blacklist

     The most famous blacklist in recent memory was the Hollywood blacklist. In the 1950's, Hollywood film studios kept a list of people suspected of being communists or communist sympathizers, and refused to hire any of them. This was what it meant to be "blacklisted".  Hollywood didn't think this up all by itself. A ( probably ) small but vocal portion of the public complained ( loudly ) whenever they thought that Hollywood movies were being sympathetic to communism. The studios were afraid of them, and instituted the "blacklist" in an effort to appease them. Hollywood, in particular, was being investigated by the House Un-American Activities Committee ( HUAC )--a committee set up by the U.S. Congress to investigate suspected communists and "fellow-travelers". You can search this under "HUAC" or "Hollywood Blacklist" or  "Mc Carthyism".
     The anti-communists feared that the people who made movies, along with other writers and artists, were in a position to promote a communist point of view. To some of these anti-communists, any movie or book that criticized our society in any way was suspect. If the author thought that poverty was a bad thing, for example, it meant that he or she was opposed to capitalism, and therefore in favor of communism. This extremism took several years to die out. The HUAC investigations, led by Joseph McCarthy, became famous as a "witch hunt". Those who confessed and threw themselves on the mercy of the committee might be left alone--but only if they agreed to provide the names of other communists. Anyone who maintained his or her innocence was suspect, and remained suspect.