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

Supreme Court briefAug 3, 2026

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No. 25-170

In the Supreme Court of the United States

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

Petitioners,

COUNTY COMMISSIONERS OF

BOULDER COUNTY, ET AL.,

Respondents.

ON WRIT OF CERTIORARI

TO THE SUPREME COURT OF COLORADO

BRIEF OF OUR CHILDREN’S TRUST,

ALINA MIRANDA, ADITHYA BHASKARA,

WAVERLY FISHER, MADDISON SCHINK,

MURIEL S., EVERETT F., PENNY S., ETHAN

M., and DR. LISA PATEL AS AMICI CURIAE IN

SUPPORT OF RESPONDENTS

JULIA A. OLSON

Counsel of Record

NATHAN BELLINGER

LAURA MEBERT

AVI LIPMAN

OUR CHILDREN’S TRUST

1216 Lincoln St.

Eugene, OR 97401

(415) 786-4825

julia@ourchildrenstrust.org

QUESTION PRESENTED

Whether the Clean Air Act preempts state-law tort

claims seeking monetary damages for physical harm

to plaintiff local governments’ communities caused by

in-state and interstate greenhouse gas pollution from

defendant companies’ products.

TABLE OF CONTENTS

QUESTION PRESENTED ........................................... i

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

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

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

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

Fossil-Fuel Air Pollution Disproportionately

Harms the Health, Safety, and Welfare of

Children ............................................................. 5

II. The Federal Constitution Preserves State

Sovereign Authority to Protect Health,

Safety, and Welfare ......................................... 12

A. The “Structure of Our Constitutional

System” Reserves to the States Any

Powers Not Explicitly Granted to the

Federal Government or Prohibited to the

States ............................................................ 13

B. States Have “Inherent Power” to Exercise

Their Police Powers to Ensure the Safety

of Their Citizens ........................................... 16

C. The Public Trust Doctrine Requires States

to Seek Compensation for Damage to

Public Trust Assets ...................................... 21

III. A Broad Preemption Holding Would Impede

Individual Constitutional Rights That Are

Not Before This Court ..................................... 27

CONCLUSION .......................................................... 32

iii

TABLE OF AUTHORITIES

CASES

Alfred L. Snapp & Son, Inc. v.

Puerto Rico, ex rel., Barez,

458 U.S. 592 (1982) ................................................ 18

Ariz. Ctr. for Law in Pub. Int. v Hassell,

837 P.2d 158 (Ariz. Ct. App. 1991) ........................ 25

Atherton v. D.C. Off. of Mayor,

567 F.3d 672 (D.C. Cir. 2009) ................................ 27

Berman v. Parker,

348 U.S. 26 (1954) .................................................. 16

Bond v. United States,

572 U.S. 844 (2014) ................................................ 19

Caetano v. Massachusetts,

577 U.S. 411 (2016) ................................................ 17

Ching v. Case,

449 P.3d 1146 (Haw. 2019) .................................... 29

Cipollone v. Liggett Grp., Inc.,

505 U.S. 504 (1992) ................................................ 20

Geer v. Connecticut,

161 U.S. 519 (1896) .......................................... 23, 25

Georgia v. Tenn. Copper Co.,

206 U.S. 230 (1907) .......................................... 14, 15

Gonzales v. Oregon,

546 U.S. 243 (2006) ................................................ 16

Gregory v. Ashcroft,

501 U.S. 452 (1991) ............ 12, 14, 15, 17, 18, 19, 27

Gutierrez v. Saenz,

606 U.S. 305 (2025) ................................................ 27

Held v. State,

560 P.3d 1235 (Mont. 2024) ................................... 30

Hodel v. Va. Surface Min. & Reclamation Ass’n,

452 U.S. 264 (1981) .......................................... 15, 18

Idaho v. Coeur d’Alene Tribe,

521 U.S. 261 (1997) ................................................ 24

Ill. Cent. R.R. Co. v. Illinois,

146 U.S. 387 (1892) .............................. 23, 24, 25, 29

In re Haw. Elec. Light Co.,

526 P.3d 329 (Haw. 2023) ...................................... 30

In re Maui Elec. Co.,

506 P.3d 192 (Haw. 2022) ...................................... 30

Keith v. Clark,

97 U.S. 454 (1878) .................................................. 17

Kelley v. Johnson,

425 U.S. 238 (1976) ................................................ 18

Kelly v. 1250 Oceanside Partners,

140 P.3d 985 (Haw. 2006) ...................................... 25

Kremer v. Chem. Const. Corp.,

456 U.S. 461 (1982) ................................................ 31

Lawrence v. Clark Cnty.,

254 P.3d 606 (Nev. 2011) ....................................... 23

Martin v. Waddell’s Lessee,

41 U.S. 367 (1842) .................................................. 23

Mayor, Alderman & Commonalty of N.Y. v. Miln,

36 U.S. 102 (1837) ...................................... 13, 15, 17

Missouri v. Illinois,

180 U.S. 208 (1901) ................................................ 18

Mont. Coal. for Stream Access, Inc. v. Curran,

682 P.2d 163 (Mont. 1984) ..................................... 23

Nat’l Audubon Soc’y v. Super. Ct.,

658 P.2d 709 (Cal. 1983) ........................................ 23

New York v. United States,

505 U.S. 144 (1992) .................................... 14, 15, 16

Nw. Fertilizing Co. v. Vill. of Hyde Park,

97 U.S. 659 (1878) .................................................. 20

Obergefell v. Hodges,

576 U.S. 644 (2015) ................................................ 17

Ohio v. EPA,

603 U.S. 279 (2024) ................................................ 29

Pollard v. Hagan,

44 U.S. 212 (1845) .................................................. 24

PPL Mont., LLC v. Montana,

565 U.S. 576 (2012) .................................... 23, 24, 29

Queenside Hills Realty Co. v. Saxl,

328 U.S. 80 (1946) ............................................ 17, 18

Robinson Twp. v. Commonwealth,

83 A.3d 901 (Pa. 2013) ..................................... 25, 26

Sandin v. Conner,

515 U.S. 472 (1995) ................................................ 28

Sprietsma v. Mercury Marine,

537 U.S. 51 (2002) ............................................ 20, 21

Sturges v. Crowninshield,

17 U.S. (4 Wheat.) 122 (1819) ............................... 16

Tafflin v. Levitt,

493 U.S. 455 (1990) ................................................ 16

United States v. 1.58 Acres of Land,

523 F. Supp. 120 (D. Mass. 1981) ......................... 25

United States v. Darby,

312 U.S. 100 (1941) ................................................ 13

United States v. Lopez,

514 U.S. 549 (1995) ................................................ 16

United States v. White Mountain Apache Tribe,

537 U.S. 465 (2003) ................................................ 22

United States v. Windsor,

570 U.S. 744 (2013) ................................................ 28

Wilkinson v. Austin,

545 U.S. 209 (2005) ................................................ 27

Wis. Pub. Intervenor v. Mortier,

501 U.S. 597 (1991) ................................................ 19

Wolff v. McDonnell,

418 U.S. 539 (1974) .......................................... 28, 31

Wyeth v. Levine,

555 U.S. 555 (2009) ................................................ 19

CONSTITUTIONAL PROVISIONS

Colo. Const. art. XIV, § 16 ......................................... 26

Colo. Const. art. XX ................................................... 26

Haw. Const. art. XI, § 1 ............................................. 30

Haw. Const. art. XI, § 9 ............................................. 30

Mont. Const. art. II, § 3 ............................................. 29

Mont. Const. art. IX, § 1 ............................................ 30

Mont. Const. art. IX, § 3(2) ....................................... 30

Penn. Const. art. I, § 27 ............................................ 29

Tex. Const. art. XVI, § 59(a) ..................................... 30

U.S. Const. amend. V .......................... 5, 27, 28, 29, 31

U.S. Const. amend. X .......... 4, 5, 12, 13, 15, 17, 24, 26

U.S. Const. amend. XIV ............................ 5, 27, 28, 31

U.S. Const. pmbl. ....................................................... 22

vii

STATUTES

42 U.S.C. § 7401(a)(3) .................................... 20, 26, 29

Colo. Rev. Stat. Ann. § 25-7-102 ............................... 18

Haw. Rev. Stat. § 225P-8 .......................................... 30

Mich. Comp. L. § 324.1701 ........................................ 30

OTHER AUTHORITIES

2 William Blackstone, Commentaries on the Laws of

England (1766)....................................................... 22

Aaron S. Bernstein et al., Warm Season and

Emergency Department Visits to U.S. Children’s

Hospitals, 130 Env’t Health Persp. 17001 (2022) 10

Am. Pub. Health Ass’n v. U.S. EPA, No. 26-2037

(D.C. Cir.) ............................................................... 20

Anthony Costello et al., Managing the Health Effects

of Climate Change, 373 Lancet 1693 (2009) ......... 10

Ava Berger, Climate Change Is Now Threatening a

Pillar of Childhood: Summer Break, NPR (July 26,

2026), https://www.npr.org/2026/07/26/nx-s15900911/wildfire-smoke-fires-camp-minnesota ... 12

