(Slip Opinion)              OCTOBER TERM, 2011                                       1

                                       Syllabus

         NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
       being done in connection with this case, at the time the opinion is issued.
       The syllabus constitutes no part of the opinion of the Court but has been
       prepared by the Reporter of Decisions for the convenience of the reader.
       See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.


SUPREME COURT OF THE UNITED STATES

                                       Syllabus

                  REYNOLDS v. UNITED STATES

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

   No. 10–6549. Argued October 3, 2011—Decided January 23, 2012
The federal Sex Offender Registration and Notification Act (Act) re-
  quires convicted sex offenders to provide state governments with, and
  to update, information, e.g., names and current addresses, for state
  and federal sex offender registries. It is a crime if a person who is
  “required to register under [the Act]” and who “travels in interstate
  . . . commerce” knowingly “fails to register or update a registration.”
  18 U. S. C. §2250(a). The Act defines “sex offender” to include offend-
  ers who were convicted before the Act’s effective date, 42 U. S. C.
  §16911(1), and says that “the Attorney General shall have the au-
  thority to specify the applicability of the [registration] requirements”
  to pre-Act offenders, §16913(d). The Act, which seeks to make more
  uniform and effective a patchwork of pre-Act federal and 50 state reg-
  istration systems, became law in July 2006. In February 2007, the
  Attorney General promulgated an Interim Rule specifying that the
  Act applies to all pre-Act offenders. He has since promulgated fur-
  ther rules, regulations, and specifications.
      Petitioner Reynolds, a pre-Act offender, registered in Missouri in
  2005 but moved to Pennsylvania in September 2007 without updat-
  ing the Missouri registration or registering in Pennsylvania. He was
  indicted for failing to meet the Act’s registration requirements be-
  tween September 16 and October 16, 2007. He moved to dismiss the
  indictment on the ground that the Act was not applicable to pre-Act
  offenders during that time, arguing that the Attorney General’s Feb-
  ruary 2007 Interim Rule was invalid because it violated the Constitu-
  tion’s “nondelegation” doctrine and the Administrative Procedure
  Act’s notice and comment requirements. The District Court rejected
  on the merits of Reynolds’ legal attack on the Interim Rule, but the
  Third Circuit rejected his argument without reaching the merits,
2                    REYNOLDS v. UNITED STATES

                                  Syllabus

    concluding that the Act’s registration requirements applied to pre-Act
    offenders even in the absence of a rule by the Attorney General.
    Thus, it found, the Interim Rule’s validity made no legal difference in
    the outcome.
Held: The Act does not require pre-Act offenders to register before the
 Attorney General validly specifies that the Act’s registration provi-
 sions apply to them. Pp. 6–13.
    (a) This conclusion is supported by a natural reading of the Act’s
 text, which consists of four statements. Statement One says that “[a]
 sex offender shall register, and keep the registration current.”
 Statement Two says that, generally, the offender must initially regis-
 ter before completing his “sentence of imprisonment.” Statement
 Three says that the sex offender must update a registration within
 three business days of any change of “name, residence, employment,
 or student status.” Statement Four says that “[t]he Attorney General
 shall have the authority to specify the applicability of the require-
 ments . . . to sex offenders convicted before the enactment of” the Act.
 §16913. Read naturally, the Fourth Statement modifies the First. It
 deals specifically with a subset (pre-Act offenders) of the First State-
 ment’s broad general class (all sex offenders) and thus should control
 the Act’s application to that subset. See Gozlon-Peretz v. United
 States, 498 U. S. 395, 407. Also, by giving the Attorney General au-
 thority to specify the Act’s “applicability,” not its “nonapplicability,”
 the Fourth Statement is more naturally read to confer authority to
 apply the Act, not authority to make exceptions. This reading effi-
 ciently resolves what may have been Congress’ concern about the
 practical problems of applying the new registration requirements to a
 large number of pre-Act offenders, which could have been expensive
 and might not have proved feasible to do immediately. It might have
 thought that such concerns warranted different treatment for differ-
 ent categories of pre-Act offenders. And it could have concluded that
 it was efficient and desirable to ask the Justice Department, charged
 with responsibility for implementation, to examine pre-Act offender
 problems and to apply the new requirements accordingly. This read-
 ing also takes Congress to have filled potential lacunae (created by
 related Act provisions) in a manner consistent with basic criminal
 law principles. The Second Statement, e.g., requires a sex offender to
 register before completing his prison term, but says nothing about
 when a pre-Act offender who has left prison is to register. An Attor-
 ney General ruling could diminish such uncertainties, helping to
 eliminate the kind of vagueness and uncertainty that criminal law
 must seek to avoid. Pp. 6–9.
    (b) The Government’s three principal contrary arguments—that
 the Court’s reading conflicts with the Act’s purpose of establishing a
                     Cite as: 565 U. S. ____ (2012)                     3

