Paul Chambers has announced that he is seeking to go to the High Court to challenge his conviction under section 127 of the Communications Act 2003.

He has instructed me to put the challenge together and I have, in turn, instructed Ben Emmerson QC, the leading human rights and criminal law barrister. The barristers who fought the Crown Court appeal -- Stephen Ferguson and Sarah Przybylska -- continue to be involved. There has been legal help from a number of other firms and individuals. This is a case which has attracted a great deal of support and offers of practical assistance.

Why? After all, it was just a £350 fine (although now with prosecution costs, Paul is being asked to pay £2,600). And there has been no custodial sentence.

But the case continues to cause concern about and widespread ridicule of the English criminal justice system. Writers as accomplished as Graham Linehan, Charlie Brooker, and Nick Cohen have brilliantly exposed the misconceived and illiberal nature of this prosecution and of the upheld conviction. And, although neither Paul nor I have encouraged the "#IAmSpartacus" movement (I personally prefer the use of the Betjeman line about dropping bombs on Slough), it is perhaps significant that Paul's original tweet or variations of it seems now to have been tweeted over 18,000 times. However, it appears that only Paul will incur criminal liability for the words in question.

Paul's original tweet was the hyperbolic statement of exasperation of someone discovering that he may not get to see a girl he fancied. It was not intended to be menacing, and indeed it was not menacing.

Look at the tweet carefully: "Crap! Robin Hood airport is closed. You've got a week and a bit to get your shit together otherwise I'm blowing the airport sky high!". From the very first word -- an expletive followed by an exclamation mark -- it is clear to any reader that it was not serious. The proposition which follows -- an emphatic and sweary call for an airport to be opened rather than for it to be closed -- is simply nonsensical as a threat on its own terms. This is not how a terrorist, a hoaxer, or anyone with any menacing intent, would actually make their wrongful statements

At the trial and the appeal, it became clear that no one did find it menacing.

The airport security manager who found it on a random search of Twitter did not know whether it was a jest or not; his manager graded it as having no credibility, but was process-bound to forward it to the airport police; the police saw it as so menacing that they waited three days before acting on it and then, after interviewing Paul, simply said there was no evidence that it was any more than a joke intended just for his Twitter followers; however, the police passed any charging decision on to the Crown Prosecution Service, who quickly realised there was insufficient evidence of intent for the "bomb hoax" offence under the 1977 Criminal Law Act.

So the CPS used the then obscure section 127 of the Communications Act, for which there are no recorded cases other than in respect of nuisance telephone calls, and baldly asserted that the provision now covered communications on social media as well. The CPS turned up to court and told the magistrate and the defence that not only did section 127 cover social media, but that it was also an offence of "strict liability" which required no evidence of intent. (The CPS now accept that the offence does require proof of intent, but one wonders if the prosecution would have proceeded had they realised that at the time.)

The Magistrates' and Crown Courts then found Paul's tweet to be menacing and that he intended to send a menacing communication. They also found that section 127 covers messages sent on a social media platform as much as it would cover nuisance telephone calls. The challenge to be brought by Paul and his legal team at the High Court will seek to establish whether the criminal courts applied the correct legal tests for whether the message was menacing and whether it was sent with any menacing intent; the challenge will also seek to clarify the extent (if any) to which section 127 applies to messages created in and published on social media platforms. It has the makings of a landmark judgment regardless of its outcome: like the Lady Chatterley or Oz trials of previous generations, this case perhaps forces the question as to whether the law has kept up with wider social and cultural changes.

It is brave of Paul to take this case forward. If he loses he faces the upholding of a criminal conviction and the continuance of a criminal record. He is also exposed, if he loses, to the legal costs of the other side. There has been a great deal of generous support for Paul. In part this is because he is clearly a decent bloke placed in an unfair and adverse predicament for a mere exasperated tweet which not a single person whatsoever has yet found menacing.

But there is also a wider battle. English criminal law and practice now appears to have an unfortunate and casual attitude to imposing criminal liability and even using the power of arrest for simple speech acts. As social media is used more and more for everyday communication, this inappropriate use of criminality and of the coercive force of the police has to be somehow checked and the value of routine free expression asserted and endorsed.

To his and other people's surprise, Paul has become the everyman of the social media generation. For there, but for the grace of a god, go almost all of us.

David Allen Green is legal correspondent of the New Statesman and was shortlisted for the George Orwell prize for blogging in 2010. He is also head of the media law practice at Preiskel & Co, who are acting on a cost-only basis for Paul Chambers in his High Court challenge.