A young woman walks into a bar, drinks too much and carelessly shows the man next to her that she is carrying a wad of notes in her handbag. He mugs her on her way home and the police arrest him. The jurors mutter that she has no one to blame but herself, but they don't mean it. However much of an idiot they think she has been, they still know that a mugging is the responsibility of a mugger and the guilty man must pay.

A young woman walks into a bar, drinks too much and carelessly flirts with the man next to her. He follows her and rapes her. The jurors mutter that she has no one to blame but herself, but this time they mean it. She is more than just an idiot.

The supposed provocation she offered absolves the alleged rapist of responsibility. It's her fault now.

Take the case of a young and previously confident woman I know who walked into a bar. A man she had been chatting to followed her into the lavatories. There was DNA evidence that he had sex with her and she emerged covered in bruises. CCTV cameras were not in the lavatories, but they were outside, and showed the man's friends dragging her out of the pub and dumping her on the street. The jury nevertheless acquitted after it heard the man say that she had consented and his lawyers add that she was drunk and had once committed a minor offence. She attempted suicide. Her parents saved her, but the combination of the confrontation in the bar and public humiliation in the courtroom has left her profoundly depressed.

A generation back, liberal-minded people blamed prejudiced officialdom for the law's double standards and I can see survivals of old misogyny today. You cannot say that the judiciary has learnt the lessons of feminism when it is so determined to pimp the English libel law to the world's rich that it allows Roman Polanski to sue via video link from Paris because the police would arrest him for the statutory rape of a 13-year-old if he set foot in a British court.

A lord chief justice who announces that he wants to impose sharia on British women with brown skins, but not British women with white skins, also has much to discover about anti-sexism and, indeed, anti-racism. But it is no use pretending that today's judges are as prejudiced as the jowly monsters of the 1970s. No judge in the 21st century would dare say that a woman who goes out in a short skirt invites men to attack her, even if he thinks it.

The police have transformed their behaviour, too. In 1982, the BBC provoked national outrage when it broadcast a gruesome fly-on-the-wall documentary showing detectives mocking and bullying a confused rape victim. Today, lawyers complain that police treat women too gently for their own good and do not prepare then for the tough cross examination defence barristers will inflict on them when they reach the witness box.

As for the government, Labour's women ministers have made it their business to reform the law. From the 2003 Sexual Offences Act that tightened up the definition of consent to Baroness Stern's announcement last week that she wanted to see drunken men who force themselves on their wives and girlfriends treated as rapists, they have tried to turn Britain into a country where "no" means "no" under any circumstances.

All for nothing. Journalists usually trot out the statistic that only 6% of women who report a rape see their attacker convicted. Although shocking, the figure is misleading because most reports of crime don't lead to a sentence. Conviction rates are more telling. The Crown Prosecution Service only takes a case to court when it believes it has a fair chance of winning. Usually, its prosecutors call the odds right and last year won 86.6% of the cases they initiated. In rape trials, however, they secured guilty verdicts in just 58% of cases.

Usually, I am happy to denounce the authorities for just about anything, but with rape I have to denounce the public. Julie Bindel, who can often seem the last principled feminist in England, has sat through dozens of rape cases and told me: "I gaze into juries' eyes and see middle-aged women in particular wanting to blame the victim. They look at the man in the dock and think he's like their sons."

Women barristers, both prosecutors and defenders, told the same story. "If the defendant's of previously good character and there has been any kind of drunken flirtation before, they want to find reasons to acquit," said one. "Juries don't like branding a man a rapist," said a second. "If she knows him and led him on, juries appear to say, 'Yes, he had sex with you without your consent, but you should have known better.'"

On the one hand, juries are doing the job they have been doing for centuries. Drink, drugs and flirtations produce enough mixed signals to cause reasonable doubt in a defendant's favour when he says that he thought she consented and she says he raped her. On the other, they are sending an unforgiving message. You shouldn't generalise about generations. There are as many shy, sensible or cautious young women now as there have always been. But today's dominant style is for women to be bawdy and empowered: to try to drink as much as the men around them, talk as dirty and boast about their control of their lives. They are not enjoying the liberation that the feminists of the 1970s imagined, but a kind of social equality. If men can behave badly, women can too.

Then they provide a convincing account of rape backed up in my friend's case with DNA evidence and bruises, and too often they find that, far from being empowered, they are publicly dishonoured. The jury, a representative sample of the people who pass them in the street, takes their account of themselves literally and says that, if the defendant is really so brassy and sassy and in control of her life, then rape isn't the responsibility of the rapist and the victim must pay.