The Ministry of Justice promised to provide public guidelines to the new extreme porn legislation this week and – behold! – here they are.

They have been greeted with some degree of criticism from those opposed to the legislation, on the grounds that they add little new to what was already known and fail to make matters as clear as they could. Much of this criticism, however, is as much to do with the substance of the law as the guidelines.

What almost all those involved agree – whether for or against – is that we shall not know how wide-reaching this new law will be until the first few cases are heard before a court. Everything else is mere parlour room speculation – and readers who wish to indulge in a little speculation of their own should proceed rapidly to the end of this artcle.

To fall foul of the new law – ss 62-67 of the Criminal Justice Act 2008 – images must be pornographic, grossly offensive and portray activity that threatens harm to life or limb, or involves sex with a corpse or animal.

"Life-threatening" is defined according to the usual dictionary definition: "serious injury" is not defined, but "could include the insertion of sharp objects or the mutilation of breasts or genitals".

"Explicit and realistic" take their ordinary dictionary definition.

The guidance is clear that the material will include "images which are indistinguishable from photographs and films": that includes cgi; and also, if Sadville ever gets its act together, some of the more extreme performances of virtual sadism.

Deleting an image will be sufficient to prove you no longer "possess" it – unless you have the skill to recover it. In which case you could still be done: techies beware.

Two interesting features of this new law arise in respect of potential defences. The first is where the material in question is a BBFC classified film, that should be an absolute defence. However, if you extract images or sequences from that film, your defence may fall.

That raises the interesting question of whether the BBFC would ever pass for viewing any scene, however transitory, that would fall foul of the Obscene Publications Act. The interesting answer from the BBFC was that although they knew of no such instance, the theoretical possibility was always there, not least because juries in different parts of the UK might have different views on what constituted obscenity.

Back in 1997, the Police took possession of material produced by Nigel Wingrove. Mr Wingrove is no stranger to controversy, being both the impresario behind the Satanic Sluts, and an avant-garde filmmaker famed as producer of Visions of Ecstasy, the only work still banned by the BBFC on the grounds of potential blasphemy.

When Mr Wingrove objected that the material in question had been passed by the BBFC, the Police suggested that they might have to raid that body as well.

Such a move would have been devastating for film in the UK, which is why it never happened. The BBFC has no formal powers at all to ban film: but Councils use its recommendations almost without question. Loss of faith in the BBFC system could lead to a collapse of the classification system – and the need for government to intervene.