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
SUNCOR ENERGY (U.S.A.) INC., ET AL.,
Petitioners,
v.
COUNTY COMMISSIONERS OF BOULDER COUNTY, ET AL.,
Respondents.
On Writ of Certiorari
to the Supreme Court of Colorado
BRIEF FOR JONATHAN H. ADLER
AS AMICUS CURIAE SUPPORTING
RESPONDENTS AND AFFIRMANCE
Tejinder Singh
Counsel of Record
SPARACINO PLLC
1920 L Street, NW
Suite 835
Washington, DC 20036
202.629.3530
tejinder@sparacinopllc.com
TABLE OF CONTENTS
TABLE OF AUTHORITIES ....................................... iii
INTEREST OF THE AMICUS ................................... 1
SUMMARY OF ARGUMENT ..................................... 2
ARGUMENT ................................................................ 4
I. Federal Environmental Law Was Enacted
Against a Background of State-Law
Environmental Protection ..................................... 4
A. Common Law Environmental Protection ....... 5
B. State Environmental Regulation .................... 7
II. Congress Sought to Supplement and
Encourage State Pollution Control Efforts,
Not to Supplant Them ........................................... 9
A. Cooperative Federalism Aims to
Encourage State Regulation ......................... 10
B. Preemption Is Rare Under Federal
Environmental Law....................................... 11
III.The Clean Air Act Does Not Preempt StateLaw Claims Seeking Compensation for Harms
Allegedly Caused by Climate Change ................. 12
A. The Clean Air Act Preserves State
Authority to Address Pollution Subject to
Federal Regulation ........................................ 13
B. International Paper Co. v. Ouellette
Confirms that Interstate Pollution May Be
Subject to State Law ..................................... 19
C. Congress Has the Authority to Preempt
State Law But Has Not Done So .................. 22
ii
IV. The Constitution Does Not Preempt StateLaw Claims Seeking Compensation for Harms
Allegedly Caused by Climate Change ................. 24
A. Federal Common Law Has Been
Displaced and Cannot Preempt State-Law
Claims ............................................................ 25
B. Constitutional Limits on State Authority
Do Not Justify Closing the Courthouse
Doors .............................................................. 30
CONCLUSION .......................................................... 31
iii
TABLE OF AUTHORITIES
Cases
American Electric Power Co. v. Connecticut,
564 U.S. 410 (2011) ......................................... 28, 29
Bates v. Dow AgroSciences LLC,
544 U.S. 431 (2005) ............................................... 12
Bd. of Cnty. Comm’rs of Boulder Cnty. v. Suncor Energy (U.S.A.) Inc.,
25 F.4th 1238 (10th Cir. 2022).............................. 29
Bell v. Cheswick Generating Station,
734 F.3d 188 (3d Cir. 2013)................................... 17
BMW of N. Am., Inc. v. Gore,
517 U.S. 559 (1996) ............................................... 30
Carmichael v. City of Texarkana,
94 F. 561 (C.C.W.D. Ark. 1899) .............................. 6
City of Hoboken v. Chevron Corp.,
45 F.4th 699 (3d Cir. 2022) ................................... 29
City of Milwaukee v. Illinois,
451 U.S. 304 (1981) ............................................... 28
County of San Mateo v. Chevron Corp.,
32 F.4th 733 (9th Cir. 2022).................................. 29
District of Columbia v. Exxon Mobil Corp.,
89 F.4th 144 (D.C. Cir. 2023) .......................... 29, 30
Freeman v. Grain Processing Corp.,
848 N.W.2d 58 (Iowa 2014) ................................... 17
Georgia v. Tennessee Copper Co.,
206 U.S. 230 (1907) ............................................... 27
Gregory v. Ashcroft,
501 U.S. 452 (1991) ............................................... 23
iv
Hencely v. Fluor Corp.,
146 S. Ct. 1086 (2026) ................................. 4, 24, 25
Her Majesty v. City of Detroit,
874 F.2d 332 (6th Cir. 1989) ................................. 17
Illinois v. City of Milwaukee,
406 U.S. 91 (1972) ................................................. 27
In re Methyl Tertiary Butyl Ether (“MTBE”) Prods.
Liab. Litig.,
725 F.3d 65 (2d Cir. 2013)..................................... 12
International Paper Co. v. Ouellette,
479 U.S. 481 (1987) ..................11, 19, 20, 21, 25, 29
Massachusetts v. EPA,
549 U.S. 497 (2007) ......................................... 18, 28
Medtronic, Inc. v. Lohr,
518 U.S. 470 (1996) ............................................... 23
Merrick v. Diageo Americas Supply, Inc.,
805 F.3d 685 (6th Cir. 2015) ........................... 16, 17
Michie v. Great Lakes Steel Div., Nat’l Steel Corp.,
495 F.2d 213 (6th Cir. 1974) ................................... 6
Minnesota by Ellison v. Am. Petroleum Inst.,
63 F.4th 703 (8th Cir. 2023).................................. 29
Monsanto Co. v. Durnell,
146 S. Ct. 2001 (2026) ........................................... 12
Nat’l Pork Producers Council v. Ross,
598 U.S. 356 (2023) ............................................... 30
New Jersey v. City of New York,
283 U.S. 473 (1931) ............................................... 27
New York v. United States,
505 U.S. 144 (1992) ............................................... 10
Ohio v. Wyandotte Chems. Corp.,
401 U.S. 493 (1971) ................................................. 6
v
Ouellette v. Int’l Paper Co.,
666 F. Supp. 58 (D. Vt. 1987) ................................ 20
Phillips Petroleum Co. v. Shutts,
472 U.S. 797 (1985) ............................................... 30
Puerto Rico Dep’t of Consumer Affairs v. ISLA Petroleum Corp.,
485 U.S. 495 (1988) ........................................... 4, 24
Rice v. Santa Fe Elevator Corp.,
331 U.S. 218 (1947) ............................................... 23
Sackett v. EPA,
598 U.S. 651 (2023) ......................................... 23, 24
Smith & Wesson Brands, Inc. v. Estados Unidos Mexicanos,
605 U.S. 280 (2025) ............................................... 22
State v. Lord,
16 N.H. 357 (1844) .................................................. 6
Union Electric Co. v. EPA,
427 U.S. 246 (1976) ......................................... 15, 16
United States Forest Serv. v. Cowpasture River Pres.
