Whether a court of appeals may categorically foreclose appellate review of a defendant's disparity claim under 18 U.S.C. § 3553(a)(6) by requiring 'identical' rather than 'similar' defendants as comparators

A core purpose of the Sentencing Reform Act of 1984 is to eliminate arbitrary sentencing disparities. As part of that reform, 18 U.S.C. § 3553(a)(6) requires sentencing courts to consider “the need to avoid unwarranted sentence disparities among defendants with similar records who have been found guilty of similar conduct.” The First Circuit requires defendants to be “identically situated” before meaningful disparity review applies. Most other circuits require disparity analysis even when defendants may differ in their records or circumstances. This case presents the following question: Whether a court of appeals may categorically foreclose appellate review of a defendant’s disparity claim under 18 U.S.C. § 3553(a)(6)_ by requiring “identical” rather than “similar” defendants as comparators, when the statutory language expressly requires consideration of “the need to avoid unwarranted sentencing disparities among codefendants with similar records who have been found guilty of similar conduct.” i