(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 con-
  struct 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 pollu-
  tant 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 promul-
  gated 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 Le-
gal 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 purport-
    ed 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 ac-
    tions 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 interpre-
  tation 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 green-
  house gases, 549 U. S., at 529, but where the term “air pollutant” ap-
  pears in the Act’s operative provisions, including the PSD and Title V
  permitting provisions, EPA has routinely given it a narrower, con-
  text-appropriate meaning. Massachusetts did not invalidate those
  longstanding constructions. The Act-wide definition is not a com-
  mand 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 con-
  text, and a statutory term “may take on distinct characters from as-
  sociation with distinct statutory objects calling for different imple-
  mentation 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 em-
  powered 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 incon-
  sistent 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 nu-
  merical 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 pollu-
  tants to comply with BACT for greenhouse gases. Pp. 24–29.
        (a) Concerns that BACT, which has traditionally been about end-
  of-stack controls, is fundamentally unsuited to greenhouse-gas regu-
  lation, 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 tra-
  ditional, end-of-stack BACT technologies. Moreover, assuming that
  BACT may be used to force improvements in energy efficiency, im-
  portant 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 specif-
  ic 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 dra-
  matic 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, SO-
TOMAYOR, 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, Wash-
   ington, 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 deter-
mine 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 emis-
sions from both stationary sources, such as factories and
powerplants, and moving sources, such as cars, trucks,
and aircraft. This litigation concerns permitting obliga-
tions 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 imple-
mentation plans.” 42 U. S. C. §7410. A State must desig-
nate every area within its borders as “attainment,” “non-
attainment,” 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 sta-
tionary 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 technol-
ogy” (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 poten-
tial 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 im-
pose any substantive pollution-control requirements.
Instead, it is designed to facilitate compliance and en-
forcement 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, moni-
toring, 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 “author-
ize[d] EPA to regulate greenhouse gas emissions from new
motor vehicles” if the Agency “form[ed] a ‘judgment’ that
——————
    1 Although 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.” Massachu­
setts 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 rule-
making, 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 depend-
ing 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 con-
ventional 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 build-
ings, hotels, large retail establishments, and similar facili-
ties.” 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
——————
  2 Comments from other Executive Branch agencies reprinted in the

notice echoed those concerns. See, e.g., 73 Fed. Reg. 44360 (Depart-
ments 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 emis-
sions. EPA found that greenhouse-gas emissions from
new motor vehicles contribute to elevated atmospheric
concentrations of greenhouse gases, which endanger pub-
lic 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, hydrofluorocar-
bons, 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 greenhouse-
gas 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 statu-
tory 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 greenhouse-
gas emissions; however, sources required to obtain permits
anyway because of their emission of conventional pollu-
tants (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 exemp-
tions 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 peti-
tions for review in the D. C. Circuit under 42 U. S. C.
§7607(b), challenging EPA’s greenhouse-gas-related ac-
tions. The Court of Appeals dismissed some of the peti-
tions 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 Endan-
germent Finding and Tailpipe Rule. Id., at 119, 126.
Next, it held that EPA’s interpretation of the PSD permit-
ting requirement as applying to “any regulated air pollu-
——————
  3 EPA 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 green-
house gases.” Id., at 137. Because it deemed petitioners’
arguments about the PSD program insufficiently applica-
ble 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 Trig-
gering 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 emis-
sions from new motor vehicles triggered permitting re-
quirements 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 greenhouse-
gas 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 reasona-
bly 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 greenhouse-
gas 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
——————
  4 The 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 syllo-
gism: Under Massachusetts, the general, Act-wide defini-
tion 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 prem-
ises only if the air pollutants referred to in the permit-
requiring 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] radioac-
tive . . . substance or matter which is emitted into or oth-
erwise enters the ambient air.” §7602(g). In Massachu­
setts, the Court held that the Act-wide definition includes
greenhouse gases because it is all-encompassing; it “em-
braces 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 pollu-
tant.” 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 Direc-
tor, 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, bur-
densome 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 per-
        formance 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 pro-
        vision as limited to air pollutants for which EPA
        has promulgated new source performance stand­
        ards. 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 monitor-
      ing 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 in-
      terprets that provision as limited to visibility­
      impairing 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 suffi-
ciently 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 regu-
late in any way that would be “extreme,” “counterintui-
tive,” 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 new-
motor-vehicle emission regulations. Ibid.
