Lord McAlpine’s recently reported litigation against tweeters stemmed from a Newsnight broadcast in November 2012 which reported allegations of sexual abuse of boys at the Bryn Estyn children’s home in Wales in the 1970s and 1980s. The broadcast was followed by substantial social media commentary. While Newsnight did not specifically name the former Tory Party treasurer during the broadcast, the Tory peer was later incorrectly named and identified on Twitter as the abuser.

Lord McAlpine recently settled defamation complaints against the BBC and ITV in December 2012 for Stg£185,000 and Stg£125,000 respectively. He also received unreserved apologies for the damage and distress that had been caused to him.

Lord McAlpine was also pursuing defamation claims against Twitter users arising from the same complaint. A reported 10,000 tweeters who posted initial defamatory tweets and re-tweets could potentially be named as defendants. However, he announced recently that he is dropping defamation claims against Twitter users with less than 500 followers, instead asking them to make a small donation to the Children In Need charity. The Tory peer has said that he wants to draw the “unfortunate episode” to a close.

It is notable that Twitter users could face the threat of criminal prosecution in the UK under the Malicious Communications Act, 1988, should it transpire that their messages are held to be grossly offensive.

Lord McAlpine's litigation is likely to involve some of the first English High Court defamation trials over defamatory Twitter posts.

Lord McAlpine’s defamation actions against tweeters marks a growing trend of defamation claims arising from material published on Twitter. Separately last year, Chris Cairns, a former New Zealand cricket captain, was awarded £90,000 in the High Court in England after he was wrongly accused of match-fixing in a tweet. This amounted to £3,750 per word. The decision was unsuccessfully appealed to the Court of Appeal which ruled that the award was proportionate to the seriousness of the defamatory allegation, its direct impact on Mr Cairns and it further served to vindicate his reputation.

Despite these decisions, there still appears to be a lack of awareness by some that a tweet constitutes a publication, and can therefore give rise to a defamation claim in the same way as an article in an online magazine or newspaper. Twitter users who seek to disguise their identity by using pseudonyms in a bid to avoid defamation claims are also likely to be identified, especially in circumstances where court orders are obtained directing the disclosure of email account holder names and other personal data.