Caroline J. Smith, Pediatric Thermoregulation:

Considerations in the Face of Global Climate

Change, 11 Nutrients 2010 (2019) ........................ 10

CDC, Preparing for the Regional Health Impacts of

Climate Change in the United States (2024) .......... 8

Charles L. Wilkinson, The Public Trust Doctrine

in Public Land Law, 14 U.C. Davis L. Rev. 269

(1980) ...................................................................... 21

Climate Change in Boulder County,

https://bouldercounty.gov/climate/impacts/ ............ 8

viii

Courtney W. Mangus & Therese L. Canares, HeatRelated Illness in Children in an Era of Extreme

Temperatures, 40 Pediatrics in Rev. 97 (2019) ..... 10

Frederica P. Perera, Multiple Threats to Child

Health from Fossil Fuel Combustion: Impacts of

Air Pollution and Climate Change, 125 Env’t

Health Persps. 141 (2017) ....................................... 6

Frederica Perera et al., Climate Change, Fossil-Fuel

Pollution, and Children’s Health, 386 NEJM 2303

(2022) ........................................................................ 7

Gerald Torres & Nathan Bellinger, The Public Trust:

The Law’s DNA, 4 Wake Forest J.L. & Pol’y 281

(2014) ...................................................................... 22

Gilmer, Cochran’s Law Lexicon (5th ed. 1973) ........ 17

J. Inst. 2.1.1 (T. Sanders trans., 4th ed. 1867)......... 23

James Gustave Speth, They Knew (2022) .................. 4

Janet Currie et al., Does Pollution Increase School

Absences?, 91 Rev. Econ. Stat. 682 (2009) .............. 9

Kevin Cromar et al., Adverse Health Impacts of

Outdoor Air Pollution, Including from Wildland

Fires, in the United States: “Health of the Air,”

2018-2020. 21 Ann. Am. Thoracic Soc. 76 (2024) ... 9

Lancet Countdown on Health and Climate

Change, Policy Brief for the United States of

America (2019) ....................................................... 11

Li-Zi Lin et al., The Epidemiological Evidence

Linking Exposure to Ambient Particulate Matter

with Neurodevelopmental Disorders: A Systematic

Review and Meta-Analysis, 209 Env’t Rsch. 112876

(2022) ........................................................................ 7

Lukoye Atwoli et al., Call for Emergency Action to

Limit Global Temperature Increases, Restore

Biodiversity, and Protect Health, 385 NEJM 1134

(2021) ........................................................................ 9

Maria Harris et al., Prenatal and Childhood TrafficRelated Pollution Exposure and Childhood

Cognition in the Project Viva Cohort, 123 Env’t

Health Persp. 1072 (2015) ....................................... 7

Mary Christina Wood & Dan Galpern, Atmospheric

Recovery Litigation: Making the Fossil Fuel

Industry Pay to Restore a Viable Climate System,

45 Env’t L. 259 (2015) ...................................... 23, 26

Mary Christina Wood, Advancing the Sovereign

Trust of Government to Safeguard the Environment

for Present and Future Generations (Part I):

Ecological Realism and the Need for a Paradigm

Shift, 39 Env’t L. 43 (2009) ................................... 22

Matthew Hale, De Jure Maris, Harg. Law Tracts,

reprinted in Stuart Moore, A History of the

Foreshore and the Law Relating Thereto (3rd ed.

1888) ....................................................................... 23

Michael C. Blumm & Lynn S. Schaffer, The Federal

Public Trust Doctrine: Misinterpreting Justice

Kennedy and Illinois Central Railroad, 45 Env’t L.

399 (2015) ............................................................... 24

Min Zhang et al., Wildfire Smoke PM2.5 and

Mortality Rate in the Contiguous United States: A

Causal Modeling Study, 12 Sci. Advances

eadw5890 (2026) ...................................................... 9

Minghao Qiu et al., Wildfire Smoke Exposure and

Mortality Burden in the USA Under Climate

Change, 647 Nature 935 (2025) .............................. 9

Noelle Phillips, Suncor’s Commerce City Refinery

Emits Black Smoke After Maintenance, Denv. Post

(July 28, 2026),

https://www.denverpost.com/2026/07/28/suncorscommerce-city-black-smoke/ .................................... 4

Private Resp’t-Intervenors’ Opp’n to Mot. to Stay

Final Rule, Am. Pub. Health Ass’n, No. 26-2038

(D.C. Cir. June 29, 2026), Dkt. No. 2181086 ........ 20

Qian Di et al., Air Pollution and Mortality in the

Medicare Population, 376 NEJM 2513 (2017)........ 7

Rebecca E. Berger et al., Air Pollution Still Kills,

376 NEJM 2591 (2017) ............................................ 7

Regulate, Black’s Law Dictionary (12th ed. 2024) ... 21

Rescission of the Greenhouse Gas Endangerment

Finding, 91 Fed. Reg. 7686 (Feb. 18, 2026) .......... 20

Samantha Ahdoot et al., Am. Acad. Pediatrics,

Climate Change and Children’s Health: Building a

Healthy Future for Every Child, 153 Pediatrics

e2023065505 (2024) ........................................... 6, 10

Sean Lyness, The Local Public Trust Doctrine, 34

Geo. Env’t L. Rev. 1 (2021) .............................. 25, 26

Shuaixing Song et al., Ambient Fine Particulate

Matter and Pregnancy Outcomes: An Umbrella

Review, 235 Env’t Rsch. 116652 (2023) .................. 7

Stephanie Holm & John Balmes, Systematic Review

of Ozone Effects on Human Lung Function, 2013

Through 2020, 161 Chest 190 (2022) ...................... 7

The Federalist No. 45 (James Madison) (C. Rossiter

ed., 1961) .......................................................... 14, 17

The Federalist No. 46 (James Madison)................... 23

The White House, Restoring the Quality of Our

Environment (1965) ................................................. 4

U.S. EPA, Integrated Science Assessment for Oxides

of Nitrogen – Health Criteria (2016) ....................... 7

USGCRP, Fifth National Climate Assessment

(2023) ...................................................................... 10

Weizhi Deng et al., Fires Reverse Progress Toward

Ozone Air Quality Standards in the United States,

392 Sci. 1088 (2026) ................................................. 9

World Health Org., The Health Argument for Climate

Action (2021) .......................................................... 10

Xue-yan Zheng et al., Short-term Exposure to Ozone,

Nitrogen Dioxide, and Sulphur Dioxide and

Emergency Department Visits and Hospital

Admissions Due to Asthma: A Systematic Review

and Meta-analysis, 150 Env’t Int’l 106435 (2021) . 9

Yangmingkai Li et al., Growing Impacts of Fire

Smoke on Ozone Pollution and Associated

Mortality Burden in the United States, 12 Sci.

Advances eaec2903 (2026) ....................................... 9

Yizhou Zhuang et al., Quantifying Contributions of

Natural Variability and Anthropogenic Forcings on

Increased Fire Weather Risk Over the Western

United States, 118 PNAS e2111875118 (2021) ...... 8

Zhiwei Xu et al., The Impact of Heat Waves on

Children’s Health: A Systematic Review, 58 Int’l J.

