Gun rights advocates are fighting to have the names of firearm owners kept private.
Members of the Illinois State Rifle Association are appealing to a Peoria County judge not to let state police release the names of people with Firearm Owners Identification cards, according to the Associated Press.
They think it will make it easier for criminals to steal guns or victimize people who don't have them.
Friday's hearing is the latest in an ongoing debate in Illinois, triggered by Attorney General Lisa Madigan ruling last week that FOID cardholders' names are public information under Illinois law.
State police are considering their own legal action to overturn the ruling.