                 FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                   No. 09-30047
                Plaintiff-Appellee,
               v.                             D.C. No.
                                          3:90-cr-00052-PA-1
LEROY MORALES,
                                               OPINION
             Defendant-Appellant.
                                      
       Appeal from the United States District Court
                for the District of Oregon
        Owen M. Panner, District Judge, Presiding

                 Argued and Submitted
           November 4, 2009—Portland, Oregon

                   Filed January 5, 2010

Before: Alex Kozinski, Chief Judge, Raymond C. Fisher and
             Richard A. Paez, Circuit Judges.

             Opinion by Chief Judge Kozinski




                            199
                  UNITED STATES v. MORALES               201




                        COUNSEL

Argued by Stephen R. Sady, Assistant Federal Public
Defender, Portland, Oregon; briefed by Alison M. Clark,
Assistant Federal Public Defender, Portland, Oregon, for the
defendant-appellant.

Argued by Leah K. Bolstad, Assistant United States Attorney,
Portland, Oregon; briefed by Karin J. Immergut, United States
Attorney, District of Oregon, Portland, Oregon; and Kathleen
L. Bickers, Assistant United States Attorney, Portland, Ore-
gon, for the plaintiff-appellee.
202               UNITED STATES v. MORALES
                         OPINION

KOZINSKI, Chief Judge:

  We consider whether a defendant is eligible for a reduction
of his supervised release revocation sentence because the
guideline range for his original crime was lowered.

                            Facts

   In 1990, Leroy Morales pled guilty to distribution of crack
cocaine and was sentenced to 110 months in prison and 5
years supervised release. Morales served his time but, while
on supervised release, he was convicted of robbery in state
court. Because of this conviction, the federal district court
revoked Morales’s supervised release and sentenced him to 36
months, which he is to serve on completion of his state sen-
tence.

   Effective November 2007, the United States Sentencing
Commission lowered the offense levels for crack cocaine, see
U.S.S.G. app. C, amend. 706 (2007), and this change is retro-
active, id. at amend. 713 (2008). Morales moved to reduce his
sentence for violating supervised release in March 2008. He
argued that, had he been sentenced under the revised guide-
lines, his sentencing range would have been 92-115 months
instead of 110-137 months. Based on this difference, he
requested an 18-month reduction of his supervised release
revocation sentence. The district court concluded that it had
no authority to reduce Morales’s sentence and denied the
motion. Morales appeals.

                          Analysis

   [1] We review de novo whether the district court had juris-
diction to modify Morales’s sentence. United States v. Leni-
ear, 574 F.3d 668, 672 (9th Cir. 2009). Generally, courts may
                   UNITED STATES v. MORALES                 203
not alter a term of imprisonment once it is imposed. Id. at
673. But 18 U.S.C. § 3582(c)(2) creates an exception:

    [I]n the case of a defendant who has been sentenced
    to a term of imprisonment based on a sentencing
    range that has subsequently been lowered by the
    Sentencing Commission . . . the court may reduce
    the term of imprisonment . . . if such a reduction is
    consistent with applicable policy statements issued
    by the Sentencing Commission.

A defendant must meet two criteria to be eligible for a sen-
tence reduction under this provision: (1) He must have been
sentenced to a term of imprisonment based on a sentencing
range that was later lowered by the Commission; and (2) the
reduction must be consistent with the Commission’s applica-
ble policy statements. Leniear, 574 F.3d at 673. Unless a
defendant satisfies both requirements, the district court lacks
jurisdiction to consider a reduction. Id. at 672-73.

   [2] In United States v. Etherton, we held that a defendant
was eligible for a reduction of his supervised release revoca-
tion sentence because the guideline range for his original
crime was lowered. 101 F.3d 80, 81 (9th Cir. 1996). We
explained that “a term of supervised release . . . is ‘simply
part of the whole matrix of punishment which arises out of a
defendant’s original crimes.’ ” Id. (quoting United States v.
Paskow, 11 F.3d 873, 883 (9th Cir. 1993) (alteration in origi-
nal)). We thus affirmed the district court’s reduction of Ether-
ton’s supervised release revocation sentence because the
guideline range for his underlying crime—conspiracy to man-
ufacture and distribute marijuana plants—had been reduced.
Id. at 81-82.

  [3] We take our duty to follow circuit precedent seriously.
See Miller v. Gammie, 335 F.3d 889, 899-900 (9th Cir. 2003)
(en banc). And Etherton clearly held that “[b]ecause Etherton
had been sentenced ‘based on a sentencing range that has sub-
204                UNITED STATES v. MORALES
sequently been lowered,’ the court had authority to exercise
its discretion to reduce the sentence under section
3582(c)(2).” 101 F.3d at 81. The facts in Etherton are materi-
ally indistinguishable from those here: Both defendants were
originally convicted of drug crimes and later sentenced for
supervised release violations, and both argued that their
supervised release revocation sentence should be reduced
because the guideline range for their drug crime had been
lowered. Nevertheless, we conclude that the district court here
didn’t have jurisdiction to reduce Morales’s sentence.

   [4] Just one year after Etherton, the Commission amended
its commentary to U.S.S.G. § 1B1.10, which is a policy state-
ment applicable to section 3582(c)(2), Leniear, 574 F.3d at
674. Section 1B1.10(a)(1) provides that when “a defendant is
serving a term of imprisonment, and the guideline range
applicable to that defendant has subsequently been lowered
. . . the court may reduce the defendant’s term of imprison-
ment as provided by 18 U.S.C. § 3582(c)(2),” and the text of
this section hasn’t significantly changed since Etherton. The
amendment added Application Note 4 (now numbered Appli-
cation Note 4(A)), which says that “[o]nly a term of imprison-
ment imposed as part of the original sentence is authorized to
be reduced under this section. This section does not authorize
a reduction in the term of imprisonment imposed upon revo-
cation of supervised release.” As if the note weren’t clear
enough, the Commission’s explanation of the amendment
says that “contrary to the holding in United States v. Etherton,
a reduction in the term of imprisonment imposed upon revo-
cation of supervised release is not authorized by the policy
statement.” U.S.S.G. app. C, amend. 548 (1997) (citation
omitted).

