Dillon v. US, No. 09-6338, involved defendant's motion for a sentence reduction under 18 U.S.C. section 3582(c)(2). The Supreme Court affirmed the Third Circuit's affirmance of the denial of the motion, holding that Booker's holdings did not apply to section 3582(c)(2) proceedings, and therefore did not require treating U.S.S.G. secton 1B1.10(b) as advisory.
As the Court wrote: "A federal court generally "may not modify a term of imprisonment once it has been imposed." 18 U. S. C. §3582(c). Congress has provided an exception to that rule "in the case of a defendant who has been sentenced to a term of imprisonment based on a sentencing range that has subsequently been lowered by the Sentencing Commission." §3582(c)(2). In those circumstances, §3582(c)(2) authorizes a court to reduce the term of imprisonment "if such a reduction is consistent with" applicable Commission policy statements. The policy statement governing §3582(c)(2) proceedings instructs courts not to reduce a term of imprisonment below the minimum of an amended sentencing range except to the extent the original term of imprisonment was below the range then applicable. See United States Sentencing Commission, Guidelines Manual §1B1.10(b)(2) (Nov. 2009) (USSG). This case presents the question whether our decision in United States v. Booker, 543 U. S. 220 (2005), which rendered the Guidelines advisory to remedy the Sixth Amendment problems associated with a mandatory sentencing regime, requires treating §1B1.10(b) as nonbinding. We conclude that Booker does not demand that result."