Whitman v. American Trucking Associations, Inc.

OCTOBER TERM, 2000

															Syllabus

															WHITMAN, ADMINISTRATOR OF ENVIRONMENTAL PROTECTION AGENCY, ET
AL. v. AMERICAN TRUCKING ASSOCIATIONS, INC., ET AL.

															CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE
DISTRICT OF COLUMBIA CIRCUIT

															No. 99-1257. Argued November 7, 2000-Decided February 27,
2001*

															Section 109(a) of the Clean Air Act (CAA) requires the
Environmental Protection Agency (EPA) Administrator to promulgate
national ambient air quality standards (NAAQS) for each air
pollutant for which "air quality criteria" have been issued under §
108. Pursuant to § 109(d)(1), the Administrator in 1997 revised the
ozone and particulate matter NAAQS. Respondents in No. 99-1257,
private parties and several States (hereinafter respondents),
challenged the revised NAAQS on several grounds. The District of
Columbia Circuit found that, under the Administrator's
interpretation, § 109(b)(1)-which instructs the EPA to set
standards "the attainment and maintenance of which ... are
requisite to protect the public health" with "an adequate margin of
safety"-delegated legislative power to the Administrator in
contravention of the Federal Constitution, and it remanded the
NAAQS to the EPA. The Court of Appeals also declined to depart from
its rule that the EPA may not consider implementation costs in
setting the NAAQS. And it held that, although certain
implementation provisions for the ozone NAAQS contained in Part D,
Subpart 2, of Title I of the CAA did not prevent the EPA from
revising the ozone standard and designating certain areas as
"nonattainment areas," those provisions, rather than more general
provisions contained in Subpart 1, constrained the implementation
of the new ozone NAAQS. The court rejected the EPA's argument that
it lacked jurisdiction to reach the implementation question because
there had been no "final" implementation action.

															Held:

															1. Section 109(b) does not permit the Administrator to consider
implementation costs in setting NAAQS. Because the CAA often
expressly grants the EPA the authority to consider implementation
costs, a provision for costs will not be inferred from its
ambiguous provisions. Union Elec. Co. v. EPA, 427 U. S.
246 ,257, and n. 5. And since

															*Together with No. 99-1426, American Trucking Associations,
Inc., et al. v. Whitman, Administrator of Environmental Protection
Agency, et al., also on certiorari to the same court. 458 § 109(b)(1) is the engine that drives nearly all of Title I of
the CAA, the textual commitment of costs must be clear; Congress
does not alter a regulatory scheme's fundamental details in vague
terms or ancillary provisions, see MCI Telecommunications
Corp. v. American Telephone & Telegraph Co., 512 U. S. 218 ,
231. Respondents' arguments founder upon this principle. It is
implausible that § 109(b)(1)'s modest words "adequate margin" and
"requisite" give the EPA the power to determine whether
implementation costs should moderate national air quality
standards. Cf. ibid. And the cost factor is both so
indirectly related to public health and so full of potential
for canceling the conclusions drawn from direct health effects that
it would have been expressly mentioned in §§ 108 and 109 had
Congress meant it to be considered. Other CAA provisions, which do
require cost data, have no bearing upon whether costs are to be
taken into account in setting the NAAQS. Because the text of §
109(b)(1) in its context is clear, the canon of construing texts to
avoid serious constitutional problems is not applicable. See, e.
g., Miller v. French, 530 U. S. 327 ,341.
pp.464-471.

															2. Section 109(b)(1) does not delegate legislative power to the
EPA.

															When conferring decisionmaking authority upon agencies, Congress
must lay down an intelligible principle to which the person or body
authorized to act is directed to conform. J. W Hampton, Jr., & Co. v. United States, 276 U. S. 394 , 409. An
agency cannot cure an unlawful delegation of legislative power by
adopting in its discretion a limiting construction of the statute.
The limits that § 109(b)(1) imposes on the EPA's discretion are
strikingly similar to the ones approved in, e. g., Touby v. United States, 500 U. S. 160 , and the
scope of discretion that § 109(b)(1) allows is well within the
outer limits of the Court's nondelegation precedents, see, e.
g., Panama Refining Co. v. Ryan, 293 U. S. 388. Statutes
need not provide a determinate criterion for saying how much of a
regulated harm is too much to avoid delegating legislative power.
Pp.472-476.

															3. The Court of Appeals had jurisdiction to consider the
implementation issue under § 307 of the CAA. The implementation
policy constitutes final agency action under § 307 because it
marked the consummation of the EPA's decisionmaking process, see Bennett v. Spear, 520 U. S. 154 . The
decision is also ripe for review. The question is purely one of
statutory interpretation that would not benefit from further
factual development, see Ohio Forestry Assn., Inc. v. Sierra Club, 523 U. S. 726 , 733;
review will not interfere with further administrative development;
and the hardship on respondent States in developing state
implementation plans satisfies the CAA's special judicialreview
provision permitting pre enforcement review, see id., at 737. 459 The implementation issue was also fairly included within the
challenges to the final ozone rule that were before the Court of
Appeals, which all parties agree is final agency action ripe for
review. Pp.476-480.

															4. The implementation policy is unlawful. Under Chevron
U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837 , if
the statute resolves the question whether Subpart 1 or Subpart 2
applies to revised ozone NAAQS, that ends the matter; but if the
statute is ambiguous, the Court must defer to a reasonable agency
interpretation. Here, the statute is ambiguous concerning the
interaction between Subpart 1 and Subpart 2, but the Court cannot
defer to the EPA's interpretation, which would render Subpart 2's
carefully designed restrictions on EPA discretion nugatory once a
new ozone NAAQS has been promulgated. The principal distinction
between the subparts is that Subpart 2 eliminates regulatory
discretion allowed by Subpart 1. The EPA may not construe the
statute in a way that completely nullifies textually applicable
provisions meant to limit its discretion. In addition, although
Subpart 2 was obviously written to govern implementation for some
time into the future, nothing in the EPA's interpretation would
have prevented the agency from aborting the subpart the day after
it was enacted. It is left to the EPA to develop a reasonable
interpretation of the nonattainment implementation provisions
insofar as they apply to revised ozone NAAQS. Pp.481-486. 175 F.3d
1027 and 195 F.3d
4 , affirmed in part, reversed in part, and remanded.

															SCALIA, J., delivered the opinion of the Court, Parts I and IV
of which were unanimous, Part II of which was joined by REHNQUIST,
C. J., and STEVENS, O'CONNOR, KENNEDY, SOUTER, THOMAS, and
GINSBURG, JJ., and Part III of which was joined by REHNQUIST, C.
J., and O'CONNOR, KENNEDY, THOMAS, GINSBURG, and BREYER, JJ.
THOMAS, J., filed a concurring opinion, post, p. 486.
STEVENS, J., filed an opinion concurring in part and concurring in
the judgment, in which SOUTER, J., joined, post, p. 487.
BREYER, J., filed an opinion concurring in part and concurring in
the judgment, post, p. 490.

															Solicitor General Waxman argued the cause for petitioners in No.
99-1257 and federal respondents in No. 99-1426. With him on the
briefs were Assistant Attorney General Schiffer, Deputy Solicitor
General Wallace, Jeffrey P. Minear, Christopher S. Vaden, David J.
Kaplan, Mary F. Edgar, Gary S. Guzy, Gerald K. Gleason, and Michael
L. Goo. 460 Edward W Warren argued the cause for American Trucking
Associations et al., respondents in No. 99-1257 and
cross-petitioners in No. 99-1426. With him on the briefs were Robert R. Gasaway, Jeffrey B. Clark, Daryl Joseffer, Charles
Fried, Robin S. Conrad, Beth L. Law, Robert S. Digges, Gary H. Baise, David M. Friedland, Erika Z. Jones,
Timothy S. Bishop, Jan S. Amundson, Dimetria G. (Jim) Daskal, Douglas 1. Greenhaus, and Chet M.
Thompson. Judith L. French, Assistant Attorney General of Ohio,
argued the cause for respondents State of Ohio et al. in No.
99-1257. With her on the brief in No. 99-1257 and on the briefs for
State of Ohio et al., respondents in support of crosspetitioners in
No. 99-1426, were Betty D. Montgomery, Attorney General, Edward B. Foley, State Solicitor, Elise W Porter,
Frank J. Reed, Jr., and James G. Tassie, Assistant Attorneys General, Mark J. Rudolph, Jennifer M.
Granholm, Attorney General of Michigan, Thomas Casey, Solicitor General, and Alan F. Hoffman and Pamela J. Stevenson, Assistant Attorneys General. Thomas F.
Reilly, Attorney General of Massachusetts, Edward G. Bohlen, Assistant Attorney General, Lisa Heinzerling,
John J. Farmer, Attorney General of New Jersey, and Howard L. Geduldig and John R. Renella, Deputy
Attorneys General, filed briefs for the Commonwealth of
Massachusetts et al., respondents in support of petitioners in No.
99-1257 and respondents in No. 99-1426. Howard 1. Fox filed briefs for the American Lung Association, respondent in
support of petitioners in No. 99-1257 and respondent in No.
99-1426. Henry v:

