McCarthyism is the term given to the unfair political methods of investigation, accusations, and trials of individuals without proper evidence. The term was first used to describe the methods used my Senator Joseph McCarthy during the 1950s to fight communism.
dictionary:
Mc·Car·thy·ism
noun
a vociferous campaign against alleged communists in the US government and other institutions carried out under Senator Joseph McCarthy in the period 1950–54. Many of the accused were blacklisted or lost their jobs, although most did not in fact belong to the Communist Party.
a campaign or practice that endorses the use of unfair allegations and investigations.
"he practiced McCarthyism long before there was a McCarthy"