. at 211, 221.

4. Finally, in Montana v. Crow Tribe of Indians, 484

U.S. 997 (1988), this Court summarily affirmed the Ninth

Circuit’s holding that Montana’s significant taxation of

coal mined on tribal land was “preempted by federal law

and policies” and “void for interfering with tribal self-government.” Crow Tribe of Indians v. Montana, 819 F.2d

895, 903 (9th Cir. 1987). The Crow had contracted with

two major energy companies to mine and bring their coal

to market, with lease agreements under the Mineral

Leasing Act of 1938. Id. at 897. Montana, however, imposed hefty taxes on the Crow’s coal. Id. Although the

“Tribe itself d[id] not pay the tax”—the lessees did—it

naturally “result[ed] in … fewer royalties to the tribe.”

Id. at 899. After all, “[t]he state taxes increase[d] the

costs of production,” which “forced the coal producers to

charge higher prices,” thereby “reducing the demand for

their Montana coal.” Id. The Crow Tribe sued.

Applying this Court’s precedents, the Ninth Circuit

held Montana’s taxes unlawful for two “independent” reasons. Id. at 897–903. First, they were preempted: They

clashed with the “firm federal policy of promoting tribal

self-sufficiency and economic development”—a policy

that Congress intended to “be given broad preemptive effect.” Id. at 898. Because “the taxes imposed by the state

interfered with the policies underlying the 1938 [Mineral

Leasing] Act”—in particular, “to ensure that Indians receive the greatest return from their property”—supreme

federal law barred their imposition. Id. (emphasis added

and quotations omitted). Second, the taxes were “invalid

because [they] erode[d] the Tribe’s sovereign authority.”

Id. at 903. “The power to tax … is an essential attribute

of self-government,” and “tax revenue from coal

24

production could generate funds for tribal services and

provide employment for tribal members.” Id. at 902. “By

taking revenue that would otherwise go towards supporting the Tribe and its programs, and by limiting the Tribe’s

ability to regulate the development of its coal resources,”

Montana infringed on the Crow’s sovereignty. Id. at 902–

03; see also id. at 902 (“The Tribe’s coal is not the state’s

to regulate. It has no such legitimate interest in appropriating Indian mineral wealth.” (citation modified)).5

Notably, the Ninth Circuit reached these same conclusions even when the taxes were never actually imposed on

the tribe’s coal. See id. at 897. It was enough that the

taxes on the books “interfer[ed] with the Tribe’s coal leasing efforts” by making it hard for would-be lessees to “find

a buyer” for the coal, which, in turn, “ma[de] it difficult for

Crow to find a lessee.” Id. at 903. Also notable, the Ninth

Circuit rejected Montana’s argument that its “heavy tax”

on the tribe’s coal was justified by the “indeterminable”

“costs associated with treating the environmental consequences of coal production.” Id. at 901. Among other

things, Montana’s stated “environmental interests” were

already protected by federal law. Id. (citing the Surface

5

This Court has reaffirmed the case’s core holding that “an unusually

large state tax” on a tribe’s mineral resources that “impose[s] a substantial burden on [a] Tribe” cannot stand. See Cotton Petroleum,

490 U.S. at 186–87 & n.17; see also Montana v. Crow Tribe of Indians,

523 U.S. 696, 706, 717 (1998) (“The negative impact of Montana’s high

taxes on the marketability of the Tribe’s coal, as the District Court

correctly comprehended, was the principal basis for the Ninth Circuit’s … preemption decision.”). Contrast Cotton Petroleum, 490 U.S.

at 186–87 (“Any impairment [by New Mexico taxes] to the federal policy favoring [Indians’] exploitation of on-reservation oil and gas resources … is simply too indirect and too insubstantial to support

Cotton’s claim of pre-emption.” (emphases added)).

25

Mining Control and Reclamation Act of 1977, 30 U.S.C.

§ 1201 et seq. (1982)).

*

As these cases show, states cannot impede tribes’ lawful means of generating revenue—commonly, natural-resource development—because (1) doing so conflicts with

federal policy favoring tribal self-government, and (2) it is

an affront to tribal sovereignty.

IV. State Attempts To Regulate Energy Companies’

Contributions To Global Emissions Are Void Because They Interfere With Federal Indian Policy

And Violate Inherent Tribal Sovereignty.

State and local governments, like Respondents, cannot regulate energy companies’ alleged contributions to

global greenhouse gas emissions. As Petitioners explain,

the Constitution’s structure, with states as “coequal sovereigns” within a federal system, forecloses state tort and

consumer-protection claims that would effectively regulate interstate—and even international—emissions that

are properly the province of the federal government. Petitioners’ Br. 3–4, 22–29. Respondents’ claims are also

foreclosed because they encroach on Indian tribes’ inherent sovereignty and conflict with the overriding federal

policy favoring tribal self-government and development of

natural resources as critical sources of tribal revenue.

