“I would love to read,” said London University Politics Professor Philip Cowley yesterday, “something decent on what sort of twattery is or is not a public order offence.”

It’s difficult to define a word like twattery, but I’ll imagine myself a highly trained Parliamentary counsel and have a stab at it:

“Twattery means behaviour, whether or not criminal, that a reasonable person would consider obnoxious, offensive or tasteless and “twat” and “twattish” shall be construed accordingly.”

I’m pretty sure the Professor was thinking of the burning of the Grenfell Tower effigy.

It was certainly twattery of a high order. As Met Commander Stuart Cundy said “to mock that disaster in such a crude way was vile.” Quite so, although it was the mockery itself, not simply its crudity, that made it so unpleasant.

But was it criminal?

Six people apparently involved in the incident have now been released from the police station where they spent something like 24 hours “helping the police with their inquiries”. They are not on bail, and we are therefore free to consider, as the Crown Prosecution Service is no doubt doing, what charges, if any, might be brought.

Clearly the CPS have a considerable advantage in knowing all the facts, not just some of them so nothing I say here should be taken to imply either their guilt or their innocence of any crime. I am nevertheless happy to add my voice to those who think that anyone involved in carrying out the stunt were complete twats.

As the Professor hints, it is to the Public Order Act that the attention of the CPS will first turn.

Generally speaking, in the privacy of your own home, with the windows shut and the curtains drawn, and as long as don’t broadcast your activity online, you are free to be as obnoxious, as nasty and offensive as you like. Obviously privacy does not give you freedom to commit any offence but with the windows and curtains shut the Public Order Acts cannot touch you until you start fighting. (There are one or two exceptions but they don’t apply here).

However, the burning took place outside; whether it was in a public space (like a park) or a private garden is not clear, but it is unlikely to make much difference.

The suspects were originally arrested under S.4A of the Public Order Act 1986 . It involves using words or (perhaps more pertinently here) displaying “any writing, sign or other visible representation which is threatening, abusive or insulting”.

Although it can’t normally be committed in a “dwelling”, a garden isn’t a dwelling for these purposes.

Was the burning of the effigy “abusive or insulting”? Quite possibly, although opinions may differ.

The offence also requires proof of: “... intent to cause a person harassment, alarm or distress.” Without such a “person”, the charge will fail.

If the burning was done as a tasteless joke, and there was no-one present to be distressed at what was going on, there could have been no such intent.

But what if the idea all along was to video the incident, and then to place the footage online with a view to mocking, and distressing, survivors of the fire? We have no idea if that was the case of course; for all we know it may have been uploaded by a shocked bystander. Nevertheless, the S.4A offence (unlike the similar but less serious offence under S.5) can sometimes be committed by placing material online with intent to distress a particular person: see S. v CPS [2008] EWHC 438 (Admin). In this case, prosecutors might plausibly argue that there was an intent to distress a whole class of people, namely Grenfell survivors.

Even if they are satisfed on all these points, they will also have to consider a principle stated in one leading public order case (but perhaps often overlooked ever since) that:

“... the criminal law should not be invoked unless and until it is established that the conduct which is the subject of the charge amounts to such a threat to public disorder as to require the invocation of the criminal as opposed to the civil law.”

Although S.4A is a relatively minor offence, triable only in the Magistrates Court, if it were proved to be “racially or religiously aggravated” this would make it triable in the Crown Court and with a potential sentence of two years imprisonment.

There is also a much simpler charge: S.127 of the Communications Act 2003. This criminalises the sending of any electronic message of a “grossly offensive ... character”. The section owes its origins to an attempt to protect female telephonists from obscene calls but it is now used to prosecute people who post “grossly offensive” material online. It was used, for example, to prosecute Count Dankula for posting a video of his pug saluting to the command “kill the Jews.”

Unlike S.4A, this offence requires no proof of intent, but the person who posts the material must “either intend his words to be grossly offensive to those to whom they relate, or be aware that they may be taken to be so”.

There are many, myself included, who believe that this offence is far too widely drawn. Partly for this reason, the CPS has guidelines that emphasise that prosecutors should only proceed under S.127 with caution and:

“... where they are satisfied there is sufficient evidence that the communication in question is more than: Offensive, shocking or disturbing; or

Satirical, iconoclastic or rude comment; or

The expression of unpopular or unfashionable opinion about serious or trivial matters, or banter or humour, even if distasteful to some or painful to those subjected to it.”

Although the guidelines do not have the force of law, the effigy burning does seem to fall into the category of “banter or humour”.

S.127 may be an easy charge to prove; that does not mean the decision to bring charges is easy. Even if the evidence is sufficient, the CPS will not prosecute unless it takes the view that a prosecution is “necessary in the public interest.” Can it be treated as twattery, or must it be prosecuted as a crime? It will be interesting to see with what aplomb Max Hill QC, the new Director of Public Prosecutions, handles his first hot potato.

As for the Professor, in short, the answer to his question is this:

Inside your home you are free to be a complete twat.

In public, you can be prosecuted for being a complete twat.

Online you can be prosecuted for being a bit of a twat.

Matthew Scott is a barrister at Pump Court Chambers and blogs at Barrister Blogger.