United States Court of Appeals
                            FOR THE EIGHTH CIRCUIT
                                    ___________

                                    No. 07-1479
                                    ___________

United States of America,             *
                                      *
           Plaintiff - Appellee,      *
                                      * Appeal from the United States
      v.                              * District Court for the Western
                                      * District of Missouri.
William Greene,                       *
                                      *
           Defendant - Appellant.     *
                                 ___________

                              Submitted: October 16, 2007
                                 Filed: January 30, 2008
                                  ___________

Before BYE, BOWMAN, and SMITH, Circuit Judges.
                           ___________

BYE, Circuit Judge.

       William Greene appeals the eighty-seven month sentence imposed following
his guilty plea to possessing with intent to distribute more than fifty grams of cocaine
base. Greene argues the district court improperly applied a presumption of
reasonableness to the applicable guidelines range. We vacate Greene's sentence and
remand for resentencing.
                                          I

       On May 17, 2006, Greene was indicted for possession with intent to distribute
more than fifty grams of cocaine base in violation of 21 U.S.C. §§ 841(a)(1),
(b)(1)(A). Pursuant to a plea agreement, Greene entered a plea of guilty on the single
count of the indictment. An initial presentence investigation report ("PSR")
concluded Greene's advisory guideline range was 108 to 135 months, based on an
adjusted offense level of 31 and a criminal history category of I. The report noted,
however, that Mr. Greene faced a ten year statutory minimum sentence that overrode
the low-end of this range.

       Following concerns over the adequacy of Greene’s counsel, the court appointed
the Federal Defender Office to represent Greene. Shortly thereafter, Greene submitted
to a proffer interview with the government and became eligible for a safety valve
reduction. This adjustment eliminated the ten year statutory minimum and reduced
Greene’s advisory range to 87 to 108 months.

       At sentencing, Greene requested a sentence below the applicable guidelines
range based on the factors set out in 18 U.S.C. § 3553(a). Specifically, Greene
requested a more lenient sentence based on (1) the Sentencing Commission’s
conclusions regarding the disparity between the penalties for cocaine powder and
cocaine base, (2) his age, (3) his medical condition, (4) his prior counsel's deficient
representation, and (5) his work record. At the time of sentencing, Greene was sixty
years old and was suffering from several health-related problems, including diabetes
and hypertension. In addition, Mr. Greene was recovering from a heart attack he
suffered in 2004.

       The district court noted under current Eighth Circuit law it had very limited
discretion in varying from the advisory guideline range. With respect to the
circumstances in this particular case, the court concluded Eighth Circuit precedent

                                         -2-
precluded it from imposing a downward variance from the low-end of the advisory
range. The court made clear, however, if it had the opportunity it would have imposed
a lower sentence based on United States v. Booker, 

(2005). The court
expressly stated in its Statement of Reasons it did not impose a downward variance
from the low-end of the advisory range because it believed it was precluded from
doing so under "current Eighth Circuit precedent." Sent. Tr. at 17. The court then
sentenced Greene to 87 months, the low-end of the applicable guidelines range.

                                         II

      Before reaching the merits of Greene's appeal, we must address the
government's motion to dismiss. After oral argument the government filed a motion
to dismiss Greene's appeal based on a waiver provision in Greene's plea agreement.
We hold the government waived this argument and, therefore, deny the government's
motion.

      This Court routinely enforces the doctrine of waiver and declines to address
arguments a party fails to raise in its opening brief. See, e.g., Hailemichael v.
Gonzales, 

, 886 n. 3 (8th Cir. 2006) (citing Akeyo v. O'Hanlon, 

, 374 n. 2 (8th Cir. 1996) ("As a general rule, we do not address arguments raised
for the first time in a reply brief. . . .")); United States v. Applied Pharmacy
Consultants, Inc., 

, 609 (8th Cir. 1999).

       Here, the government did not raise the waiver argument at sentencing in
response to Greene's request for a sentence outside the applicable guidelines range.
Nor did it raise the argument in its appellate brief. Indeed, the government's brief
expressly stated there was no plea agreement. It was not until oral argument that the
government, for the first time, suggested Greene's plea agreement foreclosed him from
seeking a sentence outside the applicable guidelines range. Because the record makes
clear the government waived this argument, we decline to address it here. See

                                         -3-
Latorre v. United States, 

, 1037 n. 1 (8th Cir. 1999) (declining to
address whether appellant's appeal was precluded by a waiver provision in the
appellant's plea agreement because the government had failed to raise the issue in the
district court or in the appeal). Instead, we proceed to the merits of Greene's claim.

