McCarthyism is the practice of making accusations of subversion or treason without proper regard for evidence. The term refers to U.S. Senator Joseph McCarthy and has its origins in the period in the United States known as the Second Red Scare, lasting roughly from 1947 to 1956 and characterized by heightened political repression as well as a campaign spreading fear of influence on American institutions and of espionage by Soviet agents.
McCarthyism has taken on a broader meaning, describing the excesses of similar efforts. The term is also now used more generally to describe reckless, unsubstantiated accusations, as well as demagogic attacks on the character or patriotism of political adversaries. During the McCarthy era, thousands of Americans were accused of being communists or communist sympathizers and became the subject of aggressive investigations and questioning before government or private-industry panels, committees and agencies. The primary targets of such suspicions were government employees, those in the entertainment industry, educators and union activists. Suspicions were often given credence despite inconclusive or questionable evidence, and the level of threat posed by a person's real or supposed leftist associations or beliefs was often greatly exaggerated. Many people suffered loss of employment or destruction of their careers; some even suffered imprisonment. Most of these punishments came about through trial verdicts later overturned, laws that were later declared unconstitutional, dismissals for reasons later declared illegal or actionable, or extra-legal procedures that would come into general disrepute.
The most notable examples of McCarthyism include the speeches, investigations, and hearings of Senator McCarthy himself; the Hollywood blacklist, associated with hearings conducted by the House Un-American Activities Committee (HUAC); and the various anti-communist activities of the Federal Bureau of Investigation (FBI) under Director J. Edgar Hoover. McCarthyism was a widespread social and cultural phenomenon that affected all levels of society and was the source of a great deal of debate and conflict in the United States.