United States v. Davis, 739 F.3d 1222 (9th Cir. Jan. 14, 2014) (affirming district court's denial of defendant's motion to reduce sentence, because an amended policy statement, USSG Manual 1B1.10(b), which generally prohibits a court from reducing a sentence to a term that is less than the minimum of the amended guidelines range, does not exceed the Sentencing Commission's authority and does not violate the separation of powers doctrine).