(Slip Opinion)              OCTOBER TERM, 2017                                       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., 

, 337.


SUPREME COURT OF THE UNITED STATES

                                       Syllabus

 SAS INSTITUTE INC. v. IANCU, DIRECTOR, UNITED
 STATES PATENT AND TRADEMARK OFFICE, ET AL.

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
                THE FEDERAL CIRCUIT

   No. 16–969.      Argued November 27, 2017—Decided April 24, 2018
Inter partes review allows private parties to challenge previously is-
  sued patent claims in an adversarial process before the Patent Office.
  At the outset, a party must file a petition to institute review, 

. §311(a), that identifies the challenged claims and the
  grounds for challenge with particularity, §312(a)(3). The patent own-
  er, in turn, may file a response. §313. If the Director of the Patent
  Office determines “there is a reasonable likelihood that the petitioner
  would prevail with respect to at least 1 of the claims challenged in
  the petition,” §314(a), he decides “whether to institute . . . review . . .
  pursuant to [the] petition,” §314(b). “If . . . review is instituted and
  not dismissed,” at the end of the litigation the Patent Trial and Ap-
  peal Board “shall issue a final written decision with respect to the pa-
  tentability of any patent claim challenged by the petitioner.” §318(a).
    Petitioner SAS sought review of respondent ComplementSoft’s
  software patent, alleging that all 16 of the patent’s claims were un-
  patentable. Relying on a Patent Office regulation recognizing a pow-
  er of “partial institution,” 37 CFR §42.108(a), the Director instituted
  review on some of the claims and denied review on the rest. The
  Board’s final decision addressed only the claims on which the Direc-
  tor had instituted review. On appeal, the Federal Circuit rejected
  SAS’s argument that §318(a) required the Board to decide the pa-
  tentability of every claim challenged in the petition.
Held: When the Patent Office institutes an inter partes review, it must
 decide the patentability of all of the claims the petitioner has chal-
 lenged. The plain text of §318(a) resolves this case. Its directive is
 both mandatory and comprehensive. The word “shall” generally im-
 poses a nondiscretionary duty, and the word “any” ordinarily implies
2                    SAS INSTITUTE INC. v. IANCU

                                  Syllabus

    every member of a group. Thus, §318(a) means that the Board must
    address every claim the petitioner has challenged. The Director’s
    “partial institution” power appears nowhere in the statutory text.
    And both text and context strongly counsel against inferring such a
    power.
       The statute envisions an inter partes review guided by the initial
    petition. See §312(a)(3). Congress structured the process such that
    the petitioner, not the Director, defines the proceeding’s contours.
    The ex parte reexamination statute shows that Congress knew exact-
    ly how to authorize the Director to investigate patentability questions
    “[o]n his own initiative, and at any time,” §303(a). The inter partes
    review statute indicates that the Director’s decision “whether” to in-
    stitute review “pursuant to [the] petition” is a yes-or-no choice.
    §314(b).
       Section 314(a)’s requirement that the Director find “a reasonable
    likelihood” that the petitioner will prevail on “at least 1 of the claims
    challenged in the petition” suggests, if anything, a regime where a
    reasonable prospect of success on a single claim justifies review of
    them all. Again, if Congress had wanted to adopt the Director’s
    claim-by-claim approach, it knew how to do so. See §304. Nor does it
    follow that, because §314(a) invests the Director with discretion on
    the question whether to institute review, it also invests him with dis-
    cretion regarding what claims that review will encompass. The rest
    of the statute confirms, too, that the petitioner’s petition, not the Di-
    rector’s discretion, should guide the life of the litigation. See, e.g.,
    §316(a)(8).
       The Director suggests that a textual discrepancy between §314(a)—
    which addresses whether to institute review based on claims found
    “in the petition”—and §318(a)—which addresses the Board’s final
    resolution of the claims challenged “by the petitioner”—means that
    the Director enjoys the power to institute a review covering fewer
    than all of the claims challenged in the petition. However, the stat-
    ute’s winnowing mechanism—which allows a patent owner to con-
    cede one part of a petitioner’s challenge and “[c]ancel any challenged
    patent claim,” §316(d)(1)(A)—fully explains why Congress adopted
    the slightly different language.
       The Director’s policy argument—that partial institution is efficient
    because it permits the Board to focus on the most promising chal-
    lenges and avoid spending time and resources on others—is properly
    addressed to Congress, not this Court. And the Director’s asserted
    “partial institution” power, which is wholly unmentioned in the stat-
    ute, is not entitled to deference under Chevron U. S. A. Inc. v. Natu-
    ral Resources Defense Council, Inc., 

. Finally, notwith-
    standing §314(d)—which makes the Director’s determination
                    Cite as: 584 U. S. ____ (2018)                   3

                               Syllabus

  whether to institute an inter partes review “final and nonappeala-
  ble”—judicial review remains available consistent with the Adminis-
  trative Procedure Act to ensure that the Patent Office does not ex-
  ceed its statutory bounds. Cuozzo Speed Technologies, LLC v. Lee,
  579 U. S. ___, distinguished. Pp. 4–14.

, reversed and remanded.

   GORSUCH, J., delivered the opinion of the Court, in which ROBERTS,
C. J., and KENNEDY, THOMAS, and ALITO, JJ., joined. GINSBURG, J., filed
a dissenting opinion, in which BREYER, SOTOMAYOR, and KAGAN, JJ.,
joined. BREYER, J., filed a dissenting opinion, in which GINSBURG and
SOTOMAYOR, JJ., joined, and in which KAGAN, J., joined except as to
Part III–A.
                        Cite as: 584 U. S. ____ (2018)                              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
                                   _________________

                                   No. 16–969
                                   _________________


SAS INSTITUTE INC., PETITIONER v. ANDREI IANCU,

      AS DIRECTOR, UNITED STATES PATENT

          AND TRADEMARK OFFICE, ET AL. 