                                Syllabus

  national registration system that includes pre-Act offenders; that the
  Court’s reading could lead to an absurdly long implementation delay;
  and that the Act should be read to apply the requirements immedi-
  ately and on their own to all pre-Act offenders to avoid the possibility
  that the Attorney General, who has, but is not required to use, “the
  authority to specify” requirements, might take no action—are unper-
  suasive. Some lower courts have read the Attorney General’s author-
  ity to apply only to pre-Act sex offenders who are unable to comply
  with the statute’s “initial registration” requirements, but that is not
  what the Act says. Pp. 9–13.
     (c) Because the Act’s registration requirements do not apply to pre-
  Act offenders until the Attorney General so specifies, the question
  whether the Attorney General’s Interim Rule is a valid specification
  matters in this case. P. 13.
380 Fed. Appx. 125, reversed and remanded.

   BREYER, J., delivered the opinion of the Court, in which ROBERTS,
C. J., and KENNEDY, THOMAS, ALITO, SOTOMAYOR, and KAGAN, JJ.,
joined. SCALIA, J., filed a dissenting opinion, in which GINSBURG, J.,
joined.
                        Cite as: 565 U. S. ____ (2012)                              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. 10–6549
                                   _________________


   BILLY JOE REYNOLDS, PETITIONER v. UNITED 

                   STATES 

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

            APPEALS FOR THE THIRD CIRCUIT

                               [January 23, 2012]


   JUSTICE BREYER delivered the opinion of the Court.
   The federal Sex Offender Registration and Notification
Act (Act), 120 Stat. 590, 42 U. S. C. §16901 et seq. (2006
ed. and Supp. III), requires those convicted of certain sex
crimes to provide state governments with (and to update)
information, such as names and current addresses, for
inclusion on state and federal sex offender registries.
§§16912(a), 16913–16914, 16919(a) (2006 ed.). The Act
makes it a crime for a person who is “required to regis-
ter” under the Act and who “travels in interstate or foreign
commerce” knowingly to “fai[l] to register or update a reg-
istration . . . .” 18 U. S. C. §2250(a). The question be-
fore us concerns the date on which this federal registra-
tion requirement took effect with respect to sex offenders
convicted before the Act became law.
   The Act defines the term “sex offender” as including
these pre-Act offenders. 42 U. S. C. §16911(1); see Carr v.
United States, 560 U. S. ___, ___ (2010) (slip op., at 7). It
says that “[a] sex offender shall register.” §16913(a). And
it further says that “[t]he Attorney General shall have the
authority to specify the applicability of the [registration]
2               REYNOLDS v. UNITED STATES

                     Opinion of the Court

requirements . . . to sex offenders convicted before the
enactment of this chapter . . . .” §16913(d) (emphasis
added). In our view, these provisions, read together, mean
that the Act’s registration requirements do not apply to
pre-Act offenders until the Attorney General specifies that
they do apply. We reverse a Court of Appeals determina-
tion that, in effect, holds the contrary.
                              I

                              A

   The new federal Act reflects Congress’ awareness that
pre-Act registration law consisted of a patchwork of fed-
eral and 50 individual state registration systems. See
73 Fed. Reg. 38045 (2008). The Act seeks to make those
systems more uniform and effective. It does so by repeal-
ing several earlier federal laws that also (but less effec-
tively) sought uniformity; by setting forth comprehensive
registration-system standards; by making federal funding
contingent on States’ bringing their systems into compli-
ance with those standards; by requiring both state and
federal sex offenders to register with relevant jurisdictions
(and to keep registration information current); and by
creating federal criminal sanctions applicable to those who
violate the Act’s registration requirements. 18 U. S. C.
§2250(a) (criminal provision); 42 U. S. C. §§16911(10),
16913–16916 (2006 ed. and Supp. III) (registration re-
quirements); §16925 (federal funding); §129, 120 Stat. 600
(repeal of earlier laws).
   The Act’s criminal penalty applies to “[w]ho[m]ever . . .
is required to register under [the Act].” 18 U. S. C.
§2250(a). It says that such a person (a federal sex offender
or a nonfederal sex offender who travels in interstate
commerce) must not knowingly fail “to register or update
a registration as required by [the Act].” Ibid. (emphasis
added); see Appendix, infra, at 14.
   The relevant registration requirements are set forth in
                  Cite as: 565 U. S. ____ (2012)               3

                      Opinion of the Court

an Act provision that states:
    “Registry requirements for sex offenders

    “(a) In general
      “A sex offender [defined to include any offender who
    was convicted of a sex offense] shall register, and keep
    the registration current, in each jurisdiction where the
    offender resides, where the offender is an employee,
    and where the offender is a student. . . .

