What is McCarthyism? Meaning and history of the term used by President Trump

As FBI Director James Comey testified before Congress on Monday, Rep. Adam Schiff invoked a term with a fraught history in American politics: McCarthyism.

The fraught term was invoked by President Donald Trump, who accused former President Barack Obama of engaging in McCarthyism by wiretapping Trump Tower. 

When asked if the FBI or Obama were engaged in McCarthyism in response to the wiretapping claims on Monday, Comey simply responded, "I try very hard not to engage in any 'isms' of any kind, including McCarthyism."

But what does McCarthyism mean? 

The term can be traced back to former Republican Sen. Joseph McCarthy, who gained prominence in the early 1950s for his attacks on alleged communists in the United States.

In a 1950 speech, McCarthy claimed the State Department "is thoroughly infested with communists," whom he said must be "swept from the national scene so that we may have a new birth of national honesty and decency in government." 

Though a subsequent Senate investigation, History.com noted, found no evidence of any communist infiltration, McCarthy and the House Un-American Activities Committee went on to hold a series of hearings targeting left-leaning Americans whom they suspected of communism. Those targeted included liberal members of the State Department and many people in the entertainment industry. 

In addition to HUAC, McCarthy was aided in his crusade by his "sidekick" Roy Cohn, the Washington Post notes — who later happened to become Trump's longtime mentor. 

Over 2,000 government employees lost their jobs as a result of McCarthyism, History.com notes. The alleged communists' careers were often irrevocably damaged by "blacklisting" — even though, Encyclopedia Britannica explains, McCarthy "failed to make a plausible case against anyone."

The powerful senator's downfall came when he decided to go after suspected communists in the military in 1954. Public opinion turned against McCarthy during the "Army-McCarthy" hearings, History.com noted, in which the Army's lawyer Joseph Welch responded to McCarthy's attacks by asking "Have you no sense of decency, sir?" 

After this, the Senate would later condemn McCarthy's "vulgar and insulting" conduct as "unbecoming a senator."

Though McCarthy died in 1957, the term that bears his name continues to live on, though it's divorced from its original "Red Scare" ties. McCarthyism is now defined by Encyclopedia Britannica as "a byname for defamation of character or reputation by means of widely publicized indiscriminate allegations, especially on the basis of unsubstantiated charges."

Or, for Trump: just another day on Twitter.