The Sentencing Guidelines have always presented novel constitutional and interpretive issues. One issue that has recently divided the lower courts is how much deference to afford to the Sentencing Commission's commentary interpreting the Guidelines.

The Supreme Court answered this question nearly 30 years ago in Stinson v. United States, reasoning that the commentary is "akin to an agency's interpretation of its own legislative rules," which "must be given 'controlling weight unless it is plainly erroneous or inconsistent with'" the Guidelines. Following Stinson, federal courts have regularly given controlling weight to Guidelines commentary.

But Stinson is now on shaky ground.