                 FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                  No. 05-30597
                Plaintiff-Appellee,
               v.                            D.C. No.
                                          CR-05-00034-RFC
ROBERT THAYER STEVENS,
                                             OPINION
             Defendant-Appellant.
                                      
       Appeal from the United States District Court
               for the District of Montana
       Richard F. Cebull, District Judge, Presiding

                  Argued and Submitted
             July 28, 2006—Portland, Oregon

                 Filed September 13, 2006

   Before: Alfred T. Goodwin, A. Wallace Tashima, and
             Susan P. Graber, Circuit Judges.

                Opinion by Judge Goodwin;
                 Dissent by Judge Graber




                           11247
                  UNITED STATES v. STEVENS            11249


                        COUNSEL

Mark S. Werner, Federal Defenders of Montana, Billings,
Montana, for the defendant-appellant.

Marcia Hurd, Assistant U.S. Attorney, Billings, Montana, for
the plaintiff-appellee.


                        OPINION

GOODWIN, Circuit Judge:

   Robert Stevens appeals a 30-year sentence imposed by the
district court after Stevens plead guilty to one count of
Receipt of Child Pornography and one count of Possession of
11250              UNITED STATES v. STEVENS
Child Pornography, both in violation of 18 U.S.C.
§ 2252A(a). For the reasons set forth below, we vacate the
sentence and remand for resentencing.

                               I

   The indictment and the plea agreement include only the
most basic description of Stevens’s criminal activities during
2003 and 2004. On count one, Receipt of Child Pornography,
Stevens admitted he “knowingly received a visual depiction
. . . of a minor engaging in sexually explicit conduct.” On
count two, Possession of Child Pornography, Stevens admit-
ted he “knowingly possessed computer disks . . . which [he]
knew contained visual depictions of minors engaged in sexu-
ally explicit conduct.” The pre-sentence report, however, pro-
vides the sordid details of, among other things, Stevens’s
numerous online contacts with apparently underage girls,
which he accompanied with pornographic materials and sex-
ual solicitations.

   The district court accepted the plea agreement and sen-
tenced Stevens on November 18, 2005. In the course of calcu-
lating the defendant’s base offense level under the advisory
sentencing guidelines, the district court imposed a seven-level
enhancement pursuant to U.S.S.G. § 2G2.2(b)(2)(D), which
penalizes “distribution to a minor that was intended to per-
suade, induce, entice, coerce, or facilitate the travel of the
minor to engage in prohibited sexual conduct.” Stevens
objected to this enhancement because the pornographic mate-
rials at issue were not transmitted to a minor, but rather were
sent to a law enforcement officer posing as a minor. The court
overruled the objection, and sentenced Stevens to 20 years of
imprisonment on count one and 10 years of imprisonment on
count two, to be served consecutively. The district court
entered the final judgment and sentence on November 23,
2005, and Stevens timely appealed.
                      UNITED STATES v. STEVENS                     11251
                                    II

   Stevens’s sole contention on appeal is that the district
court’s application of U.S.S.G. § 2G2.2(b)(2)(D), as amended
in 2004, violated the constitutional prohibition against ex post
facto laws.1

   [1] A district court generally applies the version of the Sen-
tencing Guidelines in effect on the date of a defendant’s sen-
tencing. U.S.S.G. § 1B1.11. However, the Ex Post Facto
Clause of the U.S. Constitution requires the defendant to be
sentenced under the guidelines in effect at the time of the
offense if the guidelines have undergone substantive changes
that would disadvantage the defendant. See United States v.
Alfaro, 336 F.3d 876, 881 (9th Cir. 2003).

   At both the time of sentencing and the apparent time of the
alleged conduct, U.S.S.G. § 2G2.2(b)(2)(D) provided a seven-
point base offense level increase for offenses involving
“[d]istribution to a minor that was intended to persuade,
induce, entice, coerce, or facilitate the travel of, the minor to
engage in prohibited sexual conduct . . . .” But, as Stevens
points out, the scope of this subsection’s application changed
in 2004 when the Sentencing Commission expanded the defi-
nition of “minor.”