    “(b) Initial registration
      “The sex offender shall initially register [either] be-
    fore completing a sentence of imprisonment with
    respect to the offense giving rise to the registration re-
    quirement; or [for those not sentenced to prison] not
    later than 3 business days after being sentenced . . . .

    “(c) Keeping the registration current
      “A sex offender shall [update his registration with-
    in] 3 business days after each change of name, resi-
    dence, employment, or student status [by] appear[ing]
    in person in at least 1 jurisdiction involved . . . and in-
    form[ing] that jurisdiction of all [relevant] changes . . . .

    “(d) Initial registration of sex offenders unable
    to comply with subsection (b)
      “The Attorney General shall have the authority to
    specify the applicability of the [registration] require-
    ments . . . to sex offenders convicted before the en-
    actment of this chapter or its implementation in a
    particular jurisdiction, and to prescribe rules for the
    registration of any such sex offenders and for other
    categories of sex offenders who are unable to comply
    with subsection (b).” 42 U. S. C. §16913 (emphasis
    added).
4               REYNOLDS v. UNITED STATES

                     Opinion of the Court

The new Act became law on July 27, 2006.
   On February 28, 2007, the Attorney General promulgat-
ed an Interim Rule specifying that “[t]he requirements of
[the Act] apply to all sex offenders, including sex offenders
convicted of the offense for which registration is required
prior to the enactment of that Act.” 72 Fed. Reg. 8897
(codified at 28 CFR §72.3). Subsequently, the Attorney
General promulgated further rules, regulations, and speci-
fications. See 73 Fed. Reg. 38030 (2008); 75 Fed. Reg.
81849 (2010); 76 Fed. Reg. 1630 (2011). The present case
focuses upon the applicability of the Act’s registration
requirements to pre-Act offenders during the period be-
tween (1) July 27, 2006 (when the Act took effect) and
(2) the moment when the Attorney General promulgated
a valid rule specifying the registration requirements’ ap-
plicability, namely, February 28, 2007 (or a later date if
the February 28 specification was invalid).
                               B
  Billy Joe Reynolds, the petitioner, is a pre-Act offender.
He was convicted of a Missouri sex offense in October
2001; he served four years in prison; he was released in
July 2005; he then registered as a Missouri sex offender;
but he moved to Pennsylvania in September 2007 without
updating his Missouri registration information (as Mis-
souri law required) and without registering in Pennsylva-
nia. A federal grand jury indicted him, charging him with,
between September 16 and October 16, 2007, having
“knowingly failed to register and update a registration as
required by [the Act].” App. 13; see 18 U. S. C. §2250(a).
In the Government’s view, Reynolds’ failure to update his
address information when he moved to Pennsylvania
violated the requirement that a “sex offender” update
registration information within “3 business days after
each change of . . . residence.” 42 U. S. C. §16913(c).
  Reynolds moved to dismiss the indictment on the
                 Cite as: 565 U. S. ____ (2012)           5

                     Opinion of the Court

ground that in September and October 2007 the Act’s reg-
istration requirements had not yet become applicable to
pre-Act offenders. He conceded that the Act had become
law earlier (namely, in July 2006), and he conceded that
the Attorney General had already (in February 2007)
promulgated an Interim Rule specifying that the Act’s
registration requirements were applicable to pre-Act
offenders. But he claimed that the Interim Rule was
invalid because it violated both the Constitution’s “nondel-
egation” doctrine and the Administrative Procedure Act’s
(APA) requirement for “good cause” to promulgate a rule
without “notice and comment” (as the Attorney General
had done). See A. L. A. Schechter Poultry Corp. v. United
States, 295 U. S. 495, 529 (1935) (nondelegation doctrine);
5 U. S. C. §§553(b)(3)(B), (d)(3) (APA). Because the Inter-
im Rule is invalid, he added, the law must treat him like a
pre-Act offender who traveled interstate and violated the
Act’s registration requirements before the Attorney Gen-
eral specified their applicability.
   The District Court rejected on the merits Reynolds’ legal
attack on the Interim Rule. But the Court of Appeals
rejected Reynolds’ argument without reaching those mer-
its. 380 Fed. Appx. 125 (2010). That court thought that
the Act’s registration requirements apply to pre-Act of-
fenders such as Reynolds (who was subject to a pre-
existing state-law registration requirement) from the date
of the new law’s enactment—even in the absence of any
rule or regulation by the Attorney General specifying that
the new registration requirements apply. That being so,
the validity of the Interim Rule could make no legal dif-
ference, for the Act required Reynolds to follow the
new federal registration requirements regardless of any
rulemaking.
   The Courts of Appeals have reached different conclu-
sions about whether the Act’s registration requirements
apply to pre-Act offenders prior to the time that the Attor-
6              REYNOLDS v. UNITED STATES

