L When conducting their substantive-reasonableness review of sentences, can appellate courts reweigh the sentencing factors in 18 U.S.C. § 3553(a), as the First, Eighth, Ninth, and Eleventh Circuits hold, or does this Court's decision in Gall v. United States, 552 U.S. 38 (2007), prohibit appellate courts from reweighing the sentencing factors, as the Fifth and Tenth Circuits hold?

IL What is the appropriate standard for appellate courts to apply when conducting their substantive-reasonableness review of sentences?

Can appellate courts reweigh the sentencing factors in 18 U.S.C. § 3553(a)