Candidates for higher office are indeed tested — if they win — from Day One. But the credibility of their declared principles is sometimes tested suddenly and revealingly on the campaign trail. I have often cited the voluble and often humorous Joe Biden as a passionate practitioner, and defender, of free speech. But on Oct. 23 — after participating in at least 200 interviews since chosen as Barack Obama's vice presidential on the Democratic ticket two months ago, Biden — offended at a question by an Orlando WFTV TV reporter-anchor — did not object when the Obama campaign then forbade more appearances on that station by its campaigners until the elections. An Obama gag rule.

After a series of reasonable, challenging, quietly voiced questions by interviewer Barbara West, she had said to Biden: "You may recognize this famous quote: 'From each according to his abilities (and) to each according to his needs.' That's from Karl Marx. How is Senator Obama not being a Marxist if he intends to 'spread the wealth'?"

As I watched the interview on YouTube, Biden, clearly nettled, first responded to what he called "this ridiculous question" by asking her: "Are you joking? Is that a real question?" He then launched into the standard campaign retort that Obama "is not spreading the wealth around. He is talking about giving the middle class an opportunity to get back the tax breaks they used to have."

The next day, the Orlando Sentinel's veteran TV critic, Hal Boedecker, reported: "Biden so disliked West's line of questioning that the Obama campaign canceled a WFTV interview with Jill Biden, the candidate's wife."

Then, Boedecker  continued, Laura K. McGinnis, Central Florida communications director for the Obama campaign, said the cancellation was "a result of her husband's experience yesterday during the satellite interview with Barbara West." McGinnis showed no hope for a possible free-speech pardon, adding belligerently:

"This cancellation is non-negotiable, and further opportunities for your station to interview with this campaign are unlikely, at best for the duration of the remaining days until the election." At best? Surely President Obama could be heard on the station. But in October, there was no objection from Obama to his campaign's widely publicized gag rule on WFTV.

Later, at a campaign event in North Carolina, Biden spoke of how "mean" the campaign was getting by quoting West's question about Obama's possible Marxist inclinations: "I mean, folks, this stuff you're hearing, this stuff you're hearing in this campaign, some of it's pretty ugly. … When this is over if, God willing, we win, we have to reach out to those folks." And, what, tell them what not to say?

Maybe radio and TV folks should watch their words, too. A considerable number of leading congressional Democrats are eager to bring back the Fairness Doctrine (in effect from 1949 to 1987) that empowered the government to insist that broadcast stations (and now cable) provide opposing viewpoints to controversial offending remarks on stations, on pain of the stations losing their licenses.

I've always been surprised that self-proclaimed liberal Democrats, in and out of Congress, are so eager to diminish the impact of the speech of Rush Limbaugh, Sean Hannity, Bill O'Reilly, Laura Ingraham, et al, that they want to give the government (Republican or Democratic) this censorship sword. Can you imagine the Founders' reaction? If I may gently ask Biden: "Are you in favor of bringing back the Fairness Doctrine? Is Obama?"

Reflecting on the tempestuous result of her Marx question to Biden, WFTV's West told the Orlando Sentinel: "I have a great deal of respect for him (Biden). I have a great deal of respect for Senator Obama.

"We are given four minutes of a satellite window for these interviews. Four precious minutes. I got right down to it and, yes, I think I asked him some pointed questions. These are questions that are rolling about right now and questions that need to be asked. I don't think I was rude or inconsiderate to him. I think I was probing and maybe tough.

"I can't believe that in all of his years in politics, and all of his campaigning and such, that he hasn't run into some tough questions before. He's certainly up to it in giving good answers."

Beyond this dispute whether West was being fair in her interview with Biden, there is a very strong, and alarming, prospect that the Orwellian-named Fairness Doctrine will indeed come back to give the Federal Communications Commission the stern authority to decide the proportion of partisan commentary you can safely take without being offended.

Brian Anderson, editor of the Manhattan Institute's "City Journal" and co-editor, with Adam Thierer, of the new free-speech rallying cry, "A Manifesto for Media Freedom" (Encounter Books) reports in the Oct. 20 New York Post:

"A Rasmussen poll last summer found that fully 47 percent of respondents backed the idea of requiring radio and television stations to offer 'equal amounts of conservative and liberal political commentary,' with 39 percent opposed."

Liberals, Rasmussen found, "support a Fairness Doctrines by 54 percent to 26 percent, while Republicans and unaffiliated voters were more evenly divided. The language of 'fairness' is seductive."

And it celebrates the government deciding your allotment of freedom of speech.

Nat Hentoff is a nationally renowned authority on the First Amendment and the Bill of Rights and author of many books, including "The War on the Bill of Rights and the Gathering Resistance" (Seven Stories Press, 2004).