                     Opinion of the Court

ney General specifies their applicability, i.e., from July
2006 until at least February 2007. Six Circuits have held
that the Act’s registration requirements do not apply to
pre-Act offenders unless and until the Attorney General so
specifies. United States v. Johnson, 632 F. 3d 912, 922–
927 (CA5 2011); United States v. Valverde, 628 F. 3d 1159,
1162–1164 (CA9 2010); United States v. Cain, 583 F. 3d
408, 414–419 (CA6 2009); United States v. Hatcher, 560 F.
3d 222, 226–229 (CA4 2009); United States v. Dixon, 551
F. 3d 578, 585 (CA7 2008); United States v. Madera, 528 F.
3d 852, 856–859 (CA11 2008) (per curiam). Five Circuits
have held that they apply from the date of the Act’s en-
actment, and prior to any such specification, at least with
respect to pre-Act offenders who had already registered
under state law. United States v. Fuller, 627 F. 3d 499,
506 (CA2 2010); United States v. DiTomasso, 621 F. 3d 17,
24 (CA1 2010); United States v. Shenandoah, 595 F. 3d
151, 163 (CA3 2010); United States v. Hinckley, 550 F. 3d
926, 932 (CA10 2008); United States v. May, 535 F. 3d 912,
918–919 (CA8 2008). In light of this split, we agreed to
consider the question.
                             II

                             A

  The question before us is whether the Act requires
pre-Act offenders to register before the Attorney General
validly specifies that the Act’s registration provisions ap-
ply to them. We believe that it does not. For one thing,
a natural reading of the textual language supports our
conclusion. The text consists of four statements. See
supra, at 3. Statement One says that “[a] sex offender
shall register, and keep the registration current.” State-
ment Two says that a sex offender must initially register
before completing his “sentence of imprisonment” (or, if
the sentence does not involve imprisonment, within three
days of conviction). Statement Three says that the sex
                 Cite as: 565 U. S. ____ (2012)            7

                     Opinion of the Court

offender must update a registration within three business
days of any change of “name, residence, employment, or
student status.” Statement Four says that “[t]he Attorney
General shall have the authority to specify the applicabil-
ity of the requirements of this subchapter to sex offenders
convicted before the enactment of this chapter.”
   Read naturally, the Fourth Statement modifies the First.
It specifically deals with a subset (pre-Act offenders) of
a broad general class (all sex offenders) to which the First
Statement applies. And it therefore should control the
Act’s application to that subset. See Gozlon-Peretz v.
United States, 498 U. S. 395, 407 (1991) (specific statutory
provision normally controls over one of more general
application); see also Bloate v. United States, 559 U. S.
___, ___ (2010) (slip op., at 10) (same).
   At the same time, the Fourth Statement says that the
Attorney General has authority to specify the Act’s “ap-
plicability,” not its “nonapplicability.” And it consequently
is more naturally read as conferring the authority to apply
the Act, not the authority to make exceptions. That is
how we normally understand a term such as “authority to
specify” in the context of applying new rules to persons
already governed by pre-existing rules. If, for example,
the Major League Baseball Players Association and the
team owners agreed that the Commissioner of Baseball
“shall have the authority to specify the applicability” to
the major leagues of the more stringent minor league drug
testing policy, we should think that the minor league
policy would not apply unless and until the Commissioner
so specified.
   For another thing, this reading of the Act efficiently
resolves what Congress may well have thought were prac-
tical problems arising when the Act sought to apply the
new registration requirements to pre-Act offenders. The
problems arise out of the fact that the Act seeks to make
more uniform a patchwork of pre-existing state systems.
8               REYNOLDS v. UNITED STATES

