The term "McCarthyism" refers to the practice of accusing others of traitorous activity without proper evidence; it stems from the Second Red Scare period of the United States (1950-1956), during which Senator Joseph McCarthy of Wisconsin accused many individuals in government, entertainment, education and unions of being Communist conspirators. These accusation led to trials and hearings that in some cases damaged careers. The validity of McCarthy's accusations is still debated.
In the late 1940s and early '50s, Congress, the FBI and the Department of Justice discovered many American communists who had infiltrated the government to carry out an extensive systems of espionage that provided the Soviet Union with government information and influenced U.S. policy in favor of the U.S.S.R. One of the most notable convicted communists was Alger Hiss, a State Department official who simultaneously played a key role in shaping the United Nations and served as a Communist spy.
In 1950, McCarthy delivered a speech in which he claimed to have a list of 205 communists working in the State Department. In response, the House Committee on Un-American Activities launched a series of hearings, and the FBI investigated the lives of many public officials. In many cases, the accused individuals suffered social stigmatization and damaged careers as a result of the proceedings. One of the most famous instances of negative repercussions was the Hollywood Blacklist, in which the studios denied employment to entertainment industry insiders on the basis of their real or alleged affiliations with the Communist Party.