Rapists will receive reduced prison sentences if the victim has withdrawn her consent to sex at the last minute, under new guidelines for judges.
Victims' rights groups attacked the proposal, part of a wide review of sentences for sexual offences, insisting that previous sexual contact should not lead to shorter jail terms in the case of a rape.
The Sentencing Guidelines Council directs judges that "date rape" or "acquaintance rape" is as serious as "stranger rape" - but it said there should be less severe punishments in cases where the victim "said 'no' to sexual intercourse at the last moment". The Council said that this could be a mitigating factor in cases where the victim was over 16.
Ruth Hall, from Women Against Rape, accused the Council of "talking out of both sides of its mouth" and creating a two-tier system for rape allegations. "They have no right to be telling men they are less culpable for rape in these circumstances," she said. "Women have a right to change their minds, or to go so far and no further, perhaps because they don't like what they are being asked to do or because the man turns violent."
The proposals, unveiled yesterday, had been keenly anticipated after the number of rapists successfully prosecuted fell to a record low last year, despite an increase in attacks. One in 18 reported rapes results in a conviction. Between 1995 and 2005, reported rapes rose from 5,136 to 14,002. Four out of five are between sexual acquaintances - those hardest to prosecute.
The Council's deputy chairman, Sir Igor Judge, defended the guidelines, insisting they "emphasise the seriousness with which sexual offences should be treated by sentencing judges". He said sentencers were "particularly aware of the psychological as well as the physical impact of these offences on victims", and warned: "Although the purpose of these guidelines is to achieve a consistent level of sentencing for the same type of offence, they cannot deal with the specific impact of each individual offence, which has to be taken into account by the sentencing judge."
The Director of Public Prosecutions, Ken Macdonald, said: "The guidelines should not lead to any reductions in the average length of sentence imposed. Indeed they recommend higher sentences if aggravating circumstances, such as the extreme youth or age of a victim, apply." The recommended minimum sentence for adult rape is five years.
The paper covers about 50 sex offences ranging from flashing and voyeurism to the new crimes of bestiality and necrophilia.
A Home Office spokeswoman said sex crimes "can destroy lives". The Government was "committed to rebalancing the whole criminal justice system in favour of victims", she said, adding: "The average sentence for rape is currently over seven years, and we see no reason why this should change."