Ass’n,
590 U.S. 604 (2020) ............................................... 23
United States v. Bass,
404 U.S. 336 (1971) ............................................... 23
Utility Air Regulatory Grp. v. EPA,
573 U.S. 302 (2014) ......................................... 18, 19
Virginia Uranium, Inc. v. Warren,
587 U.S. 761 (2019) ............................... 4, 14, 23, 24
W. Va. Univ. Hosps., Inc. v. Casey,
499 U.S. 83 (1991) ................................................. 16
West Virginia v. EPA,
597 U.S. 697 (2022) ............................................... 23
vi
William Aldred’s Case,
77 Eng. Rep. 816 (K.B. 1610) .................................. 5
Wisconsin v. Illinois,
278 U.S. 367 (1929) ............................................... 27
Statutes and Regulations
7 U.S.C. § 136v(b) ...................................................... 12
33 U.S.C. § 1311 ........................................................ 20
33 U.S.C. § 1341(a)(2) ................................................ 20
33 U.S.C. § 1342(b) .................................................... 20
33 U.S.C. § 1342(d) .................................................... 20
42 U.S.C. § 7401(a)(3) ................................................ 13
42 U.S.C. § 7401(b)(3) ................................................ 13
42 U.S.C. § 7401(b)(4) ................................................ 13
42 U.S.C. § 7411 ........................................................ 19
42 U.S.C. § 7416 ........................................................ 14
42 U.S.C. § 7521(a)(1) ................................................ 19
42 U.S.C. § 7543(a) .................................................... 11
42 U.S.C. § 7545(c)(4)(A) ........................................... 11
42 U.S.C. § 7573 ........................................................ 11
42 U.S.C. § 7604(e) .................................................... 14
Protection of Lawful Commerce in Arms Act,
Pub. L. No. 109-92, 119 Stat. 2095 (2005)............ 22
Repeal of Greenhouse Gas Emissions Standards for
Fossil Fuel-Fired Electric Generating Units,
90 Fed. Reg. 25,752 (proposed June 17, 2025) ..... 19
91 Fed. Reg. 7686 (Feb. 18, 2026) ............................. 19
vii
Other Authorities
Jonathan H. Adler, Displacement and Preemption of
Climate Nuisance Claims, 17 J.L. Econ. & Pol’y
217 (2022) .............................................................. 28
Jonathan H. Adler, Judicial Federalism and the Future of Federal Environmental Regulation, 90 Iowa
L. Rev. 377 (2005).................................................. 11
Karol Boudreaux & Bruce Yandle, Public Bads and
Public Nuisance: Common Law Remedies for Environmental Decline, 14 Fordham Envtl. L.J. 55
(2002) ....................................................................... 7
Robert W. Crandall, Controlling Industrial Pollution:
The Economics and Politics of Clean Air (1983) .... 9
E. Donald Elliott et al., Toward a Theory of Statutory
Evolution: The Federalization of Environmental
Law, 1 J.L. Econ. & Org. 313 (1985) ...................... 8
Indur M. Goklany, Clearing the Air: The Real Story
of the War on Air Pollution (1999).......................... 9
Lewis C. Green, State Control of Interstate Air Pollution, 33 Law & Contemp. Probs. 315 (1968)........... 6
Andrew Jackson Heimert, Keeping Pigs Out of Parlors: Using Nuisance Law to Affect the Location of
Pollution, 27 Envtl. L. 403 (1997)......................... 17
Sam Kalen, Policing Federal Supremacy: Preemption
and Common Law Damage Claims as a Ceiling to
the Clean Air Act Regulatory Floor, 68 Fla. L. Rev.
1597 (2016) ............................................................ 14
James E. Krier & Edmund Ursin, Pollution and Policy: A Case Essay on California and Federal Experience with Motor Vehicle Air Pollution, 1940-1975
(1977) ....................................................................... 8
viii
Peter Langrock, Addison County Justice: Tales from
a Vermont Courthouse (1997)............................... 20
Thomas W. Merrill, Preemption in Environmental
Law: Formalism, Federalism Theory and Default
Rules, in Federal Preemption: State’s Powers, National Interests (Richard A. Epstein & Michael S.
Greve eds., 2007) ................................................... 11
Arnold W. Reitze, Jr., Federal Control of Carbon Dioxide Emissions: What Are the Options?,
36 B.C. Envtl. Aff. L. Rev. 1 (2009) ...................... 18
William H. Rodgers, Jr., Environmental Law (2d ed.
1994) .................................................................... 5, 6
Christine Meisner Rosen, ‘Knowing’ Industrial Pollution: Nuisance Law and the Power of Tradition in a
Time of Rapid Economic Change, 1840-1864,
8 Envtl. Hist. 565 (2003) ......................................... 6
J.B. Ruhl, Making Nuisance Ecological,
58 Case W. Res. L. Rev. 753 (2008) ........................ 5
S. Rep. No. 91-1196 (1970) ........................................ 17
Arthur C. Stern, History of Air Pollution Legislation
in the United States, 32 J. Air Pollution Control
Ass’n 44 (1982) ........................................................ 8
Richard B. Stewart, Pyramids of Sacrifice? Problems
of Federalism in Mandating State Implementation
of National Environmental Policy,
86 Yale L.J. 1196 (1977)........................................ 10
Stop Climate Shakedowns Act of 2026,
H.R. 8330, 119th Cong. (2026) .............................. 22
Stop Climate Shakedowns Act of 2026,
S. 4340, 119th Cong. (2026) .................................. 22
ix
David Stradling, Smokestacks and Progressives:
Environmentalists, Engineers, and Air Quality
in America, 1881-1951 (1999) ............................. 7, 8
U.S. EPA, Monitoring and Air Quality Trends Report,
1972 (1973) .............................................................. 9
INTEREST OF THE AMICUS 1
Professor Jonathan H. Adler is the Tazewell Taylor Professor of Law at the William & Mary Law
School, where he teaches courses in administrative,
environmental, and constitutional law. He previously
served as the inaugural Johan Verheij Memorial Professor of Law and Founding Director of the Coleman
P. Burke Center for Environmental Law at the Case
Western Reserve University School of Law, where he
remains a Senior Fellow. He has published extensively
on the intersection of federalism and environmental
law, including as applied to climate change, as well as
the history and evolution of federal environmental
law. He has submitted or participated in amicus briefs
on a range of subjects within his expertise, including
prior cases concerning the regulation of greenhouse
gases under the Clean Air Act. Because this case has
significant implications for federalism and environmental law, Professor Adler has an interest in this
case’s proper resolution.
Professor Adler takes no position on the threshold
questions of appellate jurisdiction presented in this
case, nor on the substantive merits of the underlying
tort claims. He submits this brief only to address the
questions of preemption.
No counsel for any party authored this brief in whole or part,
and no person other than amicus and his counsel made a monetary contribution intended to fund preparation or submission of
this brief. The William & Mary Law School provides financial
support for faculty members’ research and scholarship that
helped defray the costs of preparing this brief. The School is not
a signatory to this brief, however, and the views expressed here
are solely those of the amicus curiae.
1
2
SUMMARY OF ARGUMENT
Global climate change presents many complex
and intractable legal and policy questions. Assuming
this Court has jurisdiction, the legal questions in this
case are comparatively simple and straightforward.
Nothing in federal law, let alone the Constitution,
preempts state-law claims seeking relief from injuries
allegedly caused or exacerbated by petitioners’ conduct.
At issue in this case is whether allegedly aggrieved parties, including subnational governments,
may seek redress under state law from defendants otherwise subject to state court jurisdiction for harms allegedly caused or contributed to by petitioners’ conduct. In order to succeed, respondents will ultimately
need to show that the damages they allege were
caused by actions taken by defendants, that such actions are within the jurisdiction of state courts, and
that such actions may be the subject of tort liability
under state law. Allowing this case to proceed does not
allow any State to impose a universal rule on all fossil
fuel producers, let alone on all greenhouse gas emissions around the globe. The fact that emissions “cannot be unmixed and traced,” Pet’rs’ Br. 28, may complicate respondents’ ability to prove their case, but it
does not justify—let alone require—preemption of
their claims.
