The government has moved to defer disposition of all sentencing appeals pending resolution of its petition for rehearing en banc in this case. We have denied the petition for rehearing and will deny the motion as well.
The Supreme Court’s decision in United States v. Booker brought about sweeping changes in the realm of federal sentencing. — U.S. -, 125 S.Ct. 738, 160 L.Ed.2d 621 (2005). Drawing upon its reasoning in Jones, Apprendi, and Blakely,1 the Booker majority held that mandatory enhancement of a sentence under the Guidelines, based on facts found by the court alone, violates the Sixth Amendment. Booker, 125 S.Ct. at 756. To remedy this constitutional infirmity, the Court excised that provision of the statute making application of the Guidelines mandatory. Id. at 764. In the aftermath of Booker, the Federal Sentencing Guidelines once a mandatory regime circumscribing the discretion of district court judges are “effectively advisory.” Id. at 757. Under the post-Boofoer sentencing framework, District Courts will consider the applicable advisory Guidelines range in addition to factors set forth in 18 U.S.C. § 3553(a). See Booker, 125 S.Ct. at 764-65. Booker is applicable to all cases on direct review. Id. at 769.
Direct appeals of sentences imposed before Booker generally present two kinds of claims: first, defendants whose sentences were enhanced by judicial factfinding raise Sixth Amendment claims; second, defen*164dants who contend the District Courts erroneously treated the Guidelines as mandatory rather than advisory.
In our review of pre-Booker cases, many of the direct appeals call for a plain error analysis because defendants did not raise the sentencing issue before the District Court. See Fed.R.Crim.P. 52(b).2 Where a defendant demonstrates “error” that is “plain,” and that “affects substantial rights,” we may correct that error where the “fairness, integrity, or public reputation of judicial proceedings” was affected. United States v. Evans, 155 F.3d 245, 251 (3d Cir.1998). As explained in Evans, an error will affect substantial rights where it is prejudicial and “affected the outcome of the district court proceedings.” Id. (quoting United States v. Olano, 507 U.S. 725, 734, 113 S.Ct. 1770, 123 L.Ed.2d 508 (1993)).
Where the District Court imposed a sentence greater than the maximum authorized by the facts found by the jury alone, the outcome of sentencing was altered to the defendant’s detriment. Mandatory enhancement of a sentence in violation of the Sixth Amendment is prejudicial and affects the substantial rights of the defendant. As we have noted, “imposing a sentence not authorized by law seriously affects the fairness, integrity, and reputation of the proceedings.” Evans, 155 F.3d at 252 (citing United States v. Dozier, 119 F.3d 239, 244-45 (3d Cir.1997)). In cases where a defendant’s sentence was enhanced based on facts neither admitted to nor found by a jury, therefore, the defendant can demonstrate plain error and may be entitled to resentencing.3 See United States v. Hughes, 401 F.3d 540 (4th Cir.2005) (finding plain error and remanding for resentencing because defendant who was sentenced to 46 months due to judicial factfinding where the jury verdict authorized only a 12-month sentence demonstrated that his substantial rights were affected).
Similarly, a defendant’s substantial rights may have been affected where the District Court erred by treating the Guidelines as mandatory rather than advisory. At this stage, we cannot ascertain *165whether the District Court would have imposed a greater or lesser sentence under an advisory framework. But the mandatory nature of the Guidelines controlled the District Court’s analysis. Because the sentencing calculus was governed by a Guidelines framework erroneously believed to be mandatory, the outcome of each sentencing hearing conducted under this framework was necessarily affected. Although plain error jurisprudence generally places the burden on an appellant to demonstrate specific prejudice flowing from the District Court’s error, in this context where mandatory sentencing was governed by an erroneous scheme prejudice can be presumed. See Olano, 507 U.S. at 735, 113 S.Ct. 1770 (noting that certain types of error should, on plain error review, “be presumed prejudicial if the defendant cannot make a specific showing of prejudice”); United States v. Adams, 252 F.3d 276, 287 (3d Cir.2001) (“Given the nature of the right [of allocution] and the difficulty of proving prejudice from its violation, we conclude that we should presume prejudice when a defendant shows a violation of the right and the opportunity for such a violation to have played a role in the district court’s sentencing decision.”) (emphasis in original); see also United States v. Barnett, 398 F.3d 516, 528 (6th Cir.2005) (presuming prejudice where “it would be exceedingly difficult” for defendant raising Booker claim to show that the district court’s failure to treat the Sentencing Guidelines as advisory affected his sentence).
Furthermore, as noted by the Court of Appeals for the Sixth Circuit, “[w]e would be usurping the discretionary power granted to the district courts by Booker if we were to assume that the district court would have given [defendant] the same sentence post-Booker.” United States v. Oliver, 397 F.3d 369, 380 n. 3 (6th Cir.2005). Failure to remand for resentencing, therefore, could adversely affect the fairness and integrity of the proceedings. Accordingly, defendants sentenced under the previously mandatory regime whose sentences are being challenged on direct appeal may be able to demonstrate plain error and prejudice. We will remand such cases for resentencing.4
Booker applies to all cases pending on direct review. By remanding, we ensure that each defendant to whom Booker applies is sentenced accordingly. This approach results in uniform treatment of post-Booker defendants on direct appeal, fostering certainty in the administration of justice and efficient use of judicial re*166sources. Moreover, as the Court of Appeals for the Second Circuit has noted, “correction of error in the context of sentencing does not precipitate ... burdensome and often lengthy consequenee[s]” on remand. United States v. Crosby, 397 F.3d 103, 117 (2d Cir.2005).
In this opinion, we express no view on waiver or alternative sentences. We will continue to review each appeal individually. Appellants have been directed to state whether they wish to challenge their sentence under Booker. For those who do not, we consider the appeal on its merits. Where an appellant raises a Booker claim and establishes plain error, however, we will decide claims of error related to the conviction, vacate the sentence, and remand for consideration of the appropriate sentence by the District Court in the first instance. Accordingly, the Government’s Motion to Defer Disposition of All Pending Criminal Appeals Presenting Booker Claims Pending Resolution of the Government’s Petition for Rehearing En Banc is denied.