                     Opinion of the Court

Doing so could require newly registering or re-registering
“a large number” of pre-Act offenders. That effort could
prove expensive. And it might not prove feasible to do so
immediately. See 73 Fed. Reg. 38063 (recognizing these
problems). Congress’ concern about these problems is re-
flected in the Act’s providing the States with three years
to bring their systems into compliance with federal stand-
ards while permitting the Attorney General to extend that
3-year grace period to five years. 42 U. S. C. §16924.
   These same considerations might have warranted dif-
ferent federal registration treatment of different catego-
ries of pre-Act offenders. Cf. 73 Fed. Reg. 38035–38036,
and 38046–38047 (final Department of Justice guidelines
allowing States to meet Act requirements without regis-
tering certain categories of pre-Act offenders); 76 Fed. Reg.
1635–1636 (supplemental guidelines allowing the same).
At least Congress might well have so thought. And conse-
quently, Congress might well have looked for a solution.
Asking the Department of Justice, charged with respon-
sibility for implementation, to examine these pre-Act
offender problems and to apply the new registration re-
quirements accordingly could have represented one effi-
cient and desirable solution (though we express no view
on Reynolds’ related constitutional claim). Cf. 42 U. S. C.
§§16912(b), 16914(a)(7), (b)(7), 16919, 16941, 16945
(granting the Attorney General authority to administer
various aspects of the Act). And that is just the solution
that the Act’s language says that Congress adopted.
   Finally, our reading of the Act takes Congress to have
filled potential lacunae (created by related Act provisions)
in a manner consistent with basic background principles
of criminal law. The Second Statement, for example, says
that a sex offender must register before completing his
prison term, but the provision says nothing about when a
pre-Act offender who completed his prison term pre-Act
must register. Although a state pre-Act offender could not
                  Cite as: 565 U. S. ____ (2012)            9

                      Opinion of the Court

be prosecuted until he traveled interstate, there is no
interstate requirement for a federal pre-Act offender. And
to apply the Act to either of these pre-Act offenders from
the date of enactment would require reading into the
statute, silent on the point, some kind of unsaid equiva-
lent (e.g., registering or updating within a “reasonable
time” or “within three days of first post-Act travel in inter-
state commerce” or “as preexisting state law requires”).
  Pre-Act offenders, aware of such complexities, lacunae,
and difficulties, might, on their own, reach different con-
clusions about whether, or how, the new registration
requirements applied to them. A ruling from the Attorney
General, however, could diminish or eliminate those un-
certainties, thereby helping to eliminate the very kind of
vagueness and uncertainty that criminal law must seek to
avoid. Cf., e.g., United States v. Lanier, 520 U. S. 259, 266
(1997) (noting that “the canon of strict construction of
criminal statutes, or rule of lenity, ensures fair warning by
so resolving ambiguity in a criminal statute as to apply it
only to conduct clearly covered”).
                                B
  The Government makes three principal arguments to
the contrary. First, it says that our interpretation of the
Act conflicts with one basic statutory purpose, namely, the
“establish[ment of] a comprehensive national system for
the registration of [sex] offenders,” 42 U. S. C. §16901,
that includes offenders who committed their offenses
before the Act became law. The Act reflects that purpose
when it defines “sex offender” broadly to include any
“individual who was convicted of a sex offense.” §16911(1).
And we have recognized that purpose in stating that, in
general, the Act’s criminal provisions apply to any pre-Act
offender required to register under the Act who later
travels interstate and fails to register. See Carr, 560
U. S., at ___ (slip op., at 7).
10              REYNOLDS v. UNITED STATES

                     Opinion of the Court

   The Act’s history also reveals that many of its support-
ers placed considerable importance upon the registration
of pre-Act offenders. See, e.g., H. R. Rep. No. 109–218, pt.
1, p. 24 (2005) (H. R. Rep.) (“[Twenty] percent of sexual
offenders are ‘lost,’ and there is a strong public interest
in finding them and having them register with current
information to mitigate the risks of additional crimes
against children”); 152 Cong. Rec. 15333 (2006) (statement
of Sen. Cantwell) (“Child sex offenders have exploited this
stunning lack of uniformity, and the consequences have
been tragic. Twenty percent of the Nation’s 560,000 sex
offenders are ‘lost’ because State offender registry pro-
grams are not coordinated well enough”); id., at 15338
(statement of Sen. Kyl) (“There currently are over 100,000
sex offenders in this country who are required to register
but are ‘off the system.’ They are not registered. The
penalties in this bill should be adequate to ensure that
these individuals register”); id., at 13050 (statement of
Sen. Frist) (“There are currently 550,000 registered sex
offenders in the U. S. and at least 100,000 of them are
missing from the system. Every day that we don’t have
this national sex offender registry, these missing sex
predators are out there somewhere”).
   The difficulty with the Government’s argument, how-
ever, is that it overstates the need for instantaneous regis-
tration of pre-Act offenders. Our different reading, we
concede, involves implementation delay. But that delay
need not be long (the Attorney General issued his Interim
Rule 217 days after the effective date of the new law).
And that delay can be justified by the need to accommo-
date other Act-related interests. See supra, at 7–9.
   Second, the Government suggests that our reading leads
to an absurd result. As it points out, the Fourth Statement
grants the Attorney General the “authority to specify”
the registration requirements’ applicability not only to
pre-Act offenders but also to those convicted prior to the
                  Cite as: 565 U. S. ____ (2012)            11