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

           APPEALS FOR THE FEDERAL CIRCUIT

                                 [April 24, 2018]


   JUSTICE GORSUCH delivered the opinion of the Court.
   A few years ago Congress created “inter partes review.”
The new procedure allows private parties to challenge
previously issued patent claims in an adversarial process
before the Patent Office that mimics civil litigation. Re-
cently, the Court upheld the inter partes review statute
against a constitutional challenge. Oil States Energy
Services, LLC v. Greene’s Energy Group, LLC, ante, p. ___.
Now we take up a question concerning the statute’s opera-
tion. When the Patent Office initiates an inter partes
review, must it resolve all of the claims in the case, or may
it choose to limit its review to only some of them? The
statute, we find, supplies a clear answer: the Patent Office
must “issue a final written decision with respect to the
patentability of any patent claim challenged by the peti-
tioner.” 

. §318(a) (emphasis added). In this
context, as in so many others, “any” means “every.” The
agency cannot curate the claims at issue but must decide
them all.
   “To promote the Progress of Science and useful Arts,”
2               SAS INSTITUTE INC. v. IANCU

                      Opinion of the Court

Congress long ago created a patent system granting inven-
tors rights over the manufacture, sale, and use of their
inventions. U. S. Const., Art. I, §8, cl. 8; see 

.
§154(a)(1). To win a patent, an applicant must (among
other things) file “claims” that describe the invention and
establish to the satisfaction of the Patent Office the inven-
tion’s novelty and nonobviousness. See §§102, 103, 112(b),
131; Cuozzo Speed Technologies, LLC v. Lee, 579 U. S. ___,
___–___ (2016) (slip op., at 2–3).
   Sometimes, though, bad patents slip through. Maybe
the invention wasn’t novel, or maybe it was obvious all
along, and the patent owner shouldn’t enjoy the special
privileges it has received. To remedy these sorts of prob-
lems, Congress has long permitted parties to challenge the
validity of patent claims in federal court. See §§282(b)(2)–
(3). More recently, Congress has supplemented litigation
with various administrative remedies. The first of these
was ex parte reexamination. Anyone, including the Direc-
tor of the Patent Office, can seek ex parte reexamination
of a patent claim. §§302, 303(a). Once instituted, though,
an ex parte reexamination follows essentially the same
inquisitorial process between patent owner and examiner
as the initial Patent Office examination. §305. Later,
Congress supplemented ex parte reexamination with inter
partes reexamination. Inter partes reexamination (since
repealed) provided a slightly more adversarial process,
allowing a third party challenger to submit comments
throughout the proceeding. §314(b)(2) (2006 ed.) (re-
pealed). But otherwise it too followed a more or less in-
quisitorial course led by the Patent Office. §314(a). Ap-
parently unsatisfied with this approach, in 2011 Congress
repealed inter partes reexamination and replaced it with
inter partes review. See 

. §§311–319 (2012 ed.).
   The new inter partes review regime looks a good deal
more like civil litigation. At its outset, a party must file “a
petition to institute an inter partes review of [a] patent.”
                 Cite as: 584 U. S. ____ (2018)            3

                     Opinion of the Court

§311(a). The petition “may request to cancel as unpatent-
able 1 or more claims of [the] patent” on the ground that
the claims are obvious or not novel. §311(b); see §§102
and 103. In doing so, the petition must identify “each
claim challenged,” the grounds for the challenge, and the
evidence supporting the challenge. §312(a)(3). The patent
owner, in turn, may respond with “a preliminary response
to the petition” explaining “why no inter partes review
should be instituted.” §313. With the parties’ submissions
before him, the Director then decides “whether to institute
an inter partes review . . . pursuant to [the] petition.”
§314(b). (In practice, the agency’s Patent Trial and Appeal
Board exercises this authority on behalf of the Director,
see 37 CFR §42.4(a) (2017).) Before instituting review, the
Director must determine, based on the parties’ papers,
“that there is a reasonable likelihood that the petitioner
would prevail with respect to at least 1 of the claims chal-
lenged in the petition.” 

. §314(a).
   Once the Director institutes an inter partes review, the
matter proceeds before the Board with many of the usual
trappings of litigation. The parties conduct discovery and
join issue in briefing and at an oral hearing. §§316(a)(5),
(6), (8), (10), (13). During the course of the case, the pa-
tent owner may seek to amend its patent or to cancel one
or more of its claims. §316(d). The parties may also settle
their differences and seek to end the review. §317. But
“[i]f an inter partes review is instituted and not dis-
missed,” at the end of the litigation the Board “shall issue
a final written decision with respect to the patentability of
any patent claim challenged by the petitioner.” §318(a).
   Our case arose when SAS sought an inter partes review
of ComplementSoft’s software patent. In its petition, SAS
alleged that all 16 of the patent’s claims were unpatent-
able for various reasons. The Director (in truth the Board
acting on the Director’s behalf) concluded that SAS was
likely to succeed with respect to at least one of the claims
4               SAS INSTITUTE INC. v. IANCU

                      Opinion of the Court

and that an inter partes review was therefore warranted.
But instead of instituting review on all of the claims chal-
lenged in the petition, the Director instituted review on
only some (claims 1 and 3–10) and denied review on the
rest. The Director did all this on the strength of a Patent
Office regulation that purported to recognize a power of
“partial institution,” claiming that “[w]hen instituting
inter partes review, the [Director] may authorize the re-
view to proceed on all or some of the challenged claims and
on all or some or the grounds of unpatentability asserted
for each claim.” 37 CFR §42.108(a). At the end of litiga-
tion, the Board issued a final written decision finding
claims 1, 3, and 5–10 to be unpatentable while upholding
claim 4. But the Board’s decision did not address the
remaining claims on which the Director had refused
review.
   That last fact led SAS to seek review in the Federal
Circuit. There SAS argued that 

. §318(a) re-
quired the Board to decide the patentability of every claim
SAS challenged in its petition, not just some. For its part,
the Federal Circuit rejected SAS’s argument over a vigor-
ous dissent by Judge Newman. SAS Institute, Inc. v.
ComplementSoft, LLC, 