   Massachusetts does not strip EPA of authority to ex-
clude greenhouse gases from the class of regulable air
pollutants under other parts of the Act where their inclu-
sion 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 Mas­
sachusetts “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
——————
  5 Our 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 power-
plant 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 Act-
wide 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 draftsman-
ship. 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 Massa­
chusetts, 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 dif-
ferent 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 pollu-
tant” 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 green-
house 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 trans-
form 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 interpreta-
tion 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 rea-
sonable 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 interpreta-
tion.” 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
——————
  6 During  the course of this litigation, several possible limiting con-
structions for the PSD trigger have been proposed. Judge Kavanaugh
argued below that it would be plausible for EPA to read “any air pollu-
tant” 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 attain-
ment or unclassifiable. That approach would bring EPA’s interpreta-
tion of the PSD trigger in line with its longstanding interpretation of
the permitting requirements for nonattainment areas. Others main-
tain 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 green-
house gases would be inconsistent with—in fact, would
overthrow—the Act’s structure and design. In the Tailor-
ing 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. Tailor-
ing 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 mil-
lion 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 in-
tent,” 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 emis-
sion 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 rele-
vant 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, resource-
intensive, 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 require-
ments but imposes elaborate procedural mandates. It
requires the applicant to submit, within a year of becom-
ing subject to Title V, a permit application and a “compli-
ance plan” describing how it will comply with “all applica-
ble 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 re-
spond 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 per-
mit; 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 interpre-
tation 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 signifi-
cance.” 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 con-
front a singular situation: an agency laying claim to ex-
travagant statutory power over the national economy
while at the same time strenuously asserting that the
authority claimed would render the statute “unrecogniza-
ble to the Congress that designed” it. Tailoring Rule
31555. Since, as we hold above, the statute does not com-
pel EPA’s interpretation, it would be patently unreason-
able—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
——————
  7 A few additional points bear mentioning.      The Solicitor General
conjectures that EPA might eventually alter its longstanding interpre-
tation 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 “gen-
eral” or “electronic” permitting—to reduce the administrability prob-
lems 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 be-
cause that rule did not injure petitioners but merely re-
laxed 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 interpreta-
tion 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 statu-
tory 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 discre-
tion. 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 require-
ments; 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, modi-
fication, 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-gas-
inclusive 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 provid-
ing 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 eligibil-
ity 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 require-
ments imposed by a federal statute. An agency confront-
ing 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 exe-
cuting the laws necessarily includes both authority and
responsibility to resolve some questions left open by Con-
gress 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 Con-
gress, 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 reaf-
firm 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 interpre-
tations of statutory provisions and then edit other statu-
tory 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 demo-
cratic 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 pollu-
tant” to denote less than the full range of pollutants covered by the Act-
wide 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 pro-
gram’s overall regulatory scheme. But there is no ambiguity whatso-
ever 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 partic-
ulate 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 limita-
tion 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-by-
case 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 con-
ventional 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 Peti-
tioner 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 un-
bounded 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 effi-
ciency, 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” regu-
latory 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 de-
mand 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 con-
sider 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] misin-
terpretation.” 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 enti-
ties, 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 com-
ply 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 pur-
poses of defining a “major emitting facility” (or a “modifi-
cation” 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 regula-
tion under this chapter” for purposes of requiring BACT
for “anyway” sources. The judgment of the Court of Ap-
peals 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 green-
house 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, conse-
quently, 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 “con-
tribute to . . . air pollution which may reasonably be antic-
ipated to endanger public health or welfare,” §7521(a)(1).
549 U. S., at 532–533. The EPA determined that green-
house 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 Massachu-
setts 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 sta-
tionary 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” con-
structed in the United States must meet certain require-
ments, including obtaining a permit that imposes emis-
sions 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, counter-
productive, and perhaps impossible; it would also contra-
vene Congress’s intent that the programs’ coverage be
limited to those large sources whose emissions are sub-
stantial enough to justify the regulatory burdens. Ibid.
The EPA recognized as much, and it addressed the prob-
lem 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 rela-
tively 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 green-
house 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 trans-
form 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 uni-
verse.” 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 cus-
tomer 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 inter-
preting 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. Bor-
den Co., 145 F. 2d 63, 64 (CA2 1944). The pursuit of that
underlying purpose may sometimes require us to “aban-
don” 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 refer-
ence to air pollutants” in the Clean Air Act need not “en-
compass 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 pollu-
tants” 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 stand-
ards. 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 green-
house 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 defini-
tion, 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 perspec-
tive—that is, from a perspective that assumes that Con-
gress 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 regula-
tion 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. Ra-
ther, the purpose was to limit the PSD program’s obliga-
tions 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 spon-
sor of the Clean Air Act amendments at issue here, Sena-
tor Edmund Muskie, told the Senate that the program
would not cover “houses, dairies, farms, highways, hospi-
tals, 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 be-
    cause 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 mecha-
    nism 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 stand-
    ard 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 pro-
gram 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 delete-
rious 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 con-
gressional objective. Nothing in the statutory text, the
legislative history, or common sense suggests that Con-
gress, 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 burn-
ing 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 obsoles-
cence.” 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 pro-
grams 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 discre-
tion 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 produc-
tive 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 Administra-
tor’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 En-
dangerment 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 avail-
able 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 hold-
ing 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 respect-
fully 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 co-
gently 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 green-
house gases. 549 U. S., at 528–529. I believed Massachu-
setts 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 Signifi-
cant 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 thresh-
olds at issue in Part II–A apply to any “pollutant.” The
Act’s general definition of this term is broad, and in Mas-
sachusetts v. EPA, supra, the Court held that this defini-
tion 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 “pollu-
tant” 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 emis-
sion of a qualifying quantity of some other pollutant that
is regulated under the Act.
                             B
  The Court’s second reason for holding that BACT ap-
plies 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 signifi-
cant 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 facil-
ity 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 pro-
posed 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 permit-
ting 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 environ-
mental 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 deter-
mination. 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 con-
sumption 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 ef-
fects that are likely to occur if that step is taken. But
in the case of greenhouse gases, how can a permit-
ting authority make this individualized, source-specific
determination?
   The EPA instructs permitting authorities to take into
——————
    1 The
        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 effective-
ness, 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 hazard-
ous 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 environ-
mental or economic effects that might result from mandat-
ing 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 envi-
    ronmental impacts of a particular level of GHG
    [greenhouse gas] reduction and a collateral increase in
    another regulated NSR pollutant,[2] rather than at-
    tempting to determine or characterize specific envi-
    ronmental impacts from GHGs emitted at particular
    locations, EPA recommends that permitting authori-
    ties 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 envi-
       ronmental or other impacts resulting from the collat-
       eral emissions increase of other regulated NSR pollu-
       tants.” Guidance 42.
   As best I can make out, what this means is that permit-
ting 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 reduc-
tion 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 incon-
sistent 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 conven-
tional 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.




——————
    3 WhileI 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.