   [2] At the time Stevens committed the crimes, application
note 1 to U.S.S.G. § 2G2.2 defined “minor” as “an individual
who has not attained the age of 18 years.” In 2005, at the time
the district court imposed Stevens’s sentence, the Sentencing
Commission had amended the application note, so that it
defined “minor” as “(A) an individual who had not attained
the age of 18 years; (B) an individual, whether fictitious or
  1
    We observe, however, that Stevens’s charged offenses did not involve
“distribution.” Were the issue before us, we would question the applica-
tion of U.S.S.G. § 2G2.2(b)(2)(D) to offenses involving only “receipt” and
“possession.”
11252               UNITED STATES v. STEVENS
not, who a law enforcement officer represented to a partici-
pant (i) had not attained the age of 18 years, and (ii) could be
provided for the purposes of engaging in sexually explicit
conduct; or (C) an undercover law enforcement officer who
represented to a participant that the officer had not attained
the age of 18 years.”

   Stevens argues that this modification is a substantive
change rather than a clarification, and that therefore the dis-
trict court erred by retroactively applying the amended defini-
tion. We agree.

   [3] We have repeatedly stated that a guidelines amendment
is substantive unless it “plainly serve[s] to clarify pre-existing
law, rather than to alter it.” See United States v. Bishop, 1
F.3d 910, 912 (9th Cir. 1993). Our decisions also favor the
use of ordinary rules of construction to interpret guidelines
definitions and their amendments. See United States v. Lopez-
Solis, 447 F.3d 1201, 1205 (9th Cir. 2006). “Under ordinary
rules of construction, the free-standing terms in the amended
definition . . . have distinct definitions.” 447 F.3d at 1205
n.10. Further, statutory construction which renders some
words surplusage is to be avoided, and while “definitions may
overlap, no definition should be completely subsumed within
another.” Id.

   [4] Applying these principles, we hold that the 2004
amendment is substantive, not clarifying. The Government’s
contention that the unamended definition of “minor,” a person
“who has not attained the age of 18 years,” includes a law
enforcement officer over the age of 18 who is posing as a per-
son under the age of 18, conflicts with the unambiguous lan-
guage of the definition. We cannot adopt such an
interpretation, as it would render the 2004 amendment unnec-
essary and meaningless.

  [5] In addition, although the Sentencing Commission’s
characterization of the amendment is not binding, we gener-
                   UNITED STATES v. STEVENS              11253
ally afford it some weight. See, e.g., United States v. Aquino,
242 F.3d 859, 865 (9th Cir. 2001). Here, the Commission
characterized the amendment as “expanding” the definition of
“minor,” which strongly suggests that the Commission con-
sidered the amendment to be a substantive one. U.S.S.G.,
Amendment 664, Supplement to Appendix C (November 1,
2004) (“In response to the increase in the use of undercover
officers in child pornography investigations, the amendment
expands the definition of ‘minor.’ ”)

   The district court, however, reached the opposite conclu-
sion after relying on a decision of the Eleventh Circuit which
was published before the Sentencing Commission’s 2004
amendment, United States v. Morton, 364 F.3d 1300 (11th
Cir. 2004), vacated and remanded, 543 U.S. 1136, opinion
reinstated by 144 Fed. Appx. 804 (11th Cir.), and cert.
denied, 126 S.Ct. 785 (2005).

   In Morton, the Eleventh Circuit considered whether a base
offense level enhancement pursuant to U.S.S.G. § 2G2.2(b)(4)
involving “a pattern of activity involved the sexual abuse or
exploitation of a minor” was properly imposed where the
“minor” in question was actually a law enforcement officer
masquerading as a minor. 364 F.3d at 1301. As in the present
appeal, the defendant argued that the enhancement was
improper because the definition of “minor” provided by the
Sentencing Commission was limited to “individual[s] who
ha[ve] not attained the age of 18 years.”