															Nickel, F. William Brownell, Lucinda Minton Langworthy, David E.
Menotti, William F. Pedersen, Jeffrey A. Knight, G. William Frick,
M. Elizabeth Cox, Russel S. Frye, Richard Wasserstrom, Grant
Crandall, David F. Zoll, Alexandra Dapolito Dunn, Julie Becker,
Harold P. Quinn, Jr., Newman R. Porter, David M. Flannery, and Kurt
E. Blase filed briefs for Appalachian Power Co. et al., respondents
in 461 No. 99-1257 and respondents in support of cross-petitioners in
No. 99-1426. Robert E. Yuhnke filed a brief for Citizens for
Balanced Transportation et al., respondents in No. 99-1426.t

															tBriefs of amici curiae urging reversal were filed for
the State of New York et al. by Eliot Spitzer, Attorney
General of New York, Preeta D. Bansal, Solicitor General, Daniel X. Smirlock, Deputy Solicitor General, and Lisa
Feiner and J. Jared Snyder, Assistant Attorneys General,
and by the Attorneys General for their respective States as
follows: Bill Lockyer of California, Richard
Blumenthal of Connecticut, Andrew Ketterer of Maine, J. Joseph Curran, Jr., of Maryland, Philip McLaughlin of
New Hampshire, D. Michael Fisher of Pennsylvania, Sheldon
Whitehouse of Rhode Island, and William H. Sorrell of
Vermont; for the State of North Carolina by Michael F. Easley, Attorney General, Daniel C. Oakley, Senior Deputy Attorney General, and Marc D. Bernstein, Assistant Attorney General; for the American Boiler Manufacturers
Association by Gene E. Godley and Shannon H. Ratliff
II; and for the American Crop Protection Association et al. by Herbert L. Fenster and Lawrence S. Ebner. Briefs of amici curiae urging affirmance were filed for
the State of California et al. by Bill Lockyer, Attorney
General of California, Richard M. Frank, Chief Assistant
Attorney General, Theodora P. Berger, Senior Assistant
Attorney General, and Susan L. Durbin and Sean B.
Hecht, Deputy Attorneys General, Richard Blumenthal, Attorney General of Connecticut, Thomas J. Miller, Attorney General of Iowa, Andrew Ketterer, Attorney General
of Maine, J. Joseph Curran, Jr., Attorney General of
Maryland, Patricia Madrid, Attorney General of New Mexico, Eliot Spitzer, Attorney General of New York, Preeta D.
Bansal, Solicitor General, and Daniel X. Smirlock, Deputy Solicitor General, William H. Sorrell, Attorney
General of Vermont, and Christine O. Gregoire, Attorney General of Washington; for the Commonwealth of Virginia by Mark L. Earley, Attorney General, William Hurd, Solicitor General, Roger L. Chaffe, Senior Assistant
Attorney General, and Stewart T. Leeth, Assistant Attorney
General; for the American Institute of Certified Public Accountants
et al. by Theodore B. Olson, Douglas R. Cox, and Mark A.
Perry; for the Association of American Physicians &
Surgeons et al. by Erik S. Jaffe; for the Clean Air
Trust et al. by Christopher H. Schroeder; for the Lincoln
Institute for Research and Education et al. by William J. Olson, John S. Miles, Herbert W Titus, and Lawrence J. Straw, Jr.; for the Manufacturers
Alliance/MAPI Inc. et al. by David Schoenbrod and Marci
A. Hamilton; for the United States Public Interest Research
Group 462 JUSTICE SCALIA delivered the opinion of the Court.

															These cases present the following questions: (1) Whether §
109(b)(1) of the Clean Air Act (CAA) delegates legislative power to
the Administrator of the Environmental Protection Agency (EP A).
(2) Whether the Administrator may consider the costs of
implementation in setting national ambient air quality standards
(NAAQS) under § 109(b)(1). (3) Whether the Court of Appeals had
jurisdiction to review the EP A's interpretation of Part D of Title
I of the CAA, 42 U. S. C. §§ 7501-7515, with respect to
implementing the revised ozone NAAQS. (4) If so, whether the EPA's
interpretation of that part was permissible.

															I

															Section 109(a) of the CAA, as added, 84 Stat. 1679, and amended,
42 U. S. C. § 7409(a), requires the Administrator of the EPA to
promulgate NAAQS for each air pollutant for which "air quality
criteria" have been issued under § 108, 42 U. S. C. § 7408. Once a
N AAQS has been promulgated, the Administrator must review the
standard (and the criteria

															Education Fund by James Keith Weeks and David M.
Driesen; and for Senator James H. Inhofe et al. by Paul
Rosenzweig. Briefs of amici curiae were filed for the AEI-Brookings Joint
Center for Regulatory Studies et al. by Robert E. Litan; for Alcan
Aluminum Corp. by Lawrence A. Salibra II; for Environmental Defense
et al. by Richard L. Revesz and Ann Brewster Weeks; for General
Electric Co. by Laurence H. Tribe, Jonathan S. Massey, Thomas C.
Goldstein, Benjamin W Heineman, Jr., Brackett B. Denniston III, and
Matthew Tanzer; for the Institute for Justice et al. by William H.
Mellor, Clint Bolick, Deborah Simpson, Timothy Lynch, and Ronald D.
Rotunda; for Intel Corp. et al. by Richard P. Bress, Claudia M.
O'Brien, and Gregory S. Slater; for the Mercatus Center by Ernest
Gelhorn and Ann G. Weymouth; for the Pacific Legal Foundation et
al. by M. Reed Hopper; for People for the U. S. A. et al. by
Christopher C. Horner; for the Washington Legal Foundation et al.
by Paul D. Clement, Jeffrey S. Bucholtz, Daniel J. Popeo, and Paul
D. Kamenar; for Senator Orrin Hatch et al. by Carter G. Phillips,
Alan Charles Raul, Stephen B. Kinnaird, Lloyd N. Cutler, and C.
Boyden Gray; and for Gary E. Marchant et al. by Cary
Coglianese. 463 on which it is based) "at five-year intervals" and make "such
revisions ... as may be appropriate." CAA § 109(d)(1), 42 U. S. C.
§ 7409(d)(1). These cases arose when, on July 18, 1997, the
Administrator revised the NAAQS for particulate matter and ozone.
See NAAQS for Particulate Matter, 62 Fed. Reg. 38652 (codified in
40 CFR § 50.7 (1999)); NAAQS for Ozone, id., at 38856 (codified in
40 CFR §§ 50.9, 50.10 (1999)). American Trucking Associations,
Inc., and its corespondents in No. 99-1257-which include, in
addition to other private companies, the States of Michigan, Ohio,
and West Virginia-challenged the new standards in the Court of
Appeals for the District of Columbia Circuit, pursuant to 42 U. S.
C. § 7607(b)(1).

															The District of Columbia Circuit accepted some of the challenges
and rejected others. It agreed with the No. 991257 respondents
(hereinafter respondents) that § 109(b)(1) delegated legislative
power to the Administrator in contravention of the United States
Constitution, Art. I, § 1, because it found that the EP A had
interpreted the statute to provide no "intelligible principle" to
guide the agency's exercise of authority. American Trucking
Assns., Inc. v. EPA, 175 F.3d
1027 , 1034 (1999). The court thought, however, that the EPA
could perhaps avoid the unconstitutional delegation by adopting a
restrictive construction of § 109(b)(1), so instead of declaring
the section unconstitutional the court remanded the NAAQS to the
agency. Id., at 1038. (On this delegation point, Judge Tatel
dissented, finding the statute constitutional as written. Id., at 1057.) On the second issue that the Court of Appeals
addressed, it unanimously rejected respondents' argument that the
court should depart from the rule of Lead Industries Assn.,
Inc. v. EPA, 647 F.2d
1130 , 1148 (CADC 1980), that the EPA may not consider the cost
of implementing a NAAQS in setting the initial standard. It also
rejected respondents' argument that the implementation provisions
for ozone found in Part D, Subpart 2, of Title I of the CAA, 42 U.
S. C. §§ 7511-751lf, were 464 so tied to the existing ozone standard that the EPA lacked the
power to revise the standard. The court held that although Subpart
2 constrained the agency's method of implementing the new standard,
175 F. 3d, at 1050, it did not prevent the EP A from revising the
standard and designating areas of the country as "nonattainment
areas," see 42 U. S. C. § 7407(d)(1), by reference to it, 175 F.
3d, at 1047-1048. On the EPA's petition for rehearing, the panel
adhered to its position on these points, and unanimously rejected
the EPA's new argument that the court lacked jurisdiction to reach
the implementation question because there had been no "final"
implementation action. American Trucking Assns., Inc. v. EPA, 195 F.3d
4 (CADC 1999). The Court of Appeals denied the EP A's
suggestion for rehearing en bane, with five judges dissenting. Id., at 13.

															The Administrator and the EP A petitioned this Court for review
of the first, third, and fourth questions described in the first
paragraph of this opinion. Respondents conditionally
cross-petitioned for review of the second question. We granted
certiorari on both petitions, 529 U. S. 1129 (2000); 530 u. S. 1202
(2000), and scheduled the cases for argument in tandem. We have now
consolidated the cases for purposes of decision.

