Notable concurrence laments that Eleventh Circuit's "sentencing precedent is a crazy quilt"

A helpful colleague made sure I did not miss a remarkable concurring opinion by Eleventh Circuit Judge Kevin Newsom in US v. Curtin, No. 22-10509 (11th Cir. Aug. 28, 2023) (available here).  Judge Newman authored the lengthy opinion for the Court, which affirms the conviction and above-guideline sentence for a defendant convicted of multiple changes stemming from a threat made against a federal magistrate judge.  But his lengthier concurring opinion is the real must-read for sentencing fans, and the start and end of that opinion highlights why:

Among the many issues that this case presents, one recurs with some frequency, and our treatment of it has always struck me as a little odd.  Our precedent has (albeit haphazardly) categorized a criminal defendant’s argument that the district court considered an impermissible factor in imposing a sentence as a challenge to the sentence’s “substantive” reasonableness, rather than an allegation of “procedural” error.  See Maj. Op. at 17.  That didn’t — and for reasons I’ll explain, still doesn’t — make much sense to me.  So I decided to look into it.

The deeper I dug, though, the more problems I uncovered. As it turns out, our sentencing precedent is pretty hopelessly conflicted — not only with respect to the categorization of particular sentencing-related challenges as “substantive” or “procedural,” but also with respect to the rules that govern the preservation of those challenges for appeal and, as a result, the standards by which we review alleged sentencing errors. In the pages that follow, I hope to (1) unmask the contradictions in our precedent and (2) briefly propose a better way of classifying and adjudicating sentencing-related challenges....

Clearly, I got more than I bargained for in this case — and, by extension, so did you.  What I found, though — and what I hope I’ve demonstrated — is that our sentencing precedent is a crazy quilt.  First, we’ve been freakishly inconsistent in our characterization of sentencing challenges as “substantive,” “procedural,” or (tellingly) both.  And in important respects, even where we have settled into something that might be called a pattern, we’ve chosen poorly.  Nowhere is that more true, in my view, than in our classification as substantive of what is to me the self-evidently procedural challenge to a district court’s consideration of an improper sentencing factor.  Second, we’ve been just as erratic in our pronouncements about what suffices to preserve sentencing-related challenges: One day, a boilerplate objection will suffice, the next day it won’t.

Enough is enough.  We should convene the full Court to restore some order. And when we do, we should take our cue from the Supreme Court’s own sentencing decisions.  To start, we should hold that all (as I’ve called them) “input”-related challenges are allegations of “procedural error” and should be assessed at the outset, before turning to evaluate, as a matter of “substantive reasonableness,” the district court’s “output” — i.e., the sentence itself.  And when determining whether a defendant has properly preserved his sentencing-related challenge — whether substantive or procedural — we should apply the usual rules and ask whether he specifically stated the grounds of his particular objection, in a manner that clearly put the district court on notice of its alleged error.