The term McCarthyism refers to the practice of making public accusations of subversion or treason, usually of being a Communist, without proper evidence.
The term originated in the United States in the 1950s when the American politician Joseph McCarthy, who was a U.S. Senator at the time, <u>accused many Americans of being infiltrated Communists, even though there weren't unsubstantiated charges, and which resulted in a series of investigations and hearing in an effort to expose them</u>. The accusations and investigations were in America's spotlight for a while.