(Slip Opinion) OCTOBER TERM, 2013 1 

Syllabus 

NOTE: Where it is feasible, a syllabus (headnote) will be released, as is

being done in connection with this case, at the time the opinion is issued.

The syllabus constitutes no part of the opinion of the Court but has been

prepared by the Reporter of Decisions for the convenience of the reader. 

See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337. 

SUPREME COURT OF THE UNITED STATES 

Syllabus 

UTILITY AIR REGULATORY GROUP v. 

ENVIRONMENTAL PROTECTION AGENCY ET AL. 

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR 

THE DISTRICT OF COLUMBIA CIRCUIT 

No. 12–1146. Argued February 24, 2014—Decided June 23, 2014 * 

The Clean Air Act imposes permitting requirements on stationary

sources, such as factories and powerplants. The Act’s “Prevention of 

Significant Deterioration” (PSD) provisions make it unlawful to construct or modify a “major emitting facility” in “any area to which [the 

PSD program] applies” without a permit. §§7475(a)(1), 7479(2)(C). A 

“major emitting facility” is a stationary source with the potential to

emit 250 tons per year of “any air pollutant” (or 100 tons per year for

certain types of sources). §7479(1). Facilities seeking to qualify for a 

PSD permit must, inter alia, comply with emissions limitations that

reflect the “best available control technology” (BACT) for “each pollutant subject to regulation under” the Act. §7475(a)(4). In addition, 

Title V of the Act makes it unlawful to operate any “major source,” 

wherever located, without a permit. §7661a(a). A “major source” is a 

stationary source with the potential to emit 100 tons per year of “any

air pollutant.” §§7661(2)(B), 7602(j).

 In response to Massachusetts v. EPA, 549 U. S. 497, EPA promulgated greenhouse-gas emission standards for new motor vehicles, and 

—————— 

*Together with No. 12–1248, American Chemistry Council et al. v. 

Environmental Protection Agency et al., No. 12–1254, Energy-Intensive 

Manufacturers Working Group on Greenhouse Gas Regulation et al. v. 

Environmental Protection Agency et al., No. 12–1268, Southeastern Legal Foundation, Inc., et al. v. Environmental Protection Agency et al., 

No. 12–1269, Texas et al. v. Environmental Protection Agency et al., and 

No. 12–1272, Chamber of Commerce of United States States et al. v. 

Environmental Protection Agency et al., also on certiorari to the same 

court. 
 

 

 

 

 

 

2 UTILITY AIR REGULATORY GROUP v. EPA 

Syllabus 

made stationary sources subject to the PSD program and Title V on

the basis of their potential to emit greenhouse gases. It recognized,

however, that requiring permits for all sources with greenhouse-gas

emissions above the statutory thresholds would radically expand

those programs and render them unadministrable. So EPA purported to “tailor” the programs to accommodate greenhouse gases by

providing, among other things, that sources would not become newly 

subject to PSD or Title V permitting on the basis of their potential to

emit greenhouse gases in amounts less than 100,000 tons per year. 

Numerous parties, including several States, challenged EPA’s actions in the D. C. Circuit, which dismissed some of the petitions for

lack of jurisdiction and denied the remainder. 

Held: The judgment is affirmed in part and reversed in part. 

684 F. 3d 102, affirmed in part and reversed in part. 

JUSTICE SCALIA delivered the opinion of the Court with respect to

Parts I and II, concluding:

1. The Act neither compels nor permits EPA to adopt an interpretation of the Act requiring a source to obtain a PSD or Title V permit 

on the sole basis of its potential greenhouse-gas emissions. Pp. 10– 

24. 

(a) The Act does not compel EPA’s interpretation. Massachusetts 

held that the Act-wide definition of “air pollutant” includes greenhouse gases, 549 U. S., at 529, but where the term “air pollutant” appears in the Act’s operative provisions, including the PSD and Title V

permitting provisions, EPA has routinely given it a narrower, context-appropriate meaning. Massachusetts did not invalidate those 

longstanding constructions. The Act-wide definition is not a command to regulate, but a description of the universe of substances EPA

may consider regulating under the Act’s operative provisions.

Though Congress’s profligate use of “air pollutant” is not conducive to 

clarity, the presumption of consistent usage “ ‘readily yields’ ” to context, and a statutory term “may take on distinct characters from association with distinct statutory objects calling for different implementation strategies.” Environmental Defense v. Duke Energy Corp., 

549 U. S. 561, 574. Pp. 10–16. 

(b) Nor does the Act permit EPA’s interpretation. Agencies empowered to resolve statutory ambiguities must operate “within the

bounds of reasonable interpretation,” Arlington v. FCC, 569 U. S. ___, 

___. EPA has repeatedly acknowledged that applying the PSD and

Title V permitting requirements to greenhouse gases would be inconsistent with the Act’s structure and design. A review of the relevant 

statutory provisions leaves no doubt that the PSD program and Title

V are designed to apply to, and cannot rationally be extended beyond, 

a relative handful of large sources capable of shouldering heavy sub-
 

 

 

 

Cite as: 573 U. S. ____ (2014) 3 

Syllabus 

stantive and procedural burdens. EPA’s interpretation would also

bring about an enormous and transformative expansion in EPA’s 

regulatory authority without clear congressional authorization. FDA 

v. Brown & Williamson Tobacco Corp., 529 U. S. 120, 160. Pp. 16–20.

(c) EPA lacked authority to “tailor” the Act’s unambiguous numerical thresholds of 100 or 250 tons per year to accommodate its

greenhouse-gas-inclusive interpretation of the permitting triggers. 

Agencies must always “ ‘give effect to the unambiguously expressed 

intent of Congress.’ ” National Assn. of Home Builders v. Defenders 

of Wildlife, 551 U. S. 644, 665. The power to execute the laws does 

not include a power to revise clear statutory terms that turn out not

to work in practice. Pp. 20–24.

2. EPA reasonably interpreted the Act to require sources that 

would need permits based on their emission of conventional pollutants to comply with BACT for greenhouse gases. Pp. 24–29.

(a) Concerns that BACT, which has traditionally been about endof-stack controls, is fundamentally unsuited to greenhouse-gas regulation, which is more about energy use, are not unfounded. But an 

EPA guidance document states that BACT analysis should consider

options other than energy efficiency, including “carbon capture and 

storage,” which EPA contends is reasonably comparable to more traditional, end-of-stack BACT technologies. Moreover, assuming that

BACT may be used to force improvements in energy efficiency, important limitations on BACT may work to mitigate concerns about

“unbounded” regulatory authority. Pp. 24–27.

(b) EPA’s decision to require BACT for greenhouse gases emitted

by sources otherwise subject to PSD review is, as a general matter, a 

permissible interpretation of the statute under Chevron U. S. A. Inc. 

v. Natural Resources Defense Council, Inc., 467 U. S. 837. The specific phrasing of the BACT provision—which requires BACT “for each

pollutant subject to regulation under” the Act, §7475(a)(4)—does not 

suggest that the provision can bear a narrowing construction. And 

even if the text were not clear, applying BACT to greenhouse gases is

not so disastrously unworkable, and need not result in such a dramatic expansion of agency authority, as to make EPA’s interpretation

unreasonable. Pp. 27–29.

 SCALIA, J., announced the judgment of the Court and delivered an 

opinion, Parts I and II of which were for the Court. ROBERTS, C. J., and 

KENNEDY, J., joined that opinion in full; THOMAS and ALITO, JJ., joined 

as to Parts I, II–A, and II–B–1; and GINSBURG, BREYER, SOTOMAYOR, 

and KAGAN, JJ., joined as to Part II–B–2. BREYER J., filed an opinion 

concurring in part and dissenting in part, in which GINSBURG, SOTOMAYOR, and KAGAN, JJ., joined. ALITO, J., filed an opinion concurring 

in part and dissenting in part, in which THOMAS, J., joined. 
 

 

_________________ 

_________________ 

 

Cite as: 573 U. S. ____ (2014) 1 

Opinion of the Court 

NOTICE: This opinion is subject to formal revision before publication in the

preliminary print of the United States Reports. Readers are requested to

notify the Reporter of Decisions, Supreme Court of the United States, Washington, D. C. 20543, of any typographical or other formal errors, in order

that corrections may be made before the preliminary print goes to press. 

SUPREME COURT OF THE UNITED STATES 

Nos. 12–1146, 12–1248, 12–1254, 12–1268, 12–1269, and 12–1272 

UTILITY AIR REGULATORY GROUP, 

PETITIONER 

12–1146 v. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

AMERICAN CHEMISTRY COUNCIL, ET AL., 

PETITIONERS 

12–1248 v. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

ENERGY-INTENSIVE MANUFACTURERS WORKING 

GROUP ON GREENHOUSE GAS REGULATION,
 

ET AL., PETITIONERS 

12–1254 v. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

SOUTHEASTERN LEGAL FOUNDATION, INC., 

ET AL., PETITIONERS 

12–1268 v. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

TEXAS, ET AL., PETITIONERS 

12–1269 v. 

ENVIRONMENTAL PROTECTION AGENCY, 

 ET AL.; AND 
 

2 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of the Court 

CHAMBER OF COMMERCE OF THE UNITED 

STATES, ET AL., PETITIONERS 

12–1272 v. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF 

APPEALS FOR THE DISTRICT OF COLUMBIA CIRCUIT 

[June 23, 2014] 

JUSTICE SCALIA announced the judgment of the Court

and delivered the opinion of the Court with respect to

Parts I and II. 

Acting pursuant to the Clean Air Act, 69 Stat. 322, as

amended, 42 U. S. C. §§7401–7671q, the Environmental

Protection Agency recently set standards for emissions of 

“greenhouse gases” (substances it believes contribute to

“global climate change”) from new motor vehicles. We 

must decide whether it was permissible for EPA to determine that its motor-vehicle greenhouse-gas regulations 

automatically triggered permitting requirements under 

the Act for stationary sources that emit greenhouse gases. 

I. Background

A. Stationary-Source Permitting 

The Clean Air Act regulates pollution-generating emissions from both stationary sources, such as factories and 

powerplants, and moving sources, such as cars, trucks,

and aircraft. This litigation concerns permitting obligations imposed on stationary sources under Titles I and V 

of the Act. 

Title I charges EPA with formulating national ambient 

air quality standards (NAAQS) for air pollutants. §§7408– 

7409. To date, EPA has issued NAAQS for six pollutants: 

sulfur dioxide, particulate matter, nitrogen dioxide, carbon

monoxide, ozone, and lead. Clean Air Act Handbook 125 

(J. Domike & A. Zacaroli eds., 3d ed. 2011); see generally 

40 CFR pt. 50 (2013). States have primary responsibility 
 

Cite as: 573 U. S. ____ (2014) 3 

Opinion of the Court 

for implementing the NAAQS by developing “State implementation plans.” 42 U. S. C. §7410. A State must designate every area within its borders as “attainment,” “nonattainment,” or “unclassifiable” with respect to each

NAAQS, §7407(d), and the State’s implementation plan

must include permitting programs for stationary sources

that vary according to the classification of the area where 

the source is or is proposed to be located. §7410(a)(2)(C), 

(I).

Stationary sources in areas designated attainment or 

unclassifiable are subject to the Act’s provisions relating to

“Prevention of Significant Deterioration” (PSD). §§7470– 

7492. EPA interprets the PSD provisions to apply to 

sources located in areas that are designated attainment or 

unclassifiable for any NAAQS pollutant, regardless of 

whether the source emits that specific pollutant. Since the 

inception of the PSD program, every area of the country 

has been designated attainment or unclassifiable for at 

least one NAAQS pollutant; thus, on EPA’s view, all stationary sources are potentially subject to PSD review. 