Petitioners charge that respondents’ claims are
barred because both the Clean Air Act and the Constitution categorically preclude any claims seeking redress for harms caused by interstate pollution. Yet neither the Clean Air Act nor the Constitution imposes
3
such a rule. To the contrary, as this Court has long understood, such suits may proceed, subject to certain
limitations, even if they are viewed as efforts to seek
redress for interstate pollution subject to federal regulation.
That the Clean Air Act may constitute a broad,
“comprehensive” regulatory scheme does not mean
that it preempts state-law efforts to seek remedies for
the alleged harms caused by the accumulation of
greenhouse gases in the atmosphere. Like other federal environmental statutes, the Clean Air Act was enacted against a background of extensive and essential
state-law environmental protections, including those
provided by common law causes of action. That the
Clean Air Act was meant to supplement, enhance, and
encourage state-level efforts, rather than supplant or
preempt them, is evident from the text, history, and
structure of the Act. It is also what this Court has recognized.
The Constitution’s structure provides no more basis for closing the courthouse doors on respondents’ efforts to seek redress for the harms they allege. Federal
common law may once have preempted state attempts
to control interstate air pollution under state law, but
federal common law has been displaced, and no longer
serves that function. Nor does any constitutional provision or doctrine identified by petitioners provide a
basis for wholly preempting state-law claims seeking
redress for harms such as those alleged here. Petitioners’ attempt to cobble together an argument for constitutional preemption rests upon penumbras and emanations from various constitutional provisions that
cannot hold the weight of their proposed rule. That is
insufficient. “There is no federal pre-emption in vacuo,
4
without a constitutional text or a federal statute to assert it.” Hencely v. Fluor Corp., 146 S. Ct. 1086, 1093
(2026) (quoting Puerto Rico Dep’t of Consumer Affairs
v. ISLA Petroleum Corp., 485 U.S. 495, 503 (1988)).
And “[i]nvoking some brooding federal interest or appealing to a judicial policy preference should never be
enough to win preemption of a state law.” Virginia
Uranium, Inc. v. Warren, 587 U.S. 761, 767 (2019)
(lead opinion).
State law—statutes, regulations, and common law
court decisions—has played an essential role in this
nation’s history of environmental protection. Resort to
state law should not be foreclosed merely because such
claims threaten economically important interests or
rely upon expansive theories of liability or attenuated
chains of causation. If such suits are to be preempted,
that is a job for Congress, not the courts.
ARGUMENT
I.
Federal Environmental Law Was Enacted
Against a Background of State-Law
Environmental Protection
Congress enacted the Clean Air Act, 42 U.S.C.
§ 7401 et seq., 2 against a background of extensive state
regulation and common law environmental protection.
With this law, Congress expressly sought to supplement and enhance state-law efforts to maintain and
improve air quality. With few exceptions, Congress
preserved pre-existing state authority to control air
pollution and redress environmental harms without
Though technically a series of amendments to prior statutes, it
is common to refer to the law enacted in 1970 as the “Clean Air
Act,” as the prior statutes were largely non-regulatory in nature.
2
5
regard for whether States utilized administrative regulation or common law litigation.
A. Common Law Environmental Protection
Before there was federal environmental regulation, many environmental problems were addressed
through common law protections. The principle that
individuals must use their own property so as not to
harm that of others (the Latin maxim sic utere tuo ut
alienum non laedas) dates back at least to the seventeenth century. See William Aldred’s Case, 9 Co. Rep.
57b, 77 Eng. Rep. 816 (K.B. 1610).
For centuries, the common law doctrines of nuisance and trespass aided landowners who sought to
protect their property—and, by extension, their persons—from interferences caused by the activities of
others. Nuisance law, in particular, was a means
through which landowners could protect against environmental harms, such as those caused by air and water pollution. See William H. Rodgers, Jr., Environmental Law, § 2.1, at 112-13 (2d ed. 1994) (“Nuisance
actions reach pollution of all physical media—air, water, land, groundwater—by a wide variety of means.”).
The use of nuisance and other common law claims
to abate and redress environmental harms has a long
history in the United States. See J.B. Ruhl, Making
Nuisance Ecological, 58 Case W. Res. L. Rev. 753, 753
(2008) (“Common law nuisance doctrine has the reputation of having provided much of the strength and
content of environmental law prior to the rise of federal statutory regimes in the 1970s.”). As the environmental consequences of economic development
emerged, landowners and others regularly sought recourse in courts, invoking nuisance and other common
6
law causes of action. See Christine Meisner Rosen,
‘Knowing’ Industrial Pollution: Nuisance Law and the
Power of Tradition in a Time of Rapid Economic
Change, 1840-1864, 8 Envtl. Hist. 565, 565 (2003);
Rodgers, supra, § 2.1, at 112-13 (“Nuisance actions
have challenged virtually every major industrial and
municipal activity that today is the subject of comprehensive environmental regulation.”). Most such suits
addressed local concerns, where causation and state
court jurisdiction over defendants were easiest to
demonstrate. See Lewis C. Green, State Control of Interstate Air Pollution, 33 Law & Contemp. Probs. 315,
315-16 (1968) (noting jurisdictional and causation
problems). Nonetheless, there was no bar on pursuing
common law claims for environmental harms that
originated across state lines. See, e.g., State v. Lord, 16
N.H. 357, 359 (1844) (“The nuisance complained of being within this State, it is not important that the dam
which occasioned it was in the State of Maine.”); Ohio
v. Wyandotte Chems. Corp., 401 U.S. 493, 500 (1971)
(declining to exercise original jurisdiction over Ohio’s
nuisance action against out-of-state and foreign corporations because “[t]he courts of Ohio . . . would decide
it under the same common law of nuisance upon which
our determination would have to rest.”); Michie v.
Great Lakes Steel Div., Nat’l Steel Corp., 495 F.2d 213,
215-16 & n.2 (6th Cir. 1974) (permitting nuisance
claims by Ontario residents against three corporations
operating seven plants across the Detroit River to proceed under Michigan law); Carmichael v. City of Texarkana, 94 F. 561, 574-75 (C.C.W.D. Ark. 1899) (sustaining a bill by Texas landowners against an Arkansas city whose sewer discharged across the state line,
the court having “failed to find a single well-considered
7
case where the American courts have not granted relief under circumstances such as are alleged in this
bill”).
As air pollution emerged as an environmental concern in the nineteenth century, state courts continued
to provide remedies under state law. During the Progressive Era, for instance, anti-smoke activists targeted individual facilities, raising complaints and occasionally filing nuisance suits to control urban air
pollution. See David Stradling, Smokestacks and Progressives: Environmentalists, Engineers, and Air
Quality in America, 1881-1951, at 3 (1999).
The gradual adoption of environmental regulations at the local, state, and federal levels did not put
an end to nuisance litigation. Far from it. The number
of environmental nuisance cases continued to rise
through the late twentieth century, even as environmental regulations proliferated at all levels of government. See Karol Boudreaux & Bruce Yandle, Public
Bads and Public Nuisance: Common Law Remedies for
Environmental Decline, 14 Fordham Envtl. L.J. 55, 64
(2002) (documenting increase in environmental public
nuisance cases between the 1960s and 1990s). Common law causes of action remain an important element
in environmental protection today, often serving to
identify and highlight under-appreciated environmental problems or spurring political action to address environmental concerns more directly.
