McCarthyism is the practice of making accusations of disloyalty, subversion, or treason without proper regard for evidence. The term has its origins in the period in the United States known as the Second Red Scare, lasting roughly from 1950 to 1954 and characterized by heightened fears of communist influence on American institutions and espionage by Soviet agents. Originally coined to criticize the anti-communist pursuits of Republican U.S. Senator Joseph McCarthy of Wisconsin, "McCarthyism" soon took 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 and/or destruction of their careers; some even suffered imprisonment. Most of these punishments came about through trial verdicts later overturned, laws that would be declared unconstitutional, dismissals for reasons later declared illegal or actionable, or extra-legal procedures that would come into general disrepute.