They may not brandish pitchforks, nor burn their victims at the stake, but when a Twitter lynchmob is in full flow it would take a foolhardy individual to get in its way, lest they become a target of the baying mob too.
So when Lord McAlpine was named or hinted at by several of the 'Twitterati' following a much-criticised feature on the BBC's Newsnight programme, which suggested that a "senior Conservative from the Thatcher era" was a paedophile, it was only a matter of time before he was forced to break cover and declare his innocence.
Both before and after the programme, his name was Tweeted or re-Tweeted, directly and indirectly, by some 10,000 Twitter users. These included some well-known names with big followings, such as comedian and actor Alan Davies, Guardian journalist George Monbiot and, perhaps most notably, Sally Bercow, the publicity-hungry wife of the House of Commons speaker John Bercow.
While Davies and Monbiot both subsequently apologised – Monbiot in particularly grovelling terms – Bercow did not. She subsequently quit Twitter, but not before claiming that she had not defamed McAlpine, merely noting that he appeared to be 'trending' on Twitter, and admitting that McAlpine's lawyers had, indeed, made contact: "Yes had letter from Lord McA. His lawyers ambulance chasers tbh [to be honest] #bigbullies."
Having reached settlements with the BBC and ITV for the parts they played, McAlpine is now coming after the Twitterati. Most will be let off lightly – with just a demand to pay a token sum to charity. Bercow, though, due to her large following, may not.
But according to David Engel, a partner at Addleshaw Goddard specialising in libel law, Bercow is skating on very thin ice indeed.
"Normally, the question is, what the courts call 'the natural and ordinary meaning' of the statement," says Engel. "In other words, how would it be understood by most readers or viewers? There's no room for a literal, legalistic reading of it."
What potentially skewers Bercow, though, is a very well-developed libel concept of "innuendo". "That's where the meaning, on the face of it, is one thing that may not be defamatory, but in the mind of a reader who knows certain other facts – 'extrinsic facts', as they are called – it would be libellous," says Engel.
In other words, even trying to imply something that could be construed as libellous, without specifically and directly making the claim, can and will still be found to be libel in court. That pretty well covers the various Tweets involved in the McAlpine affair, as well as sending URLs to defamatory websites or Tweets. "The test isn't whether someone is named, it's whether they are identifiable,"says Engel.