Before 1934 movie makers could basically put whatever they wanted into a movie.The industry created its own code in 1934 to self-censor against certain things. For example, nudity. They were also not supposed to show a crime or a moral act and then the person getting away with it. Although there’s some haziness to that. The industry did it voluntarily it wasn’t imposed by lawmakers, although there were probably afraid of that happening. In 1969 they ended it and it was anything goes.
Thank you. I had no clue.