   The Eleventh Circuit affirmed the sentence, holding that
law enforcement officers posing as minors qualified as “mi-
nors” for purposes of the enhancement. The court observed
that subsection (b)(4) referenced both “minor” and “victim”
in defining relevant conduct. From there, the court noted that
the definition of “victim” provided by U.S.S.G. § 2A3.2 spe-
cifically included undercover law enforcement officers. The
court then reasoned that because the terms “minor” and “vic-
11254                  UNITED STATES v. STEVENS
tim” were used interchangeably, it could expand the definition
of “minor” to be coextensive with “victim.”

   The Eleventh Circuit published its Morton opinion before
the Sentencing Commission amended the definition of
“minor” on November 1, 2004. It therefore did not have the
benefit of the Commission’s revisions, or its explanatory
notes, upon which we rely in considering the question pre-
sented in this appeal.

   Furthermore, after the Supreme Court vacated the opinion
in the wake of Booker v. United States, 453 U.S. 220 (2005),
see 543 U.S. 1136, the Eleventh Circuit reinstated its original
opinion in a short unpublished decision in 2005. See 144 Fed.
Appx. 804. Because that decision does not acknowledge the
Sentencing Commission’s 2004 amendment, id., we cannot
tell to what extent our sister circuit may have subsequently
considered and rejected the reasoning set forth above. But to
the extent that the Eleventh Circuit may still adhere to its
opinion in Morton, we respectfully disagree.

                                    III

   [6] By using the amended definition of “minor” and apply-
ing U.S.S.G. § 2G2.2(b)(2)(D), the district court increased
Stevens’s total offense level from 34 (151-188 months) to 41
(324-405 months). Despite the district court’s disdain for Ste-
vens and the crimes he freely admitted to committing, we can-
not say on this record that the court would have imposed the
same 360-month sentence had it not erred in its base offense
level calculation.2 See United States v. Crawford, 185 F.3d
  2
    The dissent argues that the district court’s error in misinterpreting
U.S.S.G. § 2G2.2(b)(2)(D) was harmless because Stevens’ actions consti-
tuted an attempt. That theory, however, was neither raised before the dis-
trict court nor argued in the parties’ principal briefs. We therefore decline
to address it. See United States v. Belden, 957 F.2d 671, 674-75 (9th Cir.
1992).
                   UNITED STATES v. STEVENS               11255
1024, 1029 (9th Cir. 1999). We therefore vacate the sentence
and remand for resentencing.

  The sentence is VACATED and the cause is REMANDED.



GRABER, Circuit Judge, dissenting:

  I respectfully dissent.

   Any error arising from the district court’s interpretation of
the term “minor” as used in U.S.S.G. § 2G2.2(b)(2)(D) is
harmless.

   First, it is undisputed that Defendant sent pornographic
images of children to a law enforcement officer, believing and
intending that he was distributing the materials to a minor.
That act constituted an attempt to distribute the materials to
a minor as a matter of law, even though the officer was not
a minor. See United States v. Meek, 366 F.3d 705, 717-18 (9th
Cir. 2004) (holding that an actual minor is not required to sus-
tain an attempt conviction under 18 U.S.C. § 2422, only that
the defendant believed that he was inducing a minor). There-
fore, the § 2G2.2(b)(2)(D) enhancement was appropriate. See
id. cmt. n.1 (defining “distribution” as “any act, including
possession with intent to distribute, production, advertise-
ment, and transportation, related to the transfer of material
involving the sexual exploitation of a minor”).

   Additionally, in reaching its sentencing decision, the dis-
trict court clearly was motivated by Defendant’s atrocious
related conduct and self-centered attitude. The record shows
that the sentence would have been the same under the advi-
sory system, regardless of which Guidelines section had
applied.

  For these reasons, I would affirm the sentence.