   Application Note 4(A) is an authoritative interpretation of
section 1B1.10, so long as it’s not inconsistent with or a
plainly erroneous reading of the guideline, or a violation of
the Constitution or a federal statute. See United States v. Ris-
ing Sun, 522 F.3d 989, 996 (9th Cir. 2008). We are not aware
                   UNITED STATES v. MORALES                   205
of any statute or constitutional provision the note violates.
And it’s not a clearly erroneous interpretation of section
1B1.10, as the policy statement is ambiguous regarding its
applicability to supervised release revocation sentences: Judge
T.G. Nelson’s dissent in Etherton shows that reasonable peo-
ple can disagree about whether the sentencing range for a vio-
lation of supervised release has been lowered just because the
range for the original crime was reduced. See Etherton, 101
F.3d at 82 (Nelson, J., dissenting).

   So, unlike the sentence reduction in Etherton, which pre-
dated Application Note 4(A), a reduction in a supervised
release revocation sentence today would be inconsistent with
an applicable policy statement. In light of this development,
two circuits have held that district courts aren’t authorized by
section 3582(c)(2) to reduce sentences for violating super-
vised release. See United States v. Fontenot, 583 F.3d 743,
744-45 (10th Cir. 2009); United States v. Forman, 553 F.3d
585, 589 (7th Cir. 2009) (per curiam). In Forman, the Seventh
Circuit specifically rejected defendant’s reliance on Etherton:
“Etherton sought to answer a question left open by the guide-
lines in effect at the time. One year later, in 1997, the Sen-
tencing Commission filled the gap with Application Note
4(A), and no court has relied on Etherton since.” 553 F.3d at
589.

   Of course, the Commission can’t tell federal courts how to
interpret statutes. See generally Neal v. United States, 516
U.S. 284, 290 (1996). Application Note 4(A) therefore
doesn’t displace Etherton’s interpretation of “based on a sen-
tencing range that has subsequently been lowered” in section
3582(c)(2). 101 F.3d at 81. But this is just the first eligibility
requirement for a reduced sentence under section 3582(c)(2).
See p. 203 supra. The second is that a reduction be consistent
with the Commission’s applicable policy statements. Id.

  [5] In affirming a sentence reduction under section
3582(c)(2), Etherton implicitly held that there were no incon-
206                UNITED STATES v. MORALES
sistent policy statements. We reach the opposite result
because the law has changed: Application Note 4(A) clarifies
that reducing a supervised release revocation sentence is
inconsistent with U.S.S.G. § 1B1.10. In Stinson v. United
States, the Supreme Court reversed the Eleventh Circuit for
failing to reconsider its interpretation of a guideline in light of
commentary later issued by the Commission. 508 U.S. 36, 39,
44 (1993). Application Note 4(A) thus justifies—indeed
requires—discarding our prior interpretation of section
1B1.10. See Miller, 335 F.3d at 900 (intervening higher
authority justifies overturning prior panel opinion).

   Morales argues that under United States v. Booker, 543
U.S. 220 (2005), Application Note 4(A) is at most advisory.
But Booker concerned the significance of the guidelines when
the district court imposes a sentence. See id. at 259. The issue
here is whether the district court even has jurisdiction under
section 3582(c)(2) to modify Morales’s sentence. In this situa-
tion, Booker doesn’t control. See Leniear, 574 F.3d at 674.

   [6] The Supreme Court explained in Braxton v. United
States that “Congress has granted the Commission the unusual
explicit power to decide whether and to what extent its
amendments reducing sentences will be given retroactive
effect, 28 U.S.C. § 994(u). This power has been implemented
in U.S.S.G. § 1B1.10, which sets forth the amendments that
justify sentence reduction.” 500 U.S. 344, 348 (1991). More-
over, 18 U.S.C. § 3582(c)(2) requires that a reduction be con-
sistent with the Commission’s policy statements. Between
sections 994(u) and 3582(c)(2), then, the Commission’s pol-
icy statement concerning whether a sentence reduction is
authorized—section 1B1.10—is binding. See United States v.
Washington, 584 F.3d 693, 699-700 (6th Cir. 2009); United
States v. Doe, 564 F.3d 305, 310 (3d Cir. 2009); United States
v. Dunphy, 551 F.3d 247, 250-51 (4th Cir. 2009); United
States v. Walsh, 26 F.3d 75, 77 (8th Cir. 1994). And Applica-
tion Note 4(A) is an authoritative interpretation of section
1B1.10. See pp. 204-205 supra. The district court therefore
                  UNITED STATES v. MORALES                 207
correctly concluded that Morales wasn’t eligible for a reduc-
tion under section 3582(c)(2).

                           *   *   *

   [7] Morales satisfies the first requirement for a sentence
reduction pursuant to section 3582(c)(2): Under Etherton,
Morales has been sentenced to a term of imprisonment “based
on a sentencing range that has subsequently been lowered.”
But Morales fails to satisfy the second: A reduction isn’t con-
sistent with the Commission’s applicable policy statements.
Thus, the district court was without jurisdiction to reduce
Morales’s sentence.

  AFFIRMED.