															II

															In Lead Industries Assn., Inc. v. EPA, supra, at
1148, the District of Columbia Circuit held that "economic
considerations [may] play no part in the promulgation of ambient
air quality standards under Section 109" of the CAA. In the present
cases, the court adhered to that holding, 175 F. 3d, at 1040-1041,
as it had done on many other occasions. See, e. g., American
Lung Assn. v. EPA, 134 F.3d
388 ,389 (1998); NRDC v. Administrator, EPA, 902 F.2d
962 , 973 (1990), vacated in part on other grounds, NRDC v. EPA, 921 F.2d 326 (CADC 1991); American
Petroleum Institute v. Costle, 665
F.2d 1176 , 1185 (1981). Respondents argue that these 465 decisions are incorrect. We disagree; and since the first step
in assessing whether a statute delegates legislative power is to
determine what authority the statute confers, we address that issue
of interpretation first and reach respondents' constitutional
arguments in Part III, infra. Section 109(b)(1) instructs the EPA to set primary ambient air
quality standards "the attainment and maintenance of which ... are
requisite to protect the public health" with "an adequate margin of
safety." 42 U. S. C. § 7409(b)(1). Were it not for the hundreds of
pages of briefing respondents have submitted on the issue, one
would have thought it fairly clear that this text does not permit
the EPA to consider costs in setting the standards. The language,
as one scholar has noted, "is absolute." D. Currie, Air
Pollution:

															Federal Law and Analysis 4-15 (1981). The EPA, "based on" the
information about health effects contained in the technical
"criteria" documents compiled under § 108(a)(2), 42 U. S. C. §
7408(a)(2), is to identify the maximum airborne concentration of a
pollutant that the public health can tolerate, decrease the
concentration to provide an "adequate" margin of safety, and set
the standard at that level. Nowhere are the costs of achieving such
a standard made part of that initial calculation.

															Against this most natural of readings, respondents make a
lengthy, spirited, but ultimately unsuccessful attack. They begin
with the object of § 109(b)(1)'s focus, the "public health." When
the term first appeared in federal clean air legislation-in the Act
of July 14, 1955 (1955 Act), 69 Stat. 322, which expressed
"recognition of the dangers to the public health" from air
pollution-its ordinary meaning was "[t]he health of the community."
Webster's New International Dictionary 2005 (2d ed. 1950).
Respondents argue, however, that § 109(b)(1), as added by the Clean
Air Amendments of 1970, 84 Stat. 1676, meant to use the term's
secondary meaning: "[t]he ways and means of conserving the
health 466 of the members of a community, as by preventive medicine,
organized care of the sick, etc." Ibid. Words that can have
more than one meaning are given content, however, by their
surroundings, FDA v. Brown & Williamson
Tobacco Corp., 529 U. S. 120 , 132-133
(2000); Jones v. United States, 527 U. S. 373, 389
(1999), and in the context of § 109(b)(1) this second definition
makes no sense. Congress could not have meant to instruct the
Administrator to set N AAQS at a level "requisite to protect" "the
art and science dealing with the protection and improvement of
community health." Webster's Third New International Dictionary
1836 (1981). We therefore revert to the primary definition of the
term: the health of the public.

															Even so, respondents argue, many more factors than air pollution
affect public health. In particular, the economic cost of
implementing a very stringent standard might produce health losses
sufficient to offset the health gains achieved in cleaning the
air-for example, by closing down whole industries and thereby
impoverishing the workers and consumers dependent upon those
industries. That is unquestionably true, and Congress was
unquestionably aware of it. Thus, Congress had commissioned in the
Air Quality Act of 1967 (1967 Act) "a detailed estimate of the cost
of carrying out the provisions of this Act; a comprehensive study
of the cost of program implementation by affected units of
government; and a comprehensive study of the economic impact of air
quality standards on the Nation's industries, communities, and
other contributing sources of pollution." § 2, 81 Stat. 505. The
1970 Congress, armed with the results of this study, see The Cost
of Clean Air, S. Doc. No. 91-40 (1969) (publishing the results of
the study), not only anticipated that compliance costs could injure
the public health, but provided for that precise exigency. Section
110(f)(1) of the CAA permitted the Administrator to waive the
compliance deadline for stationary sources if, inter 467 alia, sufficient control measures were simply unavailable
and "the continued operation of such sources is essential ... to
the public health or welfare." 84 Stat. 1683 (emphasis added).
Other provisions explicitly permitted or required economic costs to
be taken into account in implementing the air quality standards.
Section 111(b)(1)(B), for example, commanded the Administrator to
set "standards of performance" for certain new sources of emissions
that as specified in § 111(a)(1) were to "reflec[t] the degree of
emission limitation achievable through the application of the best
system of emission reduction which (taking into account the cost of
achieving such reduction) the Administrator determines has been
adequately demonstrated." Section 202(a)(2) prescribed that
emissions standards for automobiles could take effect only "after
such period as the Administrator finds necessary to permit the
development and application of the requisite technology, giving
appropriate consideration to the cost of compliance within such
period." 84 Stat. 1690. See also § 202(b)(5)(C) (similar limitation
for interim standards); § 211(c)(2) (similar limitation for fuel
additives); § 231(b) (similar limitation for implementation of
aircraft emission standards). Subsequent amendments to the CAA have
added many more provisions directing, in explicit language, that
the Administrator consider costs in performing various duties. See, e. g., 42 U. S. C. § 7545(k)(1) (reformulate gasoline to
"require the greatest reduction in emissions ... taking into
consideration the cost of achieving such emissions reductions"); §
7547(a)(3) (emission reduction for nonroad vehicles to be set
"giving appropriate consideration to the cost" of the standards).
We have therefore refused to find implicit in ambiguous sections of
the CAA an authorization to consider costs that has elsewhere, and
so often, been expressly granted. See Union Elec. Co. v. EPA, 427 U. S.
246 , 257, and n. 5 (1976). Cf. General Motors Corp. v. United States, 496 U. S. 530 , 538, 541
(1990) 468 (refusing to infer in certain provisions of the CAA deadlines
and enforcement limitations that had been expressly imposed
elsewhere).

															Accordingly, to prevail in their present challenge, respondents
must show a textual commitment of authority to the EPA to consider
costs in setting NAAQS under § 109(b)(1). And because § 109(b)(1)
and the NAAQS for which it provides are the engine that drives
nearly all of Title I of the CAA, 42 U. S. C. §§ 7401-7515, that
textual commitment must be a clear one. Congress, we have held,
does not alter the fundamental details of a regulatory scheme in
vague terms or ancillary provisions-it does not, one might say,
hide elephants in mouseholes. See MC! Telecommunications
Corp. v. American Telephone & Telegraph Co.,
512 U. S. 218, 231 (1994); FDA v. Brown & Williamson Tobacco Corp., supra, at 159-160. Respondents'
textual arguments ultimately founder upon this principle.

															Their first claim is that § 109(b)(1)'s terms "adequate margin"
and "requisite" leave room to pad health effects with cost
concerns. Just as we found it "highly unlikely that Congress would
leave the determination of whether an industry will be entirely, or
even substantially, rateregulated to agency discretion-and even
more unlikely that it would achieve that through such a subtle
device as permission to 'modify' rate-filing requirements," MC!
Telecommunications Corp. v. American Telephone & Telegraph Co., supra, at 231, so also we find it implausible
that Congress would give to the EPA through these modest words the
power to determine whether implementation costs should moderate
national air quality standards. Accord, Christensen v. Harris County, 529 U. S. 576 , 590, n.
(2000) (SCALIA, J., concurring in part and concurring in judgment)
("The implausibility of Congress's leaving a highly significant
issue unaddressed (and thus 'delegating' its resolution to the
administering agency) is assuredly one of the factors 469 to be considered in determining whether there is ambiguity"
(emphasis deleted)).l

															The same defect inheres in respondents' next two arguments: that
while the Administrator's judgment about what is requisite to
protect the public health must be "based on [the] criteria"
documents developed under § 108(a)(2), see § 109(b)(1), it need not
be based solely on those criteria; and that those criteria
themselves, while they must include "effects on public health or
welfare which may be expected from the presence of such pollutant
in the ambient air," are not necessarily limited to those
effects. Even if we were to concede those premises, we still would
not conclude that one of the unenumerated factors that the agency
can consider in developing and applying the criteria is cost of
implementation. That factor is both so indirectly related to
public health and so full of potential for canceling the
conclusions drawn from direct health effects that it would surely
have been expressly mentioned in §§ 108 and 109 had Congress meant
it to be considered. Yet while those provisions describe in detail
how the health effects of pollutants in the ambient air are to be
calculated and given effect, see § 108(a)(2), they say not a word
about costs.

															Respondents point, finally, to a number of provisions in the CAA
that do require attainment cost data to be generated. Section
108(b)(1), for example, instructs the Administrator to "issue to
the States," simultaneously with the criteria documents,
"information on air pollution control techniques, which information
shall include data relating to the cost of installation and
operation." 42 U. S. C. § 7408(b)(l). And

															1 None of the sections of the CAA in which the District of
Columbia Circuit has found authority for the EPA to consider costs
shares § 109(b)(1)'s prominence in the overall statutory scheme.
See, e. g., Michigan v. EPA, 213
F.3d 663 , 678-679 (CADC 2000); George E. Warren Corp. v. EPA, 159 F.3d
616 , 623-624 (CADC 1998); Natural Resources Defense Council,
Inc. v. EPA, 824 F.2d
1146 , 1154-1163 (CADC 1987) (en bane). 470 § 109(d)(2)(C)(iv) requires the Clean Air Scientific Advisory
Committee to "advise the Administrator of any adverse public
health, welfare, social, economic, or energy effects which may
result from various strategies for attainment and maintenance" of
NAAQS.2 42 U. S. C. § 7409(d)(2)(C)(iv). Respondents argue that
these provisions make no sense unless costs are to be considered in
setting the NAAQS. That is not so. These provisions enable the
Administrator to assist the States in carrying out their statutory
role as primary implementers of the NAAQS. It is to the
States that the CAA assigns initial and primary responsibility for
deciding what emissions reductions will be required from which
sources. See 42 U. S. C. §§ 7407(a), 7410 (giving States the duty
of developing implementation plans). It would be impossible to
perform that task intelligently without considering which abatement
technologies are most efficient, and most economically
feasible-which is why we have said that "the most important forum
for consideration of claims of economic and technological
infeasibility is before the state agency formulating the
implementation plan," Union Elec. Co. v. EPA, 427 U.
S., at 266. Thus, federal clean air legislation has, from the very
beginning, directed federal agencies to develop and transmit
implementation data, including cost data, to the States. See 1955
Act,

