In 1927, the Motion Picture Producers and Distributors of America — now the MPAA — produced and published the following list, titled "The Dont's and Be Carefuls," in an effort to clean up Hollywood's increasingly controversial output and help the studios avoid further clashes with the country's regional censorship boards. The list consisted of 11 things to be completely avoided in future movies (the "Don'ts"), and 25 things that required careful consideration before inclusion (the "Be Carefuls").
The list was unenforceable however, and so to some extent ignored. In 1930, it was ditched in favour of the Motion Picture Production Code, which in turn gave way to the MPAA film rating system we now know.
(Source: Hollywood's America; Image: Flesh and the Devil, 1926, via.)
"The Don'ts and Be Carefuls"
Motion Picture Producers and Distributors of America, 1927
Resolved, That those things which are included in the following list shall not appear in pictures produced by the members of this Association, irrespective of the manner in which they are treated.
1. Pointed profanity — by either title or lip — this includes the words "God," "Lord," "Jesus," Christ" (unless they be used reverently in connection with proper religious ceremonies), "hell," "damn," "Gawd," and every other profane and vulgar expression however it may be spelled;
2. Any licentious or suggestive nudity-in factor in silhouette; and any lecherous or licentious notice thereof by other characters in the picture;
3. The illegal traffic in drugs;
4. Any interference of sex perversion;
5. White slavery;
6. Miscegenation (sex relationships between the white and black races);
7. Sex hygiene and venereal diseases;
8. Scenes of actual childbirth — in fact or in silhouette;
9. Children's sex organs;
10. Ridicule of the clergy;
11. Willful offense to any nation, race or creed;
And be it further resolved, That special care be exercised in the manner in which the following subjects are treated, to the end that vulgarity and suggestiveness be eliminated and that good taste may be emphasized:
1. The use of the flag;
2. International relations (avoiding picturizing in an unfavorable light another country's religion, history, institutions, prominent people, and citizenry);
4. The use of firearms;
5. Theft, robbery, safe-cracking, and dynamiting of trains, mines, building, etc. (having in mind the effect which a too-detailed description of these may have upon the moron);
6. Brutality and possible gruesomeness;
7. Techniques of committing murder by whatever method;
8. Methods of smuggling;
9. Third-degree methods;
10. Actual hangings or electrocutions as legal punishment for crime;
11. Sympathy for criminals;
12. Attitude toward public characters and institutions;
14. Apparent cruelty to children and animals;
15. Branding of people or animals;
16. The sale of women, or of a woman selling her virtue;
17. Rape or attempted rape;
18. First-night scenes;
19. Man and woman in bed together;
20. Deliberate seduction of girls;
21. The institution of marriage;
22. Surgical operations;
23. The use of drugs;
24. Titles or scenes having to do with law enforcement or law-enforcing officers;
25. Excessive or lustful kissing, particularly when one character or the other is a "heavy."