Enforcement of the Hays Code, which censored films' portrayal of activities deemed corrupting or vulgar at the time, went into effect on this day in 1934. Facing all sorts of legal threats from activists and regulators with varying standards across the country, major studio companies chose to self-censor, jointly issuing the Motion Picture Production Code in 1930. It banned all sorts of things, including acts that were common in everyday life for the time.
Under the rules, movies meant for the general public had to tiptoe around tons of subjects, and several on-screen behaviors were outright banned. The code said plots including adultery "should be avoided" and absolutely could not portray it in comedic settings. The use of "vulgar expressions (and oaths)" was entirely prohibited. Nudity wasn't allowed, and religious figures could only be shown with reverence. The can-can dance was also called out specifically as a no-no. All crime had to be punished on-screen, and seduction was banned except where essential to the plot, in which case it was only allowed to be implied. Impure love, meaning the kind "forbidden by human and divine law," was also out unless it was shown to be "clearly wrong" during the movie.
Thing is, there was no way to enforce the rules, and Hollywood pretty much ignored them … until 1934, when the Production Code Administration was set up. Its staff literally approved and rejected proposed plots, scripts, and final drafts of movies. If the PCA didn't sign off on a movie, the industry wouldn't distribute it. Movies became squeaky-clean. But in 1952, the Supreme Court said movies had free-speech protections, removing a major reason for the self-censorship. The code started to loosen; in 1968, it was replaced by a parental advisory board that issued age ratings for movies instead of broadly banning what could be shown.