															2 Respondents contend that this advice is required to be
included in the NAAQS rulemaking record-which, if true, would
suggest that it was relevant to the standard-setting process. But
the provision respondents cite for their contention, 42 U. S. C. §
7607(d)(3), requires only that "pertinent findings,
recommendations, and comments by the Scientific Review Committee"
be included. The Committee's advice concerning certain aspects of
"adverse public health ... effects" from various attainment
strategies is unquestionably pertinent; but to say that
Committeegenerated cost data are pertinent is to beg the question.
Likewise, while "all written comments" must be placed in the
docket, § 7607(d)(4)(B)(i), the EPA need respond only to the
"significant" ones, § 7407(d)(6)(B); comments regarding cost data
are not significant if cost data are irrelevant. 471 § 2(b), 69 Stat. 322; Clean Air Act of 1963, amending §§ 3(a),
(b) of the CAA, 77 Stat. 394; 1967 Act, §§ 103(a)-(d), 104, 107(c),
81 Stat. 486-488. That Congress chose to carry forward this
research program to assist States in choosing the means through
which they would implement the standards is perfectly sensible, and
has no bearing upon whether cost considerations are to be taken
into account in formulating the standards.3

															It should be clear from what we have said that the canon
requiring texts to be so construed as to avoid serious
constitutional problems has no application here. No matter how
severe the constitutional doubt, courts may choose only between
reasonably available interpretations of a text. See, e. g.,
Miller v. French, 530 U. S. 327 , 341
(2000); Pennsylvania Dept. of Corrections v. Yeskey, 524 U. S. 206 ,
212 (1998). The text of § 109(b), interpreted in its statutory and
historical context and with appreciation for its importance to the
CAA as a whole, unambiguously bars cost considerations from the
NAAQS-setting process, and thus ends the matter for us as well as
the EPA.4 We therefore affirm the judgment of the Court of Appeals
on this point.

															3 Respondents scarcely mention in their arguments the secondary NAAQS required by § 109(b)(2), 42 U. S. C. §
7409(b)(2). For many of the same reasons described in the body of
the opinion, as well as the text of § 109(b)(2), which instructs
the EPA to set the standards at a level "requisite to protect the
public welfare from any known or anticipated adverse effects associated with the presence of such air pollutant in the
ambient air" (emphasis added), we conclude that the EPA may not
consider implementation costs in setting the secondary NAAQS.

															4 Respondents' speculation that the EPA is secretly considering
the costs of attainment without telling anyone is irrelevant to our
interpretive inquiry. If such an allegation could be proved, it
would be grounds for vacating the NAAQS, because the Administrator
had not followed the law. See, e. g., Chevron U. S. A.
Inc. v. Natural Resources Defense Council, Inc., 467 U. S.
837 ,842-843 (1984); Atlantic Mut. Ins. Co. v. Commissioner, 523 U. S. 382 , 387
(1998). It would not, however, be grounds for this Court's changing
the law. 472 III

															Section 109(b)(1) of the CAA instructs the EPA to set "ambient
air quality standards the attainment and maintenance of which in
the judgment of the Administrator, based on [the] criteria
[documents of § 108] and allowing an adequate margin of safety, are
requisite to protect the public health." 42 U. S. C. § 7409(b)(1).
The Court of Appeals held that this section as interpreted by the
Administrator did not provide an "intelligible principle" to guide
the EP A's exercise of authority in setting NAAQS. "[The] EPA," it
said, "lack[ed] any determinate criteria for drawing lines. It has
failed to state intelligibly how much is too much." 175 F. 3d, at
1034. The court hence found that the EPA's interpretation (but not
the statute itself) violated the nondelegation doctrine. Id., at 1038. We disagree.

															In a delegation challenge, the constitutional question is
whether the statute has delegated legislative power to the agency.
Article I, § 1, of the Constitution vests "[a]lliegislative Powers
herein granted ... in a Congress of the United States." This text
permits no delegation of those powers, Loving v. United
States, 517 U. S.
748 , 771 (1996); see id., at 776-777 (SCALIA, J.,
concurring in part and concurring in judgment), and so we
repeatedly have said that when Congress confers decisionmaking
authority upon agencies Congress must "lay down by
legislative act an intelligible principle to which the person or
body authorized to [act] is directed to conform." J. W Hampton,
Jr., & Co. v. United States, 276 U. S. 394 , 409
(1928). We have never suggested that an agency can cure an unlawful
delegation of legislative power by adopting in its discretion a
limiting construction of the statute. Both Fahey v. Mallonee, 332
U. S. 245 , 252-253 (1947), and Lichter v. United
States, 334 U. S.
742 , 783 (1948), mention agency regulations in the course of
their nondelegation discussions, but Lichter did so because
a subsequent Congress had incorporated the regulations into a
revised version of the statute, ibid., and Fahey because the custom- 473 ary practices in the area, implicitly incorporated into the
statute, were reflected in the regulations, 332 U. S., at 250. The
idea that an agency can cure an unconstitutionally standardless
delegation of power by declining to exercise some of that power
seems to us internally contradictory. The very choice of which
portion of the power to exercise-that is to say, the prescription
of the standard that Congress had omitted-would itself be an
exercise of the forbidden legislative authority. Whether the
statute delegates legislative power is a question for the courts,
and an agency's voluntary selfdenial has no bearing upon the
answer.

															We agree with the Solicitor General that the text of § 109(b)(1)
of the CAA at a minimum requires that "[f]or a discrete set of
pollutants and based on published air quality criteria that reflect
the latest scientific knowledge, [the] EPA must establish uniform
national standards at a level that is requisite to protect public
health from the adverse effects of the pollutant in the ambient
air." Tr. of Oral Arg. in No. 99-1257, p. 5. Requisite, in turn,
"mean[s] sufficient, but not more than necessary." Id., at
7. These limits on the EPA's discretion are strikingly similar to
the ones we approved in Touby v. United States, 500 U. S. 160 (1991), which permitted the Attorney General to designate a drug as
a controlled substance for purposes of criminal drug enforcement if
doing so was" 'necessary to avoid an imminent hazard to the public
safety.'" Id., at 163. They also resemble the Occupational
Safety and Health Act of 1970 provision requiring the agency to
"'set the standard which most adequately assures, to the extent
feasible, on the basis of the best available evidence, that no
employee will suffer any impairment of health' "-which the Court
upheld in Industrial Union Dept., AFL-CIO v. American
Petroleum Institute, 448 U. S. 607 , 646
(1980), and which even then-JusTIcE REHNQUIST, who alone in that
case thought the statute violated the nondelegation doctrine, see
id., at 671 (opinion concurring in judgment), would have upheld if,
like the statute 474 here, it did not permit economic costs to be considered. See American Textile Mfrs. Institute, Inc. v. Donovan, 452 U. S. 490 ,
545 (1981) (REHNQUIST, J., dissenting).

															The scope of discretion § 109(b)(1) allows is in fact well
within the outer limits of our nondelegation precedents. In the
history of the Court we have found the requisite "intelligible
principle" lacking in only two statutes, one of which provided
literally no guidance for the exercise of discretion, and the other
of which conferred authority to regulate the entire economy on the
basis of no more precise a standard than stimulating the economy by
assuring "fair competition." See Panama Refining Co. v. Ryan, 293 U. S. 388 (1935); A. L. A. Schechter Poultry
Corp. v. United States, 295 U. S. 495 (1935). We
have, on the other hand, upheld the validity of § 11(b)(2) of the
Public Utility Holding Company Act of 1935, 49 Stat. 821, which
gave the Securities and Exchange Commission authority to modify the
structure of holding company systems so as to ensure that they are
not "unduly or unnecessarily complicate[d]" and do not "unfairly or
inequitably distribute voting power among security holders." American Power & Light Co. v. SEC, 329 U.
S. 90, 104 (1946). We have approved the wartime conferral of agency
power to fix the prices of commodities at a level that" 'will be
generally fair and equitable and will effectuate the [in some
respects conflicting] purposes of thee] Act.'" Yakus v. United States, 321 U. S. 414 , 420,
423-426 (1944). And we have found an "intelligible principle" in
various statutes authorizing regulation in the "public interest."
See, e. g., National Broadcasting Co. v. United
States, 319 U. S.
190 , 225-226 (1943) (Federal Communications Commission's power
to regulate airwaves); New York Central Securities Corp. v. United States, 287 U. S. 12 , 24-25 (1932)
(Interstate Commerce Commission's power to approve railroad
consolidations). In short, we have "almost never felt qualified to
second-guess Congress regarding the permissible degree of policy
judgment that can be left to those executing or apply- 475 ing the law." Mistretta v. United States, 488 U. S. 361 , 416 (1989)
(SCALIA, J., dissenting); see id., at 373 (majority opinion).