B. State Environmental Regulation
As the environmental effects of industrialization
and economic development became more prevalent
and well understood, early environmentalists turned
8
to state and local legislatures to enact nuisance-control measures that could supplement common law litigation as a means of limiting pollution. See Stradling,
supra, at 4 (“the late 1800s and the early 1900s contain
abundant examples of urban and suburban environmental activism, much of it successful”). At the same
time as Progressive Era anti-smoke activists sought to
harness nuisance law, local governments began adopting smoke-control ordinances to improve local air quality. Philadelphia, for example, enacted a smoke-control ordinance in 1905, which quickly reduced smoke
levels in the heart of the city. See Arthur C. Stern, History of Air Pollution Legislation in the United States,
32 J. Air Pollution Control Ass’n 44, 44 (1982). By
1970, when the Clean Air Act was enacted, over 100
municipalities had meaningful smoke-control ordinances.
State regulations also followed in much of the
country, beginning with Oregon in 1951. By 1970,
every State had an air pollution control program, although stringency varied. Stern, supra, at 47. California, in particular, adopted far-reaching pollution control strategies, particularly with regard to motor vehicles. See generally James E. Krier & Edmund Ursin,
Pollution and Policy: A Case Essay on California and
Federal Experience with Motor Vehicle Air Pollution,
1940-1975 (1977). Indeed, it was California’s aggressiveness in regulating automobile emissions that led
Congress to preempt other States from adopting vehicle emission standards of their own. See E. Donald Elliott et al., Toward a Theory of Statutory Evolution:
The Federalization of Environmental Law, 1 J.L. Econ.
& Org. 313, 330-31 (1985).
9
State-level air pollution controls were more than
symbolic, producing meaningful reductions in key air
pollutants. See U.S. EPA, Monitoring and Air Quality
Trends Report, 1972, at 1-6, 1-12 (1973) (noting pre1970 air pollution declines); Indur M. Goklany, Clearing the Air: The Real Story of the War on Air Pollution
111-12 (1999) (same). For some pollutants, the reductions were actually more rapid prior to the enactment
of the Clean Air Act. See Robert W. Crandall, Controlling Industrial Pollution: The Economics and Politics
of Clean Air 19 (1983) (“[P]ollution reduction was more
effective in the 1960s, before there was a serious federal policy dealing with stationary sources, than since
the 1970 Clean Air Act Amendments”). While state
and local government efforts were no doubt insufficient to meet the public’s growing demand for environmental protection, they played an important role in reducing pollution prior to the adoption of meaningful
federal environmental regulation.
II.
Congress Sought to Supplement and
Encourage State Pollution Control Efforts,
Not to Supplant Them
Congress was well aware of the extensive and expanding state-level efforts to control pollution when
considering, and ultimately adopting, federal environmental laws. Congress enacted laws that would supplement state efforts and provide powerful incentives
for further state regulatory action. The express purpose of many federal statutes was to augment incomplete or insufficiently protective state and local efforts.
10
A. Cooperative Federalism Aims to Encourage
State Regulation
While federal environmental laws grant expansive regulatory authority to federal agencies, most environmental statutes are implemented following a “cooperative federalism” model. See New York v. United
States, 505 U.S. 144, 167 (1992) (describing the
model). Under this model, the federal government outlines the contours of a given regulatory program.
States are then encouraged to implement the program
in lieu of the federal government. Provided the federal
standards are met, States are free to tailor the details
of their individual programs to accommodate local conditions and concerns, as well as to adopt more stringent measures to control pollution or address its consequences. State programs that meet federal standards are typically eligible for federal financial assistance. Those that do not face potential sanctions, including federal preemption of their programs. Under
the “cooperative federalism” model, conditional
preemption is a tool to prevent unduly lax state efforts,
not a means to prevent States from being unduly aggressive.
This cooperative federalism model was explicitly
adopted so as to ensure continued state involvement
in environmental protection. Federal environmental
law relies upon the ability of state policymakers to
identify, implement, and enforce environmental requirements. See Richard B. Stewart, Pyramids of Sacrifice? Problems of Federalism in Mandating State Implementation of National Environmental Policy, 86
Yale L.J. 1196, 1196 (1977) (noting that the federal
government “is dependent upon state and local authorities to implement [environmental] policies because of
11
the nation’s size and geographic diversity, the close interrelation between environmental controls and local
land use decisions, and federal officials’ limited implementation and enforcement resources.”); see also Jonathan H. Adler, Judicial Federalism and the Future of
Federal Environmental Regulation, 90 Iowa L. Rev.
377, 381-88 (2005). This model also expressly preserves the ability of States to be more protective and
more aggressive in addressing environmental harms.
See, e.g., Int’l Paper Co. v. Ouellette, 479 U.S. 481, 48990 (1987) (“Even if the Federal Government administers the permit program, the source State may require
discharge limitations more stringent than those required by the Federal Government.”).
B. Preemption
Is
Rare
Environmental Law
Under
Federal
Because Congress sought to supplement and enhance state environmental efforts, federal environmental law rarely preempts state environmental law.
Federal preemption of state environmental law is the
exception, and is nearly always explicit in the statutory text.
As a general rule, federal environmental law only
preempts state laws that risk imposing multifarious
standards on products sold in national markets, such
as automobiles, see 42 U.S.C. § 7543(a), motor fuels,
see 42 U.S.C. § 7545(c)(4)(A), and aircraft, see 42
U.S.C. § 7573. See Thomas W. Merrill, Preemption in
Environmental Law: Formalism, Federalism Theory,
and Default Rules, in Federal Preemption: States’
Powers, National Interests 178 (Richard A. Epstein &
Michael S. Greve eds., 2007) (observing that federal
environmental laws “aim to eliminate state regulation
12
where it would undermine the efficient scope of markets for particular commercial commodities”). State
pollution control measures are rarely preempted.
Even when Congress chooses to preempt state
law, federal preemption tends to be narrowly targeted
at the specific federal interest to be protected. So, for
example, the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) preempts state labeling requirements for federally registered pesticides that are different from or in addition to those imposed by the EPA
on a federally approved label. See 7 U.S.C. § 136v(b);
Monsanto Co. v. Durnell, 146 S. Ct. 2001, 2017 (2026).
Yet FIFRA does not preempt other requirements imposed on the sale or use of pesticides by state law,
whether imposed by legislation, regulation, or common
law tort principles. See Bates v. Dow AgroSciences
LLC, 544 U.S. 431, 444 (2005). Federal preemption of
state-law regulations governing gasoline content does
not preempt state-law claims against fuel manufacturers, refiners, and distributors seeking damages for environmental contamination caused by such fuels. See
In re Methyl Tertiary Butyl Ether (“MTBE”) Prods.
Liab. Litig., 725 F.3d 65, 102 (2d Cir. 2013).
III.