It is unlawful to construct or modify a “major emitting

facility” in “any area to which [the PSD program] applies” 

without first obtaining a permit. §§7475(a)(1), 7479(2)(C).

To qualify for a permit, the facility must not cause or

contribute to the violation of any applicable air-quality 

standard, §7475(a)(3), and it must comply with emissions

limitations that reflect the “best available control technology” (or BACT) for “each pollutant subject to regulation

under” the Act. §7475(a)(4). The Act defines a “major

emitting facility” as any stationary source with the potential to emit 250 tons per year of “any air pollutant” (or 100

tons per year for certain types of sources). §7479(1). It 

defines “modification” as a physical or operational change

that causes the facility to emit more of “any air pollutant.” 
 

 

 

4 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of the Court 

§7411(a)(4).1 

In addition to the PSD permitting requirements for

construction and modification, Title V of the Act makes it 

unlawful to operate any “major source,” wherever located,

without a comprehensive operating permit. §7661a(a). 

Unlike the PSD program, Title V generally does not impose any substantive pollution-control requirements.

Instead, it is designed to facilitate compliance and enforcement by consolidating into a single document all of a 

facility’s obligations under the Act. The permit must 

include all “emissions limitations and standards” that 

apply to the source, as well as associated inspection, monitoring, and reporting requirements. §7661c(a)–(c). Title V 

defines a “major source” by reference to the Act-wide

definition of “major stationary source,” which in turn 

means any stationary source with the potential to emit 

100 tons per year of “any air pollutant.” §§7661(2)(B),

7602(j). 

B. EPA’s Greenhouse-Gas Regulations 

In 2007, the Court held that Title II of the Act “authorize[d] EPA to regulate greenhouse gas emissions from new 

motor vehicles” if the Agency “form[ed] a ‘judgment’ that 

—————— 

1Although the statute sets numerical thresholds (100 or 250 tons per

year) for emissions that will make a facility “major,” it does not specify

by how much a physical or operational change must increase emissions

to constitute a permit-requiring “modification.” Nor does it say how 

much of a given regulated pollutant a “major emitting facility” must

emit before it is subject to BACT for that pollutant. EPA, however, has 

established pollutant-specific numerical thresholds below which a 

facility’s emissions of a pollutant, and increases therein, are considered 

de minimis for those purposes. See 40 CFR §§51.166(b)(2)(i), (23), (39),

(j)(2)–(3), 52.21(b)(2)(i), (23), (40), (j)(2)–(3); see also Alabama Power Co. 

v. Costle, 636 F. 2d 323, 360–361, 400, 405 (CADC 1979) (recognizing

this authority in EPA); cf. Wisconsin Dept. of Revenue v. William 

Wrigley, Jr., Co., 505 U. S. 214, 231 (1992) (“[D]e minimis non curat lex

. . . is part of the established background of legal principles against

which all enactments are adopted”). 
Cite as: 573 U. S. ____ (2014) 5 

Opinion of the Court 

such emissions contribute to climate change.” Massachusetts v. EPA, 549 U. S. 497, 528 (quoting §7521(a)(1)). In 

response to that decision, EPA embarked on a course of 

regulation resulting in “the single largest expansion in the

scope of the [Act] in its history.” Clean Air Act Handbook, 

at xxi. 

EPA first asked the public, in a notice of proposed rulemaking, to comment on how the Agency should respond to 

Massachusetts. In doing so, it explained that regulating

greenhouse-gas emissions from motor vehicles could have

far-reaching consequences for stationary sources. Under 

EPA’s view, once greenhouse gases became regulated 

under any part of the Act, the PSD and Title V permitting

requirements would apply to all stationary sources with

the potential to emit greenhouse gases in excess of the

statutory thresholds: 100 tons per year under Title V, and 

100 or 250 tons per year under the PSD program depending on the type of source. 73 Fed. Reg. 44420, 44498, 

44511 (2008). Because greenhouse-gas emissions tend to 

be “orders of magnitude greater” than emissions of conventional pollutants, EPA projected that numerous small 

sources not previously regulated under the Act would be 

swept into the PSD program and Title V, including “smaller

industrial sources,” “large office and residential buildings, hotels, large retail establishments, and similar facilities.” Id., at 44498–44499. The Agency warned that this

would constitute an “unprecedented expansion of EPA 

authority that would have a profound effect on virtually 

every sector of the economy and touch every household in 

the land,” yet still be “relatively ineffective at reducing 

greenhouse gas concentrations.” Id., at 44355.2 

—————— 

2Comments from other Executive Branch agencies reprinted in the 

notice echoed those concerns. See, e.g., 73 Fed. Reg. 44360 (Departments of Agriculture, Commerce, Transportation, and Energy noting 

EPA would “exercis[e] de facto zoning authority through control over

thousands of what formerly were local or private decisions, impacting 
 

6 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of the Court 

In 2009, EPA announced its determination regarding 

the danger posed by motor-vehicle greenhouse-gas emissions. EPA found that greenhouse-gas emissions from 

new motor vehicles contribute to elevated atmospheric 

concentrations of greenhouse gases, which endanger public health and welfare by fostering global “climate change.” 

74 Fed. Reg. 66523, 66537 (hereinafter Endangerment

Finding). It denominated a “single air pollutant” the

“combined mix” of six greenhouse gases that it identified 

as “the root cause of human-induced climate change”:

carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. Id., at 

66516, 66537. A source’s greenhouse-gas emissions would

be measured in “carbon dioxide equivalent units” (CO2e),

which would be calculated based on each gas’s “global 

warming potential.” Id., at 66499, n. 4. 

Next, EPA issued its “final decision” regarding the

prospect that motor-vehicle greenhouse-gas standards

would trigger stationary-source permitting requirements. 

75 Fed. Reg. 17004 (2010) (hereinafter Triggering Rule). 

EPA announced that beginning on the effective date of its

greenhouse-gas standards for motor vehicles, stationary

sources would be subject to the PSD program and Title V 

on the basis of their potential to emit greenhouse gases. 

As expected, EPA in short order promulgated greenhousegas emission standards for passenger cars, light-duty 

—————— 

the construction of schools, hospitals, and commercial and residential

development”); id., at 44383 (Council of Economic Advisers and Office

of Science and Technology Policy stating that “[s]mall manufacturing

facilities, schools, and shopping centers” would be subject to “full major 

source permitting”); id., at 44385 (Council on Environmental Quality

noting “the prospect of essentially automatic and immediate regulation 

over a vast range of community and business activity”); id., at 44391 

(Small Business Administration finding it “difficult to overemphasize

how potentially disruptive and burdensome such a new regulatory

regime would be to small entities” such as “office buildings, retail

establishments, hotels, . . . schools, prisons, and private hospitals”). 
 

Cite as: 573 U. S. ____ (2014) 7 

Opinion of the Court 

trucks, and medium-duty passenger vehicles to take effect 

on January 2, 2011. 75 Fed. Reg. 25324 (hereinafter 

Tailpipe Rule).

EPA then announced steps it was taking to “tailor” the

PSD program and Title V to greenhouse gases. 75 Fed. 

Reg. 31514 (hereinafter Tailoring Rule). Those steps were 

necessary, it said, because the PSD program and Title V

were designed to regulate “a relatively small number of 

large industrial sources,” and requiring permits for all

sources with greenhouse-gas emissions above the statutory thresholds would radically expand those programs,

making them both unadministrable and “unrecognizable 

to the Congress that designed” them. Id., at 31555, 31562. 

EPA nonetheless rejected calls to exclude greenhouse 

gases entirely from those programs, asserting that the Act

is not “ambiguous with respect to the need to cover 

[greenhouse-gas] sources under either the PSD or title V 

program.” Id., at 31548, n. 31. Instead, EPA adopted a

“phase-in approach” that it said would “appl[y] PSD and

title V at threshold levels that are as close to the statutory 

levels as possible, and do so as quickly as possible, at least 

to a certain point.” Id., at 31523. 

The phase-in, EPA said, would consist of at least three 

steps. During Step 1, from January 2 through June 30,

2011, no source would become newly subject to the PSD

program or Title V solely on the basis of its greenhousegas emissions; however, sources required to obtain permits 

anyway because of their emission of conventional pollutants (so-called “anyway” sources) would need to comply

with BACT for greenhouse gases if they emitted those 

gases in significant amounts, defined as at least 75,000 

tons per year CO2e. Ibid. During Step 2, from July 1,

2011, through June 30, 2012, sources with the potential to 

emit at least 100,000 tons per year CO2e of greenhouse

gases would be subject to PSD and Title V permitting for 

their construction and operation and to PSD permitting 
 

 

 

8 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of the Court 

for modifications that would increase their greenhouse-gas 

emissions by at least 75,000 tons per year CO2e. Id., at 

31523–31524.3 At Step 3, beginning on July 1, 2013, EPA 

said it might (or might not) further reduce the permitting

thresholds (though not below 50,000 tons per year CO2e),

and it might (or might not) establish permanent exemptions for some sources. Id., at 31524. Beyond Step 3, EPA 

promised to complete another round of rulemaking by

April 30, 2016, in which it would “take further action to 

address small sources,” which might (or might not) include

establishing permanent exemptions. Id., at 31525. 

EPA codified Steps 1 and 2 at 40 CFR §§51.166(b)(48) 

and 52.21(b)(49) for PSD and at §§70.2 and 71.2 for Title 

V, and it codified its commitments regarding Step 3 and 

beyond at §§52.22, 70.12, and 71.13. See Tailoring Rule

31606–31608. After the decision below, EPA issued its 

final Step 3 rule, in which it decided not to lower the 

thresholds it had established at Step 2 until at least 2016.

77 Fed. Reg. 41051 (2012). 

C. Decision Below 

Numerous parties, including several States, filed petitions for review in the D. C. Circuit under 42 U. S. C. 

§7607(b), challenging EPA’s greenhouse-gas-related actions. The Court of Appeals dismissed some of the petitions for lack of jurisdiction and denied the remainder. 

Coalition for Responsible Regulation, Inc. v. EPA, 684 

F. 3d 102 (2012) (per curiam). First, it upheld the Endangerment Finding and Tailpipe Rule. Id., at 119, 126. 

Next, it held that EPA’s interpretation of the PSD permitting requirement as applying to “any regulated air pollu-

—————— 

3EPA stated that its adoption of a 75,000-tons-per-year threshold for

emissions requiring BACT and modifications requiring permits was not

an exercise of its authority to establish de minimis exceptions and that 

a truly de minimis level might be “well below” 75,000 tons per year. 

Tailoring Rule 31560; cf. n. 1, supra. 
Cite as: 573 U. S. ____ (2014) 9 

Opinion of the Court 

tant,” including greenhouse gases, was “compelled by the 

statute.” Id., at 133–134. The court also found it “crystal 

clear that PSD permittees must install BACT for greenhouse gases.” Id., at 137. Because it deemed petitioners’ 

arguments about the PSD program insufficiently applicable to Title V, it held they had “forfeited any challenges to

EPA’s greenhouse gas-inclusive interpretation of Title V.” 

Id., at 136. Finally, it held that petitioners were without

Article III standing to challenge EPA’s efforts to limit the 

reach of the PSD program and Title V through the Triggering and Tailoring Rules. Id., at 146. The court denied 

rehearing en banc, with Judges Brown and Kavanaugh 

each dissenting. No. 09–1322 etc. (Dec. 20, 2012), App.

139, 2012 WL 6621785. 

We granted six petitions for certiorari but agreed to

decide only one question: “‘Whether EPA permissibly

determined that its regulation of greenhouse gas emissions from new motor vehicles triggered permitting requirements under the Clean Air Act for stationary sources

that emit greenhouse gases.’” 571 U. S. ____ (2013). 