															It is true enough that the degree of agency discretion that is
acceptable varies according to the scope of the power
congressionally conferred. See Loving v. United States,
517 U. S., at 772-773; United States v. Mazurie, 419 U. S. 544 ,
556-557 (1975). While Congress need not provide any direction to
the EP A regarding the manner in which it is to define "country
elevators," which are to be exempt from newstationary-source
regulations governing grain elevators, see 42 U. S. C. § 7411(i),
it must provide substantial guidance on setting air standards that
affect the entire national economy. But even in sweeping regulatory
schemes we have never demanded, as the Court of Appeals did here,
that statutes provide a "determinate criterion" for saying "how
much [of the regulated harm] is too much." 175 F. 3d, at 1034. In Touby, for example, we did not require the statute to decree
how "imminent" was too imminent, or how "necessary" was necessary
enough, or even-most relevant here-how "hazardous" was too
hazardous. 500 U. S., at 165-167. Similarly, the statute at issue
in Lichter authorized agencies to recoup "excess profits"
paid under wartime Government contracts, yet we did not insist that
Congress specify how much profit was too much. 334 U. S., at
783-786. It is therefore not conclusive for delegation purposes
that, as respondents argue, ozone and particulate matter are
"nonthreshold" pollutants that inflict a continuum of adverse
health effects at any airborne concentration greater than zero, and
hence require the EPA to make judgments of degree. "[A] certain
degree of discretion, and thus of lawmaking, inheres in most
executive or judicial action." Mistretta v. United
States, supra, at 417 (SCALIA, J., dissenting) (emphasis
deleted); see 488 U. S., at 378-379 (majority opinion). Section
109(b)(1) of the CAA, which to repeat we interpret as requiring the
EPA to set air quality standards at the level that is "requi- 476 site"-that is, not lower or higher than is necessary-to protect
the public health with an adequate margin of safety, fits
comfortably within the scope of discretion permitted by our
precedent.

															We therefore reverse the judgment of the Court of Appeals
remanding for reinterpretation that would avoid a supposed
delegation of legislative power. It will remain for the Court of
Appeals-on the remand that we direct for other reasons-to dispose
of any other preserved challenge to the NAAQS under the
judicial-review provisions contained in 42 U. S. C. §
7607(d)(9).

															IV

															The final two issues on which we granted certiorari concern the
EP A's authority to implement the revised ozone NAAQS in areas
whose ozone levels currently exceed the maximum level permitted by
that standard. The CAA designates such areas "nonattainment," §
107(d)(1), 42 U. S. C. § 7407(d)(1); see also Pub. L. 105-178, §
6103, 112 Stat. 465 (setting timeline for new ozone designations),
and it exposes them to additional restrictions over and above the
implementation requirements imposed generally by § 110 of the CAA.
These additional restrictions are found in the five substantive
subparts of Part D of Title I, 42 U. S. C. §§ 7501-7515. Subpart 1,
§§ 7501-7509a, contains general nonattainment regulations that
pertain to every pollutant for which a NAAQS exists. Subparts 2
through 5, §§ 75117514a, contain rules tailored to specific
individual pollutants. Subpart 2, added by the Clean Air Act
Amendments of 1990, § 103, 104 Stat. 2423, addresses ozone. 42 U.
S. C. §§ 7511751lf. The dispute before us here, in a nutshell, is
whether Subpart 1 alone (as the agency determined), or rather
Subpart 2 or some combination of Subparts 1 and 2, controls the
implementation of the revised ozone NAAQS in nonattainment
areas. 477 A

															The Administrator first urges, however, that we vacate the
judgment of the Court of Appeals on this issue because it lacked
jurisdiction to review the EP A's implementation policy. Section
307(b)(1) of the CAA, 42 U. S. C. § 7607(b)(1), gives the court
jurisdiction over "any ... nationally applicable regulations
promulgated, or final action taken, by the Administrator," but the
EPA argues that its implementation policy was not agency "action,"
was not "final" action, and is not ripe for review. We reject each
of these three contentions.

															At the same time the EP A proposed the revised ozone NAAQS in
1996, it also proposed an "interim implementation policy" for the N
AAQS, see 61 Fed. Reg. 65752 (1996), that was to govern until the
details of implementation could be put in final form through
specific "rulemaking actions." The preamble to this proposed policy
declared that "the interim implementation policy ... represent[s]
EP A's preliminary views on these issues and, while it may include
various statements that States must take certain actions, these
statements are made pursuant to EP A's preliminary interpretations,
and thus do not bind the States and public as a matter of law." Ibid. If the EPA had done no more, we perhaps could accept
its current claim that its action was not final. However, after the
agency had accepted comments on its proposed policy, and on the
same day that the final ozone NAAQS was promulgated, the White
House published in the Federal Register what it titled a
"Memorandum for the Administrator of the Environmental Protection
Agency" that prescribed implementation procedures for the EP A to
follow. 62 Fed. Reg. 38421 (1997). (For purposes of our analysis we
shall assume that this memorandum was not itself action by the
EPA.) The EPA supplemented this memorandum with an explanation of
the implementation procedures, which it published in the
explanatory preamble to its final ozone 478 NAAQS under the heading, "Final decision on the primary
standard." Id., at 38873. "In light of comments received
regarding the interpretation proposed in the Interim Implementation
Policy," the EPA announced, it had "reconsidered that
interpretation" and settled on a new one. Ibid. The
provisions of "subpart 1 of part D of Title I of the Act" will
immediately "apply to the implementation of the new 8-hour [ozone]
standards." Ibid.; see also id., at 38885 (new
standard to be implemented "simultaneously [with the old standard]
... under the provisions of ... subpart 1"). Moreover, the
provisions of subpart 2 "will [also] continue to apply as a matter
of law for so long as an area is not attaining the [old] i-hour
standard." Id., at 38873. Once the area reaches attainment
for the old standard, however, "the provisions of subpart 2 will
have been achieved and those provisions will no longer apply." Ibid.; see also id., at 38884-38885.

															We have little trouble concluding that this constitutes final
agency action subject to review under § 307. The bite in the phrase
"final action" (which bears the same meaning in § 307(b)(1) that it
does under the Administrative Procedure Act (APA), 5 U. S. C. §
704, see Harrison v. PPG Industries, Inc., 446 U. S. 578 , 586
(1980)), is not in the word "action," which is meant to cover
comprehensively every manner in which an agency may exercise its
power. See FTC v. Standard Oil Co. of Cal., 449 U. S. 232 , 238, n. 7
(1980). It is rather in the word "final," which requires that the
action under review "mark the consummation of the agency's
decisionmaking process." Bennett v. Spear, 520 U. S. 154 , 177-178
(1997). Only if the "EP A has rendered its last word on the matter"
in question, Harrison v. PPG Industries, Inc., supra, at 586, is its action "final" and thus reviewable. That standard is
satisfied here. The EP A's "decisionmaking process," which began
with the 1996 proposal and continued with the reception of public
comments, concluded 479 when the agency, "in light of [these comments]," and in
conjunction with a corresponding directive from the White House,
adopted the interpretation of Part D at issue here. Since that
interpretation issued, the EP A has refused in subsequent
rulemakings to reconsider it, explaining to disappointed commenters
that its earlier decision was conclusive. See 63 Fed. Reg. 31014,
31018-31019 (1998). Though the agency has not dressed its decision
with the conventional procedural accoutrements of finality, its own
behavior thus belies the claim that its interpretation is not
final.

															The decision is also ripe for our review. "Ripeness 'requir[es]
us to evaluate both the fitness of the issues for judicial decision
and the hardship to the parties of withholding court
consideration.'" Texas v. United States, 523 U. S. 296 , 300-301
(1998) (quoting Abbott Laboratories v. Gardner, 387 U. S. 136, 149 (1967)). The question before us here is purely one
of statutory interpretation that would not "benefit from further
factual development of the issues presented." Ohio Forestry
Assn., Inc. v. Sierra Club, 523 U. S. 726 , 733
(1998). Nor will our review "inappropriately interfere with further
administrative action," ibid., since the EPA has concluded
its consideration of the implementation issue. Finally, as for
hardship to the parties: The respondent States must-on pain of
forfeiting to the EP A control over implementation of the
NAAQS-promptly undertake the lengthy and expensive task of
developing state implementation plans (SIP's) that will attain the
new, more stringent standard within five years. See 42 U. S. C. §§
7410, 7502. Whether or not this would suffice in an ordinary case
brought under the review provisions of the APA, see 5 U. S. C. §
704, we have characterized the special judicial-review provision of
the CAA, 42 U. S. C. § 7607(b), as one of those statutes that
specifically provides for "preenforcement" review, see Ohio
Forestry Assn., Inc. v. Sierra Club, supra, at 737. Such
statutes, we have said, permit "judicial review directly, even
before the 480 concrete effects normally required for APA review are felt." Lujan v. National Wildlife Federation, 497 U. S. 871 , 891
(1990). The effects at issue here surely meet that lower
standard.