If tribes were to engage in oil-and-gas drilling or coal

mining themselves, they would enjoy immunity from

state-law suits like Respondents’ under this Court’s wellestablished precedents. See Bay Mills, 572 U.S. at 785;

U.S. Fid. & Guar. Co., 309 U.S. at 512. But “most tribes

do not have the resources to start a production company

to develop their resources, such as oil and gas.” U.S. Gov’t

26

Accountability Off., GAO-15-502, Indian Energy Development: Poor Management by BIA Has Hindered Energy

Development on Indian Lands, at 30 (2015), tinyurl.com/GAO-BIA-Rpt; cf. Bracker, 448 U.S. at 139

(Apache outsourced logging because the tribe “could not”

do so “as economically on its own”). So most tribes depend

upon third-party energy companies, like Petitioners here,

to capitalize on their lands’ abundant energy resources.6

Respondents—and many other states and localities

across the country—are threatening the economic viability of these companies with climate lawfare. See, e.g., District of Columbia v. Exxon Mobil, et al., No. 2020-CA002892-B (D.C. Sup. Ct. June 25, 2020) (D.C.’s nominal

consumer-protection action seeking to impose liability for

climate change). Because these energy companies’ “production … of fossil fuels” plays a “substantial role” in

“contributing to” global emissions, J.A. 2 ¶ 2, Respondents seek to impose catastrophic liability for the local effects of climate change. Indeed, one of Respondents’ lawyers candidly explained that this lawsuit seeks to (indirectly) impose a draconian nationwide “carbon tax” on fossil-fuel producers who will then “have to” “declare bankruptcy.” See Federalist Soc’y, Can State Courts Set

Global Climate Policy?, at 32:55–35:05, YOUTUBE (Oct. 8,

2025), tinyurl.com/FedSoc-Bookbinder (comments of David Bookbinder).

Respondents’ unabashed attempt to use state law in

state court before a state jury to drive fossil-fuel

6

For example, a subsidiary of Petitioner Exxon Mobil Corporation

has three natural-gas wells “located on Jicarilla Apache tribal land in

New Mexico.” U.S. Env’t Prot. Agency, Region 6, Federal Synthetic

Minor New Source Review Permit, No. R6NSR-NM-004 (July 13,

2017), perma.cc/KLG7-ZHFP; Exxon Mobil Corp., Current Report

(Form 8-K) (June 25, 2010), tinyurl.com/Exxon-XTO-8K.

27

producers into bankruptcy imperils tribes’ ability to find

energy producers to help develop their natural resources.

See Crow Tribe, 819 F.2d at 903 (state law made it “difficult” for tribe “to find a lessee” for coal mining). This

threatens tribes’ inherent sovereignty, clashes with federal policy favoring Indian mineral leasing and tribal selfgovernment, and violates well-established Indian

preemption doctrine under this Court’s precedents.

1. State and local climate lawsuits jeopardize tribes’

inherent sovereignty. For many tribes, including amicus

COLT’s member tribes, fossil-fuel development on tribal

land constitutes a substantial—if not the sole—source of

tribal income and on-reservation employment. See Sec.

I.B., supra; see also Crow Tribe, 819 F.2d at 901 (“Coal

production is vital to the economic development of the

Crow Tribe.”); accord Cotton Petroleum, 490 U.S. at 209

(Blackmun, J., dissenting) (“[O]il and gas production is the Jicarilla Apache economy—a common pattern

in reservations with substantial oil and gas reserves.”

(emphasis original)); cf. Cabazon, 480 U.S. at 218–19

(bingo was the “sole source of revenues for the operation

of the tribal governments and the provision of tribal services” because the “Reservations contain[ed] no natural

resources”). This revenue and employment is crucial to

Indian economic independence and self-government. See

Bracker, 448 U.S. at 142–43; Crow Tribe, 819 F.2d at 896;

cf. Merrion, 455 U.S. at 137 (highlighting the importance

of a tribe’s “authority, as sovereign, to control economic

activity within its jurisdiction, and to defray the cost of

providing governmental services”). State-and-local attempts to dismantle the national fossil-fuel industry severely undermines this tribal sovereignty, transforming

“sovereignty by the barrel” into “liability by the barrel.”

Cf. Crane-Murdoch, supra; Davies, supra.

