Lord McAlpine’s decision to use the full force of the law to pursue those who made false statements about him on Twitter could change the nature of social media forever.

McAlpine is apparently considering taking action against the 10,000 or so people who tweeted or re-tweeted the totally false allegation made by the BBC’s Newsnight programme of his involvement in child abuse. He has already received payments from both the BBC and ITV, but is now pursuing those who tweeted his name.

There is no doubt that McAlpine was smeared, and the nature of that smear has generated strong public sympathy for him. However, pursuing every tweeter with the full force of the law may cause that sympathy to evaporate, particularly if some of them are older, infirmor simply have no money. That does not make their actions right but, in PR terms, pursuing them may turn Lord McAlpine from victim to villain.

He and his advisers appear to have thought this through, as they seem to be adopting a potentially different approach to those who are famous and ‘ordinary people’. That may fend of some critics but the law is meant to apply regardless of social status, income or prominence in the public eye. A decision to pursue some tweeters but not others may be difficult to defend in the court of public opinion.

Before PROs rush off and start talking to lawyers about taking action they need to stop and take stock. Just as using the law to deal with the traditional media can go wrong, so too can it backfire with the social media. Legal action, or threats of it, can be seen as too heavy handed, entrench views, cause an adverse reaction or loss of sympathy or simply persuade people to ‘get you back at playtime’. Here McAlpine is an innocent victim but, in cases where the public doesn’t see it that way, attempts to take legal action may just aggravate the situation. How would anyone cope with a ‘viral’ campaign where hundreds of thousands or even millions of people across the world were all tweeting the same name or allegation?

Lawyers and those involved in PR do not always want the same things and do not always speak the same language. PROs need to be careful what they wish for. Whilst taking strong action may seem like the right thing to do, both the financial and reputational costs could be high. There is no guarantee of a successful outcome and, in that event, the PR would need to be put into overdrive.

What this will do is make people think twice before tweeting, recognising that it is no longer a zero cost and risk-free way of spleen venting or allegation hurling. In this case the media has assumed that a name check in a tweet equals liability. It may not be that straightforward, yet the popular media already have Sally Bercow losing her house because of her infamous tweet. It may also make it less conversational, less an instant reaction to events and, in turn, more sterile and less interesting.

So next time you need to know which footballer has misbehaved you may not be able to turn to Twitter for the answer. Even if you do, think twice before re-tweeting it to your followers.