The most sweeping censorship is always the most objectionable. In principle, however, there is nothing wrong with David Cameron’s sweeping proposal that the customers of internet service providers must prove that they are 18 or over before they can watch online pornography. The rule for liberal democracies is (or ought to be) that consenting adults are free to watch, read and listen to what they want. It stops child pornography – because by definition children are not consenting adults – and it could stop children accessing pornographic sites. Children are no more able to give informed consent to watching pornography than they are to appearing in it – if ‘appear’ is not too weak a verb to describe the rape and abuse of children on camera. If the law stops them walking into a shop and legally buying pornographic magazines, it can stop (or attempt to stop) them watching pornography online.

Age verification procedures already exist to make a system of opting in to watch pornography online work. The only question is whether David Cameron is serious about using them. Since the arrival of Lynton Crosby, 10 Downing Street appears to have gone back in time to the worst days of Tony Blair’s first term when Alastair Campbell and his creatures pleased the press by manufacturing supposedly tough crime initiatives, which turned out to be recycled, unworkable or fictitious.

A letter from civil servants to internet service providers shows that the Conservatives supposedly tough proposal that customers must opt in and prove their age before they can watch porn may be as phoney as a New Labour crime stunt. The civil servants asked the ISPs to pretend the existing voluntary system of parental controls was something new when it was nothing of the sort. As one ISP told the BBC, the government was asking it to mislead customers for the sake of a few good headlines.

But as I said, if there is more to the proposal that we opt in to porn sites than spin and deceit, there is nothing wrong with it in principle. Perhaps surprisingly, serious doubts begin with the government’s plans to make the possession of pornography depicting rape illegal.

I suppose the principled objection that the state should not intervene if the actors involved in a rape scene are consenting adults and the viewers are grown-ups too, will not satisfy many readers. I mentioned in the Observer a few weeks ago that there is no reliable evidence that images of violence against women provoke violence against women. Studies are riddled with uncertainty. Indeed, if you can imagine a psychologist devising a reliable experiment he knew would provoke a man to rape, his university would tell him that he could not ethically run it for fear of the consequences. Nevertheless, no one would recommend a man who derived pleasure from rape scenes to a woman friend, let alone a sister or daughter. I cannot see many MPs standing up in Parliament and saying ‘I watch rape porn and it has never done me any harm’. In truth, I can’t imagine any man saying that: it’s not the kind of vice men admit to. Cameron is thus likely to get his way without significant opposition.

You might think that when material is so taboo no one will confess to enjoying it, the case for prohibition is complete. But be careful about giving the state more power. I wrote last year about the police and Crown Prosecution Service’s tyrannical treatment of Simon Walsh. They arrested the City lawyer under the existing law against the possession of ‘extreme pornography’. In fact, the ‘pornography’ consisted of images Walsh and his circle of gay friends had taken of each other playing violent games and circulated among themselves. The jury concluded that, however obscene the sexual practices on display were, they were not as obscene as the notion that the CPS could poke its nose into the nation’s bedrooms. The court acquitted, but not before the prosecution had ruined Walsh’s legal career. As soon as they heard of his arrest, his fellow barristers at London’s 5 Essex Court Chambers forgot everything they had learned about the presumption of innocence, and asked the police to seize his pass so that he could not re-enter their offices. Boris Johnson behaved just as badly. He removed Walsh from the London Fire Authority without, once again, taking the decent precaution of waiting to hear whether he was innocent or guilty.

There is a parallel here with other forms of eavesdropping on the Net. The state’s expansion of surveillance of the Web sounded reasonable until you found that the authorities were not only targeting serious criminals and terrorists (as promised) but parents trying to get their children into a decent school as well. Mutatis mutandis, the expansion of legislation prohibiting pornographic images may sound equally reasonable until you remember it gives more powers to police and prosecutors. The record shows they cannot be trusted to use them justly.

Tags: Censorship, Children, David Cameron, Freedom of speech, Internet, Lynton Crosby, Policing, pornography