															Beyond all this, the implementation issue was fairly included
within the challenges to the final ozone rule that were properly
before the Court of Appeals. Respondents argued below that the EPA
could not revise the ozone standard, because to do so would trigger
the use of Subpart 1, which had been supplanted (for ozone) by the
specific rules of Subpart 2. Brief for Industry Petitioners and
Intervenors in No. 97-1441 (and consolidated cases) (CADC), pp.
32-34. The EP A responded that Subpart 2 did not supplant but
simply supplemented Subpart 1, so that the latter section still
"applies to all nonattainment areas for all NAAQS, ... including
nonattainment areas for any revised ozone standard." Final Brief
for EPA in No. 97-1441 (and consolidated cases) (CADC), pp. 67-68.
The agency later reiterated that Subpart 2 "does not supplant
implementation provisions for revised ozone standards. This
interpretation fully harmonizes Subpart 2 with EP A's clear
authority to revise any NAAQS." Id., at 71. In other words,
the EPA was arguing that the revised standard could be issued,
despite its apparent incompatibility with portions of Subpart 2, because it would be implemented under Subpart 1 rather
than Subpart 2. The District of Columbia Circuit ultimately
agreed that Subpart 2 could be harmonized with the EP A's authority
to promulgate revised NAAQS, but not because Subpart 2 is
entirely inapplicable-which is one of EPA's assignments of error.
It is unreasonable to contend, as the EPA now does, that the Court
of Appeals was obligated to reach the agency's preferred result,
but forbidden to assess the reasons the EP A had given for reaching
that result. The implementation issue was fairly included within
respondents' challenge to the ozone rule, which all parties agree
is final agency action ripe for review. 481 B

															Our approach to the merits of the parties' dispute is the
familiar one of Chevron U. S. A. Inc. v. Natural
Resources Defense Council, Inc., 467 U. S. 837 (1984). If
the statute resolves the question whether Subpart 1 or Subpart 2
(or some combination of the two) shall apply to revised ozone
NAAQS, then "that is the end of the matter." Id., at 842843.
But if the statute is "silent or ambiguous" with respect to the
issue, then we must defer to a "reasonable interpretation made by
the administrator of an agency." Id., at 844. We cannot
agree with the Court of Appeals that Subpart 2 clearly controls the
implementation of revised ozone NAAQS, see 175 F. 3d, at 1048-1050,
because we find the statute to some extent ambiguous. We conclude,
however, that the agency's interpretation goes beyond the limits of
what is ambiguous and contradicts what in our view is quite clear.
We therefore hold the implementation policy unlawful. See AT&T Corp. v. Iowa Utilities Bd., 525 U. S. 366 , 392
(1999).

															The text of Subpart 1 at first seems to point the way to a clear
answer to the question, which Subpart controls? Two sections of
Subpart 1, 7502(a)(1)(C) and 7502(a)(2)(D), contain switching
provisions stating that if the classification of ozone
nonattainment areas is "specifically provided [for] under other
provisions of [Part D]," then those provisions will control instead
of Subpart l's. Thus, it is true but incomplete to note, as the
Administrator does, that the substantive language of Subpart 1 is
broad enough to apply to revised ozone standards. See, e. g., § 7502(a)(1)(A) (instructing the Administrator to classify
nonattainment areas according to "any revised standard, including a
revision of any standard in effect on November 15, 1990"); §
7502(a)(2)(A) (setting attainment deadlines). To determine whether
that language does apply one must resolve the further
textual issue whether some other provision, namely Subpart
2, provides for the classification of ozone nonattainment areas.
If 482 it does, then according to the switching provisions of Subpart 1
it will control.

															So, does Subpart 2 provide for classifying nonattainment ozone
areas under the revised standard? It unquestionably does. The
backbone of the subpart is Table 1, printed in § 7511(a)(1) and
reproduced in the margin here,5 which defines five categories of
ozone nonattainment areas and prescribes attainment deadlines for
each. Section 7511(a)(1) funnels all nonattainment areas into the
table for classification, declaring that "[e]ach area designated
nonattainment for ozone ... shall be classified at the time of such
designation, under table 1, by operation of law." And once an area
has been classified, "the primary standard attainment date for
ozone shall be as expeditiously as practicable but not later than
the date provided in table 1." The EPA argues that this text is not
as clear or comprehensive as it seems, because the title of §
7511(a) reads "Classification and attainment dates for 1989
nonattainment areas," which suggests that Subpart 2 applies only to
areas that were in nonattainment in 1989, and not to areas later
designated non- TABLE 1 Area class Design value* Primary standard attainment date** Marginal .............. 0.121 up to 0.138 .............. 3 years after November 15, 1990 Moderate.............. 0.138 up to 0.160 .............. 6 years after November 15, 1990 Serious ................ 0.160 up to 0.180 .............. 9 years after November 15, 1990 Severe ................. 0.180 up to 0.280 .............. 15 years after November 15, 1990 Extreme............... 0.280 and above ............... 20 years after November 15, 1990 483 attainment under a revised ozone standard. The suggestion must
be rejected, however, because § 7511(b)(1) specifically provides
for the classification of areas that were in attainment in
1989 but have subsequently slipped into nonattainment. It thus
makes clear that Subpart 2 is not limited solely to 1989
nonattainment areas. This eliminates the interpretive role of the
title, which may only "she[d] light on some ambiguous word or
phrase in the statute itself," Carter v. United
States, 530 U. S.
255 , 267 (2000) (internal quotation marks omitted) (quoting Pennsylvania Dept. of Corrections v. Yeskey, 524 U.
S., at 212, in turn quoting Trainmen v. Baltimore & Ohio R. Co., 331 U. S. 519 , 528-529
(1947)).

															It may well be, as the EPA argues-and as the concurring opinion
below on denial of rehearing pointed out, see 195 F. 3d, at
11-12-that some provisions of Subpart 2 are ill fitted to
implementation of the revised standard. U sing the old i-hour
averages of ozone levels, for example, as Subpart 2 requires, see §
7511(a)(1); 44 Fed. Reg. 8202 (1979), would produce at best an
inexact estimate of the new 8-hour averages, see 40 CFR § 50.10,
and App. I (1999). Also, to the extent that the new ozone standard
is stricter than the old one, see Reply Brief for Petitioners in
No. 99-1257, p. 17 ("the stricter 8-hour NAAQS"); 62 Fed. Reg.
38856, 38858 (1997) (8-hour standard of 0.09 ppm rather than 0.08
ppm would have "generally represent[ed] the continuation of the
[old] level of protection"), the classification system of Subpart 2
contains a gap, because it fails to classify areas whose ozone
levels are greater than the new standard (and thus nonattaining)
but less than the approximation of the old standard codified by
Table 1. And finally, Subpart 2's method for calculating attainment
dates-which is simply to count forward a certain number of years
from November 15, 1990 (the date the 1990 CAA Amendments took
force), depending on how far out of attainment the area
started-seems to make no sense for areas that are first classified
under a new standard after November 15, 1990. 484 If, for example, areas were classified in the year 2000, many of
the deadlines would already have expired at the time of
classification.

															These gaps in Subpart 2's scheme prevent us from concluding that
Congress clearly intended Subpart 2 to be the exclusive, permanent
means of enforcing a revised ozone standard in nonattainment areas.
The statute is in our view ambiguous concerning the manner in which
Subpart 1 and Subpart 2 interact with regard to revised ozone
standards, and we would defer to the EP A's reasonable resolution
of that ambiguity. See FDA v. Brown & Williamson Tobacco Corp., 529 U. S., at 132; INS v. Aguirre-Aguirre, 526 U. S. 415 , 424
(1999). We cannot defer, however, to the interpretation the EPA has
given.

															Whatever effect may be accorded the gaps in Subpart 2 as
implying some limited applicability of Subpart 1, they cannot be
thought to render Subpart 2's carefully designed restrictions on
EPA discretion utterly nugatory once a new standard has been
promulgated, as the EP A has concluded. The principal distinction
between Subpart 1 and Subpart 2 is that the latter eliminates
regulatory discretion that the former allowed. While Subpart 1
permits the EPA to establish classifications for nonattainment
areas, Subpart 2 classifies areas as a matter of law based on a
table. Compare § 7502(a)(1) with § 7511(a)(1) (Table 1). Whereas
the EPA has discretion under Subpart 1 to extend attainment dates
for as long as 12 years, under Subpart 2 it may grant no more than
2 years' extension. Compare §§ 7502(a)(2)(A) and (C) with §
7511(a)(5). Whereas Subpart 1 gives the EPA considerable discretion
to shape nonattainment programs, Subpart 2 prescribes large parts
of them by law. Compare §§ 7502(c) and (d) with § 7511a. Yet
according to the EPA, Subpart 2 was simply Congress's "approach to
the implementation of the [old] i-hour" standard, and so there was
no reason that "the new standard could not simultaneously be
implemented under ... subpart 1." 62 Fed. Reg. 485 38856, 38885 (1997); see also id., at 38873 ("[T]he provisions
of subpart 1 ... would apply to the implementation of the new
8-hour ozone standards"). To use a few apparent gaps in Subpart 2
to render its textually explicit applicability to nonattainment
areas under the new standard utterly inoperative is to go over the
edge of reasonable interpretation. The EPA may not construe the
statute in a way that completely nullifies textually applicable
provisions meant to limit its discretion.

															The EP A's interpretation making Subpart 2 abruptly obsolete is
all the more astonishing because Subpart 2 was obviously written to
govern implementation for some time. Some of the elements required
to be included in SIP's under Subpart 2 were not to take effect
until many years after the passage of the CAA. See § 7511a(e)(3)
(restrictions on "electric utility and industrial and commercial
boiler[s]" to be "effective 8 years after November 15, 1990"); §
7511a(c)(5)(A) (vehicle monitoring program to "[b]egi[n] 6 years
after November 15, 1990"); § 7511a(g)(1) (emissions milestone
requirements to be applied "6 years after November 15, 1990, and at
intervals of every 3 years thereafter"). A plan reaching so far
into the future was not enacted to be abandoned the next time the
EP A reviewed the ozone standard-which Congress knew could happen
at any time, since the technical staff papers had already been
completed in late 1989. See 58 Fed. Reg. 13008, 13010 (1993); see
also 42 U. S. C. § 7409(d)(1) (NAAQS must be reviewed and, if
appropriate, revised at least once every five years). Yet nothing
in the EPA's interpretation would have prevented the agency from
aborting Subpart 2 the day after it was enacted. Even now, if the
EP A's interpretation were correct, some areas of the country could
be required to meet the new, more stringent ozone standard in at
most the same time that Subpart 2 had allowed them to meet the
old standard. Compare § 7502(a)(2) (Subpart 1 attainment dates)
with § 7511(a) (Subpart 2 attainment dates). Los Angeles, for
instance, "would 486 486 WHITMAN v. AMERICAN TRUCKING ASSNS., INC.

