"For nearly 20 years, federal judges were required to impose sentences within the applicable guideline range unless the court found the existence of an aggravating or mitigating circumstance not adequately taken into consideration by the Commission in formulating the sentencing guidelines.240 This system changed in 2005, when the Supreme Court held in United States v. Booker that the mandatory operation of the guidelines violated the Sixth Amendment right to a jury trial and the associated right to have all 'elements' of the offense proved beyond a reasonable doubt.241 The Court remedied the constitutional violation by striking two provisions from the Sentencing Reform Act, thereby rendering the guidelines 'effectively advisory.'242 The Court reasoned that although an advisory guideline system lacked the mandatory features that Congress enacted, it nevertheless 'retains other features that help to further congressional objectives, including providing certainty and fairness in meeting the purposes of sentencing, avoiding unwarranted sentencing disparities, and maintaining sufficient flexibility to permit individualized sentences when warranted.'243 The Court concluded that an advisory guideline system would 'continue to move sentencing in Congress’s preferred direction, helping to avoid excessive sentencing disparities while maintaining flexibility sufficient to individualize sentences where necessary.'244
"Booker and its progeny explicitly and repeatedly reinforced the continued importance of the guidelines in the sentencing determination.245 District courts are required to properly calculate and consider the guidelines when sentencing.246 'The district court, in determining the appropriate sentence in a particular case, therefore, must consider the properly calculated guideline range, the grounds for departure provided in the policy statements, and then the factors under 18 U.S.C. § 3553(a).'247 Most circuits agree on the three-step approach reflected in USSG §1B1.1 (Application Instructions), including the consideration of departure provisions in the Guidelines Manual, in determining the sentence to be imposed.248"

Source

"Report to Congress: Mandatory Minimum Penalties in the Federal Criminal Justice System" (Washington, DC: US Sentencing Commission, October 2011), pp. 39-40.
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