The Clean Air Act Does Not Preempt StateLaw Claims Seeking Compensation for
Harms Allegedly Caused by Climate
Change
The Clean Air Act does not preempt state efforts
to mitigate or redress the consequences of air pollution
under state law, nor does it preempt efforts to hold
manufacturers responsible for their products or marketing decisions. The text, structure, and purpose of
the Act all indicate that Congress sought to preserve
13
the ability of state law to address air pollution concerns, with but a few exceptions such as the preemption of state automobile emission standards and fuels.
Thus even if the Court concludes respondents’ claims
should be evaluated as an effort to control interstate
air pollution (a characterization respondents contest
and the lower court rejected), respondents’ claims are
still not preempted.
A. The Clean Air Act Preserves State Authority
to Address Pollution Subject to Federal
Regulation
The Clean Air Act expressly recognizes the importance of state law to controlling air pollution and
ensuring air quality. Congress made the express finding that “air pollution prevention (that is, the reduction or elimination, through any measures, of the
amount of pollutants produced or created at the
source) and air pollution control at its source is the primary responsibility of States and local governments.”
42 U.S.C. § 7401(a)(3). It further provided that the
Act’s purposes included “provid[ing] . . . assistance” to
state and local governments in their efforts. Id.
§ 7401(b)(3); see also id. § 7401(b)(4) (declaring purpose of encouraging “regional air pollution prevention
and control programs”).
The text and structure of the Clean Air Act expressly allow States to adopt more aggressive air pollution control and mitigation efforts than were mandated or provided for in the Act. The “cooperative federalism” structure of the Clean Air Act provides that,
with few exceptions, state air pollution control standards are only preempted insofar as they are less stringent than federal standards. Accordingly, 42 U.S.C.
14
§ 7416 provides that, with the exception of mobile
source emission standards, “nothing in this chapter
shall preclude or deny the right of any State or political subdivision thereof to adopt or enforce (1) any
standard or limitation respecting emissions of air pollutants or (2) any requirement respecting control or
abatement of air pollution,” unless the state standard
in question is less stringent than that provided for under federal law. In plainer terms, the Act creates a federal floor below which States may not drop without encouraging federal intervention, but does not create a
ceiling.
The Act is also explicit that its authorization of
citizen suits to enforce its terms should not be understood to curtail or limit pre-existing common law
rights. Thus, 42 U.S.C. § 7604(e) provides that
“[n]othing in this section shall restrict any right which
any person . . . may have under any statute or common
law to seek enforcement of any emission standard or
limitation or to seek any other relief . . . .” It further
preserves the rights of public entities, including “local”
authorities to obtain “any judicial remedy or sanction
in any State or local court.” These clauses make clear
that Congress was seeking to preserve the ability of
citizens and subnational governments to utilize state
law for environmental protection, including by resort
to the courts, not preempt them. Virginia Uranium is
instructive: There, too, “Congress conspicuously chose
to leave untouched the States’ historic authority over
the regulation of mining activities on private lands
within their borders.” 587 U.S. at 765. Congress made
the same choice here. See also Sam Kalen, Policing
Federal Supremacy: Preemption and Common Law
15
Damage Claims as a Ceiling to the Clean Air Act Regulatory Floor, 68 Fla. L. Rev. 1597, 1602 (2016) (“The
CAA’s drafters unquestionably sought to preserve
common law damage claims.”).
The Clean Air Act’s text should be sufficient to resolve petitioners’ statutory preemption claim. Resort
to the Clean Air Act’s structure confirms that it was
meant to be a supplement, not a substitute, for statelevel action, even if that allowed States to pursue policy measures disfavored by the federal government. In
Union Electric Co. v. EPA, 427 U.S. 246, 262 (1976),
for example, this Court expressly rejected the claim
that the EPA may reject a State Implementation Plan
on the grounds that it is “more stringent than federal
law demands,” even if the EPA were to conclude that
the State were adopting regulations that were economically or technologically infeasible. So long as the plans
met the minimum requirements detailed in the Act—
that is, the plans were above the federal floor—the Administrator “must” approve them. Id. at 265. That a
State that adopts unnecessarily stringent air quality
regulations might lose industry to other States was
“fully consistent with the structure and purpose” of the
Act. Id.
Petitioners repeatedly claim that Congress’s erection of a “comprehensive” regulatory scheme governing air pollutants lodges exclusive authority for determining whether and how stringently to regulate air
pollutants in the hands of the federal government. See
Pet’rs’ Br. 4, 13, 15, 44. Even if petitioners’ interpretation of the Act were accurate—and it is not—the conclusion would not follow. However comprehensive the
Act’s regulatory scheme may be, it does not oust States
16
from setting air pollution controls for most sources, either through regulation or common law litigation. As
already noted, the Act’s savings clauses expressly hold
to the contrary. Indeed, Union Electric concerned the
“heart” of the CAA—the provisions requiring States to
submit and enforce implementation plans adequate to
achieve federal air quality standards or be subject to
sanctions. See 427 U.S. at 249.
In accord with the Act’s text and structure, lower
courts have consistently concluded that nothing in the
Act itself precludes state common law claims against
air polluters, even those that are subject to the Act’s
regulatory and permit requirements. The case of Merrick v. Diageo Americas Supply, Inc., 805 F.3d 685 (6th
Cir. 2015), is illustrative. In Merrick, local landowners
complained that ethanol emissions from a distillery
caused the growth of “whiskey fungus” on their properties. Id. at 686. Although the distillery operated under permits issued pursuant to the Clean Air Act, the
court readily concluded that the Act did not preclude
the plaintiffs from pursuing nuisance claims, any more
than the satisfaction of federal emission standards
would preclude the State from adopting more stringent regulations. “State courts are arms of the ‘State,’
and the common law standards they adopt are ‘requirement[s] respecting control or abatement of air
pollution,’” the court explained, rejecting any claim
that the Act would preempt state common law nuisance suits while not preempting state regulations. Id.
at 690. As the court noted: “A federal statute does not
preempt state law if Congress did not intend the statute to do so, and ‘the best evidence of’ Congress’s intent
‘is the statutory text adopted by both Houses of Congress and submitted to the President.’” Id. (quoting W.
17
Va. Univ. Hosps., Inc. v. Casey, 499 U.S. 83, 98 (1991)).
The court also relied on Congress’s own understanding: “Compliance with standards under this Act would
not be a defense to a common law action for pollution
damages.” Id. at 691 (quoting S. Rep. No. 91-1196, at
38 (1970)).
Other courts presented with similar questions
have reached the same conclusion: Regulation of facilities under the Clean Air Act does not immunize them
from potential liability under state law. See, e.g., Bell
v. Cheswick Generating Station, 734 F.3d 188, 197-98
(3d Cir. 2013) (CAA does not preempt class action nuisance claims for air pollution against comprehensively
regulated facility); Freeman v. Grain Processing Corp.,
848 N.W.2d 58, 85 (Iowa 2014) (rejecting CAA preemption claim); Her Majesty v. City of Detroit, 874 F.2d
332, 342-43 (6th Cir. 1989) (same). The Act expressly
authorizes States to maintain more stringent pollution
standards, and in most States, compliance with pollution permits does not preempt nuisance or other common law claims. See Andrew Jackson Heimert, Keeping Pigs Out of Parlors: Using Nuisance Law to Affect
the Location of Pollution, 27 Envtl. L. 403, 435 (1997)
(“the vast majority of states specifically preserve nuisance remedies in their statutes or their courts have
inferred such preservation.”); see also id. at 493-512
(appendices summarizing applicable laws in all fifty
States). Further, “many cases have held that a party
seeking to show a nuisance is not required to show a
violation of some other law.” Freeman, 848 N.W.2d at
70 (collecting cases).
