Warriors Of The Code by Robert Vaughan
A tired old lawyer with a secret past, and the young protégé that he rescued from a wagon train attack that killed his parents and left him an orphan, are warriors in the tough town of Tombstone. Warriors of the code . . . they are equally adept with the Commentaries of Law, a book by William Blackstone . . . or the revolver, a pistol by Samuel Colt.