"No picture should lower the moral standards of those who see it. This is done: (a) When evil is made to appear attractive, and good is made to appear unattractive. (b) When the sympathy of the audience is thrown on the side of crime, wrong-doing, evil, sin. The same thing is true of a film that would throw sympathy against goodness, honor, innocence, purity, honesty."
January 1, 1970
https://en.wikiquote.org/wiki/Hays_Code