(2016). We granted
certiorari to decide the question ourselves. 581 U. S. ___
(2017).
   We find that the plain text of §318(a) supplies a ready
answer. It directs that “[i]f an inter partes review is insti-
tuted and not dismissed under this chapter, the [Board]
shall issue a final written decision with respect to the
patentability of any patent claim challenged by the peti-
tioner . . . .” §318(a) (emphasis added). This directive is
both mandatory and comprehensive. The word “shall”
generally imposes a nondiscretionary duty. See Lexecon
Inc. v. Milberg Weiss Bershad Hynes & Lerach, 

, 35 (1998). And the word “any” naturally carries “an
expansive meaning.” United States v. Gonzales, 520 U. S.
                 Cite as: 584 U. S. ____ (2018)            5

                     Opinion of the Court

1, 5 (1997). When used (as here) with a “singular noun in
affirmative contexts,” the word “any” ordinarily “refer[s] to
a member of a particular group or class without distinc-
tion or limitation” and in this way “impl[ies] every member
of the class or group.” Oxford English Dictionary (3d ed.,
Mar. 2016), www.oed.com/view/Entry/8973 (OED) (empha-
sis added) (all Internet materials as last visited Apr. 20,
2018). So when §318(a) says the Board’s final written
decision “shall” resolve the patentability of “any patent
claim challenged by the petitioner,” it means the Board
must address every claim the petitioner has challenged.
   That would seem to make this an easy case. Where a
statute’s language carries a plain meaning, the duty of an
administrative agency is to follow its commands as writ-
ten, not to supplant those commands with others it may
prefer. Social Security Bd. v. Nierotko, 

, 369
(1946). Because SAS challenged all 16 claims of Comple-
mentSoft’s patent, the Board in its final written decision
had to address the patentability of all 16 claims. Much as
in the civil litigation system it mimics, in an inter partes
review the petitioner is master of its complaint and nor-
mally entitled to judgment on all of the claims it raises,
not just those the decisionmaker might wish to address.
   The Director replies that things are not quite as simple
as they seem. Maybe the Board has to decide every claim
challenged by the petitioner in an inter partes review.
But, he says, that doesn’t mean every challenged claim
gains admission to the review process. In the Director’s
view, he retains discretion to decide which claims make it
into an inter partes review and which don’t. The trouble
is, nothing in the statute says anything like that. The
Director’s claimed “partial institution” power appears
nowhere in the text of §318, or anywhere else in the stat-
ute for that matter. And what can be found in the statutory
text and context strongly counsels against the Director’s
view.
6               SAS INSTITUTE INC. v. IANCU

                     Opinion of the Court

   Start where the statute does. In its very first provision,
the statute says that a party may seek inter partes review
by filing “a petition to institute an inter partes review.”
§311(a). This language doesn’t authorize the Director to
start proceedings on his own initiative. Nor does it con-
template a petition that asks the Director to initiate what-
ever kind of inter partes review he might choose. Instead,
the statute envisions that a petitioner will seek an inter
partes review of a particular kind—one guided by a peti-
tion describing “each claim challenged” and “the grounds
on which the challenge to each claim is based.” §312(a)(3).
From the outset, we see that Congress chose to structure a
process in which it’s the petitioner, not the Director, who
gets to define the contours of the proceeding. And “[ j]ust
as Congress’ choice of words is presumed to be deliberate”
and deserving of judicial respect, “so too are its structural
choices.” University of Tex. Southwestern Medical Center
v. Nassar, 

, 353 (2013).
   It’s telling, too, to compare this structure with what
came before. In the ex parte reexamination statute, Con-
gress embraced an inquisitorial approach, authorizing the
Director to investigate a question of patentability “[o]n his
own initiative, and at any time.” §303(a). If Congress had
wanted to give the Director similar authority over the
institution of inter partes review, it knew exactly how to
do so—it could have simply borrowed from the statute
next door. But rather than create (another) agency-led,
inquisitorial process for reconsidering patents, Congress
opted for a party-directed, adversarial process. Congress’s
choice to depart from the model of a closely related statute
is a choice neither we nor the agency may disregard. See

–354.
   More confirmation comes as we move to the point of
institution. Here the statute says the Director must de-
cide “whether to institute an inter partes review . . . pur-
suant to a petition.” §314(b). The Director, we see, is
                  Cite as: 584 U. S. ____ (2018)            7

                      Opinion of the Court

given only the choice “whether” to institute an inter partes
review. That language indicates a binary choice—either
institute review or don’t. And by using the term “pursu-
ant to,” Congress told the Director what he must say yes
or no to: an inter partes review that proceeds “[i]n accord-
ance with” or “in conformance to” the petition. OED,
www.oed.com/view/Entry/155073. Nothing suggests the
Director enjoys a license to depart from the petition and
institute a different inter partes review of his own design.
   To this the Director replies by pointing to another part
of §314. Section 314(a) provides that the Director may not
authorize an inter partes review unless he determines
“there is a reasonable likelihood” the petitioner will pre-
vail on “at least 1 of the claims challenged in the petition.”
The Director argues that this language requires him to
“evaluate claims individually” and so must allow him to
institute review on a claim-by-claim basis as well. Brief
for Federal Respondent 28. But this language, if any-
thing, suggests just the opposite. Section 314(a) does not
require the Director to evaluate every claim individually.
Instead, it simply requires him to decide whether the
petitioner is likely to succeed on “at least 1” claim. Once
that single claim threshold is satisfied, it doesn’t matter
whether the petitioner is likely to prevail on any additional
claims; the Director need not even consider any other
claim before instituting review. Rather than contemplate
claim-by-claim institution, then, the language anticipates
a regime where a reasonable prospect of success on a
single claim justifies review of all.
   Here again we know that if Congress wanted to adopt
the Director’s approach it knew exactly how to do so. The
ex parte reexamination statute allows the Director to
assess whether a request raises “a substantial new ques-
tion of patentability affecting any claim” and (if so) to
institute reexamination limited to “resolution of the ques-
tion.” §304 (emphasis added). In other words, that stat-
8               SAS INSTITUTE INC. v. IANCU