															THOMAS, J., concurring

															be required to attain the revised NAAQS under Subpart 1 no later
than the same year that marks the outer time limit for attaining
Subpart 2's one-hour ozone standard." Brief for Petitioners in No.
99-1257, p. 49. An interpretation of Subpart 2 so at odds with its
structure and manifest purpose cannot be sustained.

															We therefore find the EPA's implementation policy to be
unlawful, though not in the precise respect determined by the Court
of Appeals. After our remand, and the Court of Appeals' final
disposition of these cases, it is left to the EPA to develop a
reasonable interpretation of the nonattainment implementation
provisions insofar as they apply to revised ozone NAAQS.

															***

															To summarize our holdings in these unusually complex cases: (1)
The EPA may not consider implementation costs in setting primary
and secondary NAAQS under § 109(b) of the CAA. (2) Section
109(b)(1) does not delegate legislative power to the EPA in
contravention of Art. I, § 1, of the Constitution. (3) The Court of
Appeals had jurisdiction to review the EP A's interpretation of
Part D of Title I of the CAA, relating to the implementation of the
revised ozone NAAQS. (4) The EPA's interpretation of that Part is
unreasonable.

															The judgment of the Court of Appeals is affirmed in part and
reversed in part, and the cases are remanded for proceedings
consistent with this opinion.

															It is so ordered.

															JUSTICE THOMAS, concurring.

															I agree with the majority that § 109's directive to the agency
is no less an "intelligible principle" than a host of other
directives that we have approved. Ante, at 474-476. I also
agree that the Court of Appeals' remand to the agency to make its
own corrective interpretation does not accord with our
understanding of the delegation issue. Ante, at 472-473. I
write separately, however, to express my con- 487 cern that there may nevertheless be a genuine constitutional
problem with § 109, a problem which the parties did not
address.

															The parties to these cases who briefed the constitutional issue
wrangled over constitutional doctrine with barely a nod to the text
of the Constitution. Although this Court since 1928 has treated the
"intelligible principle" requirement as the only constitutional
limit on congressional grants of power to administrative agencies,
see J. W Hampton, Jr., & Co. v. United
States, 276 U. S.
394 , 409 (1928), the Constitution does not speak of
"intelligible principles." Rather, it speaks in much simpler terms:
"All legislative Powers herein granted shall be vested in a
Congress." U. S. Const., Art. 1, § 1 (emphasis added). I am not
convinced that the intelligible principle doctrine serves to
prevent all cessions of legislative power. I believe that there are
cases in which the principle is intelligible and yet the
significance of the delegated decision is simply too great for the
decision to be called anything other than "legislative."

															As it is, none of the parties to these cases has examined the
text of the Constitution or asked us to reconsider our precedents
on cessions of legislative power. On a future day, however, I would
be willing to address the question whether our delegation
jurisprudence has strayed too far from our Founders' understanding
of separation of powers.

															JUSTICE STEVENS, with whom JUSTICE SOUTER joins, concurring in
part and concurring in the judgment.

															Section 109(b)(1) delegates to the Administrator of the
Environmental Protection Agency (EPA) the authority to promulgate
national ambient air quality standards (NAAQS). In Part III of its
opinion, ante, at 472-476, the Court convincingly explains
why the Court of Appeals erred when it concluded that § 109
effected "an unconstitutional delegation of legislative power." American Trucking Assns., Inc. v. EPA, 175 F.3d
1027 , 1033 (CADC 1999) (per curiam). 488 I wholeheartedly endorse the Court's result and endorse its
explanation of its reasons, albeit with the following caveat.

															The Court has two choices. We could choose to articulate our
ultimate disposition of this issue by frankly acknowledging that
the power delegated to the EPA is "legislative" but nevertheless
conclude that the delegation is constitutional because adequately
limited by the terms of the authorizing statute. Alternatively, we
could pretend, as the Court does, that the authority delegated to
the EPA is somehow not "legislative power." Despite the fact that
there is language in our opinions that supports the Court's
articulation of our holding,l I am persuaded that it would be both
wiser and more faithful to what we have actually done in delegation
cases to admit that agency rulemaking authority is "legislative
power." 2

															The proper characterization of governmental power should
generally depend on the nature of the power, not on the identity of
the person exercising it. See Black's Law Dictionary 899 (6th ed.
1990) (defining "legislation" as, inter alia, "[f]ormulation
of rule[s] for the future"); 1 K. Davis & R. Pierce,
Administrative Law Treatise § 2.3, p. 37 (3d ed. 1994) ("If
legislative power means the power to make rules of conduct that
bind everyone based on resolution of major policy issues, scores of
agencies exercise legislative power routinely by

															1 See, e. g., Touby v. United States, 500 U. S. 160 , 165
(1991); United States v. Shreveport Grain & Elevator Co., 287 U. S. 77 , 85
(1932); J. W Hampton, Jr., & Co. v. United States, 276 U. S. 394 , 407
(1928); Field v. Clark, 143 U. S. 649 , 692
(1892).

															2 See Mistretta v. United States, 488 U. S. 361 , 372 (1989)
("[O]ur jurisprudence has been driven by a practical understanding
that in our increasingly complex society ... Congress simply cannot
do its job absent an ability to delegate power ... "). See also Loving v. United States, 517 U. S. 748 , 758 (1996)
("[The nondelegation] principle does not mean ... that only
Congress can make a rule of prospective force"); 1 K. Davis &
R. Pierce, Administrative Law Treatise § 2.6, p. 66 (3d ed. 1994)
("Except for two 1935 cases, the Court has never enforced its
frequently announced prohibition on congressional delegation of
legislative power"). 489 promulgating what are candidly called 'legislative rules' "). If
the N AAQS that the EP A promulgated had been prescribed by
Congress, everyone would agree that those rules would be the
product of an exercise of "legislative power." The same
characterization is appropriate when an agency exercises rulemaking
authority pursuant to a permissible delegation from Congress.

															My view is not only more faithful to normal English usage, but
is also fully consistent with the text of the Constitution. In
Article I, the Framers vested "All legislative Powers" in the
Congress, Art. I, § 1, just as in Article II they vested the
"executive Power" in the President, Art. II, § 1. Those provisions
do not purport to limit the authority of either recipient of power
to delegate authority to others. See Bowsher v. Synar, 478 U.
S. 714 , 752 (1986) (STEVENS, J., concurring in judgment)
("Despite the statement in Article I of the Constitution that 'All
legislative powers herein granted shall be vested in a Congress of
the United States,' it is far from novel to acknowledge that
independent agencies do indeed exercise legislative powers"); INS v. Chadha, 462 U. S. 919 , 985-986
(1983) (White, J., dissenting) ("[L]egislative power can be
exercised by independent agencies and Executive departments ... ");
1 Davis & Pierce, Administrative Law Treatise § 2.6, at 66
("The Court was probably mistaken from the outset in interpreting
Article 1's grant of power to Congress as an implicit limit on
Congress' authority to delegate legislative power"). Surely the
authority granted to members of the Cabinet and federal law
enforcement agents is properly characterized as "Executive" even
though not exercised by the President. Cf. Morrison v. Olson, 487 U.
S. 654 , 705-706 (1988) (SCALIA, J., dissenting) (arguing that
the independent counsel exercised "executive power" unconstrained
by the President).

															It seems clear that an executive agency's exercise of rulemaking
authority pursuant to a valid delegation from Congress is
"legislative." As long as the delegation provides a 490 490 WHITMAN v. AMERICAN TRUCKING ASSNS., INC.

															Opinion of BREYER, J.

															sufficiently intelligible principle, there is nothing inherently
unconstitutional about it. Accordingly, while I join Parts I, II,
and IV of the Court's opinion, and agree with almost everything
said in Part III, I would hold that when Congress enacted § 109, it
effected a constitutional delegation of legislative power to the EP
A.

															JUSTICE BREYER, concurring in part and concurring in the
judgment.

															I join Parts I, III, and IV of the Court's opinion. I also agree
with the Court's determination in Part II that the Clean Air Act
does not permit the Environmental Protection Agency to consider the
economic costs of implementation when setting national ambient air
quality standards under § 109(b)(1) of the Act. But I would not
rest this conclusion solely upon § 109's language or upon a
presumption, such as the Court's presumption that any authority the
Act grants the EP A to consider costs must flow from a "textual
commitment" that is "clear." Ante, at 468. In order better
to achieve regulatory goals-for example, to allocate resources so
that they save more lives or produce a cleaner
environment-regulators must often take account of all of a proposed
regulation's adverse effects, at least where those adverse effects
clearly threaten serious and disproportionate public harm. Hence, I
believe that, other things being equal, we should read silences or
ambiguities in the language of regulatory statutes as permitting,
not forbidding, this type of rational regulation.

