How did the phrase “plead the Fifth” become widely used during the McCarthy hearings?

The phrase "plead the Fifth" refers to the Fifth Amendment clause that protects individuals from being compelled to testify against themselves in a court of law.12

While the legal right has existed since the ratification of the Bill of Rights in 1791, the specific expression "pleading the Fifth" entered broad public usage during the McCarthy hearings in the early 1950s. During this period, Senator Joseph McCarthy led aggressive investigations into alleged communist subversion within the U.S. government. Many individuals summoned to testify before his Senate subcommittee—such as the U.S. Army dentist Irving Peress—invoked the Fifth Amendment to avoid answering questions about their political affiliations or activities, fearing that their testimony could be used to incriminate them.123

As these hearings were highly publicized, the frequent invocation of this constitutional safeguard by witnesses became a defining feature of the proceedings, cementing the phrase in the American lexicon.2