Are you sure it's from a movie? I've just had an intense googling session, and I can't find any reference to it other than the opening to the song Omerta by Lamb of God.
Except in peoples signatures in forums, which is really, really annoying.
I'm also assuming you mean the “Whoever appeals to the law against his fellow man is either a fool or a coward. Whoever cannot take care of themselves without that law is both. For a wounded man shall say to his assailant, ‘If I live, I will kill you. If I die, you are forgiven’. Such is the rule of honor.” quote.