Shame: The guidance was issued in the wake of the furore over Ched Evans, convicted of raping a woman, but who maintains the sex was consensual

A row broke out last night over guidelines which would see men accused of date rape being asked to prove that a woman wanted to have sex.

As part of a major shake-up of investigations into sex offences, the Director of Public Prosecutions said it was vital to remove ‘any grey area’ to recognise situations where a woman may have been unable to give consent.

Campaigners described the move as a ‘huge step forward’ in ensuring fewer rapists escaped justice.

But critics said the guidelines threatened to undermine Britain’s long-standing principle that people were innocent until proven guilty.

Tory MP Philip Davies said: ‘It is not clear how anyone is supposed to prove that consent was given. Is the CPS really suggesting that you have to get a signed statement off someone before they have sex?

‘Nobody wants to see rapists walk free. I’m as hardline as they come on crime, but this is ridiculous. Our legal system is based on people being innocent until proven guilty and the CPS are trying to turn that on its head.’

Alison Saunders, the DPP, issued the guidance in the wake of the furore over Ched Evans, who was released from prison in October halfway through a five-year sentence for raping a 19-year-old woman in a Welsh hotel.

The footballer has always professed his innocence, saying the sex was consensual, but the woman said she was too drunk to agree.

The guidelines, issued to all police forces and prosecutors, move well beyond the idea of ‘no means no’ for the first time.

They spell out situations where victims would not be in a position to agree to sex, such as if they were incapacitated through alcohol or drugs, had mental health problems or learning difficulties, or were asleep or unconscious.

Rape suspects in positions of power – such as a teacher, employer or doctor – and domestic violence situations where a complainant ‘may be financially or otherwise’ dependent on their alleged rapist, should also be scrutinised, the Crown Prosecution Service said.

The document also made clear that behaviour such as staying silent or using contraception did not signify consent.

The guidance tells police officers and lawyers to ask how the suspect knew the alleged victim had consented to sex ‘with full capacity and freedom to do so’.

Investigators have been told to put greater emphasis on an accused man demonstrating that he had obtained the woman’s agreement ‘fully and freely’.

Alison Saunders, the DPP, left, said it was vital to recognise situations where a woman may have been unable to give consent. But Tory MP Philip Davies, right, said it wasn't clear how proof of consent could work

In August last year a leading female judge provoked controversy by criticising rape victims who drank too much and were unable to remember their attack clearly.

Judge Mary Jane Mowat said: ‘I’m not saying it’s right to rape a drunken woman, I’m not saying for a moment that it’s allowable to take advantage of a drunken woman.

‘But a jury in a position where they’ve got a woman who says, “I was absolutely off my head, I can’t really remember what I was doing, I can’t remember what I said, I can’t remember if I consented or not but I know I wouldn’t have done” – when a jury is faced with something like that, how are they supposed to react?’

Consent to sexual activity is not a grey area – in law it is clearly defined and must be given fully and freely

Mrs Saunders said: ‘Consent to sexual activity is not a grey area – in law it is clearly defined and must be given fully and freely.

‘We want police and prosecutors to make sure they ask in every case where consent is the issue: How did the suspect know the complainant was saying yes and doing so freely and knowingly?’

Sarah Green, director of the End Violence Against Women Coalition, said: ‘The guidance is a huge step forward. It will help ensure that juries are asked to look in detail at the behaviour of defendants as well as at that of the complainant.’