                     Opinion of the Court

ute allows the Director to institute proceedings on a claim-
by-claim and ground-by-ground basis. But Congress didn’t
choose to pursue that known and readily available ap-
proach here. And its choice to try something new must be
given effect rather than disregarded in favor of the comfort
of what came before. See 

–354.
   Faced with this difficulty, the Director tries another
tack. He points to the fact that §314(a) doesn’t require
him to institute an inter partes review even after he finds
the “reasonable likelihood” threshold met with respect to
one claim. Whether to institute proceedings upon such a
finding, he says, remains a matter left to his discretion.
See Cuozzo, 579 U. S., at ___ (slip op., at 9). But while
§314(a) invests the Director with discretion on the ques-
tion whether to institute review, it doesn’t follow that the
statute affords him discretion regarding what claims that
review will encompass. The text says only that the Direc-
tor can decide “whether” to institute the requested re-
view—not “whether and to what extent” review should
proceed. §314(b).
   The rest of the statute confirms, too, that the petition-
er’s petition, not the Director’s discretion, is supposed to
guide the life of the litigation. For example, §316(a)(8)
tells the Director to adopt regulations ensuring that, “after
an inter partes review has been instituted,” the patent
owner will file “a response to the petition.” Surely it
would have made little sense for Congress to insist on a
response to the petition if, in truth, the Director enjoyed
the discretion to limit the claims under review. What’s the
point, after all, of answering claims that aren’t in the
proceeding? If Congress had meant to afford the Director
the power he asserts, we would have expected it to in-
struct him to adopt regulations requiring the patent owner
to file a response to the Director’s institution notice or to
the claims on which the Director instituted review. Yet we
have nothing like that here. And then and again there is
                 Cite as: 584 U. S. ____ (2018)            9

                     Opinion of the Court

§318(a). At the end of the proceeding, §318(a) categorically
commands the Board to address in its final written
decision “any patent claim challenged by the petitioner.”
In all these ways, the statute tells us that the petitioner’s
contentions, not the Director’s discretion, define the scope
of the litigation all the way from institution through to
conclusion.
   The Director says we can find at least some hint of the
discretion he seeks by comparing §314(a) and §318(a). He
notes that, when addressing whether to institute review at
the beginning of the litigation, §314(a) says he must focus
on the claims found “in the petition”; but when addressing
what claims the Board must address at the end of the
litigation, §318(a) says it must resolve the claims chal-
lenged “by the petitioner.” According to the Director, this
(slight) linguistic discrepancy means the claims the Board
must address in its final decision are not necessarily the
same as those identified in the petition. And the only
possible explanation for this arrangement, the Director
submits, is that he must enjoy the (admittedly implicit)
power to institute an inter partes review that covers fewer
than all of the claims challenged in the petition.
   We just don’t see it. Whatever differences they might
display, §314(a) and §318(a) both focus on the petitioner’s
contentions and, given that, it’s difficult to see how they
might be read to give the Director power to decide what
claims are at issue. Particularly when there’s a much
simpler and sounder explanation for the statute’s wording.
As we’ve seen, a patent owner may move to “[c]ancel any
challenged patent claim” during the course of an inter
partes review, effectively conceding one part of a petition-
er’s challenge. §316(d)(1)(A). Naturally, then, the claims
challenged “in the petition” will not always survive to the
end of the case; some may drop out thanks to the patent
owner’s actions. And in that light it is plain enough why
Congress provided that only claims still challenged “by the
10              SAS INSTITUTE INC. v. IANCU

                      Opinion of the Court

petitioner” at the litigation’s end must be addressed in the
Board’s final written decision. The statute’s own winnow-
ing mechanism fully explains why Congress adopted
slightly different language in §314(a) and §318(a). We
need not and will not invent an atextual explanation for
Congress’s drafting choices when the statute’s own terms
supply an answer. See United States v. Ron Pair Enter-
prises, Inc., 

, 240–241 (1989) (“[A]s long as
the statutory scheme is coherent and consistent, there
generally is no need for a court to inquire beyond the plain
language of the statute”).
   Moving past the statute’s text and context, the Director
attempts a policy argument. He tells us that partial insti-
tution is efficient because it permits the Board to focus on
the most promising challenges and avoid spending time
and resources on others. Brief for Federal Respondent 35–
36; see also post, at 1 (GINSBURG, J., dissenting); post, at
7–8 (BREYER, J., dissenting). SAS responds that all patent
challenges usually end up being litigated somewhere, and
that partial institution creates inefficiency by requiring
the parties to litigate in two places instead of one—the
Board for claims the Director chooses to entertain and a
federal court for claims he refuses. Indeed, SAS notes, the
government itself once took the same view, arguing that
partial institution “ ‘undermine[s] the Congressional effi-
ciency goal’ ” for this very reason. Brief for Petitioner 30.
Each side offers plausible reasons why its approach might
make for the more efficient policy. But who should win
that debate isn’t our call to make. Policy arguments are
properly addressed to Congress, not this Court. It is
Congress’s job to enact policy and it is this Court’s job to
follow the policy Congress has prescribed. And whatever
its virtues or vices, Congress’s prescribed policy here is
clear: the petitioner in an inter partes review is entitled to
                     Cite as: 584 U. S. ____ (2018)                   11

                          Opinion of the Court

a decision on all the claims it has challenged.*
   That leaves the Director to suggest that, however this
Court might read the statute, he should win anyway
because of Chevron U. S. A. Inc. v. Natural Resources
Defense Council, Inc., 

