06/06/2013 07:47 BST | Updated 04/08/2013 06:12 BST

*Not So Innocent Face*

A frequent misconception is that there is safety in numbers known as 'the crowd mentality'. People seem to think it is ok to re-tweet defamatory material because it is already in the public arena. This is wrong.

Last month, the High Court made its first ruling that a tweet was libelous. That decision, concerning Sally Bercow's now infamous Tweet, "Why is Lord McAlpine trending? *Innocent face*" has confirmed what I have long been warning my clients, that everyone using social media sites must understand the parameters in which they are operating and that legal consequences arise out of their actions. If they do not they may very easily be caught out and sued. In some cases they could be subject to criminal prosecution.

With the advent of social media, we see everyday people now doing a job once reserved to journalists - covering news stories as they happen. Take the most recent sad and shocking example of Drummer Lee Rigby's murder. Witnesses took footage and photographs on their mobile phones; the suspects reportedly made no attempt to escape the scene or prevent anyone capturing their images suggesting perhaps that they were keen to use social media for their own self-promotional ends.

Given the exponential rise of social media, more of us want to get involved in the cyber conversation. But handle with care: Sally Bercow's case is a warning to us all to seriously consider jumping on the bandwagon.

A key issue is whether a particular tweet or post is defamatory.

The law concerning defamation (of which libel is a species) is clear - if you make a defamatory allegation about someone you can be sued. However, it is being stretched to breaking point to deal with something clearly not envisaged when it was conceived - social media. New law, a Defamation Bill, is being drafted, to address the issue but this is a slow moving process. Meanwhile, both practitioners and social media users are very much reliant on the courts providing guidance. This is why the first libel twitter trial is so important. If people are going to use social media sites they need to gain a basic understanding of the law.

To bring a claim in defamation it must be established that defamatory material referring to the Claimant (the user you refer to) was published. As to what is defamatory, a helpful definition refers to material that would "tend to lower the Claimant in the estimation of right-thinking members of society generally". Important also to bear in mind is that the test of what is defamatory is objective. This means that, if sued, your intentions (in terms of whether or not you meant to be defamatory) are irrelevant.

A frequent misconception is that there is safety in numbers known as 'the crowd mentality'.

People seem to think it is ok to re-tweet defamatory material because it is already in the public arena. This is wrong. It is no defence to say that you are simply repeating what someone else has already said. You are responsible for your own tweets. You can be sued for them. Lord McAlpine has confirmed he will be pursuing any Twitter users with over 500 followers. So if you do not know it's true, do not tweet it.

If the prospect of having to pay damages for defamation (together with the inevitable costly legal bill) is not enough to make you stop and think, remember that it's not just civil law which is being used to police social media users. Criminal prosecutions are being pursued as well.

In my view, the most high profile example of the use of criminal law happened in April 2013 when Neil Harkins and Dean Liddle received nine-month suspended prison sentences, for being in contempt of court when they published photographs on Twitter and Facebook which were said to show James Bulger's killers. There is a ban on publishing anything revealing their identities and there is no exception for social media.

Every day, social media users are being prosecuted under other criminal statues such as the Malicious Communications Act 1998 and for sending a "menacing electronic communication" under the Communications Act 2003. It has recently been reported that Shaun Tuck, a Merseyside footballer, is being investigated by both the Police and Football Association after allegedly suggesting on his personal Twitter feed that revenge should be taken in the wake of the terrorist killing of Drummer Lee Rigby. Merseyside Police has indicated that is is considering whether this constitutes a criminal offence under the Malicious Communications and/or Public Orders Acts.

With so many cases, both civil and criminal, people need to appreciate they are responsible and accountable for any material they put in to the public arena. The use of social media is having a positive impact on the media as no one person or institution has control but to quote the great Stan Lee "with great power comes great responsibility".