If the CAA does not preempt state law concerning
the emission or effects of traditional air pollutants, including under those provisions at the “heart” of the
18
Act—those provisions that are, by any account, its
most comprehensive—it defies comprehension how the
Act could preempt state regulation concerning greenhouse gas emissions or the consequences such emissions may have on local jurisdictions without any language that would remotely suggest such an effect. Yet
that is petitioners’ position.
The EPA’s regulation of greenhouse gases is anything but “comprehensive.” This Court has concluded
that greenhouse gases are air pollutants when emitted
from mobile sources, see Massachusetts v. EPA, 549
U.S. 497, 528-30 (2007), and for some stationary
sources, Utility Air Regulatory Grp. v. EPA (“UARG”),
573 U.S. 302, 331-33 (2014). Yet this Court has also
concluded that it is “obviously untenable” and “inconsistent with the statutory scheme” to treat greenhouse
gases as air pollutants for every portion of the Act. See
id. at 316, 319.
Petitioners argue the Clean Air Act “occupie[s] the
entire relevant field of regulation.” Pet’rs’ Br. 44. Not
so. Congress has enacted very little that addresses
greenhouse gas emissions or the consequences thereof.
See Arnold W. Reitze, Jr., Federal Control of Carbon
Dioxide Emissions: What Are the Options?, 36 B.C. Envtl. Aff. L. Rev. 1, 1 (2009) (“From 1999 to [2007], more
than 200 bills were introduced in Congress to regulate
[greenhouse gases], but none were enacted.”). Petitioners note the “EPA is tasked with establishing nationwide air quality standards.” Pet’rs’ Br. 45. This is a
non sequitur. Greenhouse gases have never been classified as criteria air pollutants for which the EPA sets
National Ambient Air Quality Standards. See UARG,
573 U.S. at 308. Nor, for that matter, are they air pol-
19
lutants for the purposes of triggering the Act’s Prevention of Significant Deterioration or Title V requirements. See id. at 333.
The Clean Air Act cannot plausibly be described
as authorizing the “comprehensive” regulation of
greenhouse gases, let alone of the fossil fuel industry. 3
Despite petitioners’ best efforts, they identify no regulatory controls of greenhouse gas emissions with which
state-level efforts to constrain greenhouse gas emissions could conflict, let alone any provisions of the
Clean Air Act that apply to manufacturers or distributors and that could conflict with respondents’ claims.
B. International Paper Co. v. Ouellette
Confirms that Interstate Pollution May Be
Subject to State Law
This Court’s precedents confirm that the Clean
Air Act does not categorically preclude state-law
claims seeking relief for the consequences of interstate
pollution. In International Paper Co. v. Ouellette, 479
U.S. 481 (1987), this Court concluded that state-law
claims were not wholly preempted by federal law.
The EPA has concluded that greenhouse gases are no longer
subject to regulation as air pollutants under 42 U.S.C.
§ 7521(a)(1), see 91 Fed. Reg. 7686 (Feb. 18, 2026), and has proposed barring the regulation of GHGs from stationary sources under 42 U.S.C. § 7411 as well. See Repeal of Greenhouse Gas Emissions Standards for Fossil Fuel-Fired Electric Generating Units,
90 Fed. Reg. 25,752 (proposed June 17, 2025). Moreover, the
EPA’s rationale for concluding it lacks authority to regulate
greenhouse gases under § 7521(a)(1) would, if applied consistently, preclude regulation under § 7411 as well. The United
States also offers no explanation why it is regulation under
§ 7411, and not under § 7521(a)(1), that is in “conflict with Boulder’s claims.” U.S. Br. 34 n.4. Neither provision regulates fossil
fuel producers as such.
3
20
While a majority of the Court concluded that the Clean
Water Act preempted state-law claims seeking to supplant the law of the source State with that of the affected State, the Court concluded unanimously that
state common law claims for interstate pollution were
not preempted insofar as the plaintiffs sought to apply
the law of the State in which the pollution source was
located. 4
Key to the Court’s holding in Ouellette was a
recognition that the Clean Water Act expressly limited
the rights of downstream States to having an “advisory role in regulating pollution that originates beyond
its borders” and is subject to permitting under the Act.
479 U.S. at 490. This approach was dictated by the text
and structure of the Clean Water Act, under which all
point sources are required to have permits before discharging any pollutant into any navigable water of the
United States. See 33 U.S.C. § 1311. As a cooperative
federalism statute, the Clean Water Act allows the
source State to set the stringency of the permit, subject
to the federal regulatory floor, as well as to determine
whether such a permit precludes nuisance claims under state law. Affected States are entitled to notice and
an opportunity to comment on source State permits,
but no authority to dictate their stringency. See Ouellette, 479 U.S. at 490-91 (citing 33 U.S.C. §§ 1341(a)(2),
1342(b), (d)). The text of the Clean Water Act “makes
4
On remand, the district court refused to dismiss the plaintiffs’
claims, including those for air pollution, see Ouellette v. Int’l Paper Co., 666 F. Supp. 58 (D. Vt. 1987), and the case settled. See
Peter Langrock, Addison County Justice: Tales from a Vermont
Courthouse 86 (1997).
21
it clear that affected States occupy a subordinate position to source States in the federal regulatory program.” Id. at 491.
Ouellette stressed that the federal regulatory
scheme did not preclude States from adopting more
stringent controls than required by federal law. “Because the Act specifically allows source States to impose stricter standards,” the Ouellette Court explained, “the imposition of source-state law does not
disrupt the regulatory partnership established by the
permit system.” Id. at 499. Lest there was any confusion, the Court reiterated the point, noting “nothing in
the Act bars aggrieved individuals from bringing a
nuisance claim pursuant to the law of the source
state.” Id. at 497. Attempts by an affected State to impose its own law on an out-of-state source were only
preempted because they conflicted with the Clean Water Act’s treatment of interstate pollution, and not any
broader legal principle. See Ouellette, 479 U.S. at 497
(“The CWA precludes only those suits that may require standards of effluent control that are incompatible with those established by the procedures set forth
in the Act.” (emphasis added)).
Ouellette makes clear that the enactment of a
broad federal pollution control regime does not inherently preempt all state-law claims. Any preemption of
state law must be a consequence of express statutory
provisions that explicitly oust or directly conflict with
the application of state law in a specific context. No
such arguments can be made for the preemption of
state-law claims concerning greenhouse gas emissions
under the Clean Air Act, let alone the production and
marketing of fossil fuels. If anything, the Clean Water
Act is more comprehensive and prescriptive than is the
22
Clean Air Act, and has a less expansive savings clause,
so if the Clean Water Act does not preempt all statelaw claims relating to interstate pollution, the Clean
Air Act cannot be read to do so, particularly with regard to pollutants, such as greenhouse gases, that are
only covered by a small portion of the Act’s regulatory
provisions.