(1984). Even though
the statute says nothing about his asserted “partial insti-
tution” power, the Director says the statute is at least
ambiguous on the propriety of the practice and so we
should leave the matter to his judgment. For its part, SAS
replies that we might use this case as an opportunity to
abandon Chevron and embrace the “ ‘impressive body’ ” of
pre-Chevron law recognizing that “ ‘the meaning of a stat-
utory term’ ” is properly a matter for “ ‘judicial [rather
than] administrative judgment.’ ” Brief for Petitioner 41
(quoting Pittston Stevedoring Corp. v. Dellaventura, 

, 49 (CA2 1976) (Friendly, J.)).
   But whether Chevron should remain is a question we
may leave for another day. Even under Chevron, we owe
an agency’s interpretation of the law no deference unless,
after “employing traditional tools of statutory construc-
tion,” we find ourselves unable to discern Congress’s
——————
  * JUSTICE GINSBURG suggests the Director might yet avoid this com-
mand by refusing to review a petition he thinks too broad while signal-
ing his willingness to entertain one more tailored to his sympathies.
Post, at 1 (dissenting opinion). We have no occasion today to consider
whether this stratagem is consistent with the statute’s demands. See
Cuozzo Speed Technologies, LLC v. Lee, 579 U. S. ___, ___ (2016) (slip
op., at 11) (noting that courts may invalidate “ ‘shenanigans’ ” by the
Director that are “outside [his] statutory limits”); CAB v. Delta Air
Lines, Inc., 

, 328 (1961) (questioning an agency’s “power to
do indirectly what it cannot do directly”). But even assuming (without
granting) the law would tolerate this tactic, it would show only that a
lawful means exists for the Director to achieve his policy aims—not
that he “should be allowed to improvise on the powers granted by
Congress” by devising an extralegal path to the same goal. 

That an agency’s improvisation might be thought by some more expedi-
ent than what the law allows, post, at 1, does nothing to commend it
either, for lawful ends do not justify unlawful means.
12              SAS INSTITUTE INC. v. IANCU

                     Opinion of the Court

, n. 9. And after applying
traditional tools of interpretation here, we are left with no
uncertainty that could warrant deference. The statutory
provisions before us deliver unmistakable commands. The
statute hinges inter partes review on the filing of a peti-
tion challenging specific patent claims; it makes the peti-
tion the centerpiece of the proceeding both before and after
institution; and it requires the Board’s final written deci-
sion to address every claim the petitioner presents for
review. There is no room in this scheme for a wholly
unmentioned “partial institution” power that lets the
Director select only some challenged claims for decision.
The Director may (today) think his approach makes for
better policy, but policy considerations cannot create an
ambiguity when the words on the page are clear. See SEC
v. Sloan, 

, 116–117 (1978). Neither may we
defer to an agency official’s preferences because we imag-
ine some “hypothetical reasonable legislator” would have
favored that approach. Post, at 9 (BREYER, J., dissenting).
Our duty is to give effect to the text that 535 actual legis-
lators (plus one President) enacted into law.
   At this point, only one final question remains to resolve.
Even if the statute forbids his partial institution practice,
the Director suggests we lack the power to say so. By way
of support, he points to §314(d) and our decision in Cuozzo,
579 U. S. ___. Section 314(d) says that the “determination
by the Director whether to institute an inter partes review
under this section shall be final and nonappealable.” In
Cuozzo, we held that this provision prevented courts from
entertaining an argument that the Director erred in insti-
tuting an inter partes review of certain patent claims. Id.,
at ___–___ (slip op., at 7–12). The Director reads these
authorities as foreclosing judicial review of any legal
question bearing on the institution of inter partes re-
view—including whether the statute permits his “partial
institution” practice.
                  Cite as: 584 U. S. ____ (2018)             13

                      Opinion of the Court

   But this reading overreads both the statute and our
precedent. As Cuozzo recognized, we begin with “the
‘strong presumption’ in favor of judicial review.” Id., at
___ (slip op., at 9). To overcome that presumption, Cuozzo
explained, this Court’s precedents require “clear and
convincing indications” that Congress meant to foreclose
review. Id., at ___ (slip op., at 10) (internal quotation
marks omitted). Given the strength of this presumption
and the statute’s text, Cuozzo concluded that §314(d)
precludes judicial review only of the Director’s “initial
determination” under §314(a) that “there is a ‘reasonable
likelihood’ that the claims are unpatentable on the
grounds asserted” and review is therefore justified. Id., at
___ (slip op., at 9); see id., at ___ (slip op., at 12) (review
unavailable “where a patent holder merely challenges the
Patent Office’s ‘determin[ation] that the information
presented in the petition . . . shows that there is a reason-
able likelihood’ of success ‘with respect to at least 1 of the
claims challenged’ ”); 

“petition was not
pleaded ‘with particularity’ under §312 is little more than
a challenge to the Patent Office’s conclusion, under
§314(a), that the ‘information presented in the petition’
warranted review”). In fact, Cuozzo proceeded to empha-
size that §314(d) does not “enable the agency to act outside
its statutory limits.” Id., at ___ (slip op., at 11). If a party
believes the Patent Office has engaged in “ ‘shenanigans’ ”
by exceeding its statutory bounds, judicial review remains
available consistent with the Administrative Procedure
Act, which directs courts to set aside agency action “not in
accordance with law” or “in excess of statutory jurisdic-
tion, authority, or limitations.”           Ibid.; 

.
§§706(2)(A), (C).
   And that, of course, is exactly the sort of question we are
called upon to decide today. SAS does not seek to chal-
lenge the Director’s conclusion that it showed a “reason-
able likelihood” of success sufficient to warrant “insti-
14              SAS INSTITUTE INC. v. IANCU

                     Opinion of the Court

tut[ing] an inter partes review.” 