II. Analysis 

This litigation presents two distinct challenges to EPA’s 

stance on greenhouse-gas permitting for stationary 

sources. First, we must decide whether EPA permissibly

determined that a source may be subject to the PSD and 

Title V permitting requirements on the sole basis of the

source’s potential to emit greenhouse gases. Second, we 

must decide whether EPA permissibly determined that a 

source already subject to the PSD program because of its 

emission of conventional pollutants (an “anyway” source) 

may be required to limit its greenhouse-gas emissions by

employing the “best available control technology” for 

greenhouse gases. The Solicitor General joins issue on 

both points but evidently regards the second as more 

important; he informs us that “anyway” sources account 
 

10 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of the Court 

for roughly 83% of American stationary-source greenhousegas emissions, compared to just 3% for the additional, non-

“anyway” sources EPA sought to regulate at Steps 2 and 3

of the Tailoring Rule. Tr. of Oral Arg. 52.

We review EPA’s interpretations of the Clean Air Act

using the standard set forth in Chevron U. S. A. Inc. v. 

Natural Resources Defense Council, Inc., 467 U. S. 837, 

842–843 (1984). Under Chevron, we presume that when

an agency-administered statute is ambiguous with respect 

to what it prescribes, Congress has empowered the agency

to resolve the ambiguity. The question for a reviewing 

court is whether in doing so the agency has acted reasonably and thus has “stayed within the bounds of its statutory 

authority.” Arlington v. FCC, 569 U. S. ___, ___ (2013) 

(slip op., at 5) (emphasis deleted). 

A. The PSD and Title V Triggers 

We first decide whether EPA permissibly interpreted

the statute to provide that a source may be required to 

obtain a PSD or Title V permit on the sole basis of its 

potential greenhouse-gas emissions. 

1 

EPA thought its conclusion that a source’s greenhousegas emissions may necessitate a PSD or Title V permit

followed from the Act’s unambiguous language. The Court 

of Appeals agreed and held that the statute “compelled” 

EPA’s interpretation. 684 F. 3d, at 134. We disagree.

The statute compelled EPA’s greenhouse-gas-inclusive

interpretation with respect to neither the PSD program 

nor Title V.4 

—————— 

4The Court of Appeals held that petitioners’ arguments applied only

to the PSD program and that petitioners had therefore “forfeited any

challenges to EPA’s greenhouse gas-inclusive interpretation of Title V.” 

684 F. 3d, at 136. The Solicitor General does not defend the Court of 

Appeals’ ruling on forfeiture, and he concedes that some of the argu-
Cite as: 573 U. S. ____ (2014) 11 

Opinion of the Court 

The Court of Appeals reasoned by way of a flawed syllogism: Under Massachusetts, the general, Act-wide definition of “air pollutant” includes greenhouse gases; the Act

requires permits for major emitters of “any air pollutant”;

therefore, the Act requires permits for major emitters of 

greenhouse gases. The conclusion follows from the premises only if the air pollutants referred to in the permitrequiring provisions (the minor premise) are the same air

pollutants encompassed by the Act-wide definition as

interpreted in Massachusetts (the major premise). Yet no 

one—least of all EPA—endorses that proposition, and it is 

obviously untenable.

The Act-wide definition says that an air pollutant is

“any air pollution agent or combination of such agents, 

including any physical, chemical, biological, [or] radioactive . . . substance or matter which is emitted into or otherwise enters the ambient air.” §7602(g). In Massachusetts, the Court held that the Act-wide definition includes 

greenhouse gases because it is all-encompassing; it “embraces all airborne compounds of whatever stripe.” 549 

U. S., at 529. But where the term “air pollutant” appears

in the Act’s operative provisions, EPA has routinely given

it a narrower, context-appropriate meaning. 

That is certainly true of the provisions that require PSD

and Title V permitting for major emitters of “any air pollutant.” Since 1978, EPA’s regulations have interpreted “air 

pollutant” in the PSD permitting trigger as limited to 

regulated air pollutants, 43 Fed. Reg. 26403, codified, as

amended, 40 CFR §52.21(b)(1)–(2), (50)—a class much

narrower than Massachusetts’ “all airborne compounds of 

—————— 

ments petitioners have made before this Court apply to Title V as well

as the PSD program. See Brief for Federal Respondents 56. We agree,

and we are satisfied that those arguments were also made below. See,
 

e.g., Brief for State Petitioners et al. in No. 10–1073 etc. (CADC), pp.

59–73; Brief for Non-State Petitioners et al. in No. 10–1073 etc.
 

(CADC), pp. 46–47. 
 

 

12 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of the Court 

whatever stripe,” 549 U. S., at 529. And since 1993 EPA 

has informally taken the same position with regard to the 

Title V permitting trigger, a position the Agency ultimately

incorporated into some of the regulations at issue here.

See Memorandum from Lydia N. Wegman, Deputy Director, Office of Air Quality Planning and Standards, to Air 

Division Director, Regions I–X, pp. 4–5 (Apr. 26, 1993); 

Tailoring Rule 31607–31608 (amending 40 CFR §§70.2,

71.2). Those interpretations were appropriate: It is plain

as day that the Act does not envision an elaborate, burdensome permitting process for major emitters of steam, 

oxygen, or other harmless airborne substances. It takes 

some cheek for EPA to insist that it cannot possibly give 

“air pollutant” a reasonable, context-appropriate meaning 

in the PSD and Title V contexts when it has been doing 

precisely that for decades. 

Nor are those the only places in the Act where EPA has 

inferred from statutory context that a generic reference to

air pollutants does not encompass every substance falling

within the Act-wide definition. Other examples abound: 

	 The Act authorizes EPA to enforce new source performance standards (NSPS) against a pre-existing 

source if, after promulgation of the standards, the 

source undergoes a physical or operational change 

that increases its emission of “any air pollutant.” 

§7411(a)(2), (4), (b)(1)(B). EPA interprets that provision as limited to air pollutants for which EPA 

has promulgated new source performance standards. 36 Fed. Reg. 24877 (1971), codified, as 

amended, 40 CFR §60.2; 40 Fed. Reg. 58419 (1975), 

codified, as amended, 40 CFR §60.14(a). 

	 The Act requires a permit for the construction or 

operation in a nonattainment area of a source with

the potential to emit 100 tons per year of “any air 
 

Cite as: 573 U. S. ____ (2014) 13 

Opinion of the Court 

pollutant.” §§7502(c)(5), 7602(j). EPA interprets

that provision as limited to pollutants for which the 

area is designated nonattainment. 45 Fed. Reg.

52745 (1980), promulgating 40 CFR §51.18(j)(2), as

amended, §51.165(a)(2). 

	 The Act directs EPA to require “enhanced monitoring and submission of compliance certifications” for 

any source with the potential to emit 100 tons per 

year of “any air pollutant.” §§7414(a)(3), 7602(j).

EPA interprets that provision as limited to regulated 

pollutants. 62 Fed. Reg. 54941 (1997), codified

at 40 CFR §§64.1, 64.2. 

	 The Act requires certain sources of air pollutants

that interfere with visibility to undergo retrofitting

if they have the potential to emit 250 tons per year

of “any pollutant.” §7491(b)(2)(A), (g)(7). EPA interprets that provision as limited to visibilityimpairing air pollutants. 70 Fed. Reg. 39160 

(2005), codified at 40 CFR pt. 51, App. Y, §II.A.3. 

Although these limitations are nowhere to be found in the

Act-wide definition, in each instance EPA has concluded— 

as it has in the PSD and Title V context—that the statute 

is not using “air pollutant” in Massachusetts’ broad sense 

to mean any airborne substance whatsoever. 

 Massachusetts did not invalidate all these longstanding 

constructions. That case did not hold that EPA must 

always regulate greenhouse gases as an “air pollutant” 

everywhere that term appears in the statute, but only that

EPA must “ground its reasons for action or inaction in the 

statute,” 549 U. S., at 535 (emphasis added), rather than

on “reasoning divorced from the statutory text,” id., at 

532. EPA’s inaction with regard to Title II was not sufficiently grounded in the statute, the Court said, in part 
 

14 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of the Court 

because nothing in the Act suggested that regulating

greenhouse gases under that Title would conflict with the

statutory design. Title II would not compel EPA to regulate in any way that would be “extreme,” “counterintuitive,” or contrary to “‘common sense.’” Id., at 531. At 

most, it would require EPA to take the modest step of

adding greenhouse-gas standards to the roster of newmotor-vehicle emission regulations. Ibid. 

Massachusetts does not strip EPA of authority to exclude greenhouse gases from the class of regulable air 

pollutants under other parts of the Act where their inclusion would be inconsistent with the statutory scheme. The 

Act-wide definition to which the Court gave a “sweeping” 

and “capacious” interpretation, id., at 528, 532, is not a 

command to regulate, but a description of the universe of

substances EPA may consider regulating under the Act’s 

operative provisions. Massachusetts does not foreclose the 

Agency’s use of statutory context to infer that certain of

the Act’s provisions use “air pollutant” to denote not every

conceivable airborne substance, but only those that may 

sensibly be encompassed within the particular regulatory 

program. As certain amici felicitously put it, while Massachusetts “rejected EPA’s categorical contention that 

greenhouse gases could not be ‘air pollutants’ for any 

purposes of the Act,” it did not “embrace EPA’s current,

equally categorical position that greenhouse gases must be 

air pollutants for all purposes” regardless of the statutory 

context. Brief for Administrative Law Professors et al. as 

Amici Curiae 17.5 

—————— 

5Our decision in American Elec. Power Co. v. Connecticut, 564 U. S. 

___ (2011), does not suggest otherwise. We there held that the Act’s 

authorization for EPA to establish performance standards for powerplant greenhouse-gas emissions displaced any federal-common-law 

right that might otherwise have existed to seek abatement of those

emissions. Id., at ___ (slip op., at 10). The authorization to which we 

referred was that given in the NSPS program of §7411, a part of the Act 
 

Cite as: 573 U. S. ____ (2014) 15 

Opinion of the Court 

To be sure, Congress’s profligate use of “air pollutant” 

where what is meant is obviously narrower than the Actwide definition is not conducive to clarity. One ordinarily 

assumes “‘that identical words used in different parts of 

the same act are intended to have the same meaning.’” 

Environmental Defense v. Duke Energy Corp., 549 U. S. 

561, 574 (2007). In this respect (as in countless others),

the Act is far from a chef d’oeuvre of legislative draftsmanship. But we, and EPA, must do our best, bearing in mind

the “‘fundamental canon of statutory construction that the

words of a statute must be read in their context and with a 

view to their place in the overall statutory scheme.’” FDA 

v. Brown & Williamson Tobacco Corp., 529 U. S. 120, 133 

(2000). As we reiterated the same day we decided Massachusetts, the presumption of consistent usage “‘readily 

yields’” to context, and a statutory term—even one defined 

in the statute—“may take on distinct characters from

association with distinct statutory objects calling for different implementation strategies.” Duke Energy, supra, at 

574. 

We need not, and do not, pass on the validity of all the

limiting constructions EPA has given the term “air pollutant” throughout the Act. We merely observe that taken 

together, they belie EPA’s rigid insistence that when

interpreting the PSD and Title V permitting requirements

it is bound by the Act-wide definition’s inclusion of greenhouse gases, no matter how incompatible that inclusion is 

with those programs’ regulatory structure.

In sum, there is no insuperable textual barrier to EPA’s

interpreting “any air pollutant” in the permitting triggers

of PSD and Title V to encompass only pollutants emitted

in quantities that enable them to be sensibly regulated at

the statutory thresholds, and to exclude those atypical 

—————— 

not at issue here and one that no party in American Electric Power
 

argued was ill suited to accommodating greenhouse gases. 
 