                                          III

       This court reviews a district court's sentence determination under an abuse-of-
discretion standard. The United States Supreme Court recently clarified the scope of
our review:

      [T]he appellate court . . . must first ensure that the district court
      committed no significant procedural error, such as failing to calculate (or
      improperly calculating) the Guidelines range, treating the Guidelines as
      mandatory, failing to consider the § 3553(a) factors, selecting a sentence
      based on clearly erroneous facts, or failing to adequately explain the
      chosen sentence–including an explanation for any deviation from the
      Guidelines range. Assuming that the district court's sentencing decision
      is procedurally sound, the appellate court should then consider the
      substantive reasonableness of the sentence imposed under an
      abuse-of-discretion standard.

Gall, 

, 597 (2007). See also Koon v. United States, 

, 100
(1996) ("The abuse-of-discretion standard includes review to determine that the
discretion was not guided by erroneous legal conclusions.").

       According to Greene, the record demonstrates the district court interpreted this
court’s binding precedent to require application of a presumption of reasonableness
to the applicable guidelines range and to preclude a variance in the absence of
extraordinary circumtsances. As the Supreme Court made clear in Rita v. United
States, 

(2007), the presumption of reasonableness is an appellate
presumption and "the sentencing court does not enjoy the benefit of a legal

                                         -4-
presumption that the Guidelines sentence should apply." 

See also United
States v. Wilms, 

, 282 (6th Cir. 2007) (reversing and remanding
defendant's sentence due to the district court's imposition of a presumption of
reasonableness in violation of Rita); United States v. Foreman, 

, 644 n.1
(6th Cir. 2006) ("[A] district court's job is not to impose a 'reasonable' sentence.
Rather, a district court's mandate is to impose 'a sentence sufficient, but not greater
than necessary, to comply with the purposes' of section 3553(a)(2). Reasonableness
is the appellate standard of review in judging whether a district court has
accomplished its task.").

       The record in this case makes clear the district court applied a presumption of
reasonableness to the applicable guidelines range. At sentencing, the district court
stated, "I do not believe based on current Eighth Circuit law that I am permitted to do
a variance in this case. However, if I had an opportunity to do a variance based on
Booker, I would have done so." Sent. Tr. at 17. The district court also said it would
await the Supreme Court’s decision in Rita "to figure out whether I have some
discretion or whether really I’m pretty much bound by the federal sentencing
guidelines unless there's something that they haven't taken into account." 

       In light of Rita, the district court's application of a presumption of a
reasonableness was a significant procedural error. See 

. The
district court imposed the sentence, not as a result of the district court's assessment of
the relevant factors and determination of the minimally adequate sentence, as required
by § 3553(a), but as a direct consequence of the court's incorrect conclusion it was
bound by Eighth Circuit precedent to accord the guidelines range presumptive weight.
See 

("A district court by definition abuses its discretion when
it makes an error of law.") (citing Cooter & Gell v. Hartmarx Corp., 

,
403-05 (1990)).




                                           -5-
       Further, we do not believe this error was harmless.1 The government bears the
burden of proving the district court's error was harmless and must show that no "grave
doubt" exists as to whether the error substantially influenced the outcome of the
proceedings. United States v. Cullen, 

, 905-06 (8th Cir. 2006) (citations
omitted). The record makes clear had the district court properly exercised its
discretion, it would have found that the relevant factors and purposes compelled a
sentence below the advisory Guidelines range. Sent. Tr. at 17 ("[I]f I had an
opportunity to do a variance based on Booker, I would have done so."). Given the
record, we conclude the error substantially influenced the outcome of the proceedings
and, therefore, was not harmless.

                                          IV

      Accordingly, we vacate Greene's sentence and remand for resentencing
consistent with this opinion.2
                        ______________________________




      1
       We find, and the government does not disagree, Greene raised a timely
objection during sentencing and, therefore, preserved his challenge.
      2
        We note at resentencing, the district court "may consider the disparity between
the Guidelines' treatment of crack and powder cocaine offenses" in making a
determination whether "a within-Guidelines sentence is 'greater than necessary' to
serve the objectives of sentencing." Kimbrough v. United States, ___ S.Ct. ___, 

, *5 (U.S. Dec. 10, 2007).

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