John S. Carroll is editor of the Los Angeles Times. This piece is adapted from a speech he delivered at the University of Oregon earlier this month.

One reason I was drawn to my chosen career is its informality. Unlike doctors, lawyers or even jockeys, journalists have no entrance exams, no licenses, no governing board to pass solemn judgment when they transgress. Indeed, it is the constitutional right of every citizen, no matter how ignorant or how depraved, to be a journalist. This wild liberty, this official laxity, is one of journalism's appeals.

It is also one of its myths. I've come to realize that the looseness of the journalistic life, the seeming laxity of the newsroom, is an illusion. Yes, there's informality and there's humor, but beneath the surface lies something deadly serious. It is a code. Sometimes the code is not even written down, but it is deeply believed in. And, when violated, it is enforced with tribal ferocity.

Consider, for example, recent events at the New York Times. Even before it was discovered that the young reporter Jayson Blair had fabricated several dozen stories, the news staff of the Times was unhappy. Many members felt aggrieved at what they considered a high-handed style of editing. But until Jayson Blair came along, the rumble of discontent remained just that, a low rumble.

When the staff learned that the paper had repeatedly misled its readers, the rumble became something more formidable: an insurrection. The aggrieved party was no longer merely the staff. It was the reader, and that meant the difference between a misdemeanor and a felony. Because the reader had been betrayed, the discontent acquired a moral force that could only be answered by the dismissal of the ranking editors. The Blair scandal was a terrible event, but it also said something very positive about the Times, for it demonstrated beyond question the staff's commitment to the reader.

Several years ago at the Los Angeles Times, we too had an insurrection. The paper had published a fat edition of its Sunday magazine devoted to the opening of Staples Center. But unknown to its readers -- and to the newsroom staff -- the paper had formed a secret partnership with Staples, in which the developer helped the newspaper sell ads in the magazine in return for a cut of the proceeds. Thus was the independence of the newspaper compromised -- and the reader betrayed.

I was not working at the newspaper at the time, but I've heard many accounts of a confrontation in the cafeteria between the staff and the publisher. It was not a civil discussion among respectful colleagues. Several people who told me about it invoked the image of a lynch mob. The Staples episode, too, led to the departure of the newspaper's top brass.

What does all this say about newspaper ethics? It says that certain beliefs are very deeply held. It says that a newspaper's duty to the reader is at the core of those beliefs. And it says that those who transgress against the reader will pay dearly. Such commitment, deeply imbedded in newsroom culture, is taken for granted in the so-called traditional media. In newer forms of media, however, it is a foreign language.

All across America, there are offices that resemble newsrooms, and in those offices there are people who resemble journalists, but they are not engaged in journalism. What they do is not journalism because it does not regard the reader -- or, in the case of broadcasting, the listener or the viewer -- as a master to be served.

In this realm of pseudo-journalism, the audience is regarded as something to be manipulated. And when the audience is misled, no one in the pseudo-newsroom ever offers a peep of protest.

Last Halloween, I was stuck in freeway traffic. Punching buttons on the car radio to alleviate the boredom, I came across a rebroadcast, 65 years after the fact, of Orson Welles' famous dramatization of "The War of the Worlds."

This radio drama portrayed a Martian invasion so realistically that it prompted hysteria. Believing that creatures from Mars were actually invading the town of Grover's Mill, N.J., listeners ran out into the streets, jammed police switchboards and gathered in churches to pray for deliverance. As I listened to the broadcast, it became obvious why people believed the Martians were at hand. It didn't sound like fiction; it sounded like journalism. The actors who described the unfolding events at Grover's Mill had the same stylized cadences and pronunciations as broadcast journalists of the time.

This is how the 23-year-old genius Orson Welles learned that journalism can be faked, and that people will invest their trust in something that sounds like journalism but isn't.

You may have guessed by now that I'm talking about Fox News. I am, but I am also talking about a broad array of talk shows and websites that have taken on the trappings of journalism but, when studied closely, are not journalism at all. Deceptively cloaked as journalists, these marketers of opinion are playing a nasty Halloween prank on the public, and indeed on journalism itself.

I can offer some eyewitness testimony. Last fall, The Times did something rash. Alone among the media that covered the California recall election, we decided to investigate the character of candidate Arnold Schwarzenegger.

The recall campaign lasted only two months, so we had to hurry in determining whether, as rumored, Schwarzenegger had a habit of mistreating women. It turned out that he did. By the time we nailed the story down, the campaign was almost over, and we had a very tough decision to make: whether to publish the findings a mere five days before the election.

We decided to do so, figuring that choice was better than having to explain lamely to our readers after election day why we had withheld the story. We braced for an avalanche of criticism, and we got it. What we didn't expect was criticism for things that had never occurred.

Long before we published the story, rumors circulated that we were working on it, and the effort to discredit the newspaper began.

On Fox News, Bill O'Reilly's program embarked on a campaign to convince its audience that the Los Angeles Times was an unethical outfit that attacked only Republicans and gave Democrats a free ride.

As evidence, O'Reilly said that the paper had overlooked Bill Clinton's misbehavior in Arkansas. Where, he asked, was the L.A. Times on the so-called Troopergate story? Why hadn't it sent reporters to Arkansas? How could it justify an investigation of Schwarzenegger's misbehavior with women and not Clinton's?