 

16 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of the Court 

pollutants that, like greenhouse gases, are emitted in such 

vast quantities that their inclusion would radically transform those programs and render them unworkable as 

written.6 

2 

Having determined that EPA was mistaken in thinking 

the Act compelled a greenhouse-gas-inclusive interpretation of the PSD and Title V triggers, we next consider the 

Agency’s alternative position that its interpretation was

justified as an exercise of its “discretion” to adopt “a reasonable construction of the statute.” Tailoring Rule 31517. 

We conclude that EPA’s interpretation is not permissible. 

 Even under Chevron’s deferential framework, agencies 

must operate “within the bounds of reasonable interpretation.” Arlington, 569 U. S., at ___ (slip op., at 5). And 

reasonable statutory interpretation must account for both 

“the specific context in which . . . language is used” and 

“the broader context of the statute as a whole.” Robinson 

v. Shell Oil Co., 519 U. S. 337, 341 (1997). A statutory 

—————— 

6During the course of this litigation, several possible limiting constructions for the PSD trigger have been proposed. Judge Kavanaugh 

argued below that it would be plausible for EPA to read “any air pollutant” in the PSD context as limited to the six NAAQS pollutants. See 

Coalition for Responsible Regulation, Inc. v. EPA, No. 09–1322 etc. 

(CADC, Dec. 20, 2012), App. 171–180, 2012 WL 6621785, *15–*18

(opinion dissenting from denial of rehearing en banc). Some petitioners

make a slightly different argument: that because PSD permitting is 

required only for major emitting facilities “in any area to which [the

PSD program] applies,” §7475(a), the relevant pollutants are only those

NAAQS pollutants for which the area in question is designated attainment or unclassifiable. That approach would bring EPA’s interpretation of the PSD trigger in line with its longstanding interpretation of

the permitting requirements for nonattainment areas. Others maintain that “any air pollutant” in the PSD provision should be limited to

air pollutants with localized effects on air quality. We do not foreclose 

EPA or the courts from considering those constructions in the future, 

but we need not do so today. 
 

Cite as: 573 U. S. ____ (2014) 17 

Opinion of the Court 

“provision that may seem ambiguous in isolation is often 

clarified by the remainder of the statutory scheme . . .

because only one of the permissible meanings produces a 

substantive effect that is compatible with the rest of the

law.” United Sav. Assn. of Tex. v. Timbers of Inwood 

Forest Associates, Ltd., 484 U. S. 365, 371 (1988). Thus, 

an agency interpretation that is “inconsisten[t] with the 

design and structure of the statute as a whole,” University 

of Tex. Southwestern Medical Center v. Nassar, 570 U. S. 

___, ___ (2013) (slip op., at 13), does not merit deference. 

EPA itself has repeatedly acknowledged that applying

the PSD and Title V permitting requirements to greenhouse gases would be inconsistent with—in fact, would 

overthrow—the Act’s structure and design. In the Tailoring Rule, EPA described the calamitous consequences of 

interpreting the Act in that way. Under the PSD program,

annual permit applications would jump from about 800 to 

nearly 82,000; annual administrative costs would swell

from $12 million to over $1.5 billion; and decade-long 

delays in issuing permits would become common, causing

construction projects to grind to a halt nationwide. Tailoring Rule 31557. The picture under Title V was equally

bleak: The number of sources required to have permits

would jump from fewer than 15,000 to about 6.1 million; 

annual administrative costs would balloon from $62 million to $21 billion; and collectively the newly covered 

sources would face permitting costs of $147 billion. Id., at 

31562–31563. Moreover, “the great majority of additional 

sources brought into the PSD and title V programs would 

be small sources that Congress did not expect would need

to undergo permitting.” Id., at 31533. EPA stated that 

these results would be so “contrary to congressional intent,” and would so “severely undermine what Congress 

sought to accomplish,” that they necessitated as much as a

1,000-fold increase in the permitting thresholds set forth 

in the statute. Id., at 31554, 31562. 
 

18 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of the Court 

Like EPA, we think it beyond reasonable debate that 

requiring permits for sources based solely on their emission of greenhouse gases at the 100- and 250-tons-per-year 

levels set forth in the statute would be “incompatible” with

“the substance of Congress’ regulatory scheme.” Brown & 

Williamson, 529 U. S., at 156. A brief review of the relevant statutory provisions leaves no doubt that the PSD 

program and Title V are designed to apply to, and cannot 

rationally be extended beyond, a relative handful of large 

sources capable of shouldering heavy substantive and 

procedural burdens.

Start with the PSD program, which imposes numerous 

and costly requirements on those sources that are required 

to apply for permits. Among other things, the applicant

must make available a detailed scientific analysis of the

source’s potential pollution-related impacts, demonstrate

that the source will not contribute to the violation of any 

applicable pollution standard, and identify and use the 

“best available control technology” for each regulated

pollutant it emits. §7475(a)(3), (4), (6), (e). The permitting

authority (the State, usually) also bears its share of the

burden: It must grant or deny a permit within a year,

during which time it must hold a public hearing on the 

application. §7475(a)(2), (c). Not surprisingly, EPA 

acknowledges that PSD review is a “complicated, resourceintensive, time-consuming, and sometimes contentious 

process” suitable for “hundreds of larger sources,” not 

“tens of thousands of smaller sources.” 74 Fed. Reg.

55304, 55321–55322. 

Title V contains no comparable substantive requirements but imposes elaborate procedural mandates. It 

requires the applicant to submit, within a year of becoming subject to Title V, a permit application and a “compliance plan” describing how it will comply with “all applicable requirements” under the Act; to certify its compliance 

annually; and to submit to “inspection, entry, monitoring, 
 

Cite as: 573 U. S. ____ (2014) 19 

Opinion of the Court 

. . . and reporting requirements.” §§7661b(b)–(c),

7661c(a)–(c). The procedural burdens on the permitting

authority and EPA are also significant. The permitting

authority must hold a public hearing on the application, 

§7661a(b)(6), and it must forward the application and any 

proposed permit to EPA and neighboring States and respond in writing to their comments, §7661d(a), (b)(1). If it 

fails to issue or deny the permit within 18 months, any 

interested party can sue to require a decision “without

additional delay.” §§7661a(b)(7), 7661b(c). An interested 

party also can petition EPA to block issuance of the permit; EPA must grant or deny the petition within 60 days,

and its decision may be challenged in federal court.

§7661d(b)(2)–(3). As EPA wrote, Title V is “finely crafted 

for thousands,” not millions, of sources. Tailoring Rule

31563. 

The fact that EPA’s greenhouse-gas-inclusive interpretation of the PSD and Title V triggers would place plainly 

excessive demands on limited governmental resources is

alone a good reason for rejecting it; but that is not the only 

reason. EPA’s interpretation is also unreasonable because 

it would bring about an enormous and transformative

expansion in EPA’s regulatory authority without clear

congressional authorization. When an agency claims to 

discover in a long-extant statute an unheralded power to 

regulate “a significant portion of the American economy,” 

Brown & Williamson, 529 U. S., at 159, we typically greet 

its announcement with a measure of skepticism. We 

expect Congress to speak clearly if it wishes to assign to 

an agency decisions of vast “economic and political significance.” Id., at 160; see also MCI Telecommunications 

Corp. v. American Telephone & Telegraph Co., 512 U. S. 

218, 231 (1994); Industrial Union Dept., AFL–CIO v. 

American Petroleum Institute, 448 U. S. 607, 645–646 

(1980) (plurality opinion). The power to require permits

for the construction and modification of tens of thousands, 
 

 

 

20 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of the Court 

and the operation of millions, of small sources nationwide 

falls comfortably within the class of authorizations that we 

have been reluctant to read into ambiguous statutory text.

Moreover, in EPA’s assertion of that authority, we confront a singular situation: an agency laying claim to extravagant statutory power over the national economy 

while at the same time strenuously asserting that the 

authority claimed would render the statute “unrecognizable to the Congress that designed” it. Tailoring Rule

31555. Since, as we hold above, the statute does not compel EPA’s interpretation, it would be patently unreasonable—not to say outrageous—for EPA to insist on seizing

expansive power that it admits the statute is not designed 

to grant.7 

3 

EPA thought that despite the foregoing problems, it 

could make its interpretation reasonable by adjusting the 

levels at which a source’s greenhouse-gas emissions would 

—————— 

7A few additional points bear mentioning. The Solicitor General 

conjectures that EPA might eventually alter its longstanding interpretation of “potential to emit” in order to reduce the number of sources 

required to have permits at the statutory thresholds. But neither he 

nor the Agency has given us any reason to believe that there exists a 

plausible reading of “potential to emit” that EPA would willingly adopt

and that would eliminate the unreasonableness of EPA’s interpretation.

Nor have we been given any information about the ability of other

possible “streamlining” techniques alluded to by EPA—such as “general” or “electronic” permitting—to reduce the administrability problems identified above; and in any event, none of those techniques would

address the more fundamental problem of EPA’s claiming regulatory

authority over millions of small entities that it acknowledges the Act

does not seek to regulate. Finally, the Solicitor General suggests that

the incompatibility of greenhouse gases with the PSD program and 

Title V results chiefly from the inclusion of carbon dioxide in the

“aggregate pollutant” defined by EPA. We decide these cases on the 

basis of the pollutant “greenhouse gases” as EPA has defined and 

regulated it, and we express no view on how our analysis might change

were EPA to define it differently. 
Cite as: 573 U. S. ____ (2014) 21 

Opinion of the Court 

oblige it to undergo PSD and Title V permitting. Although

the Act, in no uncertain terms, requires permits for

sources with the potential to emit more than 100 or 250 

tons per year of a relevant pollutant, EPA in its Tailoring 

Rule wrote a new threshold of 100,000 tons per year for 

greenhouse gases. Since the Court of Appeals thought the

statute unambiguously made greenhouse gases capable of

triggering PSD and Title V, it held that petitioners lacked

Article III standing to challenge the Tailoring Rule because that rule did not injure petitioners but merely relaxed the pre-existing statutory requirements. Because 

we, however, hold that EPA’s greenhouse-gas-inclusive 

interpretation of the triggers was not compelled, and 

because EPA has essentially admitted that its interpretation would be unreasonable without “tailoring,” we consider

the validity of the Tailoring Rule.

We conclude that EPA’s rewriting of the statutory 

thresholds was impermissible and therefore could not

validate the Agency’s interpretation of the triggering

provisions. An agency has no power to “tailor” legislation 

to bureaucratic policy goals by rewriting unambiguous 

statutory terms. Agencies exercise discretion only in the 

interstices created by statutory silence or ambiguity; they 

must always “‘give effect to the unambiguously expressed

intent of Congress.’” National Assn. of Home Builders v. 

Defenders of Wildlife, 551 U. S. 644, 665 (2007) (quoting 

Chevron, 467 U. S., at 843). It is hard to imagine a statutory term less ambiguous than the precise numerical 

thresholds at which the Act requires PSD and Title V

permitting. When EPA replaced those numbers with 

others of its own choosing, it went well beyond the “bounds

of its statutory authority.” Arlington, 569 U. S., at ___ 

(slip op., at 5) (emphasis deleted).

The Solicitor General does not, and cannot, defend the 

Tailoring Rule as an exercise of EPA’s enforcement discretion. The Tailoring Rule is not just an announcement of 
 

22 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of the Court 

EPA’s refusal to enforce the statutory permitting requirements; it purports to alter those requirements and to 

establish with the force of law that otherwise-prohibited

conduct will not violate the Act. This alteration of the 

statutory requirements was crucial to EPA’s “tailoring” 

efforts. Without it, small entities with the potential to

emit greenhouse gases in amounts exceeding the statutory 

thresholds would have remained subject to citizen suits—

authorized by the Act—to enjoin their construction, modification, or operation and to impose civil penalties of up to

$37,500 per day of violation. §§7413(b), 7604(a), (f)(4); 40 

CFR §19.4. EPA itself has recently affirmed that the 

“independent enforcement authority” furnished by the 

citizen-suit provision cannot be displaced by a permitting

authority’s decision not to pursue enforcement. 78 Fed. 

