 With Mr. Larkin on the Solicitor General's brief were also Acting Solicitor General Bryson, Acting Assistant Attorney General John Keeney, and John F. DePue.Robert Augustus Harper filed a brief on behalf of the Florida Association of Criminal Defense Lawyers as amicus curiae.In Justice Anthony Kennedy's unanimous majority opinion, the Court ruled that commentary issued by the United States Sentencing Commission (which promulgates the United States Sentencing Guidelines) that interprets or explains a guideline is authoritative unless it violates the Constitution or a federal statute, or is inconsistent with, or a plainly erroneous reading of, that guideline.