Biometeorology 239 (2014) .................................... 10

INTEREST OF AMICI1

Our Children’s Trust is a non-profit public

interest law firm that empowers young people to

enforce their constitutional rights in court when

governments endanger their lives, health, and futures

by fueling the climate crisis. Our Children’s Trust

represents clients in several states in constitutional

challenges

governmental

conduct

that

discriminates against and injures youth by enabling

and mandating the use of fossil fuels, which has been

documented to harm children. Our Children’s Trust

advocates for a world where the constitutional rights

of every child are upheld by courts and honored by

governments, protecting their lives, health, and

futures for generations to come.

Alina Miranda (age 21), Waverly Fisher (age

21), Adithya Bhaskara (age 22), Maddison Schink

(age 26), Muriel S. (age 17), Everett F. (age 8),

Penny S. (age 10), and Ethan M. (age 8), (collectively

Youth Amici) are from, attend school, or live in the

City of Boulder or Boulder County. They are being

directly harmed by air pollution from fossil fuels and

climate disruptions. They have an interest in ensuring

their local governments retain the authority to protect

them from Petitioners’ tortious conduct.

Dr. Lisa Patel, MD, MESc, FFAP, is the

Executive Director for the Medical Society

Consortium on Climate and Health and Clinical

Associate Professor of Pediatrics at Stanford School of

1 Pursuant to this Court’s Rule 37.6, amici state that no counsel

for either party authored this brief in whole or in part, and that

no person other than amici made a monetary contribution to fund

the preparation or submission of this brief.

Medicine. She is a national expert on climate change

and children’s health with a particular focus on air

pollution and wildfires. She is a former Presidential

Management Fellow for the Environmental Protection

Agency. She is a prior member of the Executive

Committee for the American Academy of Pediatrics

Council on Environmental Health and Climate

Change. She received her Master’s in Environmental

Sciences from Yale School of the Environment, her

medical degree from Johns Hopkins School of

Medicine, and completed her training in pediatrics at

UCSF. Dr. Patel is a practicing pediatric hospitalist,

caring for premature infants, newborns and

hospitalized children. She is amicus curiae in her

personal capacity.

Amici’s interest in this case is to assist the Court

in understanding how children’s health is

deteriorating from fossil fuel pollution, and through

that lens, the import of state sovereign authority and

duty over fossil fuel pollution-related injuries.

SUMMARY OF ARGUMENT

On December 30, 2021, the most destructive

wildfire in Colorado’s history ignited in Boulder

County: the Marshall Fire. That fire forever changed

Youth Amici’s lives. Maddison was not home at the

time, and she vividly remembers the call she received

from her grandmother. Maddison’s home needed to be

evacuated, and her grandmother was hurriedly

packing cherished items. Maddison’s grandmother

asked her to picture her room and pick three

irreplaceable items to be packed up. She told her

grandmother to grab her camera containing her

favorite photos, her favorite childhood blanket, and

her hiking backpack covered with patches from places

she had visited. Penny also vividly remembers the

Marshall Fire: the bright orange flames reaching into

the sky. The suffocating smoke. Her coughing. The

race to evacuate. Fire weather.

In the end, the Marshall Fire destroyed over 1,000

homes. Alina’s home was one of them. She lost

everything: pets, her artwork, journals, and so much

more. After the fire, she struggled to focus and had to

take a break from school. Limited housing options

forced her to be separated from her parents and she

spent five weeks sleeping in a laundry room. While the

homes of Maddison and Penny were spared, the

memories, harm to their developing bodies, anxiety,

and depression stick with them. Years later,

Maddison still experiences anxiety and sometimes

panic attacks on hot windy days, or when she sees fire

trucks or gets alerts about nearby wildfires. Penny

also experiences anxiety and knows how harmful the

new smoke season is to her still-developing lungs. She

monitors the air quality around her and consistently

sees levels that are unhealthy.

Youth Amici have experienced firsthand the

devastating toll that wildfires and smoke take on their

community. They know climate change makes such

fires more likely and more destructive. Beyond

wildfires, climate change is also causing dangerous

heat, extreme precipitation events, drought, low

snowpack, and other climate instability throughout

Boulder. Heat and poor air quality take a toll on Youth

Amici’s bodies, forcing them to miss school, work, or

cancel plans with family and friends. Maddison

currently lives in Adams County near a Suncor oil

refinery and has noticed plumes of black smoke

spewing from it and a decline in her health since

moving.2 As pediatricians like Dr. Patel explain,

climate disruptions and the polluted air Youth Amici

breathe increase their chances of developing chronic

illnesses. Children’s physical and psychological

development are altered in irrevocable ways.

It did not have to be like this. Just like the federal

government knew over half a century ago,3 Petitioners

in this case knew this would happen—they knew they

were marketing and selling a product in Colorado that

would unleash such harms and costs upon today’s

generation of Colorado children and youth. And they

did so anyway.

Youth Amici had no role in causing climate change

or fire weather in Boulder. Yet their lives are

permanently changed by it; their developing lungs

and bodies are regularly exposed to unhealthy air;

their anxiety is inescapable; their safety is no longer

something to be taken for granted, even in their own

homes. At the same time, Boulder bears the costs of

such climate disruptions and the entire community

suffers.

Importantly, as explained herein, Youth Amici

live in a country whose federal government is a

government of enumerated powers. Under the federal

Constitution, the Tenth Amendment reserves police

and public trust powers to Youth Amici’s state,

implemented by local governments. The federal

2 Noelle Phillips, Suncor’s Commerce City Refinery Emits Black

Smoke After Maintenance, Denv. Post (July 28, 2026),

https://www.denverpost.com/2026/07/28/suncors-commerce-cityblack-smoke/ .

3 See James Gustave Speth, They Knew (2022); The White House,

Restoring the Quality of Our Environment (1965).

Constitution—through the Tenth, Fifth, and

Fourteenth Amendments—recognizes and protects

the state constitutional and public-trust law Youth

Amici and other youth represented by Our Children’s

Trust rely on to preserve their inalienable rights.

Because those state laws are recognized and protected

by the federal Constitution, they are not preempted by

the Clean Air Act, the federal common law, or contrary

theories of federalism purportedly implicit in the

federal Constitution, as Petitioners argue. This Court

should reject Petitioners’ broad theory of preemption,

especially one that would encompass areas of law that

are not before the Court.

ARGUMENT

FOSSIL-FUEL AIR POLLUTION

DISPROPORTIONATELY HARMS THE

HEALTH, SAFETY, AND WELFARE OF

CHILDREN

Every step in the life-cycle of fossil fuels—from

extraction and refining to transportation and

combustion—emits air pollution that harms children’s

health in two ways: first, by harming children when

they breathe air contaminated by fossil fuel pollution,

and second, by increasing environmental health

hazards caused by greenhouse gas (GHG) pollution

and ensuing climate disruptions, including wildfires

and the associated smoke, extreme heat, flooding,

drought, and other climate disasters. See Figure 1.

These dual health hazards from fossil fuels—

breathing polluted air and climate disruptions—are

intertwined and compound one another’s effects with

devastating consequences for children.

Figure 1. Fossil fuels harm children’s health through

direct air pollution and by causing climate change.4

Children and youth shoulder disproportionate

health injuries from breathing air polluted by fossil

fuels and climate change over the course of their

lifetimes compared to adults. This is “because of their

unique behavior patterns; developing organ systems

and physiology; greater exposure to air, food, and

water contaminants per unit of body weight; and

dependence on caregivers.”5 Children with preexisting

chronic respiratory conditions are especially

vulnerable to the dual health harms from fossil fuels.

The extraction, transport, and combustion of fossil

fuels emit particulates, nitrogen oxides, volatile

organic compounds, and contribute to the formation of

ozone. These air pollutants tend to be concentrated

near the pollution sources, and disproportionately

harm children. Exposure to particulate matter

increases children’s risk of asthma, impairs lung

development,

and

increases

risk

4 Adapted from Frederica P. Perera, Multiple Threats to Child

Health from Fossil Fuel Combustion: Impacts of Air Pollution

and Climate Change, 125 Env’t Health Persps. 141, 142 (2017).

