审查电影的第一次尝试是由城市，而不是电影业。芝加哥和纽约在1900年代早期都给予警察权力来决定什么和不能被显示。1915年，美国最高法院裁定，根据第一修正案，电影不被视为受保护的言论，因此受管制。作为回应，主要的电影制片厂在1922年成立了美国电影制片商和分销商（MPPDA），一个行业游说组织。为了领导这个组织，MPPDA雇佣了前任邮政局长William Hays。海斯不仅代表电影制片人游说政客，他还告诉制片厂什么是可以接受的内容，什么是不可接受的内容。在20世纪20年代，电影制作人对题材的选择越来越大胆。按照今天的标准，偶尔瞥见一条光腿或一个暗示性的词语似乎很温顺，但在那个时代，这种行为是可耻的。像《野党》（1929）和克莱拉·鲍（Clara Bow）以及《她错怪了他》（1933）和梅·韦斯特（Mae.）这样的电影都激怒了观众，激怒了社会保守派和宗教领袖。在1930，海斯公布了他的电影制作代码，很快就被称为海斯代码。它的任务是确保电影描绘“正确的生活标准”，制片厂高管希望，避免未来政府审查的威胁。但MPPDA官员努力跟上好莱坞的产量，而海斯守则在最初几年里基本上无效。1934年，海斯聘请与天主教堂关系密切的游说家约瑟夫·I·布林来领导新的生产法典管理局。展望未来，每部电影都必须经过审查和评级才能获释。Breen和他的团队热情地投入了他们的工作。例如，《卡萨布兰卡》（1942）的著名结局场景被改变，以缓和汉弗莱·鲍嘉和英格丽·伯格曼的角色之间的性张力。在20世纪40年代，少数电影制片人通过独立于演播室系统发行电影来规避好莱坞审查人员。最著名的是《不法之徒》，一部由简·拉塞尔主演的1941部电影，给她著名的胸部提供了充足的银幕时间。在与审查制度抗争了五年之后，导演霍华德·休斯最终说服联合艺术家公司发行了这部电影，票房大跌。Breen在1951加强了代码的限制，但它的日子已经屈指可数了。20世纪60年代初，好莱坞一直遵守《电影制片法》。但是随着旧制片厂体制的崩溃和文化品味的变化，好莱坞意识到它需要一种新的方法来评价电影。在1968，美国电影协会（MPAA），MPPDA的继任者，创建了MPAA评级系统。最初，该系统有四个等级：G（一般观众），M（成熟），R（限制），和X（显式）。然而，MPAA从来没有给X级打过商标，不久，原本打算用于合法电影的影片就被色情业所接受，而色情业在宣传X级电影上胜过单片、双片甚至三片。多年来，这个体系被反复检修。1972年，M级改为PG级。12年后，“印第安纳琼斯和末日神庙”和“格林林斯”的暴力事件促使MPCC建立了PG-13级。1990年，美国电影协会公布了NC-17的评级，主要针对《亨利与琼》和《梦的安魂曲》等主流电影。柯比·迪克（Kirby Dick）的纪录片《这部电影还没有被评级》（2006）研究了美国电影协会的历史，他批评评级过于主观，尤其是对戴比的评级。性与暴力的概念就其本身而言，MPAA正试图更详细地说明评级是如何进行的。像“针对科幻暴力的评级PG-13”这样的短语现在出现在收视率中，MPAA已经开始在其网站上提供更多关于收视过程的细节。
The first attempt at censorship was in cities, not in films. Chicago and New York gave police power in the early 1900s to decide what and could not be displayed. In 1915, the Supreme Court of the United States ruled that under the First Amendment, films were not considered protected speech and were therefore regulated. In response, major film studios established MPPDA, an industry lobbying organization, in 1922. In order to lead the organization, MPPDA hired the former postmaster, William Hays. Hayes not only lobbied politicians on behalf of film producers, but also told studios what was acceptable and what was unacceptable. In 1920s, filmmakers became more and more daring in their choice of subjects. By today’s standards, occasional glimpses of a barefoot leg or a suggestive word seemed mild, but in that era it was shameful. Movies like “The Opposition” (1929) and Clara Bow, and “She Mistook him” (1933) and “Mae.” have angered audiences, social conservatives and religious leaders. In 1930, Hayes announced his film production code, which was soon called Hayes code. Its mission is to ensure that films depict “the right standard of living”, and studio executives hope to avoid the threat of future government censorship. But MPPDA officials tried to keep up with the output of Hollywood, and Hayes code was basically ineffective in the first few years. In 1934, Hayes hired Joseph I. Brin, a lobbyist closely associated with the Catholic Church, to lead the new Code of Production Authority. Looking ahead, every movie must be reviewed and rated before it can be released. Breen and his team enthusiastically invested in their work. For example, the famous ending scene of Casablanca (1942) was changed to ease the sexual tension between Humphrey Bogart and Ingrid Bergman’s roles. In the 1940s, a small number of filmmakers evaded Hollywood censors by distributing films independently of studio systems. The most famous film is The Illegal, a 1941 film starring Jane Russell, which provides ample screen time for her famous chest. Five years after struggling with censorship, director Howard Hughes finally persuaded United Artists to release the film, and box office sales plummeted. Breen has strengthened the code limit in 1951, but its days are numbered. In early 1960s, Hollywood had always followed the film production act. But as the old studio system collapsed and cultural tastes changed, Hollywood realized that it needed a new way to evaluate films. In 1968, the American Film Association (MPAA), the successor of MPPDA, created the MPAA rating system. Initially, the system had four levels: G (general audience), M (maturity), R (limitation), and X (explicit). However, MPAA has never trademarked X-rated movies. Soon, movies intended for legitimate movies were accepted by the pornography industry, which outperformed single, double or even three movies in promoting X-rated movies. Over the years, the system has been overhauled. In 1972, the M class was changed to PG grade. Twelve years later, violence at Indiana Jones and the Temple of Doomsday and Greenlins prompted MPCC to establish PG-13. In 1990, the American Film Association published NC-17 ratings, mainly for mainstream films such as Henry and Joan and Requiem of Dreams. Kirby Dick’s documentary “The Movie Hasn’t Been Ratified” (2006) examines the history of the American Film Association, criticizing ratings as too subjective, especially for Debbie. In terms of the concept of sex and violence, MPAA is trying to explain in more detail how ratings are carried out. As for science fiction violence rating PG-13 “the phrase now appears in the ratings, MPAA has started to provide more details about the ratings process on its website.