Assuming that procedural error applies, I think an important factor here is that the Court decided an issue of procedural error under Gall and not an issue of substantive reasonableness. I would argue that a procedural error under Gall is always plain.

Under Gall’s two-step review process, a procedural error requires remand because a sentence cannot be substantively reasonable if it is procedurally infirm. It is not the place of an appellate court to decide what a sentencing court might have done if it had fully and accurately considered the relevant sentencing factors. A sentence that contains a procedural error is essentially unreviewable.

It seems to follow then that, under Gall, a procedural error at sentencing necessarily affects the fairness, integrity, and public reputation of the proceeding.