5 Samantha Ahdoot et al., Am. Acad. Pediatrics, Climate Change

and Children’s Health: Building a Healthy Future for Every

Child, 153 Pediatrics e2023065505, 1 (2024).

neurodevelopmental disorders and diminished IQ.6

Exposure to fine particulate matter (2.5 micrometers

or smaller) during pregnancy increases risks for

premature birth, low birthweight, stillbirth,

hypertensive disorder of pregnancy, gestational

diabetes mellitus, gestational hypertension, and

preeclampsia.7 There is no “safe” level for fine

particulate matter, because there is no threshold

below which the risk of premature death decreases.8

Every increase of 10 micrograms per cubic meter in

fine particulate matter concentration can increase allcause mortality by 7.3%.9 Exposure to ozone and

nitrogen dioxide exacerbates existing asthma and

increases a non-asthmatic child’s risk of developing

asthma.10 Exposure to air pollution from fossil fuels

at a young age can disrupt the healthy physical and

6 Li-Zi Lin et al., The Epidemiological Evidence Linking Exposure

to Ambient Particulate Matter with Neurodevelopmental

Disorders: A Systematic Review and Meta-Analysis, 209 Env’t

Rsch. 112876 (2022); Frederica Perera et al., Climate Change,

Fossil-Fuel Pollution, and Children’s Health, 386 NEJM 2303

(2022).

7 Shuaixing Song et al., Ambient Fine Particulate Matter and

Pregnancy Outcomes: An Umbrella Review, 235 Env’t Rsch.

116652 (2023); Maria Harris et al., Prenatal and Childhood

Traffic-Related Pollution Exposure and Childhood Cognition in

the Project Viva Cohort, 123 Env’t Health Persp. 1072 (2015).

8 Rebecca E. Berger et al., Air Pollution Still Kills, 376 NEJM

2591 (2017).

9 Qian Di et al., Air Pollution and Mortality in the Medicare

Population, 376 NEJM 2513 (2017).

10 Stephanie Holm & John Balmes, Systematic Review of Ozone

Effects on Human Lung Function, 2013 Through 2020, 161 Chest

190 (2022); U.S. EPA, Integrated Science Assessment for Oxides

of Nitrogen – Health Criteria 1-17 to 1-22 (2016).

psychological development of children and result in

lifelong harms, including increased risk of disease

during adulthood.

Regarding harms to children from climate

disruptions, the extraction, transport, and combustion

of fossil fuels emit heat-trapping GHGs, especially

carbon dioxide (CO2). Hotter air holds more moisture,

drying the land. A warmer, wetter atmosphere

increases extreme heat, wildfires and wildfire smoke,

floods, droughts, severe storms, and vector-borne (e.g.,

tick- and mosquito-borne) diseases.11 These hazards

from climate change are not uniform across the

country; they are unevenly distributed and locallyspecific. The fossil fueled climate hazards harming

children and youth in Boulder, including Youth Amici,

include wildfires and associated smoke, extreme heat,

increased frequency and intensity of flooding,

declining snowpack, longer droughts, and water

shortages.12

Increased heat and drought from climate change

cause fire weather with increased risk and likelihood

of wildfires, and hence wildfire smoke.13 Wildfire

smoke contains a potent cocktail of air pollutants that

are hazardous or deadly to inhale, including

particulate matter and nitrogen dioxide (which also

result from the extraction and burning of fossil fuels,

11 CDC, Preparing for the Regional Health Impacts of Climate

Change in the United States 3 (2024).

12 Climate Change in Boulder County, https://bouldercounty.gov/

climate/impacts/ (last visited July 30, 2026).

13 Yizhou Zhuang et al., Quantifying Contributions of Natural

Variability and Anthropogenic Forcings on Increased Fire

Weather Risk Over the Western United States, 118 PNAS

e2111875118 (2021).

as noted above).14 Higher temperatures combine with

pollutants from burning fossil fuels (and from wildfire

smoke) to form ground-level ozone, which increases

respiratory-related emergency room visits15 and

mortality.16 Ozone levels above American Thoracic

Society recommendations are associated with an

estimated 6,800,000 lost school days annually.17

Although climate change is one of the greatest

public health threats facing humanity, for children it

is a public-health emergency18 because “[c]hildren are

14 Minghao Qiu et al., Wildfire Smoke Exposure and Mortality

Burden in the USA Under Climate Change, 647 Nature 935

(2025); Min Zhang et al., Wildfire Smoke PM2.5 and Mortality

Rate in the Contiguous United States: A Causal Modeling Study,

12 Sci. Advances eadw5890 (2026).

15 Xue-yan Zheng et al., Short-term Exposure to Ozone, Nitrogen

Dioxide, and Sulphur Dioxide and Emergency Department Visits

and Hospital Admissions Due to Asthma: A Systematic Review

and Meta-analysis, 150 Env’t Int’l 106435 (2021).

16 Weizhi Deng et al., Fires Reverse Progress Toward Ozone Air

Quality Standards in the United States, 392 Sci. 1088 (2026);

Yangmingkai Li et al., Growing Impacts of Fire Smoke on Ozone

Pollution and Associated Mortality Burden in the United States,

12 Sci. Advances eaec2903 (2026).

17 Janet Currie et al., Does Pollution Increase School Absences?,

91 Rev. Econ. Stat. 682 (2009); Kevin Cromar et al., Adverse

Health Impacts of Outdoor Air Pollution, Including from

Wildland Fires, in the United States: “Health of the Air,” 20182020. 21 Ann. Am. Thoracic Soc. 76 (2024).

18 Lukoye Atwoli et al., Call for Emergency Action to Limit Global

Temperature Increases, Restore Biodiversity, and Protect Health,

385 NEJM 1134 (2021) (editorial simultaneously published in

230 other medical and public-health journals); see also, e.g.,

World Health Org., The Health Argument for Climate Action 2

at higher risk of climate-related health burdens than

adults[.]”19 Children are more vulnerable to extreme

heat and are at greater risk of heat exhaustion, heat

stroke, renal dysfunction, and respiratory disease

exacerbation because young children’s temperatureregulation systems are not fully developed and

children lose fluids more quickly than adults.20 Simply

put, children are more likely to end up in the

emergency room when temperatures are higher or

when the air is polluted by wildfire smoke or other

pollutants from fossil fuels.21 A child’s repeated

exposure to polluted air and climate disruptions

compounds the harm to their health and wellbeing

throughout their development. See Figure 2.

(2021) (“Climate change is the single biggest health threat facing

humanity.”); Anthony Costello et al., Managing the Health

Effects of Climate Change, 373 Lancet 1693, 1693 (2009)

(“Climate change is the biggest global health threat of the 21st

century.”); USGCRP, Fifth National Climate Assessment 15-6

(2023) (“Climate change has profound negative effects on human

health.”).

19 Ahdoot, supra note 5.

20 Courtney W. Mangus & Therese L. Canares, Heat-Related

Illness in Children in an Era of Extreme Temperatures, 40

Pediatrics in Rev. 97 (2019); Zhiwei Xu et al., The Impact of Heat

Waves on Children’s Health: A Systematic Review, 58 Int’l J.

Biometeorology 239 (2014); Caroline J. Smith, Pediatric

Thermoregulation: Considerations in the Face of Global Climate

Change, 11 Nutrients 2010 (2019).

21 E.g., Aaron S. Bernstein et al., Warm Season and Emergency

Department Visits to U.S. Children’s Hospitals, 130 Env’t Health

Persp. 17001 (2022).