                      Opinion of the Court

“implementation” of the new Act “in a particular jurisdic-
tion.” Some jurisdictions might not implement the Act
for up to five years. See 42 U. S. C. §16924; see also Dept. of
Justice, Office of Justice Programs, Justice Department
Finds 24 Jurisdictions Have Substantially Implemented
SORNA Requirements (July 28, 2011) (stating that as
of July 28, 2011, 14 States had implemented the
Act’s requirements), http://www.ojp.usdoj.gov/newsroom/
pressreleases/2011/SMART_PR-072811.htm (all Internet
materials as visited Jan. 19, 2012, and available in Clerk
of Court’s case file). Yet, the Government concludes, it is
absurd to believe that Congress would have desired so
long a delay in the application of its new registration
requirements.
   The problem with this argument, however, is that read-
ing the two categories similarly (a matter which we need
not decide) would not require a long delay in applying the
registration requirements to post-Act offenders who com-
mitted a crime in a jurisdiction that is slow to implement
the new requirements. At most, that reading would re-
quire the Attorney General to promulgate a rule applica-
ble to all preimplementation offenders. That rule could
specify that the Act’s preregistration provisions apply to
some or to all those offenders. And it could do so quickly,
well before a jurisdiction implements the Act’s require-
ments. Indeed, the Attorney General’s Interim Rule and
the Department of Justice’s final guidelines, both issued
before any jurisdiction implemented the Act’s require-
ments, state that the Act’s requirements apply to “all sex
offenders,” including all preimplementation offenders. See
72 Fed. Reg. 8897 (codified at 28 CFR §72.3); 73 Fed. Reg.
38036; cf. Dept. of Justice, Office of Justice Programs,
Justice Department Announces First Two Jurisdictions
 to Implement Sex Offender Registration and Notifica-
tion Act (Sept. 23, 2009), http://www.ojp.usdoj.gov/newsroom/
pressreleases/2009/SMART09154.htm.
12              REYNOLDS v. UNITED STATES

                     Opinion of the Court

   Third, the Government argues against our interpreta-
tion on the ground that the Act says only that the At-
torney General “shall have the authority to specify the
applicability” of the Act’s registration requirements to pre-
Act offenders; it does not say that he “shall specify” or
otherwise require him to do so. The Act’s language, the
Government continues, consequently gives the Attorney
General the power not to specify anything; that power is
inconsistent with Congress’ intent to ensure the speedy
registration of thousands of “lost” pre-Act offenders, supra,
at 10; and we can avoid this result only by reading the
Act’s registration requirements as applying immedi-
ately and on their own to all pre-Act offenders (though
the Attorney General would have the power to make
exceptions).
   This argument bases too much upon too little. There is
no reason to believe that Congress feared that the Attor-
ney General would refuse to apply the new requirements
to pre-Act offenders. See, e.g., H. R. Rep., at 23–24; Pro-
tecting Our Nation’s Children from Sexual Predators and
Violent Criminals: What Needs To Be Done? Hearing
before the Subcommittee on Crime, Terrorism, and Home-
land Security of the House Committee on the Judiciary,
109th Cong., 1st Sess., 4–13 (2005); Office of the Press
Sec’y, The White House, President Signs H. R. 4472,
the Adam Walsh Child Protection and Safety Act of 2006
(July 27, 2006), http://georgewbush-whitehouse.archives.gov/
news/releases/2006/07/20060727-6.html. And there was no
need for a mandatory requirement to avoid that unrealistic
possibility. There is consequently no need to read the
language unnaturally as giving the Attorney General the
authority only to make exceptions from an implicit (un-
stated) rule that would otherwise apply the new registra-
tion requirements to all pre-Act offenders across the board
and immediately.
   Finally, we note that some lower courts have read the
                  Cite as: 565 U. S. ____ (2012)            13

                      Opinion of the Court

Attorney General’s specification authority as applying
only to those pre-Act sex offenders unable to comply with
the statute’s “initial registration” requirements. See 42
U. S. C. §16913(b). That, however, is not what the statute
says. Rather, its Fourth Statement, §16913(d), says that
the Attorney General has the authority (1) to specify the
applicability of the registration requirements to pre-Act
(and preimplementation) offenders, “and ” (2) to prescribe
rules for their registration, “and ” (3) to prescribe registra-
tion rules for other categories of sex offenders who are
unable to comply with the initial registration require-
ments. See supra, at 3. The word “and” means that the
Attorney General’s authority extends beyond those pre-Act
“sex offenders who are unable to comply” with the initial
registration requirements.
                            III
   For these reasons, we conclude that the Act’s registra-
tion requirements do not apply to pre-Act offenders until
the Attorney General so specifies. Whether the Attorney
General’s Interim Rule sets forth a valid specification
consequently matters in the case before us. And we re-
verse the Third Circuit’s judgment to the contrary. We
remand the case for further proceedings consistent with
this opinion.
                                              So ordered.
14              REYNOLDS v. UNITED STATES

