A Welsh politician has become the first UK citizen to lose a ‘twibel’ libel case based on something posted on social media site Twitter.

Trouble flared during a 2009 County Council by-election campaign when eventual winner, Plaid Cymru candidate Colin Elsbury, tweeted that leading rival Eddie Talbot had been removed from a polling station by police.

This assertion turned out not to be true, which after an historic High Court case has left Elsbury with a £3,000 ($4,800) damages bill plus an estimated £50,000 in legal costs.

“It was a genuine case of mistaken identity which I have acknowledged,” Elsbury said of his defeat. “This case will no doubt act as a warning to people, including politicians, to be extremely careful when using Twitter and other social media such as blogs.”

In terms of libel law in the online sphere, Twitter’s main worry for anyone posting comments is that it is instantaneous and can spread messages widely in seconds. The first Uk twibel case suggests that the usual defence that an error was later corrected in a subsequent posting is unlikely to be an adequate defence for social media.

Although it will make legal history in terms of English civil law, this is not the first time careless tweets have landed someone in trouble.

Last November, Paul Chambers became a cause celebre after being prosecuted for making a flippant remark to a small group of friends about the closure of a UK airport. "Crap! Robin Hood airport is closed. You've got a week and a bit to get your shit together otherwise I'm blowing the airport sky high!!," he tweeted. The airport took a dim and rather literal view of his sense of humour.

Further afield, in September a South African campaigner against alleged police indiscretions was threatened with prosecution after regularly tweeting fellow motorists on the location of speed traps and hidden police vehicles.