Figure 2. Illustrating the compounding harms to

children’s health caused by air pollution and climate

change.22

The harms to children’s health, however, are not

only physical. When the air is smoky or temperatures

are dangerously hot, children’s lives shut down and

their pursuit of happiness vanishes: one by one,

religious, educational, cultural, and recreational

activities are canceled or foregone out of necessity, to

protect children’s health and safety. Being prisoners

in their own homes, with an air purifier or air

conditioner, if they are lucky, is a pale substitute for a

Saturday walk to synagogue for Shabbat, fishing with

parents, a pick-up game of basketball, a hike with a

Adapted from Lancet Countdown on Health and Climate

Change, Policy Brief for the United States of America (2019).

youth group, or attending summer camps—a

quintessential aspect of childhood now routinely

disrupted by extreme climate events.23 Each canceled

or foregone activity is a loss—a lost opportunity for

childhood joy, healthful physical activity, and

intergenerational bonding. The losses are more than

mere inconveniences and disrupt an essential part of

childhood development, with lifelong consequences.

These are the freedoms truly at stake for children

in Boulder. These are among the interests the

Respondents here have the legal power and duty to

protect.

II. THE FEDERAL CONSTITUTION

PRESERVES STATE SOVEREIGN

AUTHORITY TO PROTECT HEALTH,

SAFETY, AND WELFARE

There is nothing about the “structure of our

Constitutional system” that divests Respondents of

their right to pursue relief against private

corporations for damages they knowingly inflicted. On

the contrary, “[t]he Constitution created a Federal

Government of limited powers.” Gregory v. Ashcroft,

501 U.S. 452, 457 (1991). Pursuant to the Tenth

Amendment, the states and their people “retain

substantial

sovereign

authority

under

our

constitutional system.” Id. at 457. The powers

reserved to the states “extend to all the objects, which

in the ordinary course of affairs, concern the lives,

23 Ava Berger, Climate Change Is Now Threatening a Pillar of

Childhood: Summer Break, NPR (July 26, 2026),

https://www.npr.org/2026/07/26/nx-s1-5900911/wildfire-smokefires-camp-minnesota.

liberties and properties of the people; and the internal

order, improvement and prosperity of the state.”

Mayor, Alderman & Commonalty of N.Y. v. Miln, 36

U.S. 102, 133 (1837). The Tenth Amendment reserves

police powers and sovereign duties concerning public

welfare to the states, including duties under the

Public Trust Doctrine, unless “delegated to the United

States.”

Petitioners’ preemption argument rests on four

faulty contentions: that (a) “the structure of our

constitutional system continues to foreclose resort to

state law unless Congress affirmatively authorizes its

application”; (b) “States have no residual or inherent

power under our Constitution to regulate in this area,”

claims for harms caused by diffuse interstate and

international

emissions”;

and

(d)

“allowing

respondents’ state-law claims to proceed is

incompatible with . . . the Clean Air Act, and this

Court’s precedents.” Each of these propositions

fundamentally misunderstands federalism.

A. The “Structure of Our Constitutional

System” Reserves to the States Any

Powers Not Explicitly Granted to the

Federal Government or Prohibited to the

States

“The powers not delegated to the United States by

the Constitution, nor prohibited by it to the States, are

reserved to the States respectively, or to the people.”

U.S. Const. amend. X. “The [Tenth] amendment states

but a truism that all [power] is retained which has not

been surrendered.” United States v. Darby, 312 U.S.

100, 124 (1941). Quoting James Madison, this Court

has observed, “[t]he powers delegated by the proposed

Constitution to the federal government are few and

defined. Those which are to remain in the State

governments are numerous and indefinite.” Gregory,

501 U.S. at 458 (quoting The Federalist No. 45, at 29293 (James Madison) (C. Rossiter ed., 1961)). Unless

the Constitution enumerates a power as belonging to

the federal government, the power is reserved to the

states. New York v. United States, 505 U.S. 144, 176

(1992).

The states, Petitioners argue, “surrendered their

ability to redress inherently transboundary issues

such as global climate change when they agreed to

enter the Union.” Not so. In forming a union, the

states may have surrendered “forcible abatement”

through, e.g., a military, but “they did not thereby

agree to submit to whatever might be done. They did

not renounce the possibility of making reasonable

demands on the ground of their still remaining quasisovereign interests[.]” Georgia v. Tenn. Copper Co.,

206 U.S. 230, 237 (1907).

In Tennessee Copper, Georgia sought injunctive

relief against foreign corporations for air pollution

discharges in Tennessee harming Georgia’s territory.

206 U.S. at 236. As a result of such discharge, Georgia

alleged, “a wholesale destruction of forests, orchards,

and crops is going on, and other injuries are done and

threatened in five counties of the state.” Id. at 236. In

sustaining Georgia’s right to pursue its claims, this

Court held in relevant part:

It is a fair and reasonable demand on the

part of a sovereign that the air over its

territory should not be polluted on a

great scale by sulphurous acid gas, that

the forests on its mountains, be they

better or worse, and whatever domestic

destruction they have suffered, should

not be further destroyed or threatened by

the act of persons beyond its control, that

the crops and orchards on its hills should

not be endangered from the same source.

Id. at 238. The same principle applies here.

Respondents, a Colorado county and municipality,

seek to require Petitioners to share a portion of the

financial burden their communities must bear in

coping with an altered climate brought about in part

by Petitioners’ tortious conduct.

Importantly, a Tenth Amendment-reserved power

can only be preempted through the federal exercise of

an enumerated power, such as the commerce power.

Mayor, 36 U.S. at 139; New York, 505 U.S. at 159 (“the

core of sovereignty retained by the States under the

Tenth Amendment” encompasses all power not

expressly “delegated to the Federal Government

under the affirmative provisions of the Constitution”);

Hodel v. Va. Surface Min. & Reclamation Ass’n, 452

U.S. 264, 291 (1981). This enumeration requirement

dooms

Petitioners’

“structural”

constitutional

preemption

argument,

which

identifies

enumerated federal power whatsoever. Instead, it

performs an 18-page interpretative dance. See Pets.’

Br. at 21-39.

Respondents “retain substantial sovereign powers

under our constitutional scheme, powers with which

Congress does not readily interfere.” Gregory, 501 U.S.

at 461. Among these is the power to seek redress

against Petitioners for intentionally misleading the

public about the role their fossil fuel products have

played in exacerbating the impacts of climate change

and knowingly causing and contributing to the

alteration of the climate. Nothing about the

“structure” of our “constitutional system” has divested

Respondents of their power, and even duty, to seek

redress for these injuries—which Respondents’

citizens are suffering in their home jurisdictions. See

Tafflin v. Levitt, 493 U.S. 455, 458 (1990) (“under our

federal system, the States possess sovereignty

concurrent with that of the Federal Government”).

B. States Have “Inherent Power” to

Exercise Their Police Powers to Ensure

the Safety of Their Citizens

Boulder’s tort claims are not a regulation. But

even if they were, the states enjoy expansive police

power to protect the health and well-being of their

citizens that may not be abridged unless prohibited to

the states or explicitly granted to the federal

government. New York, 505 U.S. at 176. This police

power encompasses seeking redress against

tortfeasors.

Police power is the plenary power to make any and

all laws necessary “as to the protection of the lives,

limbs, health, comfort, and quiet of all persons,”

among other ends. Gonzales v. Oregon, 546 U.S. 243,

270 (2006); Berman v. Parker, 348 U.S. 26, 32 (1954).

States have police power; the federal government does

not. United States v. Lopez, 514 U.S. 549, 566 (1995).

The states’ police powers preceded the adoption of the

Constitution, and thus, according to Chief Justice

John Marshall, “remain, after the adoption of the

[C]onstitution, what they were before, except so far as

they may be abridged by [the Constitution].” Sturges

v. Crowninshield, 17 U.S. (4 Wheat.) 122, 193 (1819).

“The powers reserved to the several States will

extend to all the objects which, in the ordinary course

of affairs, concern the lives, liberties, and properties of

the people, and the internal order, improvement, and

prosperity of the State.” Gregory, 501 U.S. at 458

(quoting The Federalist No. 45, at 292-93). Among

these “numerous and indefinite” powers is the

protection of citizens’ health and well-being.

Queenside Hills Realty Co. v. Saxl, 328 U.S. 80, 82

(1946) (“Protection of the safety of persons is one of the

traditional uses of the police power of the States.”).

