Freshman Republican Sen. Ted Cruz of Texas is just the latest in a long series of public figures to be reviled for “McCarthyism” following his recent questioning of Chuck Hagel, President Obama’s nominee for secretary of defense. The response? Conservatives have rushed to defend their own against the charge. To understate the case, that’s not enough. It’s time to debunk McCarthyism itself.

No matter how much evidence vindicating the late Sen. Joe McCarthy comes out, what we call McCarthyism remains anathema in American life. Simply to utter the word is to deep-freeze debate, even thought itself. Even as we learn about the history-changing extent to which American traitors working for the Kremlin penetrated and subverted the U.S. government (including many individuals investigated by McCarthy), the unsupportable fact remains that nothing in American public life is worse than to be compared to the man best known for his uncompromising fight against the secret, massive assault on our nation. When will we realize it’s time to make amends and honor his memory?

Liberals and conservatives alike continue to fall for the poisonous bait. Last summer, for example, Romney adviser Eric Fehrnstrom called Senate Majority Leader Harry Reid’s accusations that Mitt Romney hadn’t paid his taxes “baseless” and “shameless,” and compared them to so-called McCarthyism. The Hill newspaper’s write-up of Fehrnstrom’s comments perfectly sums up society’s ignorance on the issue:

“This reminds me of the McCarthy hearings back in the 1950s,” Fehrnstrom said, referring to former Republican Sen. Joseph McCarthy of Wisconsin, who led a controversial search for communist sentiment during the Cold War. “I would ask (Reid) one simple question: ‘Have you no sense of decency, sir? Is there nothing that you won’t do to debase yourself and the office you hold in the name of dirty politics?’”

“Baseless” and “shameless” were indeed apt descriptions for Reid’s smear tactics, but they don’t describe the exhaustive investigations mounted in the middle of the 20th century by teams of Red-hunters, including McCarthy’s, in the House and Senate. As for their quarry, it was not, as The Hill delicately stated, “communist sentiment during the Cold War.” Literally hundreds of Soviet agents taking orders from the KGB and related Soviet intelligence agencies to bring down the American republic had become deeply embedded in the U.S. government in the 1930s and 1940s. Most of them remained undiscovered, and many were active well into the 1950s.

After World War II, Red-hunters in Congress did their best to expose this communist menace — a menace that we now know, following declassification of some FBI and intelligence files in Washington and Moscow, was much worse than we thought. Thanks to Joe McCarthy, many Americans whom the left angelicized as “free thinkers” or “liberals” were finally unmasked as hardened Soviet agents. These would include, to take 10 examples from M. Stanton Evans’ masterpiece, “Blacklisted by History: The Untold Story of Senator Joe McCarthy and His Fight Against America’s Enemies,” Solomon Adler, Cedric Belfrage, T.A. Bisson, V. Frank Coe, Lauchlin Currie, Harold Glasser, David Karr, Mary Jane Keeney, Leonard Mins and Franz Neumann.

As for “Have you no sense of decency, sir?”

This tiresome catchphrase may quiver with righteousness on history’s eternal wavelength, but it is probably the biggest crock of all. As Evans writes, Army counsel Joseph Welch famously hurled the question as an accusation at McCarthy. McCarthy’s transgression, we are supposed to believe, was outing Welch’s young legal associate, Frederick G. Fisher Jr., as a former member of the National Lawyers Guild, a notorious communist front group.

The truth is quite different. Six weeks earlier, Welch himself was quoted in The New York Times, confirming that Fisher had belonged to the communist front and that, as a result, Welch himself had “relieved (Fisher) from duty.” Welch’s hearing-room histrionics, in other words, were a lot of hot air. But they worked. To this day, the truth remains lost to most people, while this thinnest fiction is immortal.

Many other charges against McCarthy similarly disintegrate on examination. The problem is, there is far too little examination.

Even this week, when the National Review took up editorial arms to defend Ted Cruz from croaky cries of “McCarthyism” coming from Democrats in Congress and cable TV hosts, the editorial explained how it was that Cruz had not engaged in the “M-word.” It further declared Cruz “has not, as Senator McCarthy was reputed to have done, slandered an honorable man by cavalierly associating him with an odious and politically radioactive ‘ism.’”

“Reputed” by whom, and according to what facts? Failing to unmask the McCarthyism libel for what it is and always was — bunk and agitprop designed to demonize conservatives, from Joe then to Ted today — does exactly what conservatives continue to take pains to disavow.

It slanders a patriot — Joe McCarthy — by cavalierly associating him with an odious and politically radioactive “ism.”

It’s time to thank the man instead.