The Attorney General is in a bit of a bind. Dominic Grieve will shortly have to decide whether to authorise the prosecution of those alleged to have identified the victim of Ched Evans, a footballer jailed for rape last week. If he decides the prosecution will go ahead, then once again the criminal law will be entering the realm of social media.

A number of people on Twitter named the victim, contrary to the Sexual Offences Amendment Act 1992. North Wales Police, which is investigating, announced yesterday that they would be making arrests of Twitter users. But those who will be watching Grieve's decision with particular interest are the traditional media who have broken this law in the past. The law in this area is quite tough, because it is believed victims are often deterred from coming forward by a fear of being identified. Newspapers have been prosecuted even for publishing identifying details, for instance, a photograph of a soldier, which, although pixellated, included the rank pips on her uniform; the fact that a victim had cerebral palsy; that the offence took place in a shower – showing the victim lived with the offender.

All the above were clumsy, accidental identifications. The newspapers had no intent to identify, they simply were not careful enough. Those editors who have personally been charged, along with their titles, will be very interested to see whether an allegedly deliberate identification on Twitter will attract similar prosecution.

If Grieve does not give the go-ahead for a prosecution – and that depends on whether North Wales Police and the local Crown prosecutors send him a file – then it sends a message that there is one law for old media and no law for the new. He has in the past warned bloggers and tweeters that they are bound by the Contempt of Court Act just like their mainstream media counterparts. If he does go ahead with prosecution however, it raises the spectre of much more complicated decisions in future. What if instead of 40 people accused of breaking the law it is 400, or 4,000? The scale of potential prosecutions as a result of unwise tweeting is huge. And while few may argue against prosecution in this instance, what of a greyer area? What if the Tweetmob breaches a superinjunction and names a company accused of pollution – as happened in the case of Trafigura? No prosecutions there, as the "guilty" numbered in thousands. What of the "I am Spartacus" tweeters who repeated the phrase used by Paul Chambers, which resulted in his conviction in the Twitterjoke trial? Again, no action by the CPS.

In my view, Grieve has little choice but to allow the prosecutions to go ahead. What message will it send to the victims of sexual offences if he does not? But in doing so he will have made a rod for his own back and many people will have to be more careful about what they tweet.

The writer is a journalist and media law consultant