Reg. 12477, 12486–12487 (2013). The Solicitor General is 

therefore quite right to acknowledge that the availability 

of citizen suits made it necessary for EPA, in seeking

to mitigate the unreasonableness of its greenhouse-gasinclusive interpretation, to go beyond merely exercising its

enforcement discretion. See Tr. of Oral Arg. 87–88. 

For similar reasons, Morton v. Ruiz, 415 U. S. 199 

(1974)—to which the Solicitor General points as the best

case supporting the Tailoring Rule, see Tr. of Oral Arg. 71, 

80–81—is irrelevant. In Ruiz, Congress had appropriated

funds for the Bureau of Indian Affairs to spend on providing assistance to “‘Indians throughout the United States’” 

and had not “impose[d] any geographical limitation on the 

availability of general assistance benefits.” Id., at 206– 

207, and n. 7. Although we held the Bureau could not 

deny benefits to off-reservation Indians because it had not

published its eligibility criteria, we stated in dictum that 

the Bureau could, if it followed proper administrative

procedures, “create reasonable classifications and eligibility requirements in order to allocate the limited funds

available.” Id., at 230–231. That dictum stands only for 
 

Cite as: 573 U. S. ____ (2014) 23 

Opinion of the Court 

the unremarkable proposition that an agency may adopt 

policies to prioritize its expenditures within the bounds 

established by Congress. See also Lincoln v. Vigil, 508 

U. S. 182, 192–193 (1993). Nothing in Ruiz remotely

authorizes an agency to modify unambiguous requirements imposed by a federal statute. An agency confronting resource constraints may change its own conduct, but

it cannot change the law.

Were we to recognize the authority claimed by EPA in

the Tailoring Rule, we would deal a severe blow to the

Constitution’s separation of powers. Under our system of

government, Congress makes laws and the President,

acting at times through agencies like EPA, “faithfully 

execute[s]” them. U. S. Const., Art. II, §3; see Medellín v. 

Texas, 552 U. S. 491, 526–527 (2008). The power of executing the laws necessarily includes both authority and

responsibility to resolve some questions left open by Congress that arise during the law’s administration. But it 

does not include a power to revise clear statutory terms 

that turn out not to work in practice. See, e.g., Barnhart 

v. Sigmon Coal Co., 534 U. S. 438, 462 (2002) (agency 

lacked authority “to develop new guidelines or to assign 

liability in a manner inconsistent with” an “unambiguous

statute”).

In the Tailoring Rule, EPA asserts newfound authority 

to regulate millions of small sources—including retail

stores, offices, apartment buildings, shopping centers, 

schools, and churches—and to decide, on an ongoing basis 

and without regard for the thresholds prescribed by Congress, how many of those sources to regulate. We are not 

willing to stand on the dock and wave goodbye as EPA 

embarks on this multiyear voyage of discovery. We reaffirm the core administrative-law principle that an agency

may not rewrite clear statutory terms to suit its own sense 

of how the statute should operate. EPA therefore lacked 

authority to “tailor” the Act’s unambiguous numerical 
 

 

 

24 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of the Court 

thresholds to accommodate its greenhouse-gas-inclusive 

interpretation of the permitting triggers. Instead, the 

need to rewrite clear provisions of the statute should have 

alerted EPA that it had taken a wrong interpretive turn.

Agencies are not free to “adopt . . . unreasonable interpretations of statutory provisions and then edit other statutory provisions to mitigate the unreasonableness.” App. 175,

2012 WL 6621785, *16 (Kavanaugh, J., dissenting from

denial of rehearing en banc). Because the Tailoring Rule 

cannot save EPA’s interpretation of the triggers, that 

interpretation was impermissible under Chevron.8 

B. BACT for “Anyway” Sources 

For the reasons we have given, EPA overstepped its 

statutory authority when it decided that a source could 

—————— 

8 JUSTICE BREYER argues, post, at 10 (opinion concurring in part and 

dissenting in part), that when the statutory permitting thresholds of 

100 or 250 tons per year do not provide a “sensible regulatory line,” 

EPA is entitled to “read an unwritten exception” into “the particular

number used by the statute”—by which he apparently means that the 

Agency is entitled to substitute a dramatically higher number, such as

100,000. We are aware of no principle of administrative law that would 

allow an agency to rewrite such a clear statutory term, and we shudder

to contemplate the effect that such a principle would have on democratic governance.

JUSTICE BREYER, however, claims to perceive no difference between 

(a) reading the statute to exclude greenhouse gases from the term “any 

air pollutant” in the permitting triggers, and (b) reading the statute to

exclude sources emitting less than 100,000 tons per year from the

statutory phrase “any . . . source with the potential to emit two hundred 

and fifty tons per year or more.” See post, at 7. The two could scarcely 

be further apart. As we have explained (and as EPA agrees), statutory

context makes plain that the Act’s operative provisions use “air pollutant” to denote less than the full range of pollutants covered by the Actwide definition. See Part II–A–1, supra. It is therefore incumbent on 

EPA to specify the pollutants encompassed by that term in the context 

of a particular program, and to do so reasonably in light of that program’s overall regulatory scheme. But there is no ambiguity whatsoever in the specific, numerical permitting thresholds, and thus no room 

for EPA to exercise discretion in selecting a different threshold. 
Cite as: 573 U. S. ____ (2014) 25 

Opinion of the Court 

become subject to PSD or Title V permitting by reason of 

its greenhouse-gas emissions. But what about “anyway” 

sources, those that would need permits based on their 

emissions of more conventional pollutants (such as particulate matter)? We now consider whether EPA reasonably 

interpreted the Act to require those sources to comply with

“best available control technology” emission standards for 

greenhouse gases. 

1 

To obtain a PSD permit, a source must be “subject to the

best available control technology” for “each pollutant 

subject to regulation under [the Act]” that it emits. 

§7475(a)(4). The Act defines BACT as “an emission limitation based on the maximum degree of reduction of each

pollutant subject to regulation” that is “achievable . . . 

through application of production processes and available 

methods, systems, and techniques, including fuel cleaning, 

clean fuels, or treatment or innovative fuel combustion 

techniques.” §7479(3). BACT is determined “on a case-bycase basis, taking into account energy, environmental, and 

economic impacts and other costs.” Ibid. 

Some petitioners urge us to hold that EPA may never 

require BACT for greenhouse gases—even when a source 

must undergo PSD review based on its emissions of conventional pollutants—because BACT is fundamentally

unsuited to greenhouse-gas regulation. BACT, they say,

has traditionally been about end-of-stack controls “such as 

catalytic converters or particle collectors”; but applying it

to greenhouse gases will make it more about regulating 

energy use, which will enable regulators to control “every 

aspect of a facility’s operation and design,” right down to 

the “light bulbs in the factory cafeteria.” Brief for Petitioner Energy-Intensive Manufacturers Working Group on

Greenhouse Gas Regulation et al. in No. 12–1254, p. 7; see 

Joint Reply Brief for Petitioners in No. 12–1248 etc., pp. 
 

26 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of the Court 

14–15 (“BACT for [greenhouse gases] becomes an unbounded exercise in command-and-control regulation” of

everything from “efficient light bulbs” to “basic industrial 

processes”). But see Brief for Calpine Corp. as Amicus 

Curiae 10 (“[I]n Calpine’s experience with ‘anyway’ 

sources, the [greenhouse-gas] analysis was only a small 

part of the overall permitting process”). 

EPA has published a guidance document that lends 

some credence to petitioners’ fears. It states that at least 

initially, compulsory improvements in energy efficiency

will be the “foundation” of greenhouse-gas BACT, with

more traditional end-of-stack controls either not used or 

“added as they become more available.” PSD and Title V 

Permitting Guidance for Greenhouse Gases 29 (Mar. 2011) 

(hereinafter Guidance); see Peloso & Dobbins, Greenhouse 

Gas PSD Permitting: The Year in Review, 42 Tex. Env.

L. J. 233, 247 (2012) (“Because [other controls] tend to

prove infeasible, energy efficiency measures dominate the

[greenhouse-gas] BACT controls approved by the states 

and EPA”). But EPA’s guidance also states that BACT 

analysis should consider options other than energy efficiency, such as “carbon capture and storage.” Guidance 

29, 32, 35–36, 42–43. EPA argues that carbon capture is

reasonably comparable to more traditional, end-of-stack 

BACT technologies, id., at 32, n. 86, and petitioners do not 

dispute that.

Moreover, assuming without deciding that BACT may 

be used to force some improvements in energy efficiency,

there are important limitations on BACT that may work 

to mitigate petitioners’ concerns about “unbounded” regulatory authority. For one, BACT is based on “control 

technology” for the applicant’s “proposed facility,”

§7475(a)(4); therefore, it has long been held that BACT 

cannot be used to order a fundamental redesign of the 

facility. See, e.g., Sierra Club v. EPA, 499 F. 3d 653, 654– 

655 (CA7 2007); In re Pennsauken Cty., N. J., Resource 
Cite as: 573 U. S. ____ (2014) 27 

Opinion of the Court 

Recovery Facility, 2 E. A. D. 667, 673 (EAB 1988). For 

another, EPA has long interpreted BACT as required only 

for pollutants that the source itself emits, see 44 Fed. Reg.

51947 (1979); accordingly, EPA acknowledges that BACT 

may not be used to require “reductions in a facility’s demand for energy from the electric grid.” Guidance 24. 

Finally, EPA’s guidance suggests that BACT should not

require every conceivable change that could result in

minor improvements in energy efficiency, such as the

aforementioned light bulbs. Id., at 31. The guidance

explains that permitting authorities should instead consider whether a proposed regulatory burden outweighs 

any reduction in emissions to be achieved, and should 

concentrate on the facility’s equipment that uses the

largest amounts of energy. Ibid. 

2 

The question before us is whether EPA’s decision to 

require BACT for greenhouse gases emitted by sources

otherwise subject to PSD review is, as a general matter, a 

permissible interpretation of the statute under Chevron. 

We conclude that it is. 

The text of the BACT provision is far less open-ended 

than the text of the PSD and Title V permitting triggers. 

It states that BACT is required “for each pollutant subject

to regulation under this chapter” (i.e., the entire Act), 

§7475(a)(4), a phrase that—as the D. C. Circuit wrote 35

years ago—“would not seem readily susceptible [of] misinterpretation.” Alabama Power Co. v. Costle, 636 F. 2d 323, 

404 (1979). Whereas the dubious breadth of “any air 

pollutant” in the permitting triggers suggests a role for 

agency judgment in identifying the subset of pollutants 

covered by the particular regulatory program at issue, the 

more specific phrasing of the BACT provision suggests 

that the necessary judgment has already been made by

Congress. The wider statutory context likewise does not 
 

28 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of the Court 

suggest that the BACT provision can bear a narrowing 

construction: There is no indication that the Act elsewhere 

uses, or that EPA has interpreted, “each pollutant subject 

to regulation under this chapter” to mean anything other 

than what it says. 

Even if the text were not clear, applying BACT to

greenhouse gases is not so disastrously unworkable, and 

need not result in such a dramatic expansion of agency 

authority, as to convince us that EPA’s interpretation is 

unreasonable. We are not talking about extending EPA 

jurisdiction over millions of previously unregulated entities, but about moderately increasing the demands EPA 

(or a state permitting authority) can make of entities 

already subject to its regulation. And it is not yet clear

that EPA’s demands will be of a significantly different 

character from those traditionally associated with PSD 

review. In short, the record before us does not establish 

that the BACT provision as written is incapable of being 

sensibly applied to greenhouse gases.