C. Congress Has the Authority to Preempt
State Law But Has Not Done So
There is little question Congress has the constitutional authority to limit or preclude suits against fossil
fuel companies for harms associated with their products. Where Congress was concerned that tort litigation might have untoward effects, it has enacted broad
legislation to preclude disfavored litigation. Congress
enacted, and this Court has enforced, the Protection of
Lawful Commerce in Arms Act, Pub. L. No. 109-92,
119 Stat. 2095 (2005) (codified at 15 U.S.C.
§§ 7901-03), to curb suits against firearms manufacturers. See generally Smith & Wesson Brands, Inc. v.
Estados Unidos Mexicanos, 605 U.S. 280 (2025). If
Congress were equally concerned about suits against
fossil fuel companies, it could enact equivalent legislation, but it has not done so. 5
This Court should be particularly reluctant to infer preemption of state law where doing so would preclude the application of state law to matters without a
Bills are pending in the current Congress to preempt suits
against energy companies inter alia seeking damages for harms
allegedly caused by climate change. See Stop Climate Shakedowns Act of 2026, S. 4340, 119th Cong. (2026); Stop Climate
Shakedowns Act of 2026, H.R. 8330, 119th Cong. (2026).
5
23
clear command from Congress to do so. “The preemption of state laws represents ‘a serious intrusion into
state sovereignty’” of the sort that should only result
from “a clear congressional command.” Va. Uranium,
587 U.S. at 773 (lead opinion) (quoting Medtronic, Inc.
v. Lohr, 518 U.S. 470, 488 (1996) (plurality opinion)).
Lacking such a command, there is ample “reason to
hesitate before concluding that Congress meant” to
broadly preempt the application of state law without
even hinting at that intent, particularly given the “economic and political significance” of the preemption asserted. See West Virginia v. EPA, 597 U.S. 697, 721,
723 (2022); see also Rice v. Santa Fe Elevator Corp.,
331 U.S. 218, 230 (1947) (Congress must make its intention “clear and manifest” to preempt “the historic
police powers of the States”); Gregory v. Ashcroft, 501
U.S. 452, 460-61 (1991) (plain-statement rule protecting state sovereignty); United States v. Bass, 404 U.S.
336, 349 (1971) (“unless Congress conveys its purpose
clearly, it will not be deemed to have significantly
changed the federal-state balance”).
This Court “require[s] Congress to enact exceedingly clear language if it wishes to significantly alter
the balance between federal and state power and the
power of the Government over private property.” Sackett v. EPA, 598 U.S. 651, 679 (2023) (quoting United
States Forest Serv. v. Cowpasture River Pres. Ass’n,
590 U.S. 604, 621-22 (2020)). An “overly broad” interpretation of the Act’s preemptive effect “would impinge” upon the States’ longstanding and traditional
authority to protect their environment and safeguard
the well-being of their citizens. Id. at 680. Petitioners,
however, offer only a “passing attempt to square
24
[their] interpretation” with the text, structure, and
history of the Act. Id. 6
IV.
The Constitution Does Not Preempt StateLaw Claims Seeking Compensation for
Harms Allegedly Caused by Climate
Change
Petitioners’ argument that the Constitution categorically precludes state-law claims seeking relief for
injuries allegedly caused by interstate pollution is
even less grounded than their statutory argument. In
effect, petitioners argue for a categorical rule barring
any resort to state law for injuries caused by any phenomenon that extends beyond a State’s borders that is
unmoored from constitutional text, structure, and history. No such constitutional principle exists, and for
good reason.
Just last Term, in Hencely v. Fluor Corp., 146 S.
Ct. 1086 (2026), the Court held that state tort claims
against a federal contractor were not preempted where
the Federal Government “neither ordered nor authorized” the challenged conduct, id. at 1099, explaining
that “[t]here is no federal pre-emption in vacuo, without a constitutional text or a federal statute to assert
it,” id. at 1093 (quoting Puerto Rico Dep’t of Consumer
Affairs v. ISLA Petroleum Corp., 485 U.S. 495, 503
(1988)). “No provision of the Constitution and no federal statute justifie[d] that preemption of the State’s
6
Petitioners also suggest this Court should find preemption because of respondents’ alleged “intent” to advance their policy preferences through this litigation, yet “this Court has generally” focused its preemption inquiry on “what” was done, “not why” it was
done. Va. Uranium, 587 U.S. at 774 (lead opinion).
25
ordinary authority over tort suits. Nor d[id] any precedent of this Court command such a result.” Id. at
1099. Petitioners identify no text either. They identify
instead an inference drawn from the interstate character of the harm, and ask this Court to give that inference a preemptive force that neither the Constitution nor any statute supplies.
This Court has never endorsed a categorical rule
barring the application of state law to phenomena of
an interstate character, and to do so would itself impose a severe indignity upon state sovereignty. While
this Court once recognized that federal common law
was available for the resolution of interstate disputes
between States, including suits filed by States seeking
injunctive relief against emissions from other States,
such federal common law no longer exists and no
longer preempts state-law claims (if it ever did).
As this Court recognized in Ouellette, state-law
claims that do not conflict with federal law may proceed, subject to choice-of-law and other constraints,
and this includes claims that arise from interstate pollution. If, as in Ouellette, a State could maintain statelaw claims against an industrial facility for emissions
governed and permitted by the Clean Water Act, there
is no barrier to the claims here which concern the production and distribution of fuels that generate emissions that are not subject to any such permits under
federal law and, in many applications, are not subject
to federal regulation at all.
A. Federal Common Law Has Been Displaced
and Cannot Preempt State-Law Claims
Petitioners maintain that “the foundational principle of equal sovereignty” requires that all “disputes
26
over the regulation of air and water in their ambient
or interstate aspects” must be governed by “federal
law.” Pet’rs’ Br. 13. Accordingly, petitioners maintain
that the rule of decision in any case implicating interstate pollution must be provided by federal law, and
that the application of state law to all such cases is
precluded. Petitioners are correct that the Constitution prevents States from imposing their legal and policy choices on their neighbors, but they are wrong that
this principle has ever required a categorical prohibition on the application of state law to disputes related
to interstate pollution.
The principle petitioners invoke, moreover, has to
run both ways. If Colorado may not impose its policy
judgments upon conduct occurring elsewhere, then
neither may other States impose upon Colorado the
costs of the conduct they license. Petitioners’ proposed
rule is not neutral as between the two. It would leave
an affected State and its subdivisions without recourse
under any State’s law, while leaving source States free
to authorize the conduct that generates the harm—
converting a principle of equal sovereignty into a oneway immunity for source States. This Court’s decisions
do not prefer one sovereign over the other. They accommodate both.
Prior to the enactment of federal environmental
laws, this Court heard cases arising under its original
jurisdiction in which one State would seek the abatement of pollution emanating from another State. If the
Court concluded that upstream or upwind jurisdictions failed to respect the territory of their downstream or downwind neighbors, the Court issued injunctions against pollution sources. See, e.g., Georgia
27
v. Tennessee Copper Co., 206 U.S. 230, 239 (1907) (issuing an injunction against the discharge of noxious
gases that crossed state lines and harmed Georgian
land); Wisconsin v. Illinois, 278 U.S. 367, 420-21
(1929) (enjoining the defendants from excessively diverting waters from the Great Lakes to the Chicago
Drainage Canal for the purpose of sewage disposal);
New Jersey v. City of New York, 283 U.S. 473, 476, 48283 (1931) (issuing an injunction restraining New York
City from dumping garbage into the ocean).