Under the Tenth Amendment, “[i]t is not only the

right, but the bounden and solemn duty of a state, to

advance the safety, happiness and prosperity of its

people, and to provide for its general welfare, by any

and every act of legislation which it may deem to be

conducive to these ends[.]” Mayor, 36 U.S. at 139.

Protecting the safety of the public is the primary

purpose for which government exists, and is supported

by authorities dating back to Roman times. Two

thousand years ago, Cicero gave us the Latin phrase

“salus populi suprema lex esto,” meaning “the safety

of the community is the highest law.” Gilmer,

Cochran’s Law Lexicon 265 (5th ed. 1973); see also

Keith v. Clark, 97 U.S. 454, 460 (1878) (“Cicero and

subsequent public jurists define a State to be a body

political or society of men united together for the

purpose of promoting their mutual safety”); Obergefell

v. Hodges, 576 U.S. 644, 657 (2015) (citing Cicero for

deep roots of fundamental right to marry); Caetano v.

Massachusetts, 577 U.S. 411, 421 (2016) (Alito,

Thomas, JJ., concurring) (“A State’s most basic

responsibility is to keep its people safe.”).

Here, Respondents have “a quasi-sovereign

interest in the health and well-being—both physical

and economic—of [their] residents in general.” Alfred

L. Snapp & Son, Inc. v. Puerto Rico, ex rel., Barez, 458

U.S. 592, 607 (1982). Respondents’ claims against

Petitioners are consistent with, and a fulfillment of,

that interest. See Missouri v. Illinois, 180 U.S. 208,

241 (1901) (“But it must surely be conceded that, if the

health and comfort of the inhabitants of a state are

threatened, the state is the proper party to represent

and defend them.”); see also Kelley v. Johnson, 425

U.S. 238, 247 (1976) (“The promotion of safety of

persons and property is unquestionably at the core of

the State’s police power[.]”). Indeed, Colorado has a

policy “to achieve the maximum practical degree of air

purity in every portion of the state”, has declared “that

the prevention, abatement, and control of air pollution

in each portion of the state are matters of statewide

concern and are affected with a public interest”, and

has exercised its police power “for the purpose of

protecting the health, peace, safety, and general

welfare of the people of this state” to reduce, prevent,

and control air pollution. Colo. Rev. Stat. Ann. § 25-7102.

A state’s police power “is one of the least limitable

of governmental powers.” Queenside Hills Realty, 328

U.S. at 83. While “federal statutes enacted under the

commerce power [may] preempt particular exercises

of state police power,” Hodel, 452 U.S. at 292,

Congress “must make its intention to do so

unmistakably clear in the language of the statute.”

Gregory, 501 U.S. at 460 (citation modified). “[I]t is

incumbent upon the federal courts to be certain of

Congress’ intent” to preempt. Id. (emphasis added,

citation omitted); Wis. Pub. Intervenor v. Mortier, 501

U.S. 597, 605 (1991) (a state’s exercise of police power

may not be foreclosed by Congress “unless that was

[Congress’s] clear and manifest purpose” (citation

omitted)). This unmistakable-clarity requirement

exists because “Congress does not readily interfere”

with the “substantial sovereign powers” states retain

“under our constitutional scheme[.]” Gregory, 501 U.S.

at 461; see also Wyeth v. Levine, 555 U.S. 555, 565

(2009) (presumption against preemption); Bond v.

United States, 572 U.S. 844, 866 (2014) (“Absent a

clear statement” by Congress, this Court “will not

presume Congress to have authorized such a stark

intrusion into traditional state authority.”).

While the Clean Air Act is an exercise of

Congress’s commerce power, Petitioners cannot

identify any statutory language making an

unmistakably clear statement of congressional intent

to foreclose Respondents from pursuing tort claims

against Petitioners under state law—because none

exists. Tacitly acknowledging this fatal flaw,

Petitioners instead ask the Court to examine whether

Congress

has

“affirmatively

authorize[d]”

Respondents to pursue damages claims against

tortfeasors for deceiving and harming Respondents’

citizens. But that gets the inquiry exactly backwards,

inverting the fundamental principle of federalism.

In the alternative, Petitioners mischaracterize the

lawsuit as an attempt to “regulate in this area,” and

argue field preemption under the Clean Air Act. Even

if this case involved regulation (it does not),

Petitioners’ field-preemption argument fails because

the Clean Air Act does not “make reasonable the

inference that Congress left no room for the States to

supplement it,” as field preemption requires; it does

the opposite. Cipollone v. Liggett Grp., Inc., 505 U.S.

504, 516 (1992) (citation omitted). “To regulate and

abate nuisances is one of [the] ordinary functions” of

states’ police power. Nw. Fertilizing Co. v. Vill. of

Hyde Park, 97 U.S. 659, 667 (1878). The Clean Air Act

expressly states that “air pollution control at its

source is the primary responsibility of States[.]” 42

U.S.C. § 7401(a)(3) (emphasis added). Moreover,

Petitioners’ field-preemption argument is ironic,

considering that the federal government currently

denies that the Clean Air Act authorizes federal

regulation of GHGs at all, a matter being litigated in

the D.C. Circuit. See Rescission of the Greenhouse Gas

Endangerment Finding, 91 Fed. Reg. 7686, 7686 (“The

EPA determines that CAA section 202(a)(1) does not

authorize the Agency to prescribe emission standards

in response to global climate change concerns.”); Am.

Pub. Health Ass’n v. U.S. EPA, No. 26-2037 (D.C. Cir.).

The American Petroleum Institute, of which

Petitioner Exxon Mobil is a member, is currently

urging the D.C. Circuit Court to assume the Clean Air

Act does not authorize EPA to regulate GHGs. Private

Resp’t-Intervenors’ Opp’n to Mot. to Stay Final Rule

at 14, Am. Pub. Health Ass’n, No. 26-2038, Dkt. No.

2181086.

But the Court need not reach that issue, because

Respondents’ tort claims do not constitute regulation.

In Sprietsma v. Mercury Marine, this Court rejected

the argument that an express preemption clause in

the Federal Boat Safety Act directed at “a [state or

local] law or regulation” encompassed common-law

tort claims. 537 U.S. 51, 63 (2002). The Court reached

this conclusion based not only on the plain language

of the preemption clause, but also because “[i]t would

have been perfectly rational for Congress not to pre-

empt common-law claims, which—unlike most

administrative

and

legislative

regulations—

necessarily perform an important remedial role in

compensating accident victims.” Id. at 64 (emphasis

added).

The same is true here. The County and City of

Boulder are not engaged in an effort to “control (an

activity or process) esp. through the implementation

of rules.” Regulate, Black’s Law Dictionary (12th ed.

2024). Rather, Respondents’ litigation seeks to hold

Petitioners accountable for their deceptive and

destructive conduct and, in so doing, achieve a

remedial outcome for the benefit of their residents. In

short, even if Petitioners were correct (they are not)

that states lack power to “regulate in this area,” their

position has no bearing on this Court’s analysis.

C. The Public Trust Doctrine Requires

States to Seek Compensation for Damage

to Public Trust Assets

The Public Trust Doctrine provides an additional

and independent basis for the power—and duty—of

state and local governments to protect (and recover

losses of) natural resources, including air and water,

that are essential for their citizens’ health, safety, and

welfare, especially children and future generations.

State public trust obligations cannot be preempted.

The Public Trust Doctrine is “rooted in the precept

that some resources are so central to the well-being of

the community that they must be protected by

distinctive, judge-made principles.” Charles F.

Wilkinson, The Public Trust Doctrine in Public Land

Law, 14 U.C. Davis L. Rev. 269, 315 (1980). Pursuant

to the Public Trust Doctrine, the sovereign trustees—

governments—are affirmatively obligated to prevent

substantial impairment or waste of trust property,

and use skill and care to preserve the trust property

for present and future generations. See Mary

Christina Wood, Advancing the Sovereign Trust of

Government to Safeguard the Environment for Present

and Future Generations (Part I): Ecological Realism

and the Need for a Paradigm Shift, 39 Env’t L. 43, 69

(2009).