We acknowledge the potential for greenhouse-gas BACT 

to lead to an unreasonable and unanticipated degree of 

regulation, and our decision should not be taken as an 

endorsement of all aspects of EPA’s current approach, nor

as a free rein for any future regulatory application of

BACT in this distinct context. Our narrow holding is that

nothing in the statute categorically prohibits EPA from

interpreting the BACT provision to apply to greenhouse

gases emitted by “anyway” sources.

However, EPA may require an “anyway” source to comply with greenhouse-gas BACT only if the source emits 

more than a de minimis amount of greenhouse gases. As 

noted above, the Tailoring Rule applies BACT only if a

source emits greenhouse gases in excess of 75,000 tons per

year CO2e, but the Rule makes clear that EPA did not 

arrive at that number by identifying the de minimis level. 

See nn. 1, 3, supra. EPA may establish an appropriate de 
 

 

Cite as: 573 U. S. ____ (2014) 29 

Opinion of SCALIA, J. 

minimis threshold below which BACT is not required for a

source’s greenhouse-gas emissions. We do not hold that 

75,000 tons per year CO2e necessarily exceeds a true de 

minimis level, only that EPA must justify its selection on 

proper grounds. Cf. Alabama Power, supra, at 405.9 

* * * 

To sum up: We hold that EPA exceeded its statutory 

authority when it interpreted the Clean Air Act to require

PSD and Title V permitting for stationary sources based 

on their greenhouse-gas emissions. Specifically, the Agency 

may not treat greenhouse gases as a pollutant for purposes of defining a “major emitting facility” (or a “modification” thereof) in the PSD context or a “major source” in

the Title V context. To the extent its regulations purport

to do so, they are invalid. EPA may, however, continue to 

treat greenhouse gases as a “pollutant subject to regulation under this chapter” for purposes of requiring BACT

for “anyway” sources. The judgment of the Court of Appeals is affirmed in part and reversed in part. 

It is so ordered. 

—————— 

9 JUSTICE ALITO argues that BACT is “fundamentally incompatible”

with greenhouse gases for two reasons. Post, at 4 (opinion concurring 

in part and dissenting in part). First, BACT requires consideration of

“ambient air quality at the proposed site and in areas which may be

affected by emissions from [the proposed] facility for each pollutant 

subject to regulation under this chapter,” §7475(e)(1); see also

§7475(e)(3)(B); and it is not obvious how that requirement should apply,

or even whether it can apply, to greenhouse gases. Post, at 4–5. But 

the possibility that that requirement may be inoperative as to greenhouse gases does not convince us that they must be categorically 

excluded from BACT even though they are indisputably a “pollutant

subject to regulation.” Second, JUSTICE ALITO argues that EPA’s

guidance on how to implement greenhouse-gas BACT is a recipe for 

“arbitrary and inconsistent decisionmaking.” Post, at 8. But we are not 

reviewing EPA’s guidance in these cases, and we cannot say that it is

impossible for EPA and state permitting authorities to devise rational

ways of complying with the statute’s directive to determine BACT for 

greenhouse gases “on a case-by-case basis, taking into account energy, 

environmental, and economic impacts and other costs.” §7479(3). 
_________________ 

_________________ 

 

Cite as: 573 U. S. ____ (2014) 1 

Opinion of BREYER, J. 

SUPREME COURT OF THE UNITED STATES 

Nos. 12–1146, 12–1248, 12–1254, 12–1268, 12–1269, and 12–1272 

UTILITY AIR REGULATORY GROUP, 

PETITIONER 

12–1146 v. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

AMERICAN CHEMISTRY COUNCIL, ET AL., 

PETITIONERS 

12–1248 v. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

ENERGY-INTENSIVE MANUFACTURERS WORKING 

GROUP ON GREENHOUSE GAS REGULATION,
 

ET AL., PETITIONERS 

12–1254 v. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

SOUTHEASTERN LEGAL FOUNDATION, INC., 

ET AL., PETITIONERS 

12–1268 v. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

TEXAS, ET AL., PETITIONERS 

12–1269 v. 

ENVIRONMENTAL PROTECTION AGENCY, 

 ET AL.; AND 

CHAMBER OF COMMERCE OF THE UNITED 

STATES, ET AL., PETITIONERS 

12–1272 v. 
 

 

2 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of BREYER, J. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF 

APPEALS FOR THE DISTRICT OF COLUMBIA CIRCUIT 

[June 23, 2014] 

JUSTICE BREYER, with whom JUSTICE GINSBURG, 

JUSTICE SOTOMAYOR, and JUSTICE KAGAN join, concurring 

in part and dissenting in part. 

In Massachusetts v. EPA, 549 U. S. 497 (2007), we held 

that greenhouse gases fall within the Clean Air Act’s 

general definition of the term “air pollutant,” 42 U. S. C.

§7602(g). 549 U. S., at 528–529. We also held, consequently, that the Environmental Protection Agency is 

empowered and required by Title II of the Act to regulate

greenhouse gas emissions from mobile sources (such as 

cars and trucks) if it decides that greenhouse gases “contribute to . . . air pollution which may reasonably be anticipated to endanger public health or welfare,” §7521(a)(1).

549 U. S., at 532–533. The EPA determined that greenhouse gases endanger human health and welfare, 74 Fed.

Reg. 66496 (2009) (Endangerment Finding), and so it 

issued regulations for mobile emissions, 75 Fed. Reg. 

25324 (2010) (Tailpipe Rule).

These cases take as a given our decision in Massachusetts that the Act’s general definition of “air pollutant”

includes greenhouse gases. One of the questions posed by 

these cases is whether those gases fall within the scope of

the phrase “any air pollutant” as that phrase is used in the 

more specific provisions of the Act here at issue. The 

Court’s answer is “no.” Ante, at 10–24. I disagree. 

The Clean Air Act provisions at issue here are Title I’s

Prevention of Significant Deterioration (PSD) program, 

§7470 et seq., and Title V’s permitting regime, §7661 et 

seq. By contrast to Title II, Titles I and V apply to stationary sources, such as power plants and factories. Un-
Cite as: 573 U. S. ____ (2014) 3 

Opinion of BREYER, J. 

der the PSD program, “major emitting facilities” constructed in the United States must meet certain requirements, including obtaining a permit that imposes emissions limitations, §7475(a)(1), and using “the best 

available control technology for each pollutant subject to

regulation under [the Act] emitted from” the facility, 

§7475(a)(4). Title V requires each “major source” to obtain 

an operating permit. §7661a(a).

These cases concern the definitions of “major emitting

facility” and “major source,” each of which is defined to 

mean any stationary source that emits more than a

threshold quantity of “any air pollutant.” See §7479(1)

(“major emitting facility”); §§7602(j), 7661(2)(B) (“major

source”). To simplify the exposition, I will refer only to the 

PSD program and its definition of “major emitting facility”; 

a parallel analysis applies to Title V. 

As it is used in the PSD provisions, 

“[t]he term ‘major emitting facility’ means any of [a 

list of specific categories of] stationary sources of air 

pollutants which emit, or have the potential to emit, 

one hundred tons per year or more of any air pollutant 

. . . . Such term also includes any other source with

the potential to emit two hundred and fifty tons per 

year or more of any air pollutant.” §7479(1). 

To simplify further, I will ignore the reference to specific

types of source that emit at least 100 tons per year (tpy) of

any air pollutant. In effect, we are dealing with a statute 

that says that the PSD program’s regulatory requirements 

must be applied to 

“any stationary source that has the potential to emit 

two hundred fifty tons per year or more of any air 

pollutant.” 

The interpretive difficulty in these cases arises out of 

the definition’s use of the phrase “two hundred fifty tons 
 

 

4 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of BREYER, J. 

per year or more,” which I will call the “250 tpy threshold.” 

When applied to greenhouse gases, 250 tpy is far too low a 

threshold. As the Court explains, tens of thousands of 

stationary sources emit large quantities of one greenhouse 

gas, carbon dioxide. See ante, at 17–20, and n. 7. To 

apply the programs at issue here to all those sources 

would be extremely expensive and burdensome, counterproductive, and perhaps impossible; it would also contravene Congress’s intent that the programs’ coverage be

limited to those large sources whose emissions are substantial enough to justify the regulatory burdens. Ibid. 

The EPA recognized as much, and it addressed the problem by issuing a regulation—the Tailoring Rule—that 

purports to raise the coverage threshold for greenhouse

gases from the statutory figure of 250 tpy to 100,000 tpy 

in order to keep the programs’ coverage limited to “a relatively small number of large industrial sources.” 75 Fed. 

Reg. 31514, 31555 (2010); see id., at 31523–31524. 

The Tailoring Rule solves the practical problems that 

would have been caused by the 250 tpy threshold. But 

what are we to do about the statute’s language? The 

statute specifies a definite number—250, not 100,000—

and it says that facilities that are covered by that number 

must meet the program’s requirements. The statute says

nothing about agency discretion to change that number. 

What is to be done? How, given the statute’s language,

can the EPA exempt from regulation sources that emit

more than 250 but less than 100,000 tpy of greenhouse 

gases (and that also do not emit other regulated pollutants

at threshold levels)?

The Court answers by (1) pointing out that regulation at

the 250 tpy threshold would produce absurd results, (2) 

refusing to read the statute as compelling such results, 

and (3) consequently interpreting the phrase “any air 

pollutant” as containing an implicit exception for greenhouse gases. (Emphasis added.) Put differently, the 
Cite as: 573 U. S. ____ (2014) 5 

Opinion of BREYER, J. 

Court reads the statute as defining “major emitting facility” 

to mean “stationary sources that have the potential to 

emit two hundred fifty tons per year or more of any air 

pollutant except for those air pollutants, such as carbon 

dioxide, with respect to which regulation at that threshold 

would be impractical or absurd or would sweep in smaller 

sources that Congress did not mean to cover.” See ante, at 

15–16 (“[T]here is no insuperable textual barrier to EPA’s

interpreting ‘any air pollutant’ in the permitting triggers 

of PSD and Title V to encompass only pollutants emitted

in quantities that enable them to be sensibly regulated at

the statutory thresholds, and to exclude those atypical

pollutants that, like greenhouse gases, are emitted in such 

vast quantities that their inclusion would radically transform those programs and render them unworkable as 

written”).

I agree with the Court that the word “any,” when used 

in a statute, does not normally mean “any in the universe.” Cf. FCC v. NextWave Personal Communications 

Inc., 537 U. S. 293, 311 (2003) (BREYER, J., dissenting)

(“‘Tell all customers that . . .’ does not refer to every customer of every business in the world”). Rather, “[g]eneral

terms as used on particular occasions often carry with

them implied restrictions as to scope,” ibid., and so courts 

must interpret the word “any,” like all other words, in 

context. As Judge Learned Hand pointed out when interpreting another statute many years ago, “[w]e can best 

reach the meaning here, as always, by recourse to the 

underlying purpose, and, with that as a guide, by trying to

project upon the specific occasion how we think persons,

actuated by such a purpose, would have dealt with it, if it 

had been presented to them at the time.” Borella v. Borden Co., 145 F. 2d 63, 64 (CA2 1944). The pursuit of that

underlying purpose may sometimes require us to “abandon” a “literal interpretation” of a word like “any.” Id., at 

64–65. 
 

 

6 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of BREYER, J. 