                      Opinion of the Court
                 Appendix to opinion of the Court

                         APPENDIX

18 U. S. C. §2250(a)
     “IN GENERAL.—Whoever—
        “(1) is required to register under the Sex Offender
     Registration and Notification Act;
        “(2)(A) is a sex offender as defined for the purposes
     of the Sex Offender Registration and Notification Act
     by reason of a conviction under Federal law (including
     the Uniform Code of Military Justice), the law of the
     District of Columbia, Indian tribal law, or the law of
     any territory or possession of the United States; or
        “(B) travels in interstate or foreign commerce, or
     enters or leaves, or resides in, Indian country; and
        “(3) knowingly fails to register or update a registra-
     tion as required by the Sex Offender Registration and
     Notification Act;
     “shall be fined under this title or imprisoned not more
     than 10 years, or both.”

42 U. S. C. §16913
     “Registry requirements for sex offenders

     “(a) In general
        “A sex offender shall register, and keep the registra-
     tion current, in each jurisdiction where the offender
     resides, where the offender is an employee, and where
     the offender is a student. For initial registration pur-
     poses only, a sex offender shall also register in the
     jurisdiction in which convicted if such jurisdiction is
     different from the jurisdiction of residence.

     “(b) Initial registration
       “The sex offender shall initially register—(1) before
     completing a sentence of imprisonment with respect to
             Cite as: 565 U. S. ____ (2012)          15

                 Opinion of the Court
            Appendix to opinion of the Court

the offense giving rise to the registration requirement;
or (2) not later than 3 business days after being sen-
tenced for that offense, if the sex offender is not sen-
tenced to a term of imprisonment.

“(c) Keeping the registration current
   “A sex offender shall, not later than 3 business days
after each change of name, residence, employment, or
student status, appear in person in at least 1 jurisdic-
tion involved pursuant to subsection (a) and inform
that jurisdiction of all changes in the information re-
quired for that offender in the sex offender registry.
That jurisdiction shall immediately provide that in-
formation to all other jurisdictions in which the of-
fender is required to register.

“(d) Initial registration of sex offenders unable
to comply with subsection (b)
  “The Attorney General shall have the authority to
specify the applicability of the requirements of this
subchapter to sex offenders convicted before the en-
actment of this chapter or its implementation in a
particular jurisdiction, and to prescribe rules for the
registration of any such sex offenders and for other
categories of sex offenders who are unable to comply
with subsection (b).

“(e) State penalty for failure to comply
   “Each jurisdiction, other than a Federally recog-
nized Indian tribe, shall provide a criminal penalty
that includes a maximum term of imprisonment that
is greater than 1 year for the failure of a sex offender
to comply with the requirements of this subchapter.”
                  Cite as: 565 U. S. ____ (2012)            1

                      SCALIA, J., dissenting

SUPREME COURT OF THE UNITED STATES
                          _________________

                          No. 10–6549
                          _________________


   BILLY JOE REYNOLDS, PETITIONER v. UNITED 

                   STATES 

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

            APPEALS FOR THE THIRD CIRCUIT

                       [January 23, 2012]


   JUSTICE SCALIA, with whom JUSTICE GINSBURG joins,
dissenting.
   In my view, the registration requirements of the Sex
Offender Registration and Notification Act (Act), 120 Stat.
590, 42 U. S. C. §16901 et seq. (2006 ed. and Supp. III),
apply of their own force, without action by the Attorney
General. The Act’s statement that “[t]he Attorney General
shall have the authority to specify the applicability of
the [registration] requirements” to pre-Act sex offenders,
§16913(d), is best understood as conferring on the Attor-
ney General an authority to make exceptions to the oth-
erwise applicable registration requirements.
   To begin with, I do not share the Court’s belief that
to “specify the applicability” more naturally means, in the
present context, to “make applicable” rather than to “make
inapplicable.” See ante, at 7. The example the Court
gives, the Commissioner of Baseball’s “ ‘authority to spec-
ify the applicability’ ” of more stringent minor-league drug
testing policies to the major leagues, ibid., is entirely
inapt, because it deals with a policy that on its face is
otherwise not applicable. Since the major leagues are not
covered by the policies, the Commissioner’s “ ‘authority to
specify [their] applicability’ ” can mean nothing else but the
authority to render them applicable. What we have here,
however, is a statute that states in unqualified terms that
2                  REYNOLDS v. UNITED STATES