Recognizing the “federal interest in a uniform rule
of decision,” in the absence of an applicable federal
statute, the Court accepted the responsibility of applying federal common law to such disputes, and precluded the application of state law to such disputes. At
the same time, the Court noted that the adoption of
“new federal laws and new federal regulations” could
relieve it of the obligation to divine and apply federal
common law standards. Illinois v. City of Milwaukee
(“Milwaukee I”), 406 U.S. 91, 107 (1972).
Once Congress enacted federal pollution control
statutes, there was no longer any need for this Court
to fashion and apply a federal common law of interstate nuisance. Leaning heavily on the principle that
federal common law is to be disfavored, the Court concluded that the enactment of a relevant statute displaced the federal common law—replacing judicially
fashioned rules of decision that broadly preempted the
application of state law within the field with legislatively crafted rules that only preempt state law to the
extent dictated by Congress.
The displacement of federal common law by a federal statute presented a different question from that
28
of preemption of state law. See Jonathan H. Adler, Displacement and Preemption of Climate Nuisance
Claims, 17 J.L. Econ. & Pol’y 217, 233-47 (2022).
Whereas the latter requires due regard for state prerogatives, “[s]uch concerns are not implicated in the
same fashion when the question is whether federal
statutory or federal common law governs, and accordingly the same sort of evidence of a clear and manifest
purpose is not required.” City of Milwaukee v. Illinois
(“Milwaukee II”), 451 U.S. 304, 316-17 (1981). To the
contrary, the Court should “‘start with the assumption’
that it is for Congress, not federal courts, to articulate
the appropriate standards to be applied as a matter of
federal law,” and thus the presumption is that federal
common Aldre should be displaced. Id. at 317.
This Court has affirmed that displacement applies
equally in the context of air pollution. In American
Electric Power Co. v. Connecticut (“AEP”), 564 U.S. 410
(2011), the Court concluded that, so long as greenhouse gases are subject to regulation as air pollutants
under the Clean Air Act, this “displace[s] any federal
common law right to seek abatement of carbon-dioxide
emissions from fossil-fuel fired powerplants.” Id. at
424. 7 As in Milwaukee II, “the relevant question for
purposes of displacement is ‘whether the field has been
occupied, not whether it has been occupied in a particular manner.’” AEP, 564 U.S. at 426 (quoting Milwaukee II, 451 U.S. at 324).
Contrary to petitioners’ suggestion, AEP made
clear that federal common law no longer precluded
Of course, should this Court or Congress overturn the statutory
holding of Massachusetts v. EPA, the Clean Air Act would no
longer displace suits under federal common law.
7
29
state-law suits, as federal common law had been displaced. Rather, “the availability vel non of a state lawsuit depends, inter alia, on the preemptive effect of the
federal Act.” AEP, 564 U.S. at 429. Assuming, for the
sake of argument, that federal common law would
have preempted state-law claims concerning climate
change by preempting the relevant field, it has been
displaced by a federal statute that, as shown above,
does not preempt state-law claims.
Given its displacement, federal common law no
longer serves to preempt all state-law claims. District
of Columbia v. Exxon Mobil Corp., 89 F.4th 144, 152
(D.C. Cir. 2023) (“In the Clean Air Act, Congress displaced federal common law through comprehensive
regulation, but it did not completely preempt state
law”); see also Minnesota by Ellison v. Am. Petroleum
Inst., 63 F.4th 703, 710 (8th Cir. 2023) (“Because Congress has not acted, the presence of federal common
law here does not express Congressional intent of any
kind—much less intent to completely displace any particular state-law claim.”); City of Hoboken v. Chevron
Corp., 45 F.4th 699, 707 (3d Cir. 2022); County of San
Mateo v. Chevron Corp., 32 F.4th 733, 748 (9th Cir.
2022); Bd. of Cnty. Comm’rs of Boulder Cnty. v. Suncor
Energy (U.S.A.) Inc., 25 F.4th 1238, 1265 (10th Cir.
2022). Petitioners’ arguments to the contrary directly
contradict what this Court has found. “The Companies’ argument—that the District’s state-law claims
implicating interstate air pollution arise under federal
common law even following the Clean Air Act—simply
cannot be squared with American Electric or Ouellette.
Under the Companies’ view all state-law claims dealing with interstate pollution would remain barred by
federal common law. Yet Ouellette explicitly concluded
30
that some state-law claims could proceed despite the
Clean Water Act, confirming that the federal common
law of interstate pollution was no longer a jurisdictional bar to state-law pollution claims.” Exxon Mobil
Corp., 89 F.4th at 153. Federal common law does not
have the “Schrödinger quality” of existing for purposes
of preemption while being unavailable to provide a
rule of decision. Cf. id. at 152. The federal common law
of interstate nuisance does not preempt respondents’
claims with regard to the effects of greenhouse gas
emissions because such federal common law no longer
exists.
B. Constitutional Limits on State Authority Do
Not Justify Closing the Courthouse Doors
The Constitution properly constrains the application of state law in many instances. The Dormant
Commerce Clause bars States from adopting discriminatory policies or imposing greater burdens on out-ofstate firms than on in-state firms. See Nat’l Pork Producers Council v. Ross, 598 U.S. 356, 369 (2023). The
Due Process Clause prevents States from subjecting
those beyond a State’s jurisdiction to state law. See
Phillips Petroleum Co. v. Shutts, 472 U.S. 797, 818
(1985). States also may not impose punitive damages
for lawful out-of-state conduct that does not meaningfully affect the State’s legitimate interests. See BMW
of N. Am., Inc. v. Gore, 517 U.S. 559, 573 (1996). There
may also be First Amendment limits on the extent to
which state law may subject firms to liability for their
advertising decisions. Yet none of these limitations
justifies the categorical rule of preemption petitioners
advocate. Indeed, few (if any) of these limitations are
properly before the Court at this time.
31
The Court should decline petitioners’ invitation to
craft a new constitutional rule that would categorically
preclude States from seeking to use state law to address environmental problems that relate to interstate
pollution. Environmental problems rarely respect jurisdictional lines. Yet this has never barred the application of state law to environmental concerns, nor foreclosed efforts by state policymakers and affected parties to utilize state law to redress environmental
harms.
The Constitution provides the federal government
with ample power to direct climate change policy and
limit or preempt inconsistent, ineffective, or ill-advised state laws. Such power may be exercised by the
political branches, through the process of bicameralism and presentment. The power to adopt an unheralded, unprecedented, and unbounded rule concerning
interstate environmental problems does not lie in this
Court, and this is reason alone to reject petitioners’ arguments.
CONCLUSION
The decision below should be affirmed.
Respectfully submitted,
Tejinder Singh
Counsel of Record
SPARACINO PLLC
1920 L Street, NW
Suite 835
Washington, DC 20036
202.629.3530
tejinder@sparacinopllc.com
This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.