The law has long recognized that terms such as “any” 

admit of unwritten limitations and exceptions. Legal

philosophers like to point out that a statute providing that 

“‘[w]hoever shall willfully take the life of another shall be

punished by death’” need not encompass a man who kills

in self-defense; nor must an ordinance imposing fines upon 

those who occupy a public parking spot for more than two

hours penalize a driver who is unable to move because of a

parade. See Fuller, The Case of the Speluncean Explorers,

62 Harv. L. Rev. 616, 619, 624 (1949); see also United 

States v. Kirby, 7 Wall. 482, 485–487 (1869) (holding that

a statute forbidding knowing and willful obstruction of the

mail contains an implicit exception permitting a local

sheriff to arrest a mail carrier). The maxim cessante 

ratione legis cessat ipse lex—where a law’s rationale ceases 

to apply, so does the law itself—is not of recent origin.

See, e.g., Zadvydas v. Davis, 533 U. S. 678, 699 (2001) 

(citing 1 E. Coke, Institutes *70b); Green v. Liter, 8 Cranch 

229, 249 (1814) (Story, J.) (“cessante ratione, cessat ipsa 

lex”).

I also agree with the Court’s point that “a generic reference to air pollutants” in the Clean Air Act need not “encompass every substance falling within the Act-wide 

definition” that we construed in Massachusetts, §7602(g). 

See ante, at 12–13. As the Court notes, the EPA has 

interpreted the phrase “any air pollutant,” which is used

several times in the Act, as limited to “air pollutants for 

which EPA has promulgated [new source performance 

standards]” in the portion of the Act dealing with those

standards, as limited to “visibility-impairing air pollutants” in the part of the Act concerned with deleterious

effects on visibility, and as limited to “pollutants for which 

the area is designated nonattainment” in the part of the 

Act aimed at regions that fail to attain air quality standards. Ibid. 

But I do not agree with the Court that the only way to 
Cite as: 573 U. S. ____ (2014) 7 

Opinion of BREYER, J. 

avoid an absurd or otherwise impermissible result in these 

cases is to create an atextual greenhouse gas exception to

the phrase “any air pollutant.” After all, the word “any” 

makes an earlier appearance in the definitional provision,

which defines “major emitting facility” to mean “any . . . 

source with the potential to emit two hundred and fifty 

tons per year or more of any air pollutant.” §7479(1) 

(emphasis added). As a linguistic matter, one can just as 

easily read an implicit exception for small-scale greenhouse gas emissions into the phrase “any source” as into

the phrase “any air pollutant.” And given the purposes of

the PSD program and the Act as a whole, as well as the 

specific roles of the different parts of the statutory definition, finding flexibility in “any source” is far more sensible 

than the Court’s route of finding it in “any air pollutant.” 

The implicit exception I propose reads almost word for 

word the same as the Court’s, except that the location of 

the exception has shifted. To repeat, the Court reads the

definition of “major emitting facility” as if it referred to 

“any source with the potential to emit two hundred fifty

tons per year or more of any air pollutant except for those 

air pollutants, such as carbon dioxide, with respect to 

which regulation at that threshold would be impractical or 

absurd or would sweep in smaller sources that Congress 

did not mean to cover.” I would simply move the implicit 

exception, which I’ve italicized, so that it applies to 

“source” rather than “air pollutant”: “any source with the 

potential to emit two hundred fifty tons per year or more

of any air pollutant except for those sources, such as those 

emitting unmanageably small amounts of greenhouse 

gases, with respect to which regulation at that threshold 

would be impractical or absurd or would sweep in smaller 

sources that Congress did not mean to cover.” 

From a legal, administrative, and functional perspective—that is, from a perspective that assumes that Congress was not merely trying to arrange words on paper but 
 

 

8 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of BREYER, J. 

was seeking to achieve a real-world purpose—my way of

reading the statute is the more sensible one. For one 

thing, my reading is consistent with the specific purpose 

underlying the 250 tpy threshold specified by the statute.

The purpose of that number was not to prevent the regulation of dangerous air pollutants that cannot be sensibly 

regulated at that particular threshold, though that is the 

effect that the Court’s reading gives the threshold. Rather, the purpose was to limit the PSD program’s obligations to larger sources while exempting the many small 

sources whose emissions are low enough that imposing 

burdensome regulatory requirements on them would be 

senseless. 

Thus, the accompanying Senate Report explains that 

the PSD program “is reasonable and necessary for very

large sources, such as new electrical generating plants or

new steel mills. But the procedure would prove costly and

potentially unreasonable if imposed on construction of 

storage facilities for a small gasoline jobber or on the 

construction of a new heating plant at a junior college.” 

S. Rep. No. 95–127, p. 96 (1977). And the principal sponsor of the Clean Air Act amendments at issue here, Senator Edmund Muskie, told the Senate that the program 

would not cover “houses, dairies, farms, highways, hospitals, schools, grocery stores, and other such sources.” 123 

Cong. Rec. 18013, 18021 (1977). 

The EPA, exercising the legal authority to which it is

entitled under Chevron U. S. A. Inc. v. Natural Resources 

Defense Council, Inc., 467 U. S. 837 (1984), understood the 

threshold’s purpose in the same light. It explained that 

Congress’s objective was 

“to limit the PSD program to large industrial sources 

because it was those sources that were the primary

cause of the pollution problems in question and because those sources would have the resources to com-
Cite as: 573 U. S. ____ (2014) 9 

Opinion of BREYER, J. 

ply with the PSD requirements. Congress’s mechanism for limiting PSD was the 100/250 tpy threshold

limitations. Focused as it was primarily on NAAQS

pollutants [that is, those air pollutants for which the 

EPA has issued a national ambient air quality standard under Title I of the Act, see EPA v. EME Homer 

City Generation, L. P., 572 U. S. ___, ___ (2014) (slip 

op., at 4)], Congress considered sources that emit 

NAAQS pollutants in those quantities generally to be

the large industrial sources to which it intended PSD 

to be limited.” Tailoring Rule, 75 Fed. Reg. 31555. 

The Court similarly acknowledges that “the PSD program and Title V are designed to apply to, and cannot

rationally be extended beyond, a relative handful of large 

sources capable of shouldering heavy substantive and 

procedural burdens.” Ante, at 18; see also Alabama Power 

Co. v. Costle, 636 F. 2d 323, 353 (CADC 1979) (“Congress’s

intention was to identify facilities which, due to their size,

are financially able to bear the substantial regulatory

costs imposed by the PSD provisions and which, as a 

group, are primarily responsible for emission of the deleterious pollutants that befoul our nation’s air”). 

An implicit source-related exception would serve this

statutory purpose while going no further. The implicit

exception that the Court reads into the phrase “any air

pollutant,” by contrast, goes well beyond the limited congressional objective. Nothing in the statutory text, the

legislative history, or common sense suggests that Congress, when it imposed the 250 tpy threshold, was trying

to undermine its own deliberate decision to use the broad 

language “any air pollutant” by removing some substances 

(rather than some facilities) from the PSD program’s 

coverage.

For another thing, a source-related exception serves the

flexible nature of the Clean Air Act. We observed in Mas-
 

 

10 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of BREYER, J. 

sachusetts that “[w]hile the Congresses that drafted” the

Act “might not have appreciated the possibility that burning fossil fuels could lead to global warming, they did 

understand that without regulatory flexibility, changing 

circumstances and scientific developments would soon

render the Clean Air Act obsolete.” 549 U. S., at 532. We 

recognized that “[t]he broad language of ” the Act-wide

definition of “air pollutant” “reflects an intentional effort 

to confer the flexibility necessary to forestall such obsolescence.” Ibid. 

The Court’s decision to read greenhouse gases out of the

PSD program drains the Act of its flexibility and chips

away at our decision in Massachusetts. What sense does it 

make to read the Act as generally granting the EPA the 

authority to regulate greenhouse gas emissions and then 

to read it as denying that power with respect to the programs for large stationary sources at issue here? It is 

anomalous to read the Act to require the EPA to regulate

air pollutants that pose previously unforeseen threats to 

human health and welfare where “250 tons per year” is a 

sensible regulatory line but not where, by chemical or 

regulatory happenstance, a higher line must be drawn.

And it is anomalous to read an unwritten exception into 

the more important phrase of the statutory definition

(“any air pollutant”) when a similar unwritten exception to

less important language (the particular number used by 

the statute) will do just as well. The implicit exception

preferred by the Court produces all of these anomalies,

while the source-related exception I propose creates none

of them. 

In addition, the interpretation I propose leaves the EPA 

with the sort of discretion as to interstitial matters that 

Congress likely intended it to retain. My interpretation

gives the EPA nothing more than the authority to exempt

sources from regulation insofar as the Agency reasonably 

determines that applying the PSD program to them would 
 

Cite as: 573 U. S. ____ (2014) 11 

Opinion of BREYER, J. 

expand the program so much as to contravene Congress’s

intent. That sort of decision, which involves the Agency’s 

technical expertise and administrative experience, is the

kind of decision that Congress typically leaves to the

agencies to make. Cf. Barnhart v. Walton, 535 U. S. 212, 

222 (2002) (enumerating factors that we take to indicate

that Congress intends the agency to exercise the discretion provided by Chevron). To read the Act to grant that

discretion here is to read it as furthering Congress’s (and 

the public’s) interest in more effective, less wasteful 

regulation.

Last, but by no means least, a source-related exception

advances the Act’s overall purpose. That broad purpose,

as set forth at the beginning of the statute, is “to protect 

and enhance the quality of the Nation’s air resources so as

to promote the public health and welfare and the productive capacity of its population.” §7401(b)(1); see also 

§7470(1) (A purpose of the PSD program in particular 

is “to protect public health and welfare from any actual

or potential adverse effect which in the Administrator’s judgment may reasonably be anticipate[d] to occur 

from air pollution”); §7602(h) (“All language [in the Act] 

referring to effects on welfare includes . . . effects on . . . 

weather . . . and climate”). The expert agency charged 

with administering the Act has determined in its Endangerment Finding that greenhouse gases endanger 

human health and welfare, and so sensible regulation of 

industrial emissions of those pollutants is at the core of 

the purpose behind the Act. The broad “no greenhouse

gases” exception that the Court reads into the statute

unnecessarily undercuts that purpose, while my narrow 

source-related exception would leave the Agency with the 

tools it needs to further it. 

* * * 

I agree with the Court’s holding that stationary sources 
 

12 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of BREYER, J. 

that are subject to the PSD program because they emit 

other (non-greenhouse-gas) pollutants in quantities above 

the statutory threshold—those facilities that the Court 

refers to as “anyway” sources—must meet the “best available control technology” requirement of §7475(a)(4) with 

respect to greenhouse gas emissions. I therefore join Part 

II–B–2 of the Court’s opinion. But as for the Court’s holding that the EPA cannot interpret the language at issue

here to cover facilities that emit more than 100,000 tpy of

greenhouse gases by virtue of those emissions, I respectfully dissent. 
 

_________________ 

_________________ 

 

Cite as: 573 U. S. ____ (2014) 1 

Opinion of ALITO, J. 

SUPREME COURT OF THE UNITED STATES 

Nos. 12–1146, 12–1248, 12–1254, 12–1268, 12–1269, and 12–1272 

UTILITY AIR REGULATORY GROUP, 

PETITIONER 

12–1146 v. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

AMERICAN CHEMISTRY COUNCIL, ET AL., 

PETITIONERS 

12–1248 v. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

ENERGY-INTENSIVE MANUFACTURERS WORKING 

GROUP ON GREENHOUSE GAS REGULATION,
 

ET AL., PETITIONERS 

12–1254 v. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

SOUTHEASTERN LEGAL FOUNDATION, INC., 

ET AL., PETITIONERS 

12–1268 v. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

TEXAS, ET AL., PETITIONERS 

12–1269 v. 