															In these cases, however, other things are not equal. Here,
legislative history, along with the statute's structure, indicates
that § 109's language reflects a congressional decision not to
delegate to the agency the legal authority to consider economic
costs of compliance.

															For one thing, the legislative history shows that Congress
intended the statute to be "technology forcing." Senator Edmund
Muskie, the primary sponsor of the 1970 amend- 491 ments to the Act, introduced them by saying that Congress'
primary responsibility in drafting the Act was not "to be limited
by what is or appears to be technologically or economically
feasible," but "to establish what the public interest requires to
protect the health of persons," even if that means that "industries will be asked to do what seems to be impossible at
the present time." 116 Congo Rec. 32901-32902 (1970), 1
Legislative History of the Clean Air Amendments of 1970 (Committee
Print compiled for the Senate Committee on Public Works by the
Library of Congress), Ser. No. 93-18,

															The Senate directly focused upon the technical feasibility and
cost of implementing the Act's mandates. And it made clear that it
intended the Administrator to develop air quality standards set
independently of either. The Senate Report for the 1970 amendments
explains: "In the Committee discussions, considerable concern was
expressed regarding the use of the concept of technical feasibility
as the basis of ambient air standards. The Committee determined
that 1) the health of people is more important than the question
of whether the early achievement of ambient air quality standards
protective of health is technically feasible; and, 2) the
growth of pollution load in many areas, even with application of
available technology, would still be deleterious to public health
.... "Therefore, the Committee determined that existing sources of
pollutants either should meet the standard of the law or be closed
down .... " S. Rep. No. 91-1196, pp. 2-3 (1970), 1 Leg. Hist.
402-403 (emphasis added). Indeed, this Court, after reviewing the entire legislative
history, concluded that the 1970 amendments were "expressly
designed to force regulated sources to develop pollution control
devices that might at the time appear to be economically or
technologically infeasible." Union Elec. Co. 492 v. EPA, 427 U. S.
246 , 257 (1976) (emphasis added). And the Court added that the
1970 amendments were intended to be a "drastic remedy to ... a
serious and otherwise uncheckable problem." Id., at 256.
Subsequent legislative history confirms that the technology-forcing
goals of the 1970 amendments are still paramount in to day's Act.
See Clean Air Conference Report (1977): Statement of Intent;
Clarification of Select Provisions, 123 Congo Rec. 27070 (1977)
(stating, regarding the 1977 amendments to the Act, that "this
year's legislation retains and even strengthens the technology
forcing ... goals of the 1970 Act"); S. Rep. No. 101-228, p.5
(1989) (stating that the 1990 amendments to the Act require ambient
air quality standards to be set at "the level that 'protects the
public health' with an 'adequate margin of safety,' without
regard to the economic or technical feasibility of attainment" (emphasis added)).

															To read this legislative history as meaning what it says does
not impute to Congress an irrational intent. Technology-forcing
hopes can prove realistic. Those persons, for example, who opposed
the 1970 Act's insistence on a 90% reduction in auto emission
pollutants, on the ground of excessive cost, saw the development of
catalytic converter technology that helped achieve substantial
reductions without the economic catastrophe that some had feared.
See § 6(a) of the Clean Air Act Amendments of 1970, amending §§
202(b)(1)(A), (B), 84 Stat. 1690 (codified at 42 U. S. C. §§
7521(b)(1)(A), (B)) (requiring a 90% reduction in emissions); 1
Leg. Hist. 238, 240 (statement of Sen. Griffin) (arguing that the
emissions standards could "force [the automobile] industry out of
existence" because costs "would not be taken into account"); see
generally Reitze, Mobile Source Air Pollution Control, 6 Env. Law.
309, 326-327 (2000) (discussing the development of the catalytic
converter).

															At the same time, the statute's technology-forcing objective
makes regulatory efforts to determine the costs of implementation
both less important and more difficult. It 493 means that the relevant economic costs are speculative, for they
include the cost of unknown future technologies. It also means that
efforts to take costs into account can breed time-consuming and
potentially unresolvable arguments about the accuracy and
significance of cost estimates. Congress could have thought such
efforts not worth the delays and uncertainties that would accompany
them. In any event, that is what the statute's history seems to
say. See Union Elec., supra, at 256-259. And the matter is
one for Congress to decide.

															Moreover, the Act does not, on this reading, wholly ignore cost
and feasibility. As the majority points out, ante, at
466-467, the Act allows regulators to take those concerns into
account when they determine how to implement ambient air quality
standards. Thus, States may consider economic costs when they
select the particular control devices used to meet the standards,
and industries experiencing difficulty in reducing their emissions
can seek an exemption or variance from the state implementation
plan. See Union Elec., supra, at 266 ("[T]he most important
forum for consideration of claims of economic and technological
infeasibility is before the state agency formulating the
implementation plan").

															The Act also permits the EPA, within certain limits, to consider
costs when it sets deadlines by which areas must attain the ambient
air quality standards. 42 U. S. C. § 7502(a)(2)(A) (providing that
"the Administrator may extend the attainment date ... for a period
no greater than 10 years from the date of designation as
nonattainment, considering the severity of nonattainment and the
availability and feasibility of pollution control measures"); §
7502(a)(2)(C) (permitting the Administrator to grant up to two
additional i-year extensions); cf. §§ 7511(a)(1), (5) (setting more
rigid attainment deadlines for areas in nonattainment of the ozone
standard, but permitting the Administrator to grant up to two
i-year extensions). And Congress can change those statutory limits
if necessary. Given the ambient air quality 494 standards' substantial effects on States, cities, industries,
and their suppliers and customers, Congress will hear from those
whom compliance deadlines affect adversely, and Congress can
consider whether legislative change is warranted. See, e. g., Steel Industry Compliance Extension Act of 1981, 95 Stat. 139
(codified at 42 U. S. C. § 7413(e) (1988 ed.)) (repealed 1990)
(granting the Administrator discretion to extend the ambient air
quality standard attainment date set in the 1977 Act by up to three
years for steelmaking facilities).

															Finally, contrary to the suggestion of the Court of Appeals and
of some parties, this interpretation of § 109 does not require the
EPA to eliminate every health risk, however slight, at any economic
cost, however great, to the point of "hurtling" industry over "the
brink of ruin," or even forcing "deindustrialization." American
Trucking Assns., Inc. v. EPA, 175 F.3d
1027 , 1037, 1038, n. 4 (CADC 1999); see also Brief for
Cross-Petitioners in No. 99-1426, p. 25. The statute, by its
express terms, does not compel the elimination of all risk;
and it grants the Administrator sufficient flexibility to avoid
setting ambient air quality standards ruinous to industry.

															Section 109(b)(1) directs the Administrator to set standards
that are "requisite to protect the public health" with "an adequate
margin of safety." But these words do not describe a world that is
free of all risk-an impossible and undesirable objective. See Industrial Union Dept., AFL-CIO v. American Petroleum
Institute, 448 U.
S. 607 , 642 (1980) (plurality opinion) (the word "safe" does
not mean "riskfree"). Nor are the words "requisite" and "public
health" to be understood independent of context. We consider
football equipment "safe" even if its use entails a level of risk
that would make drinking water "unsafe" for consumption. And what
counts as "requisite" to protecting the public health will
similarly vary with background circumstances, such as the public's
ordinary tolerance of the particular health risk in the particular
context at issue. The Administrator can 495 consider such background circumstances when "decid[ing] what
risks are acceptable in the world in which we live." Natural
Resources Defense Council, Inc. v. EPA, 824 F.2d
1146 , 1165 (CADC 1987).

															The statute also permits the Administrator to take account of
comparative health risks. That is to say, she may consider whether
a proposed rule promotes safety overall. A rule likely to cause
more harm to health than it prevents is not a rule that is
"requisite to protect the public health." For example, as the Court
of Appeals held and the parties do not contest, the Administrator
has the authority to determine to what extent possible health risks
stemming from reductions in tropospheric ozone (which, it is
claimed, helps prevent cataracts and skin cancer) should be taken
into account in setting the ambient air quality standard for ozone.
See 175 F. 3d, at 1050-1053 (remanding for the Administrator to
make that determination).

															The statute ultimately specifies that the standard set must be
"requisite to protect the public health" "in the judgment of the
Administrator," § 109(b)(1), 84 Stat. 1680 (emphasis added), a
phrase that grants the Administrator considerable discretionary
standard-setting authority.

															The statute's words, then, authorize the Administrator to
consider the severity of a pollutant's potential adverse health
effects, the number of those likely to be affected, the
distribution of the adverse effects, and the uncertainties
surrounding each estimate. Cf. Sun stein, Is the Clean Air Act
Unconstitutional?, 98 Mich. L. Rev. 303, 364 (1999). They permit
the Administrator to take account of comparative health
consequences. They allow her to take account of context when
determining the acceptability of small risks to health. And they
give her considerable discretion when she does so.

															This discretion would seem sufficient to avoid the extreme
results that some of the industry parties fear. After all, the EPA,
in setting standards that "protect the public health" 496 with "an adequate margin of safety," retains discretionary
authority to avoid regulating risks that it reasonably concludes
are trivial in context. Nor need regulation lead to
deindustrialization. Preindustrial society was not a very healthy
society; hence a standard demanding the return of the Stone Age
would not prove "requisite to protect the public health."

															Although I rely more heavily than does the Court upon
legislative history and alternative sources of statutory
flexibility, I reach the same ultimate conclusion. Section 109 does
not delegate to the EPA authority to base the national ambient air
quality standards, in whole or in part, upon the economic costs of
compliance.