. §§314(a), (d).
No doubt SAS remains very pleased with the Director’s
judgment on that score. Instead, SAS contends that the
Director exceeded his statutory authority by limiting the
review to fewer than all of the claims SAS challenged.
And nothing in §314(d) or Cuozzo withdraws our power to
ensure that an inter partes review proceeds in accordance
with the law’s demands.
  Because everything in the statute before us confirms
that SAS is entitled to a final written decision addressing
all of the claims it has challenged and nothing suggests we
lack the power to say so, the judgment of the Federal
Circuit is reversed and the case is remanded for further
proceedings consistent with this opinion.
                                                 So ordered.
                 Cite as: 584 U. S. ____ (2018)            1

                   GINSBURG, J., dissenting

SUPREME COURT OF THE UNITED STATES
                         _________________

                          No. 16–969
                         _________________


SAS INSTITUTE INC., PETITIONER v. ANDREI IANCU,

      AS DIRECTOR, UNITED STATES PATENT

          AND TRADEMARK OFFICE, ET AL. 

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

           APPEALS FOR THE FEDERAL CIRCUIT

                        [April 24, 2018]


  JUSTICE GINSBURG, with whom JUSTICE BREYER,
JUSTICE SOTOMAYOR, and JUSTICE KAGAN join, dissenting.
  Given the Court’s wooden reading of 

. §318(a),
and with “no mandate to institute [inter partes] review” at
all, Cuozzo Speed Technologies, LLC v. Lee, 579 U. S. ___,
___ (2016) (slip op., at 9), the Patent Trial and Appeal
Board could simply deny a petition containing challenges
having no “reasonable likelihood” of success, §314(a).
Simultaneously, the Board might note that one or more
specified claims warrant reexamination, while others
challenged in the petition do not. Petitioners would then
be free to file new or amended petitions shorn of challenges
the Board finds unworthy of inter partes review. Why
should the statute be read to preclude the Board’s more
rational way to weed out insubstantial challenges? For
the reasons stated by JUSTICE BREYER, the Court’s opinion
offers no persuasive answer to that question, and no cause
to believe Congress wanted the Board to spend its time so
uselessly.
                 Cite as: 584 U. S. ____ (2018)            1

                     BREYER, J., dissenting

SUPREME COURT OF THE UNITED STATES
                         _________________

                          No. 16–969
                         _________________


SAS INSTITUTE INC., PETITIONER v. ANDREI IANCU,

      AS DIRECTOR, UNITED STATES PATENT

          AND TRADEMARK OFFICE, ET AL. 

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

           APPEALS FOR THE FEDERAL CIRCUIT

                        [April 24, 2018]


   JUSTICE BREYER, with whom JUSTICE GINSBURG and
JUSTICE SOTOMAYOR join, and with whom JUSTICE KAGAN
joins except as to Part III–A, dissenting.
   This case requires us to engage in a typical judicial
exercise, construing a statute that is technical, unclear,
and constitutes a minor procedural part of a larger admin-
istrative scheme. I would follow an interpretive technique
that judges often use in such cases. Initially, using “tradi-
tional tools of statutory construction,” INS v. Cardoza-
Fonseca, 

, 446 (1987), I would look to see
whether the relevant statutory phrase is ambiguous or
leaves a gap that Congress implicitly delegated authority
to the agency to fill. Chevron U. S. A. Inc. v. Natural
Resources Defense Council, Inc., 

, 842–843
(1984). If so, I would look to see whether the agency’s
interpretation is reasonable. 

Because I be-
lieve there is such a gap and because the Patent Office’s
interpretation of the ambiguous phrase is reasonable, I
would conclude that the Patent Office’s interpretation is
lawful.
                            I
  The majority sets out the statutory framework that
establishes “inter partes review.” See ante, at 2–3; 35
2               SAS INSTITUTE INC. v. IANCU

                     BREYER, J., dissenting

U. S. C. §§311–319. An example will help the reader keep
that framework in mind. Suppose the Patent Office issues
a patent containing, say, 16 different claims. A challenger,
believing the patent is invalid, seeks to invoke the inter
partes review procedure.
   The statutory chapter entitled “Inter partes review”
explains just how this is to be done. See §§311–319. First,
the challenger files a petition requesting “cancel[lation]” of
one or more of the patent claims as “unpatentable” be-
cause “prior art” shows, for example, that they are not
“novel.” §311(b); see §§102, 103. That petition must detail
the grounds for the challenge and the supporting evidence,
along with providing certain technical information. §312.
Second, the patent owner may file a “preliminary re-
sponse” to the petition. §313.
   Third, the Director of the Patent Office will decide
whether to “institute” inter partes review. §314. The
statute specifies that the Director “may not authorize an
inter partes review to be instituted unless the Director
determines . . . that there is a reasonable likelihood that
the petitioner would prevail with respect to at least 1 of
the claims challenged in the petition.” §314(a). Thus, in
my example, if the Director determines that none of the 16
challenges in the petition has likely merit, he cannot
institute an inter partes review. Even if there is one
potentially meritorious challenge, we have said that the
statute contains “no mandate to institute review,” so the
Director still has discretion to deny a petition. Cuozzo
Speed Technologies, LLC v. Lee, 579 U. S. ___, ___ (2016)
(slip op., at 9). We have also held that the Director’s
decision whether to institute review is normally not re-
viewable. Id., at ___–___ (slip op., at 11–12).
   The Director, by regulation, has delegated the power to
institute review to the Patent Trial and Appeal Board. 37
CFR §42.4(a) (2017). And the Director has further provided
by regulation that where a petition challenges several
                 Cite as: 584 U. S. ____ (2018)           3