ENVIRONMENTAL PROTECTION AGENCY, 

 ET AL.; AND 

CHAMBER OF COMMERCE OF THE UNITED 

STATES, ET AL., PETITIONERS 

12–1272 v. 
 

 

2 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of ALITO, J. 

ENVIRONMENTAL PROTECTION AGENCY, ET AL.; 

ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF 

APPEALS FOR THE DISTRICT OF COLUMBIA CIRCUIT 

[June 23, 2014] 

JUSTICE ALITO, with whom JUSTICE THOMAS joins,

concurring in part and dissenting in part.

 In Massachusetts v. EPA, 549 U. S. 497 (2007), this

Court considered whether greenhouse gases fall within the

Clean Air Act’s general definition of an air “pollutant.” 

Id., at 528–529. The Environmental Protection Agency

cautioned us that “key provisions of the [Act] cannot cogently be applied to [greenhouse gas] emissions,” Brief for 

Federal Respondent in Massachusetts v. EPA, O. T. 2006, 

No. 05–1120, p. 22, but the Court brushed the warning

aside and had “little trouble” concluding that the Act’s

“sweeping definition” of a pollutant encompasses greenhouse gases. 549 U. S., at 528–529. I believed Massachusetts v. EPA was wrongly decided at the time, and these 

cases further expose the flaws with that decision. 

I 

As the present cases now show, trying to fit greenhouse 

gases into “key provisions” of the Clean Air Act involves

more than a “little trouble.” These cases concern the 

provisions of the Act relating to the “Prevention of Significant Deterioration” (PSD), 42 U. S. C. §§7470–7492, as 

well as Title V of the Act, §7661. And in order to make 

those provisions apply to greenhouse gases in a way that 

does not produce absurd results, the EPA effectively 

amended the Act. The Act contains specific emissions 

thresholds that trigger PSD and Title V coverage, but the 

EPA crossed out the figures enacted by Congress and 

substituted figures of its own.

I agree with the Court that the EPA is neither required

nor permitted to take this extraordinary step, and I there-
 

 

Cite as: 573 U. S. ____ (2014) 3 

Opinion of ALITO, J. 

fore join Parts I and II–A of the Court’s opinion. 

II 

I do not agree, however, with the Court’s conclusion that 

what it terms “anyway sources,” i.e., sources that are 

subject to PSD and Title V permitting as the result of the 

emission of conventional pollutants, must install “best 

available control technology” (BACT) for greenhouse gases.

As is the case with the PSD and Title V thresholds, 

trying to fit greenhouse gases into the BACT analysis 

badly distorts the scheme that Congress adopted.

The Court gives two main reasons for concluding that

BACT applies to “anyway” sources, one based on text

and one based on practical considerations. Neither is 

convincing. 

A 

With respect to the text, it is curious that the Court,

having departed from a literal interpretation of the term

“pollutant” in Part II–A, turns on its heels and adopts a

literal interpretation in Part II–B. The coverage thresholds at issue in Part II–A apply to any “pollutant.” The 

Act’s general definition of this term is broad, and in Massachusetts v. EPA, supra, the Court held that this definition covers greenhouse gases. The Court does not disturb 

that holding, but it nevertheless concludes that, as used in

the provision triggering PSD coverage, the term “pollutant” actually means “pollutant, other than a greenhouse

gas.”

In Part II–B, the relevant statutory provision says 

that BACT must be installed for any “pollutant subject 

to regulation under [the Act].” §7475(a)(4). If the term 

“pollutant” means “pollutant, other than a greenhouse

gas,” as the Court effectively concludes in Part II–A, the 

term “pollutant subject to regulation under [the Act]” in

§7475(a)(4) should mean “pollutant, other than a green-
 

 

4 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of ALITO, J. 

house gas, subject to regulation under [the Act], and that

is subject to regulation under [the Act].” The Court’s 

literalism is selective, and it results in a strange and 

disjointed regulatory scheme. 

Under the Court’s interpretation, a source can emit an

unlimited quantity of greenhouse gases without triggering 

the need for a PSD permit. Why might Congress have 

wanted to allow this? The most likely explanation is that 

the PSD permitting process is simply not suited for use in

regulating this particular pollutant. And if that is so, it 

makes little sense to require the installation of BACT for 

greenhouse gases in those instances in which a source 

happens to be required to obtain a permit due to the emission of a qualifying quantity of some other pollutant that 

is regulated under the Act. 

B 

The Court’s second reason for holding that BACT applies to “anyway” sources is its belief that this can be done 

without disastrous consequences. Only time will tell

whether this hope is well founded, but it seems clear that 

BACT analysis is fundamentally incompatible with the

regulation of greenhouse-gas emissions for at least two

important reasons. 

1 

First, BACT looks to the effects of covered pollutants in 

the area in which a source is located. The PSD program is 

implemented through “emission limitations and such 

other measures” as are “necessary . . . to prevent significant deterioration of air quality in each region.” §7471 

(emphasis added). The Clean Air Act provides that BACT 

must be identified “on a case-by-case basis,” §7479(3), and 

this necessarily means that local conditions must be taken

into account. For this reason, the Act instructs the EPA to 

issue regulations requiring an analysis of “the ambient air 
Cite as: 573 U. S. ____ (2014) 5 

Opinion of ALITO, J. 

quality . . . at the site of the proposed major emitting facility and in the area potentially affected by the emissions

from such facility for each pollutant regulated under [the

Act].” §7475(e)(3)(B) (emphasis added). The Act also 

requires a public hearing on “the air quality at the proposed site and in areas which may be affected by emissions

from such facility for each pollutant subject to regulation 

under [the Act] which will be emitted from such facility.” 

§§7475(a)(2), (e)(1) (emphasis added). Accordingly, if 

BACT is required for greenhouse gases, the Act demands

that the impact of these gases in the area surrounding a 

site must be monitored, explored at a public hearing, and 

considered as part of the permitting process. The effects of 

greenhouse gases, however, are global, not local. See PSD 

and Title V Permitting Guidance for Greenhouse Gases 

41–42 (Mar. 2011) (hereinafter Guidance). As a result, the 

EPA has declared that PSD permit applicants and permitting officials may disregard these provisions of the Act. 75 

Fed. Reg. 31520 (2010). 

2 

Second, as part of the case-by-case analysis required by 

BACT, a permitting authority must balance the environmental benefit expected to result from the installation of 

an available control measure against adverse consequences

that may result, including any negative impact on the

environment, energy conservation, and the economy. And 

the EPA itself has admitted that this cannot be done on a 

case-by-case basis with respect to greenhouse gases. 

The Clean Air Act makes it clear that BACT must be 

determined on a “case-by-case basis, taking into account 

energy, environmental, and economic impacts and other 

costs.” §7479(3). To implement this directive, the EPA

adopted a five-step framework for making a BACT determination. See New Source Review Workshop Manual: 

Prevention of Significant Deterioration and Nonattain-
 

 

6 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of ALITO, J. 

ment Area Permitting (Oct. 1990).1 Under the fourth step

of this analysis, potentially applicable and feasible control

technologies that are candidates for selection as BACT for 

a particular source are eliminated from consideration

based on their “collateral impacts,” such as any adverse 

environmental effects or adverse effects on energy consumption or the economy. 

More recently, the EPA provided guidance to permitting

authorities regarding the treatment of greenhouse-gas 

emissions under this framework, and the EPA’s guidance

demonstrates the insuperable problem that results when

an attempt is made to apply this framework to greenhouse 

gas emissions. As noted above, at step 4 of the framework,

a permitting authority must balance the positive effect 

likely to result from requiring a particular source to install 

a particular technology against a variety of negative effects that are likely to occur if that step is taken. But 

in the case of greenhouse gases, how can a permitting authority make this individualized, source-specific

determination? 

The EPA instructs permitting authorities to take into 

—————— 

1The EPA describes these steps as follows:

(1) The applicant must identify all available control options that are

potentially applicable by consulting EPA’s BACT clearinghouse along

with other reliable sources. 

(2) The technical feasibility of the control options identified in step 1 

are eliminated based on technical infeasibility. 

(3) The control technologies are ranked based on control effectiveness, by considering: the percentage of the pollutant removed; expected

emission rate for each new source review (NSR) pollutant; expected 

emission reduction for each regulated NSR pollutant; and output based

emissions limit. 

(4) Control technologies are eliminated based on collateral impacts,

such as: energy impacts; other environmental impacts; solid or hazardous waste; water discharge from control device; emissions of air toxics 

and other non-NSR regulated pollutants; and economic impacts.

(5) The most effective control option not eliminated in step 4 is

proposed as BACT for the pollutant and emission unit under review. 
Cite as: 573 U. S. ____ (2014) 7 

Opinion of ALITO, J. 

consideration all the adverse effects that the EPA has 

found to result from the overall increase in greenhouse 

gases in the atmosphere. These include an increased risk 

of dangerous heat waves, hurricanes, floods, wildfires, and

drought, as well as risks to agriculture, forestry, and 

water resources. Guidance 40–41. But the EPA admits 

that it is simply not possible for a permitting authority to

calculate in any meaningful way the degree to which any 

potential reduction in greenhouse gas emissions from any 

individual source might reduce these risks. And without 

making such a calculation in even a very rough way, a

permitting authority cannot do what the Clean Air Act 

and the EPA’s framework demand—compare the benefits 

of some specified reduction in the emission of greenhouse

gases from a particular source with any adverse environmental or economic effects that might result from mandating such a reduction. 

Suppose, for example, that a permitting authority must

decide whether to mandate a change that both decreases a 

source’s emission of greenhouse gases and increases its 

emission of a conventional pollutant that has a negative 

effect on public health. How should a permitting authority 

decide whether to require this change? Here is the EPA’s 

advice: 

“[W]hen considering the trade-offs between the environmental impacts of a particular level of GHG 

[greenhouse gas] reduction and a collateral increase in

another regulated NSR pollutant,[2] rather than attempting to determine or characterize specific environmental impacts from GHGs emitted at particular

locations, EPA recommends that permitting authorities focus on the amount of GHG emission reductions 

—————— 

2 “New source review pollutants” are those pollutants for which a

National Ambient Air Quality standard has been set and a few others, 

such as sulphur dioxide. See 40 CFR 51.165(a)(1)(xxxvii) (2013). 
 

 

 

8 UTILITY AIR REGULATORY GROUP v. EPA 

Opinion of ALITO, J. 

that may be gained or lost by employing a particular 

control strategy and how that compares to the environmental or other impacts resulting from the collateral emissions increase of other regulated NSR pollutants.” Guidance 42. 

As best I can make out, what this means is that permitting authorities should not even try to assess the net

impact on public health. Instead of comparing the positive 

and negative public health effects of a particular option,

permitting authorities are instructed to compare the

adverse public health effects of increasing the emissions of

the conventional pollutants with the amount of the reduction of the source’s emissions of greenhouse gases. But 

without knowing the positive effects of the latter, this is a 

meaningless comparison. 

The EPA tries to ameliorate this problem by noting that

permitting authorities are entitled to “a great deal of

discretion,” Guidance 41, but without a comprehensible

standard, what this will mean is arbitrary and inconsistent decisionmaking. That is not what the Clean Air 

Act contemplates.3 

* * * 

BACT analysis, like the rest of the Clean Air Act, was

developed for use in regulating the emission of conventional pollutants and is simply not suited for use with

respect to greenhouse gases. I therefore respectfully

dissent from Part II–B–2 of the opinion of the Court. 

—————— 

3While I do not think that BACT applies at all to “anyway sources,” if

it is to apply, the limitations suggested in Part II–B–1 might lessen the 

inconsistencies highlighted in Part II of this opinion, and on that

understanding I join Part II–B–1.