Appellee Richard Harper, a federal prisoner, was convicted of assaulting his cellmate with a dangerous weapon, in violation of 18 U.S.C. § 113(a)(3). At sentencing, the Government urged the court to apply a four-level increase to Harper’s offense level pursuant to U.S.S.G. § 2A2.2(b)(3)(D) to account for the degree of injury his victim sustained. The court instead applied a three-level increase pursuant to U.S.S.G. § 2A2.2(b)(3)(A), reflecting a lesser degree of injury. The Government appeals the district court’s ruling.
I
Harper pled guilty to the assault. According to the Presentence Report (“PSR”), Harper quarreled with his cellmate, Lujan, after Lujan turned off the lights in the cell while Harper was reading. Harper then stabbed Lujan with a meat thermometer six times. Prison officials transported Lujan by ambulance to a local hospital, where he was treated for a collapsed lung. The meat thermometer was later found wrapped in a bloodstained shirt. The PSR recommended applying a four-level upward adjustment' to Harper’s sentence pursuant to U.S.S.G. § 2A2.2(b)(3)(D) because Lujan suffered injuries that were more than significant but less than serious. Harper objected, arguing that the severity of Lujan’s injuries warranted only a three-level increase pursuant to U.S.S.G. § 2A2.2(b)(3)(A).
At the sentencing hearing, the district court reasoned that “under
[United States
v.]
Booker
[
Two days later, we issued our opinion in
United States v. Mares,
The district court denied the motion.
United States v. Harper,
It seems clear that the Supreme Court has ruled that sentencing enhancements must be based upon jury findings, prior convictions, the court documents and statutory definitions pertinent to such convictions, and admissions by a defendant. Accordingly, a sentence enhancement should not be applied in this case based upon the court’s choice of which of two possible inferences may be drawn, by a preponderance of the evidence, from facts admitted by the Defendant.
Id. at 835-36. 1
II
As an initial matter, we must address Harper’s argument that the Government has not satisfied the statutory requirements to pursue an appeal of a sentence. The Government may file a notice of appeal for review of a sentence that was “imposed as a result of an incorrect application of the sentencing guidelines.” 18 U.S.C. § 3742(b)(2). However, “[t]he Government may not further prosecute such appeal without the personal approval of the Attorney General, the Solicitor General, or a deputy solicitor general designated by the Solicitor General.”
Id.
Harper argues that nothing in the record establishes that this approval was obtained. In response, the Government at
*735
tached to its reply brief a memo from that the Solicitor General authorizing this appeal. In
United States v. Dadi,
We now turn to the merits of the Government’s appeal. We review the district court’s interpretation of the Sentencing Guidelines de novo and its factual determinations for clear error.
United States v. Solis-Garcia,
The issue in this case is whether
Shepard v. United States,
Shepard concerned the application of 18 U.S.C. § 924(e), the Armed Career Criminal Act (“ACCA”). Id. at 1257. The ACCA mandates a fifteen-year minimum term of imprisonment for anyone possessing a firearm after three prior convictions for serious drug offenses or violent felonies. Id. The issue was whether Shepard’s prior burglary convictions, obtained pursuant to a guilty pleas, were violent felonies. The ACCA defines burglary as a violent felony only if it was committed in a building, not a vehicle. Id. The Massachusetts statute that Shepard was convicted of violating, however, criminalized burglary of both buildings and vehicles. Id. The Government argued that the district court should look to police reports that revealed that Shepard had burglarized buildings and find accordingly. Id. at 1258. The Supreme Court held that the district court could look only to the indictment and Shepard’s admissions in determining whether the ACCA applied. Id. at 1263. The Court reasoned that permitting the judge to find facts raising the statutory range of possible sentences would violate Shepard’s Sixth Amendment right to a jury trial. Id. at 1262.
Unlike in Shepard, the facts relevant to the application of U.S.S.G. § 2A2.2(b)(3)(D) to Harper do not subject him to a higher potential sentence. In this case, Harper’s guilty plea by itself authorized a sentence of zero to ten years imprisonment. 18 U.S.C. § 113(a)(3). Under an advisory Guidelines system, a judicial finding with respect to the degree of injury that Harper inflicted on Lujan no longer mandates a sentence within any particular subset of the statutory range. Application of the ACCA, however, remains mandatory for all defendants to whom it applies. See 18 U.S.C. § 924(e) (stating that a person convicted of three prior violent felonies *736 “shall be ... imprisoned not less than 15 years”). It is this mandatory increase in the upper limit of Shepard’s sentence that created a Sixth Amendment right to have the facts supporting the ACCA enhancement found by a jury beyond a reasonable doubt. Because application of U.S.S.G. § 2A2.2(b)(3)(D) has no mandatory effect on Harper’s sentence, the district court erred in declining to find the relevant facts by a preponderance of the evidence. 3
Ill
For the foregoing reasons, we VACATE Harper’s sentence and REMAND for further proceedings consistent with this opinion.
Notes
. We note that the district court did not reason and Harper does not contend that the magnitude of the sentencing enhancement amounted to a "tail that wags the dog of the substantive offense” thereby requiring the use of a more stringent standard of proof.
Cf. United States v. Hopper,
. This court and the other courts of appeals have repeatedly held
post-Shepard
that a district court may find the facts relevant to a defendant’s Guidelines calculation by a preponderance of the evidence, without the aid of a jury.
United States v. Johnson,
. We note without deciding the issue that some district courts have considered their confidence in the accuracy of their findings in determining whether to give a non-Guidelines sentence.
See, e.g., United. States v. Wendelsdorf,