The Doctrine gives force to the expectation—

central to the purpose of organized government—that

natural resources essential for a child’s survival will

remain abundant, justly distributed, and bequeathed

to future generations. See, e.g, Gerald Torres &

Nathan Bellinger, The Public Trust: The Law’s DNA,

4 Wake Forest J.L. & Pol’y 281, 283 (2014) (“[O]ne

central purpose of government is to protect the

essential natural resources that enable our society to

function, evolve, and reproduce for future

generations.”); see U.S. Const. pmbl. (forming the

Union to “secure the Blessings of Liberty to ourselves

and our Posterity”). The sovereign fiduciary duty to

protect such vital assets from irrevocable damage

remains the sine qua non of the public trust. Unlike

discretionary police powers, the Public Trust Doctrine

imposes affirmative duties on trustees to preserve and

maintain trust assets. United States v. White

Mountain Apache Tribe, 537 U.S. 465, 475 (2003).

Air and water have long been understood to be

among the resources protected by the Public Trust

Doctrine. 2 William Blackstone, Commentaries on the

Laws of England *14 (1766) (“[T]here are some few

things

which,

notwithstanding

the

general

introduction and continuance of property, must still

unavoidably remain in common . . . . Such (among

others) are the elements of light, air, and water[.]”);

Geer v. Connecticut, 161 U.S. 519, 525-26 (1896). The

fact that air and water are shared resources, not

limited to one jurisdiction, confirms the public trust

nature of them. As one leading public trust scholar

explains, “[i]t is well established that all sovereigns

with jurisdiction over the natural territory of a

transboundary asset have legitimate property claims

to the resource.” Mary Christina Wood & Dan

Galpern, Atmospheric Recovery Litigation: Making the

Fossil Fuel Industry Pay to Restore a Viable Climate

System, 45 Env’t L. 259, 287 (2015).

American courts routinely recognize the ancient

origins of the Public Trust Doctrine, tracing it to

ancient legal systems. See, e.g., Lawrence v. Clark

Cnty., 254 P.3d 606, 608 (Nev. 2011); Mont. Coal. for

Stream Access, Inc. v. Curran, 682 P.2d 163, 167

(Mont. 1984); Nat’l Audubon Soc’y v. Super. Ct., 658

P.2d 709, 718 (Cal. 1983). Specifically, the Doctrine is

traced from Roman law, through English common law,

to American colonies, to present day. PPL Mont., LLC

v. Montana, 565 U.S. 576, 603 (2012); J. Inst. 2.1.1 (T.

Sanders trans., 4th ed. 1867); Matthew Hale, De Jure

Maris, Harg. Law Tracts, reprinted in Stuart Moore,

A History of the Foreshore and the Law Relating

Thereto (3rd ed. 1888); The Federalist No. 46 (James

Madison) (“The federal and State governments are in

fact but different agents and trustees of the people”);

Martin v. Waddell’s Lessee, 41 U.S. 367, 413 (1842).

Subsequently, this Court recognized the Public Trust

Doctrine in Illinois Central Railroad Co. v. Illinois,

146 U.S. 387, 453 (1892). In Illinois Central Railroad,

this Court found the navigable waters of the Chicago

harbor, and the land under them, are “a subject of

concern to the whole people of the state” and must be

held “in trust for their common use and of common

right, as an incident of their sovereignty.” Id. at 455,

459-60.

Importantly, the people of the original thirteen

states, in forming the federal union, reserved state

public trust resources for themselves, and their

sovereign states as trustees, through the Tenth

Amendment. See Michael C. Blumm & Lynn S.

Schaffer, The Federal Public Trust Doctrine:

Misinterpreting Justice Kennedy and Illinois Central

Railroad, 45 Env’t L. 399, 406-07 (2015). Upon

federation, “[t]he shores of navigable waters, and the

soils under them, were not granted by the

Constitution to the United States, but were reserved

to the states respectively.” Pollard v. Hagan, 44 U.S.

212, 230 (1845). Concomitantly, the original thirteen

colonies passed sovereign trust obligations to the

federal government to manage federal lands that were

not yet incorporated into the union as states. “[T]he

United States is presumed to have held navigable

waters in acquired territory for the ultimate benefit of

future States.” Idaho v. Coeur d’Alene Tribe, 521 U.S.

261, 283 (1997).

Later states, including Colorado, became trustees

over public trust resources through the statehood acts

of Congress. “[B]efore the equal footing conveyance

occurred, a trust applied to the federal lands that were

subject to the conveyance.” See Blumm & Schaffer,

supra. Accordingly, as a sovereign, each new state

became trustee as “a matter of state law” to protect

the people’s beneficial use of vital natural resources.

PPL Mont., 565 U.S. at 603.

Critically, as an attribute of sovereignty, states

cannot abdicate their reserved public trust duties, nor

can the federal government “preempt” them. See, e.g.,

Geer, 161 U.S. at 527 (describing the sovereign trust

over wildlife resources as an “attribute of

government”). As this Court declared in Illinois

Central, “[t]he state can no more abdicate its trust

over property in which the whole people are interested

. . . than it can abdicate its police powers in the

administration of government[.]” 146 U.S. at 453. As

one federal district court noted: “The trust is of such a

nature that it can be held only by the sovereign, and

can only be destroyed by the destruction of the

sovereign.” United States v. 1.58 Acres of Land, 523 F.

Supp. 120, 124 (D. Mass. 1981). A state’s public trust

responsibilities cannot be abdicated even where there

has been no previous adjudication of the applicability

of the Public Trust Doctrine, and where a trustee may

have “slept on public rights.” Ariz. Ctr. for Law in Pub.

Int. v Hassell, 837 P.2d 158, 171 (Ariz. Ct. App. 1991).

Succeeding trustees are not foreclosed from

awakening to their trustee duties and protecting the

trust res, as the children of each generation so depend.

Trust obligations run to each branch of

government, including local governments. See Sean

Lyness, The Local Public Trust Doctrine, 34 Geo. Env’t

L. Rev. 1, 12-13 (2021); Robinson Twp. v.

Commonwealth, 83 A.3d 901, 977 (Pa. 2013) (“With

respect to the public trust, . . . all existing branches

and levels of government derive constitutional duties

and obligations with respect to the people.”); Kelly v.

1250 Oceanside Partners, 140 P.3d 985, 1006 (Haw.

2006) (“We therefore hold that the County has a duty,

as a political subdivision of the State, to protect the

waters located adjacent to the Property.”). Therefore,

local governments, including Respondents here, are

also trustees. The authority of local governments to

protect public trust resources is at its peak in home

rule states like Colorado. Colo. Const. art. XIV, § 16;

id. art. XX; Lyness, supra.

In Robinson Township, the Pennsylvania

Supreme Court ruled in favor of local governments,

finding a state law compelling local municipalities to

allow oil and gas drilling violated the state’s

constitutionally codified Public Trust Doctrine.

Robinson Twp., 83 A.3d at 954-59, 1000.

When third parties, such as Petitioners here, have

allegedly damaged trust assets, trustees, like

Respondents, must exercise their affirmative trust

duties to restore such assets by pursuing monetary

damages. Wood & Galpern, supra. This duty cannot be

abdicated or preempted.

***

In sum, Boulder’s tort claims are a lawful exercise

of police powers and the Public Trust Doctrine

reserved to the states under the Tenth Amendment,

which have a centuries-old history within our system

of federalism. See Resp’ts Br. at 9, 35-37. Boulder’s

suit fits comfortably within the plain text of the

federal structure: police power is textually committed

to the states by the Tenth Amendment, and state and

local governments’ “primary responsibility” for

reducing air pollution is expressly recognized by the

Clean Air Act. 42 U.S.C. § 7401(a)(3). Boulder’s suit is

therefore not displaced by the “structure” of the

Constitution, by the Clean Air Act, or by federal

common law. A holding of preemption in this case

would authorize unprecedented federal intrusion on

states’ authority, and duty, to protect the property,

health, safety, and welfare of their citizens.