                    BREYER, J., dissenting

patent claims (say, all 16 claims in my example), “the
Board may authorize the review to proceed on all or some
of the challenged claims.” §42.108(a) (emphasis added).
Thus, where some, but not all, of the challenges have
likely merit (say, 1 of the 16 has likely merit and the
others are close to frivolous), the Board is free to conduct
inter partes review only as to the challenge with likely
merit.
   Fourth, the statute next describes the relation of a
petition for review and an instituted review to other pro-
ceedings involving the challenged patent. §315. Fifth, the
statute describes what happens once the Board begins its
inter partes review, including how the Board is to take
evidence and make its decisions, §316, and the nature and
effect of settlements, §317.
   Sixth, the statute sets forth the section primarily at
issue here, which describes what happens at the end of the
process. It says:
    “Final Written Decision. If an inter partes review is
    instituted and not dismissed under this chapter, the
    Patent Trial and Appeal Board shall issue a final
    written decision with respect to the patentability of
    any patent claim challenged by the petitioner and any
    new claim added under section 316(d).” §318(a) (em-
    phasis added).
  Finally, the chapter says that a “party dissatisfied with
the final written decision . . . may appeal the decision” to
the U. S. Court of Appeals for the Federal Circuit. §319;
see §141(c).
  Thus, going through this process, if a petitioner files a
petition challenging 16 claims and the Board finds that
the challenges to 15 of the claims are frivolous, the Board
may then, as it interprets the statute, begin and proceed
through the inter partes review process as to the remain-
ing claim, number 16, but not in respect to the other 15
4               SAS INSTITUTE INC. v. IANCU

                     BREYER, J., dissenting

claims. Eventually the Board will produce a “final written
decision” as to the patentability of claim number 16, which
decision the challenger (or the patentee) can appeal to the
Federal Circuit.
                               II
   Now let us return to the question at hand, the meaning
of the phrase “any patent claim challenged by the peti-
tioner” in §318(a). Do those words unambiguously refer,
as the majority believes, to “any patent claim challenged
by the petitioner” in the petitioner’s original petition? The
words “in the petitioner’s original petition” do not appear
in the statute. And the words that do appear, “any patent
claim challenged by the petitioner,” could be modified by
using different words that similarly do not appear, for
example, the words “in the inter partes review proceed-
ing.” But without added words, the phrase “challenged by
the petitioner” does not tell us whether the relevant chal-
lenge is one made in the initial petition or only one made
in the inter partes review proceeding itself. And, linguis-
tically speaking, there is as much reason to fill that gap
with reference to the claims still being challenged in the
proceeding itself as there is to fill it with reference to
claims that were initially challenged in the petition but
which the Board weeded out before the inter partes review
proceeding began.
   Which reading we give the statute makes a difference.
The first reading, the majority’s reading, means that in
my example, the Board must consider and write a final,
and appealable, see §319, decision in respect to the chal-
lenges to all 16 claims, including the 15 frivolous challenges.
The second reading requires the Board to write a final,
appealable decision only in respect to the challenge to the
claim (number 16 in my example) that survived the
Board’s initial screening, namely, in my example, the one
challenge in respect to which the Board found a “reason-
                  Cite as: 584 U. S. ____ (2018)            5

                     BREYER, J., dissenting

able likelihood that the petitioner would prevail.” §314(a).
   I cannot find much in the statutory context to support
the majority’s claim that the statutory words “claim chal-
lenged by the petitioner” refer unambiguously to claims
challenged initially in the petition. After all, the majority
agrees that they do not refer to claims that initially were
challenged in the petition but were later settled or with-
drawn. Ante, at 9–10; see §316(d)(1)(A) (allowing the
patent owner to cancel a challenged patent claim during
inter partes review); §317 (addressing settlement). The
majority says that weeded-out challenges, unlike settled
matters or canceled claims, involve claims that are still
being “challenged ‘by the petitioner’ at the litigation’s
end.” Ante, at 9–10. But weeded-out challenges are the
same as settled matters and canceled claims in this re-
spect. The petitioner cannot continue to challenge a claim
once that challenge is weeded out by the Board at the
institution phase. He cannot pursue it before the Board in
the inter partes review, and normally he cannot pursue it
in a court of appeals. See Cuozzo, 579 U. S., at ___–___
(slip op., at 11–12). The petitioner might bring a totally
separate case in court in which he challenges the claim,
but that is a different matter that is not the subject of this
statutory chapter.
   Nor does the chapter’s structure help fill the statutory
gap. I concede that if we examine the “final written deci-
sion” section, §318(a), just after reading the three initial
sections of the statute, §§311, 312, and 313, we may be
tempted to believe that the words “any patent claim chal-
lenged” in §318(a) must refer to the claims challenged in
the petition, just as the words “each claim challenged” in
§312(a)(3) unmistakably do. But once we look at the
whole statute, this temptation disappears. The first sec-
tion, §311, describing the inter partes review process, does
not use the word “challenge.” The next section, §312,
describes the requirements for the initial petition, which is
6                SAS INSTITUTE INC. v. IANCU

                      BREYER, J., dissenting

filed before any inter partes proceeding has been insti-
tuted. It is about the petition, so it is not surprising that it
refers to the claims challenged in the petition. The next
section, §313, concerns the preliminary response, which is
similarly filed before the inter partes review proceeding
has been instituted and is thus similarly focused on the
petition, although it does not use the word “challenged.”
   The very next section, however, §314, along with part of
§315, describes preliminary screening and the institution
of the inter partes review proceeding. The remainder of
§315, and the following sections, §§316 and 317, then
describe how that proceeding, once instituted, will be
conducted (and provide for settlements). Only then does
§318 appear. That statutory provision tells the Board
that, at the conclusion of the inter partes review proceed-
ing, it must “issue a final written decision with respect to
the patentability of any patent claim challenged by the
petitioner.” §318(a). And in this context, a context about
the inter partes review proceeding itself, it is more than
reasonable to think that the phrase “patent claim chal-
lenged by the petitioner” refers to challenges made in the
proceeding, not challenges made in the petition but never
made a part of the proceeding.
   I am not helped by examining, as the majority exam-
ines, what Congress might have done had it used other
language. Ante, at 6–8. The majority points out that had
Congress meant anything other than “challenged in the
petition,” it might have said so more clearly. 

