The 19-year-old Couch is serving nearly two years in a North Texas jail for a 2013 drunken-driving wreck that killed four people.
But his lawyers claim in a motion that because he was 16 at the time, the case should have remained in juvenile court and been treated as a civil action. They argue that because the case was improperly transferred to adult criminal court, the judge had no authority to sentence Couch.