In the 1920's moviemakers struggled with censors over what could and couldn't be shown on the big screen. Sexy sirens and gun-slinging gangsters came under attack by religious and government groups and other concerned citizens. Hollywood has always had state and local censorship boards, each with it's own guidelines and requirements, but in 1930 that changed. The self imposed Production Code was adopted to ensure all films passed "inspection". Later, in 1934, the head of the Motion Picture Association, Will Hays, hired Joe Breen to strictly enforce the code. It has been those restrictions that influenced the way movies have been ever since.
Hollywood was suffering after the depression at this time. Ticket sales were down and in an effect, prices were lowered, but theatres were still dark and much of the industry was facing possible bankruptcy. This could have been another factor to the enforcement of the production code.
The production code would enforce the message that the guilty are always punished and the murder is always avenged. It also prohibited illegal drugs, excessive violence, "white slavery", profanity, "sex perversion", miscegenation, suggestive dancing, and "lustful kissing". Actresses such as Joan Crawford, Marlene Dietrich and Norma Shearer had formed and shaped this sexual, independent and commanding picture of woman and the Production Code Administration enforced the rules and had to break these new female characters down. .
In the late 30's Hollywood had almost fully recovered from the depression and had gotten back to packing theatres. Shirley Temple movies had become a huge success along with films like the 1939 hit Gone With the Wind. However, the later movie's most famous line was in jeopardy of being allowed in the film. Would the film have been quite the same if Clark Gable had not uttered those infamous words, "Frankly my dear, I don't give a damn"? It was a famous line of literature, and was almost prohibited because the Production Code's didn't allow the use of any profanity.