Pre-Code films were created before the Motion Picture Production Code or Hays Code took effect on 1 July 1934 in the United States of America. Although an existing code of conduct for the film industry came into being in 1930, many ignored it and it was not enforced very enthusiastically.

The original code was written by a Jesuit priest, Father Daniel A. Lord and officially adopted in 1930. The code was effectively ignored because many found such censorship prudish, due to the liberal social attitudes of the 1920s and early 1930s. This was a period in which the Victorian era was looked upon as being naïve and backward and was constantly ridiculed as such.

Films in the late 1920s and early 30s reflected the liberal attitudes of the day and could include sexual innuendos, references to homosexuality, miscegenation, illegal drug use, infidelity, abortion, and profane language (such as the word "damn") as well as women in their undergarments. Such behavior was common in the liberal climate of cities at that time, although it often shocked audiences in rural areas.

Popular character roles include tough-talking, assertive women, gangsters, and prostitutes.

Of particular note were both the references to sexual promiscuity, drug use, bloody gangster life, and morally ambiguous endings, which drew the ire from various religious groups - some Protestant, but overwhelmingly Roman Catholic.

In particular, Amleto Giovanni Cicognani, apostolic delegate to the Catholic Church in the U.S. called upon American Catholics to unite against the surging immorality of the cinema. As a result, many religious groups created their own leagues, such as the Catholic Legion of Decency (eventually renamed to the "National Legion of Decency") in 1933, premised around controlling and enforcing decency standards in theatres, and boycotting movies which they deemed offensive. Conservative Protestants tended to support much of the crackdown on "immorality", particularly in the South, which had its own form of censorship. By 1939 "Even black bellboys were routinely cut out of films shown in the South; from the evidence of Hollywood pictures of the 1930s, one might not suspect that black people existed in America" (mr_lincoln.html" target="_blank">http://www.sensesofcinema.com/contents/06/39/young_mr_lincoln.html). Anything relating to the state of race relations in the South or miscegenation could never be exhibited below the _Mason-Dixon line.

By 1934, theatre revenues were slumping (likely, in part, due to the Depression) and those in the film industry were unhappy with the prospect of losing even more of their audience, particularly in heavily Catholic cities (New York, Boston, Chicago, etc).

Thus, the pre-Code era effectively came to a close with the establishment of a special bureau (eventually christened The Breen Office, after Joseph Ignatius Breen, a former public relations executive), whose purpose was to review scripts and finished prints in order to ensure that they adhered to the new Code.

This effectively spelled the end of the pre-Code era, and shaped the trends in American film-making during the ensuing years. Enforcement of the code popularized several new trends, such as plots about headstrong, able, employed women (like Jean Arthur).