28

2. Federal Indian law preempts state-law climate lawsuits. As explained in Section II, supra, longstanding federal policy—embodied in many congressional enactments,

agency regulations, and presidential policy initiatives—

strongly favors Indian self-government and economic security. See Sec. II., supra; see, e.g., 25 U.S.C. § 396g

(IMLA) (authorizing Secretary of the Interior “to approve leases” of tribal mineral rights “to promote … the

welfare of the Indians”); 25 U.S.C. §§ 2102(a), 2108

(IMDA) (enabling tribes to enter mineral agreements and

offering “federal advice, assistance, and information during the negotiation”); 25 C.F.R. § 212.1(a) (BIA regulation

stating purpose of “ensur[ing] that Indian mineral owners

desiring to have their resources developed are assured

that they will be developed in a manner that maximizes

their best economic interests”); Reagan, supra (Presidential policy of encouraging tribes to “tak[e] advantage of

economic development opportunities,” including “the prudent development and management of the vast coal, oil,

[and] gas … resources found on Indian lands”); cf. Cabazon, 480 U.S. at 216–17 & n.19 (collecting statutes promoting tribal self-government); Mescalero, 462 U.S. at 335 &

n.17 (similar). These pro-Indian federal policies preempt

state-and-local lawfare designed to cripple national fossilfuel companies that support tribal energy development

critical to Indian self-government and economic security.

See Mescalero, 462 U.S. at 331–43; Bracker, 448 U.S. at

145–52; Cabazon, 480 U.S. at 216–22; Crow Tribe, 819

F.2d at 897–902, aff’d, 484 U.S. 997.7

7

Additionally, federal law extensively regulates fossil-fuel production

on tribal land. See Kodiak Oil & Gas (USA) Inc. v. Burr, 932 F.3d

1125, 1135–36 (8th Cir. 2019). This body of federal law may also

preempt Respondents’ suit on ordinary federal field-preemption principles.

29

Finally, it is no answer that Respondents and other jurisdictions seek to regulate fossil-fuel production—on

tribal lands and elsewhere—because of the “environmental consequences” that flow from increased global greenhouse-gas emissions. Crow Tribe, 819 F.2d at 901. Such

“environmental concerns have been addressed already”

by federal law. Id.; see generally Clean Air Act (CAA), 42

U.S.C. § 7401, et seq.; cf. Petitioners’ Br. 43–47 (explaining that the CAA preempts state-law climate suits).

Moreover, conflicts between sovereigns—like states and

tribes—within our federal system are to be resolved by

reference to federal law, not the law of one particular state

(or tribe). Cf. Petitioners’ Br. 22–29 (explaining that “federal law applies to disputes involving interstate pollution”); see, e.g., City of Milwaukee v. Illinois, 451 U.S. 304

313 & n.7 (1981); Int’l Paper Co. v. Ouellette, 479 U.S. 481,

488 (1987); Am. Elec. Power Co. v. Connecticut, 564 U.S.

410, 429 (2011). Accordingly, federal law must control.

*

Before the Constitution’s ratification, “the States considered themselves fully sovereign nations.” Fran. Tax

Bd. of Cal. v. Hyatt, 587 U.S. 230, 237 (2019) (Thomas, J.).

But “in ratifying the Constitution,” they “surrendered a

portion of their” inherent sovereignty by consent. Id. at

241; see id. at 245 (noting, for instance, that “the Constitution deprives [states] of the independent power … to enter into treaties” (citing U.S. CONST. art. I., § 10)). At the

Founding, Indian tribes were also recognized as “fully

sovereign nations.” Id. at 237; see Sec. I.A., supra. But

they did not ratify the Constitution, and they “surrendered” no “portion of their” inherent sovereignty. Cf. id.

at 237; see Sec. II, supra (discussing tribes’ treaty-making

after the Founding—a sovereign prerogative that the

Constitution denied to the states). So if states “retain”

30

“integral component[s]” of their “inviolable” pre-constitutional “sovereignty,” 587 U.S. at 236 (quotation omitted),

all the more so do the Indian tribes, whose inherent sovereignty “has never been extinguished.” Wheeler, 435

U.S. at 322 (quotation omitted).

Like states and foreign nations, Indian tribes cannot

“be haled involuntarily before” the court of another state

and subjected to that state’s laws. Hyatt, 587 U.S. at 239;

see Bay Mills, 572 U.S. at 785. Respondents, therefore,

cannot sue any tribe in state court for developing the energy resources of its sovereign territory. But what Respondents cannot do directly, they seek to do indirectly

through climate lawfare against the tribes’ energy-industry partners, which threatens them with insolvency. See

Bookbinder, supra. Respondents’ attempted end-run

around governmental immunity violates tribes’ inherent

sovereignty and is preempted by pro-Indian federal law.

It cannot stand. Respondents’ state-law case should be

dismissed.

CONCLUSION

The Court should reverse the judgment below.

Respectfully submitted.

MICHAEL A. FRAGOSO

CHASE T. HARRINGTON

T. ZACH HORTON

TORRIDON LAW PLLC

801 Seventeenth Street N.W.,

Suite 1100

Washington, DC 20006

(202) 249-6900

JENNIFER H. WEDDLE

Counsel of Record

GREENBERG TRAURIG, LLP

1144 Fifteenth Street,

Suite 3300

Denver, CO 80202

(303) 572-6500

weddlej@gtlaw.com

MAY 21, 2026

Counsel for Amicus Curiae