III. A BROAD PREEMPTION HOLDING

WOULD IMPEDE INDIVIDUAL

CONSTITUTIONAL RIGHTS THAT ARE

NOT BEFORE THIS COURT

Petitioners request a staggeringly broad

preemption holding: one that preempts not only statelaw tort claims against private tortfeasors, but also all

state-law claims involving GHG pollution, including

types of claims not before this Court. This Court

should not accede to Petitioners’ request, because such

a holding would obliterate children’s state-law rights

to public trust resources that are protected by their

state and federal constitutions before they are fully

developed adults, can protect themselves, or have

power to vote.

“The constitutionally mandated balance of power

between the States and the Federal Government was

adopted by the Framers to ensure the protection of our

fundamental liberties.” Gregory, 501 U.S. at 458

(citation modified). The Due Process Clauses of the

Fifth and Fourteenth Amendments protect against

invasions of individual “liberty” interests “without due

process of law[.]” U.S. Const. amends. V, XIV. A Due

Process-protected “liberty interest may arise from the

Constitution itself, by reason of guarantees implicit in

the word ‘liberty,’ . . . or it may arise from an

expectation or interest created by state laws or

policies[.]” Wilkinson v. Austin, 545 U.S. 209, 221

(2005) (citation modified); see, e.g., Gutierrez v. Saenz,

606 U.S. 305, 314 (2025) (recognizing a Fourteenth

Amendment-protected state-created liberty interest);

Atherton v. D.C. Off. of Mayor, 567 F.3d 672, 689 (D.C.

Cir. 2009) (in Fifth Amendment context).

A state-created liberty interest exists when a state

(1) “ha[s] the authority to create, or not, a right,” and

(2) “the State having created the right[, . . .] itself

recogniz[es] that its deprivation” is prohibited or

authorized only under certain circumstances. Wolff v.

McDonnell, 418 U.S. 539, 557 (1974). Under those

state-created circumstances, “the [individual’s]

interest has real substance and is sufficiently

embraced within Fourteenth Amendment ‘liberty’ to

entitle him to those minimum procedures appropriate

under the circumstances and required by the Due

Process Clause to insure that the state-created right

is not arbitrarily abrogated.” Id., holding aff’d, Sandin

v. Conner, 515 U.S. 472, 483 (1995).

For example, in United States v. Windsor, New

York enacted a statute to recognize and protect the

right of same-sex couples to marry. 570 U.S. 744, 764

(2013). Contrary to New York’s law, the federal

Defense of Marriage Act (DOMA) defined marriage as

between a man and woman. Id. at 764, 752. Yet this

Court held DOMA did not preempt New York’s

marriage law because “the definition and regulation of

marriage” is “[b]y history and tradition” within the

states’—not Congress’s—authority. Id. at 764-65. On

the contrary, because DOMA “injure[d] the very class”

which New York “sought to give further protection and

dignity” to, DOMA violated the Fifth Amendment’s

liberty protection, on equal protection grounds. Id. at

766, 769. On that basis, this Court declared DOMA

unlawful. Id. at 775.

Amicus Our Children’s Trust (OCT) represents

children in states such as Montana, Pennsylvania,

and Hawai‘i who are beneficiaries of their respective

states’ obligations to preserve the public trust with

respect to GHG emissions subject to state control. Just

as DOMA in Windsor did not preempt a New York

couple’s Fifth Amendment-protected state-law liberty

interest in the individual right to marry, the Clean Air

Act similarly does not preempt our clients’ state-law

liberty interests in the right to public natural

resources. Nor does it preempt children’s interests in

having their state or local governments recover from

tortfeasors for damages that otherwise would be paid

by the citizens, i.e., youth amici here.

Just as with marriage, protection of state citizens’

trust-beneficiary rights to use and enjoy state public

trust resources has traditionally been within states’—

not Congress’s—authority. See Section II.C, supra;

see, e.g., Ill. Cent. R.R., 146 U.S. at 453; PPL Mont.,

565 U.S. at 603-04; Ching v. Case, 449 P.3d 1146, 1175

(Haw. 2019). States have long exercised this authority

by limiting pollution originating within their borders.

The Clean Air Act expressly recognizes as much,

noting that “air pollution control at its source is the

primary responsibility of States and local

governments[.]” 42 U.S.C. § 7401(a)(3); Ohio v. EPA,

603 U.S. 279, 283 (2024).

Just as New York exercised its traditional state

powers in Windsor to protect same-sex couples’ right

to marry, many states have enshrined robust

individual public-trust rights and corresponding state

duties in their state constitutions or statutory codes.

See, e.g., Penn. Const. art. I, § 27 (“As trustee of

[Pennsylvania’s public natural] resources, the

Commonwealth shall conserve and maintain them for

the benefit of all the people.”); Mont. Const. art. II, § 3

(“All persons” have the “inalienable right[] . . . to a

clean and healthful environment”); Mont. Const. art.

IX, § 1 (“The state and each person shall maintain and

improve a clean and healthful environment in

Montana for present and future generations.”); Mont.

Const. art. IX, § 3(2) (“All . . . atmospheric waters

within the boundaries of the state are the property of

the state for the use of its people and are subject to

appropriation for beneficial uses as provided by law.”);

Held v. State, 560 P.3d 1235, 1249 (Mont. 2024)

(statute prohibiting state consideration of GHG

emissions violated plaintiffs’ state constitutional right

to a clean and healthful environment); Haw. Const.

art. XI, § 1 (“For the benefit of present and future

generations, the State . . . shall conserve and protect

Hawaii’s natural beauty and all natural resources”);

Haw. Const. art. XI, § 9 (“Each person has the right to

a clean and healthful environment”); Haw. Rev. Stat.

§ 225P-8 (requiring state to reduce GHG emissions

from transportation); In re Maui Elec. Co., 506 P.3d

192, 202 & n.15 (Haw. 2022) (the right is an

“affirmative [state] constitutional obligation[]” that

“subsumes a right to a life-sustaining climate system,”

including “[t]he need to mitigate the catastrophic

effects of anthropogenic climate change”); In re Haw.

Elec. Light Co., 526 P.3d 329, 336 (Haw. 2023); Tex.

Const. art. XVI, § 59(a) (“The conservation and

development of all of the natural resources of this

State, . . . are each and all hereby declared public

rights and duties”); Mich. Comp. L. § 324.1701 (“[A]ny

person may maintain an action . . . for declaratory and

equitable relief against any person for the protection

of the air, water, and other natural resources and the

public trust in these resources from pollution,

impairment, or destruction.”).

All states have the sovereign fiduciary duty to

protect their citizens’ state public trust assets,

including the air, see Section II.C, supra. And certain

states have codified this duty as an individual right

and strictly prohibited or narrowly constrained the

deprivation of that right; for these reasons, these

citizens’ “interest has real substance” under the

federal Constitution, thereby entitling them to the

Constitution’s due process protections, including

procedural due process. Wolff, 418 U.S. at 557.

Crucially, that procedural protection is fulfilled by

state citizens’ “full and fair opportunity to litigate” the

enforcement of their state rights in state court. See

Kremer v. Chem. Const. Corp., 456 U.S. 461, 481

(1982).

This Court should reject Petitioners’ request to

preclude “state-law claims seeking relief for injuries

allegedly caused by” GHG emissions. See Pets.’ Br. at

11. Such a ruling would have significant unintended

consequences, potentially disrupting bodies of state

law that are not before this Court, and which have

centuries-old histories within our system of

federalism. A broad preemption ruling could

unintentionally prejudice our young clients’ full and

fair opportunity to litigate their state-law rights in

state court, and would pit this Court’s preemption

doctrine against federally-protected individual rights,

because the Fifth and Fourteenth Amendments

recognize and protect OCT’s clients’ state-law rights

as a matter of federal law. A broad preemption ruling

from this Court could obliterate the very state-law

rights to resources that support life, liberty, and

property, which the federal Constitution protects,

amounting, in essence, to this Court amending the

federal Constitution.

CONCLUSION

Fossil fuel pollution has put children in a health

emergency. They depend on their state and local

governments to protect them and their survival

resources, like breathable air, throughout their lives.

This Court should affirm the judgment of the Colorado

Supreme Court, or dismiss the writ of certiorari as

improvidently granted.

Respectfully submitted,