The caller was initially vague about his problem. Kent Campbell remembers uncomfortable silences and said the man on the other end of the line nervously cleared his throat again and again.

After some coaxing, the caller finally revealed that he was a doctor and that a blogger had posted scathing comments about him as well as his line of health and beauty products. The post appeared at the top of the list in a Google search using the doctor's name, and he said it had already caused him to lose $5 million from a potential investor.

Campbell, a kind of Sam Spade for the Cyber Age, had heard it all before. A self-described crusader against internet invective, he makes a living by restoring reputations sullied by insults posted anonymously on the internet.

"People who contact me are usually very embarrassed and sometimes very angry," he says.

Often for good reason. Three decades ago, former British Prime Minister James Callaghan said that a lie can travel halfway around the world before the truth has got its boots on; the internet has greatly widened that advantage.

Whether unjust, spiteful, or just plain false, a disparaging post on the first page of a Google search can ruin a reputation regardless of redeeming information found on pages two, three and four. As a result, combating defamation on the Web has become a booming business.

Within the last two years, several lawyers have begun to specialize in defending victims of cyberslurs and smear campaigns. And dozens of so-called internet reputation management companies like Campbell's in Ventura, California, have formed to prevent or mitigate the damage of negative Web postings.

"We're engaged in guerilla war against this type of stuff," Campbell says. "Sometimes I feel like I should be wearing camo."

To help the doctor, Campbell and his team of six employees and 25 contractors had to figure out whether this was a war or just a skirmish. Lucky for the doctor, it was the latter. The author of the negative posts was a random guy expressing his opinion rather than someone making a concerted effort to defame the doctor. This was not a cutthroat competitor or vengeful ex-lover, as is often the case.

Next, Campbell says they looked for any positive content that already existed online about the doctor. He had his own Web site with patient testimonials. And he had done a spot on a local TV news program.

Campbell and his team were able to get more "Google juice" out of these sites by linking them together and persuading other bloggers to link to them. They also strategically placed phrases on the doctor's website, and distributed electronic press releases about his practice and products that included those phrases.

The order in which results appear in a Google search depends on an algorithm-a mathematical formula-that weights various websites differently as well as the positioning of keywords or phrases on those sites.

Google favors content with lots of links, particularly from sites it deems credible, including CNN, The New York Times, and, yes, Portfolio.com. The doctor was lucky that he had a link from an affiliate station of a TV network.

A study by iProspect and JupiterResearch indicates that fewer than 30 percent of people go beyond the first page of search results, and less than 8 percent make it to page three. Reputation-management experts say they concentrate on Google because it's the most popular search engine and others often mirror its results.

"When you think about how Google results impact whether you get a client, attract investors, or even get a date, you understand how huge the demand is for this type of service," says Chris Martin, founder of ReputationHawk, a reputation-management company in Baton Rouge, Louisiana.

The potential for abuse has grown as the internet has become more interactive with blogs and sites like YouTube, Facebook, and MySpace. "Anyone with a computer can disseminate lies around the world in seconds," says David Pollack, a Miami lawyer who last year won an $11.3 million verdict in an internet libel case.

Pollack's client in that case, an education consultant, was vilified by someone she had once advised. Following the verdict, Pollack says he has received hundreds of calls from people who feel they have been similarly wronged.

Suing to defend your online reputation is a difficult and expensive strategy, since most calumny is posted anonymously. Moreover, the Communications Decency Act of 1996 immunizes webmasters, Web hosts and internet service providers from liability if a third party posts something malicious on their platforms. (A judge can compel them to reveal the identity of an author if harm is established; that person can be held liable.)

"It's a long and drawn-out process, but it is possible to unmask anonymous posters," says Karl Kronenberger of Kronenberger Burgoyne, an internet law firm in San Francisco. "Even the most technologically savvy person leaves a digital footprint."

Kronenberger's clients have included a Cayman Islands medical school and a Florida relocation service. Competitors had anonymously disparaged them on consumer websites. Once exposed, the competitors were induced to retract their rants and pay damages.

Even if the person responsible for posting defamatory information is, say, an unemployed crank living in his parents' basement without financial resources (as often is the case), lawyers say that homeowners' insurance policies may cover the damages.

But even a successful lawsuit may create more negative information for a search engine to find. "It becomes a news event when you file a lawsuit," said Eugene Volokh, a professor specializing in cyberlaw at the University of California-Los Angeles. "The original falsehood then gets magnified and grabs more attention online."

Hiring an internet reputation-management consultant is the alternative. In addition to making positive references to their clients more Google-friendly, they can also create entirely new material, including blogs, Wikipedia entries, YouTube videos, and even entire websites sprinkled with key phrases.

If a client prefers a stealthier approach, reputation managers can look for content about a person or entity with a similar name to their client's, then create links to those sites. That can push those to the top of search results, moving less flattering information well down the list.

"The Google algorithm changes all the time, so it can be tricky and time-consuming," Martin says. He admits to sometimes "tearing his hair out" trying to move negative content off the first page of a Google search. But, he adds, "We figure it out eventually."

Restoring one's reputation costs between $500 and $10,000 per month, depending on how much negative information is floating around on the Web, whether it's on the first page of a Google search, and if the client wants to create new content. It can take anywhere from four months to a year to repair an online reputation. The doctor who hired Campbell will end up spending $30,000.

Some celebrities, C.E.O.'s, and surgeons have begun to hire internet-reputation management companies to constantly monitor the Web and sweep away negative information as it appears. The cost of such vigilance is $1,500 to $7,500 per month.

Even at those prices, internet-reputation management firms say there are some clients they just won't take.

"It's sickening to me that anyone with an ax to grind can go online and destroy people's lives," says Carl Sgro of I.R.M. Consultants in Bloomingdale, New Jersey. But, he added, some people deserve their bad reputations. When they call, he tells them, "I could help you, but I won't."

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