This report assesses the impact of United States v. Booker1 on federal sentencing. The report is prepared pursuant to the general statutory authority of the United States Sentencing Commission (the “Commission”) under 28 U.S.C. §§ 994-995, and the specific responsibilities enumerated in 28 U.S.C. § 995(a)(14) and (15), which require the Commission to publish data concerning the sentencing process and to collect and systematically disseminate information concerning the actual sentences imposed and the relationship of such sentences to the factors set forth in 18 U.S.C. § 3553(a). On June 24, 2004, the Supreme Court decided Blakely v. Washington,2 invalidating a sentence imposed under the State of Washington’s sentencing guideline system. The Supreme Court held that the Washington guidelines violated the right to trial by jury under the Sixth Amendment of the United States Constitution. Although the Court stated that it expressed no opinion on the federal sentencing guidelines,3 the decision had an immediate impact on the federal criminal justice system. Following Blakely, district and circuit courts voiced varying opinions on the implication of the decision for federal sentencing and no longer uniformly applied the sentencing guidelines. On January 12, 2005, the Supreme Court decided Booker, applying Blakely to the federal guideline system and determining that the mandatory application of the federal sentencing guidelines violated the right to trial by jury under the Sixth Amendment. The Court remedied the Sixth Amendment violation by excising the provisions in the Sentencing Reform Act that made the federal sentencing guidelines mandatory, thereby converting the mandatory system that had existed for almost 20 years into an advisory one. The uniformity that had been a hallmark of mandatory federal guideline sentencing no longer was readily apparent as courts began to address new issues raised by Booker. For example, some district courts began to consider only facts proved beyond a reasonable doubt at sentencing, reasoning that Booker required this elevated standard. Others continued to apply the preponderance standard generally accepted before Booker. Some district courts continued to use settled procedures for imposing sentences; others created new procedures to implement the decision. Some district courts fashioned sentences without any consideration of the applicable guideline range. In fashioning a sentence outside the applicable guideline range, some district courts decided to forego an analysis of whether a departure under the guidelines would be warranted and instead relied only on Booker to impose the sentence. The majority of district courts, however, considered the applicable guideline range first, considered guideline departure reasons under the guidelines, and then decided whether consideration of the factors listed in 18 U.S.C. § 3553(a) warranted imposition of an out-of-range sentence. While some of these questions have been answered by the courts of appeal, others remain unresolved.