Fake news  is older than the invention of the printing press, but few would argue with the proposition that it has become more prevalent and should be stopped.

But there are three key difficulties with this. The first is defining fake news; the second is the age-old balance between controlling misinformation and the principle of freedom of expression. The third is if we are to police fake news who should do it and how?

Defining fake news may seem straightforward – most would see it as news that contains facts which are wrong or inaccurate. But accusations that news is “fake” are often made in respect of opinions or versions of events that do not fit with the accuser’s own point of view. As any libel lawyer knows, there is often a very thin line between what is fact and what is opinion. Tying down a workable definition is the first hurdle.