Congress had meant “challenged in the peti-
tion,” it might have used the words “in the petition.” After
all, it used those very words only four sections earlier. See
§314(a) (referring to “claims challenged in the petition”).
This argument, like many such arguments, is a wash.
   Neither am I helped by analogizing the inter partes
review proceeding to civil litigation. Cf. ante, at 2–3, 5.
That is because, as this Court said in Cuozzo, inter partes
                  Cite as: 584 U. S. ____ (2018)            7

                     BREYER, J., dissenting

review is a “hybrid proceeding.” 579 U. S., at ___ (slip op.,
at 16). It has some adversarial characteristics, but “in
other significant respects, inter partes review is less like a
judicial proceeding and more like a specialized agency
proceeding.” Id., at ___ (slip op., at 15). Its purposes are
not limited to “helping resolve concrete patent-related
disputes among parties,” but extend to “reexamin[ing] . . .
an earlier administrative grant of a patent” and “pro-
tect[ing] the public’s ‘paramount interest in seeing that
patent monopolies . . . are kept within their legitimate
scope.’ ” 

Mfg. Co. v.
Automotive Maintenance Machinery Co., 

,
816 (1945); ellipsis in original); see also Oil States Energy
Services, LLC v. Greene’s Energy Group, LLC, ___ U. S.
___, ___–___ (2018) (slip op., at 8–9).
   Finally, I would turn to the likely purposes of the statu-
tory provision. As the majority points out, §314(a) makes
clear that the “Director” (now his delegate, the Board) is to
determine whether there is a “reasonable likelihood” of
success as to at least one of the claims the petition chal-
lenges. If not, he cannot initiate an inter partes review
proceeding. If so, §314(a) “invests the Director with dis-
cretion on the question whether to institute review.” Ante,
at 8 (emphasis deleted); 

, at ___ (slip op., at
9). As I have said, Patent Office regulations allow the
Board to proceed with inter partes review of some of the
claims a petitioner challenges (say, only those where there
is a reasonable likelihood of success), but not of others. 37
CFR §42.108(a).
   The majority points out that it does not follow from
§314(a) that the statute affords the Director discretion
regarding what claims that review will encompass. The
text says only that the Director can decide “whether” to
institute the requested review, not “whether and to what
extent” review should proceed. Ante, at 8 (emphasis de-
leted). That is certainly so. But I think that when we, as
8               SAS INSTITUTE INC. v. IANCU

                     BREYER, J., dissenting

judges, face a difficult text, it is often helpful to ask not
just “whether” or “what” but also “why.” Why, asks the
Patent Office, would Congress have intended to require
the Board to proceed with an inter partes review, take
evidence, and hear argument in respect to challenges to
claims that the Board had previously determined had no
“reasonable likelihood” of success? The statute would
seem to give the Director discretion to achieve the oppo-
site, namely, to avoid wasting the Board’s time and effort
reviewing challenges that it has already decided have no
“reasonable likelihood of success.” In my example, why
make the Board do further work on the challenges to
claims 1 through 15, which the Board has already decided
are near frivolous?
   More than that, to read §318(a) as requiring a “final
written decision” in respect to those 15 perhaps frivolous
challenges would seem to lead to judicial review of the
Board’s decision about those frivolous challenges. After
all, §319 of the statute says that a “party dissatisfied with
the final written decision of the [Board] under section
318(a),” the provision before us, “may appeal the decision”
to the Federal Circuit. And the majority’s interpretation
is anomalous in that it is difficult to imagine why Con-
gress, with one hand, would make the agency’s weeding-
out decision nonreviewable, see 

, at ___–___
(slip op., at 11–12), yet at the same time would make the
decision reviewable via the requirement that the Board
issue a “final written” appealable “decision” with respect
to that weeded-out challenge.
                              III
  I end up where I began. Section 318(a) contains a gap
just after the words “challenged by the petitioner.” Con-
siderations of context, structure, and purpose do not close
the gap. And under Chevron, “where a statute leaves a
‘gap’ or is ‘ambigu[ous],’ we typically interpret it as grant-
                 Cite as: 584 U. S. ____ (2018)            9

                     BREYER, J., dissenting

ing the agency leeway to enact rules that are reasonable in
light of the text, nature, and purpose of the statute.”

, at ___ (slip op., at 13) (quoting United
States v. Mead Corp., 

, 229 (2001); alteration
in original).
                             A
  In referring to Chevron, I do not mean that courts are to
treat that case like a rigid, black-letter rule of law, in-
structing them always to allow agencies leeway to fill
every gap in every statutory provision. See Mead 

–231. Rather, I understand Chevron as a
rule of thumb, guiding courts in an effort to respect that
leeway which Congress intended the agencies to have. I
recognize that Congress does not always consider such
matters, but if not, courts can often implement a more
general, virtually omnipresent congressional purpose—
namely, the creation of a well-functioning statutory
scheme—by using a canon-like, judicially created con-
struct, the hypothetical reasonable legislator, and asking
what such legislators would likely have intended had
Congress considered the question of delegating gap-filling
authority to the agency.
                              B
  To answer this question, we have previously held that a
“statute’s complexity, the vast number of claims that it
engenders, and the consequent need for agency expertise
and administrative experience” normally “lead us to read
[a] statute as delegating to the Agency considerable au-
thority to fill in, through interpretation, matters of detail
related to its administration.” Barnhart v. Walton, 

, 225 (2002). These considerations all favor such
a reading here. Indeed, the question before us is one of
agency administration in respect to detailed matters that
an agency working with the statute is particularly likely
10              SAS INSTITUTE INC. v. IANCU

                    BREYER, J., dissenting

to understand. In addition, the agency filled the gap here
through the exercise of rulemaking authority explicitly
given it by Congress to issue regulations “setting forth the
standards for the showing of sufficient grounds to institute
a review” and “establishing and governing inter partes
review.” §§316(a)(2), (4); Cuozzo, 579 U. S., at ___–___
(slip op., at 12–13); cf. Mead 

. Thus,
there is a gap, the agency possesses gap-filling authority,
and it filled the gap with a regulation that, for reasons I
have stated, is a reasonable exercise of that authority.
                      *     *    *
  I consequently would affirm the judgment of the Federal
Circuit. And, with respect, I dissent from the Court’s
contrary conclusion.