Drew Peterson is due in court on a weapons charge for a having a gun authorities say had a barrel that was too short.
The former Bolingbrook police sergeant is expected in Will County court Monday afternoon in Joliet.
Peterson's attorneys have asked that the felony charge be dismissed.
The semiautomatic assault rifle was seized during an investigation into the disappearance of Peterson's wife, Stacy Peterson. Peterson hasn't been charged in connection with her disappearance.
Peterson's attorney has argued he is exempt from the law because he used the rifle on duty as a police officer.
Prosecutors have said Peterson owned the gun privately. Bolingbrook police contend they didn't know about the rifle.