• by Wendy Davis , Staff Writer @wendyndavis, May 31, 2011

Last week, a California judge ordered Twitter to reveal information that identified a user who criticized three politicians in the U.K.

The U.K. paper The Guardiandescribed the court proceedings as a "landmark legal battle," but this kind of legal dispute happens a lot more often than people might think. In fact, numerous people have claimed they were libeled and gone to court in an attempt to learn their critics' identities.

Results have been mixed, but in many cases the outcome depends on whether judges believe that the critical posts were potentially libelous.

In one well-known case, New York Supreme Court Justice Joan Madden ordered Google to reveal the name of the blogger behind Skanks in NYC, which allegedly libeled model Liskula Cohen. Madden found that the blog was potentially defamatory because it implied that Cohen was promiscuous.

Other judges have refused to order critics unmasked. Less than two weeks ago, a New York appellate court ruled that the resort chain Sandals had no right to learn the identity of the author of emails that the company claimed were defamatory. The court ruled that Sandals didn't allege sufficient facts to show that the emails were libelous.

But even though some courts have denied unmasking requests, that only happens when the Web users object to having their identities revealed. People can do so anonymously but if they don't, Google, Twitter and other hosts typically don't fight users' battles for them.

In this case, the Twitter user -- who turned out to be British politician Ahmed Khan -- was notified about the unmasking request and decided not to fight it. As The Next Web points out, that decision was key to the outcome in the case.

Had Khan objected to being identified, it's uncertain whether the posts would have met the U.S. standards for libel. But a post mentioned in court papers appears to allege ballot tampering by one of the politicians who sued -- a councillor in South Tyneside. That allegation might have been sufficient to make out a valid libel claim even if Khan had contested the unmasking request.