A man who drugged and sodomised a 13-year old girl would not usually receive the uncritical support of the political and literary establishments. On the other hand, Roman Polanski is not your common-or-garden paedophile: he is possibly the world's most admired film director.

It was on his arrival in Zurich to pick up yet another lifetime achievement award that Polanski was arrested, at the request of the US Justice Department, which has sought him ever since 1978 when he fled rather then face prison for a crime to which he had pleaded guilty.

To say that the Swiss Justice Ministry's swoop on the 76-year-old French citizen has aroused outrage in high places would be an understatement. France's Foreign Minister Bernard Kouchner denounced the arrest as "sinister". Polanski's would-be hosts, the Swiss Association of Directors, are angrier still, calling it "a grotesque judicial farce and a monstrous cultural scandal". In the UK, the novelist Robert Harris – who is working with Polanski on a film of one of his books – said that he was "shocked and stunned... it strikes me as disgusting treatment." The United Nations has stepped in: the Bulgarian Director-Designate of Unesco, Irina Bokova, declaring that "Polanski is a world renowned intellectual... even though I am not aware of any details, this is shocking."

Ms Bokova should acquaint herself with the details of the original case. She might even find them quite shocking, too. In 2003 the Los Angeles Superior Court Judge David Wesley unsealed the grand jury testimony of Samantha Galley taken 26 years earlier. In it, the 13-year old, who aspired to become a model, described how Polanski offered to take photos of her for French Vogue... in the house of the film star Jack Nicholson.

There, the 44-year-old Polanski plied her with the drug Quaalude mixed in glasses of champagne. Then, after insisting that she join him in the Jacuzzi, Polanski said: "Let's go in the other room". From this point on, the testimony is harrowing, so skip the next few paragraphs if you are of a squeamish disposition.

"Q. What did you do when he said, 'Let's go into the other room'?

A. I was going 'No, I think I better go home', because I was afraid. So I just went and I sat down on the couch.

Q. What were you afraid of?

A. Him.... He sat down beside me and asked if I was OK. I said 'No'.

Q. What did he say?

A. He goes 'Well, you'll be better'. And I go, 'No I won't. I have to go home. He said 'I'll take you home soon'.

Q. Then what happened?

A. Then he went down and he started performing cuddliness... I was kind of dizzy, you know, like things were kind of blurry sometimes. I was having trouble with my coordination... I wasn't fighting really because I, you know, there was no one else there and I had no place to go."

Q. Did he ask you about being on the pill?

A. He asked, he goes, 'Are you on the pill?' and I went, 'No' and he goes 'When did you have your period?' and I said, 'I don't know. A week or two. I'm not sure'... He goes, 'Come on. You have to remember'. And I told him I didn't.... and right after I said I was not on the pill... and he goes... and then he put me – wait. Then he lifted my legs up farther and he went in through my anus.

Q. Did you resist at that time?

A. A little bit, but not really, because...

Q. Because what?

A. Because I was afraid of him."

This testimony took place barely two weeks after the incident – Samantha Galley did not obey Polanski's demand that she not tell her mother about "our little secret."

We can predict the sort of defence that Polanski's present-day supporters will make in the coming days. They will not be so crass as to suggest, as the new head of Unesco did, that because he is a "world-renowned intellectual", he should be judged differently from lesser beings – although I'm sure that some of them believe it.

They will suggest that the 13-year-old girl was mature for her age and complicit. Samantha Geimer (as she now is) has already said to those who want her somehow to take the blame, "You weren't there. You don't know." And what if she had been partially complicit? Is it less heinous because the renowned film director used his fame and the promise of his support to seduce a 13-year-old?

His supporters will also point out that Ms Geimer herself has previously urged that the proceedings be dropped, because they are embarrassing her family. She certainly deserves even more sympathy on that score; it is one of the perennial problems with rape cases that the victim will very often prefer her assailant to remain unprosecuted, rather than face the ordeal of cross-examination at the hands of his lawyers.

Polanski himself has never, so far as I know, expressed any contrition for what he did. At the time of Bill Clinton's impeachment over the Monica Lewinsky affair, the director observed that, "There's a different justice for people who are public figures than for those who are not", with the implication that somehow he too had been a victim of unfair double standards over matters of sexual behaviour.

The truth is that Polanski has been treated with extraordinary indulgence because of his fame. When in 2003 Polanski was nominated as best director for The Pianist, but didn't attend the Oscar ceremony because of his outstanding arrest warrant, the event's host, Steve Martin, joked to the Hollywood audience "Roman Polanski is here...GET HIM!" Polanski won that evening, and received a standing ovation in absentia.

I do not deny his genius, nor his contribution to cinematic art; but I also share the view expressed by the historian Lord Acton that "if we may debase the currency [of the moral code] for the sake of genius, or success, or rank, or reputation... then it serves where it ought to reign".

If that means nothing to Polanski's defenders among the literati, let them think of this: if it were their 13-year-old daughter who had been drugged and sodomised, would they still feel that the perpetrator was in fact the victim?

d.lawson@independent.co.uk