Is your client looking at a sentence driven by a sentencing guideline commentary? Does that commentary interpret a genuinely ambiguous guideline? Does the commentary fall within the identified zone of ambiguity? What is a "zone of ambiguity" anyway?
Guideline commentary can only interpret a guideline--it can't add to it. But the test for when courts may rely on the commentary is complicated and disputed.Sixth Circuit (loss commentary) and the Third Circuit (career-offender commentary). Watch for a ruling on the cert petition in Tabb (career-offender commentary; distributed for conference of 3/19/2021).
And urge your district court to wake up from its "slumber of reflexive deference" to the sentencing guidelines commentary.