Sheriff McAlister really WAS the leader of a....
... military-based squad of judicial officers.
Attached is a photo from the great 1992 movie "A Few Good Men".
A young Sheriff McAlister (Xander Berkeley) is seen as Captain Whitaker, the man in charge of assigning the defense of Dawson and Downey to Daniel Caffee (Tom Cruise).
http://i16.photobucket.com/albums/b2/HerdYou/red%20john%20good%20men_zpscxue6m8q.jpg