Whether a court of appeals that finds that a district court has failed adequately to explain a sentence can simply request further elaboration without vacating the sentence and ordering resentencing as required by 18 U.S.C. § 3742.

Whether, in the wake of Gall v. United States, 552 U.S. 38 (2007), a court of appeals may review a sentence for substantive unreasonableness under a "shocks-the-conscience" standard.

Whether a court of appeals that finds that a district court has failed adequately to explain a sentence can simply request further elaboration without vacating the sentence and ordering resentencing as required by 18 U.S.C. § 3742