                         SCALIA, J., dissenting

“a sex offender shall register,” §16913(a)—and that the
Court rightly believes was meant to cover pre-Act offend-
ers.* The issue is whether “specify the applicability”
means that no pre-Act offenders need register unless the
Attorney General says so, or rather that the Attorney
General may excuse the unqualified requirement for pre-
Act offenders. In that context, it seems to me that the
latter meaning is more natural. One specifies the applica-
bility of an application that already exists by describing or
revising its contours.
  I think it preferable to give “specify” this meaning not
only because here it is more natural, but also because
the alternative is to read the statute as leaving it up to the
Attorney General whether the registration requirement
would ever apply to pre-Act offenders, even though regis-
tration of pre-Act offenders was (as the Court acknowl-
edges) what the statute sought to achieve. For the statute
does not instruct the Attorney General to specify; it merely
gives him “authority” to do so. In this respect, the provi-
sion at issue here stands in marked contrast to other
provisions of the Act which clearly impose duties on the
Attorney General. See, e.g., §16912(b) (“The Attorney
General shall issue guidelines and regulations to interpret
and implement this subchapter”); §16917(b) (“The Attor-
ney General shall prescribe rules for the notification of
[certain] sex offenders”); §16919(a) (“The Attorney General
shall maintain a national database”); §16926(a) (“The
Attorney General shall establish and implement a Sex
Offender Management Assistance program”).
——————
   * The Court reaches this conclusion based on an inquiry into legisla-
tive history. See ante, at 9–10. That inquiry is quite superf luous,
however since the text of the Act itself makes clear that Congress
sought to “establis[h] a comprehensive national system for the registra-
tion of [sex offenders],” 42 U. S. C. §16901, with “sex offender” defined
broadly to “mea[n] an individual who was convicted of a sex offense,”
§16911(1) (emphasis added).
                  Cite as: 565 U. S. ____ (2012)              3

                      SCALIA, J., dissenting

   The Court’s response to this—that “there was no need
for a mandatory requirement to avoid [the] unrealistic
possibility” that the Attorney General would not specify,
ante, at 12—seems to me a fine answer to the question
“What mandatory requirements must a poorly drafted
statute contain in order to be workable?” It is an inade-
quate answer, however, to the question that is relevant
here: “Would Congress have written the provision this way
if it wanted pre-Act offenders covered and did not think
they were covered absent specification by the Attorney Gen-
eral?” Intelligently drafted statutes make mandatory
those executive acts essential to their functioning, whether
or not those acts would likely occur anyway. It would have
taken little effort (in fact, less effort) for Congress to write
“the Attorney General shall specify the applicability”
instead of “the Attorney General shall have authority to
specify the applicability.” The latter formulation confers
discretion, and it is simply implausible that the Attorney
General was given discretion to determine whether cover-
age of pre-Act offenders (one of the purposes of the Act)
should exist.
   Indeed, it is not entirely clear to me that Congress
can constitutionally leave it to the Attorney General to
decide—with no statutory standard whatever governing his
discretion—whether a criminal statute will or will not
apply to certain individuals. That seems to me sailing
close to the wind with regard to the principle that legisla-
tive powers are nondelegable, see Whitman v. American
Trucking Assns., Inc., 531 U. S. 457, 472–476 (2001);
Loving v. United States, 517 U. S. 748, 776–777 (1996)
(SCALIA, J., concurring in part and concurring in judg-
ment), and “[i]t is our settled policy to avoid an interpreta-
tion of a federal statute that engenders constitutional
issues if a reasonable alternative interpretation poses
no constitutional question.” Gomez v. United States, 490
U. S. 858, 864 (1989). Construing the Act to give the
4               REYNOLDS v. UNITED STATES

                     SCALIA, J., dissenting

Attorney General the power to reduce congressionally
imposed requirements fits that bill, because such a power
is little more than a formalized version of the time-
honored practice of prosecutorial discretion.
   The Court points out that there might have been need
for “different federal registration treatment of different
categories of pre-Act offenders,” ante, at 8, and that absent
a “ruling from the Attorney General” pre-Act offenders
would be uncertain “about whether, or how, the new regis-
tration requirements applied to them,” ante, at 9. But
attending to those details would certainly come within the
Attorney General’s authority to “specify” application of the
Act—and so would the temporary suspension of registra-
tion requirements pending the Attorney General’s reso-
lution of those details. And of course the uncertainty of
where to register could form the basis for the Attorney
General’s exercise of his discretion not to prosecute in
individual cases. Neither problem, it seems to me, justi-
fies the extraordinary interpretation that this Act does not
apply to pre-Act offenders unless and until the Attorney
General, in his discretion, says so.
   For these reasons, I respectfully dissent.
