A Court Order was served via Twitter on Thursday, saying the social website and micro-blogging service was the best way to reach an anonymous Tweeter who had been impersonating someone.
Solicitors Griffin Law sought the injunction against the micro-blog page arguing it was impersonating right-wing blogger Donal Blaney, the owner of Griffin Law.
The legal first could have widespread implications for the blogosphere.
"I think this is a landmark decision to issue a writ via Twitter," said Dr Konstantinos Komaitis of Strathclyde University's law faculty. "You are creating a precedent that people will be able to refer to. It only takes one litigant to open the path for others to follow," Komaitis, a lecturer in IT and Telecommunications told Reuters.
"The law tends to be quite cumbersome and slow, so to have a court deliberate on something like Twitter -- so hot, so relevant -- it shows quite impressive engagement.
Andre Walker at Griffin Law said the anonymous Tweeter targeted by the writ will get a message from the High Court the next time they open their online account.
"Whoever they are, they will be told to stop posting, to remove previous posts and to identify themselves to the High Court via a web link form," he said.
Matthew Richardson, the barrister who won the injunction, said the ruling was a huge step forward in preventing anonymous abuse of the Internet.
"People have to learn that they can no longer hide behind the cloak of anonymity the Internet provides and break the law with impunity," he said in a statement.
Online impersonations have become increasingly prevalent following the success of the Twitter website. Leading Tweeters like celebrities Ashton Kutcher and Britney Spears have hundreds of Twitter impersonators.
The problem has grown so large that Twitter earlier this year launched a system to verify the authenticity of Tweets. A seal, which appears on the top right of profile pages, is aimed for use on high profile Twitter accounts.
Impersonating people or organisations is contrary to Twitter's terms of service and Tweeters who do not wish to take out a legal writ over the problem can contact Twitter. (Editing by Steve Addison)
Comment on this article in our blog entry here.