The main doctrinal source of the modern federal sentencing regime is United States v. Booker, 543 U.S. 220 (2005). The U.S. Supreme Court in Booker famously ruled that the U.S. Sentencing Guidelines, which had been binding, must be advisory to be constitutional. A lesser-known feature of Booker is its provision for a check on the discretion of sentencing courts: appellate review of sentences for unreasonableness. Justice Antonin Scalia, writing in dissent, wondered whether this review would be “a mere formality,” and, for many years after Booker, that appeared largely to be the case in the U.S. Court of Appeals for the Second Circuit. But there have been recent changes: the court has vacated all or part of a sentence as substantively unreasonable three times in the last six months, and five times in the last 18 months, suggesting that substantive reasonableness review in the Second Circuit is finally getting teeth.

Early Post-’Booker’ Years

Appellate review of federal sentences post-Booker, as the Supreme Court clarified in Gall v. United States, 552 U.S. 38, 51 (2007), proceeds in two parts: procedural reasonableness—that is, whether the district court properly calculated the guidelines range, considered the statutory factors, and adequately explained the sentence; and substantive reasonableness, which considers the severity of the sentence taking into account the totality of the circumstances under an abuse-of-discretion standard.