I think you mean a Red Scare Witch Hunt. We had two incidents in the U.S., both during the 20th century, in which this occurred. The Red Scare refers to fear of the rise of communism. When someone was labeled a "red" they were considered a communist which was viewed as a direct threat to our democracy. The witch hunt was an investigation to ferret out subversive activities but actually was used as a tactic to intimidate & harass someone who has a different viewpoint.
The first Red Scare witch hunt occurred immediately following World War I. This link will give you more accurate info than I can write here: http://www.ushistory.org/us/47a.asp
The second one occurred during the 1950's which was spearheaded by Senator Joe McCarthy. Thus, the term McCarthyism was born. He ruined many good people's lives. Again, another link that can give you more accurate info than I can write out: http://www.ushistory.org/us/53a.asp
