It is now apparently government policy to see more men convicted of rape on less evidence. That is a brutal violation of the principles of criminal justice.

In the wake of the furore over Ulrika Jonsson’s alleged date rape, the Home Office is to announce long-awaited rape law reforms in next month’s Queen’s Speech. It is reported that the new law will severely restrict a man’s ability to claim that he “honestly believed” the woman consented to sex, unless he can satisfy the court that he made efforts to ensure that her agreement was “genuine and voluntary”. One report says that women who are under the influence of drink or drugs will “automatically be regarded as unable to give consent to sex”.

The Home Secretary, David Blunkett, has made it clear that the current rate of convictions for rape is “unacceptable”, and the explicit aim of these reforms is to find more men guilty. Justice in rape cases is thus to be made subject to external, political measurements. As if the Government’s obsession with setting targets has not done enough damage to the health and education systems, it is now to be forced upon sexual offences law.

These reforms will shift the burden of proof on to the defendant, undermining the presumption of innocence. It will be possible to convict a man of “accidentally” raping somebody who he genuinely believed consented to sex. That is as absurd as it is unjust. Yet it will be widely accepted because sexual offences are such an emotive issue, and none of us wants to be seen as championing some kind of “rights for rapists”.

But we should be more, not less, wary of the extension of legal power when it encroaches on sexual relations between partners and acquaintances (now blamed for most rapes). These proposed reforms raise authoritarian notions of policing relationships, in the user-friendly language of feminism. They risk taking sex further down the road from a private to a public affair, which has to be negotiated under the voyeuristic eye of the courts.

Despite the ostensible aim of protecting women it will, as usual, be the authorities who are “empowered”. Prosecutors and judges will be left to redefine what it means for individuals to give consent — ticking boxes to decide whether the man was sufficiently diligent in obtaining “voluntary and genuine agreement”, or whether the woman said “no” loudly enough.

Presumably the courts will have to define exactly what it means for a woman to be “drunk”. Bring on the bedside Breathalyser tests. Indeed these proposals will mean no woman who has had a drink can ever be considered truly capable of giving consent. Are lawmakers so unworldly that they cannot tell the difference between a woman who is drugged and raped, and one who has a few drinks and ends up in a bed she regrets the morning after? New Labour is in danger of making enthusiastic seduction a crime.

The Home Office has dismissed as “complete nonsense” any notion of people having to sign a contract before getting into bed. Yet such is the logic of these reforms that we might find lawyers with an eye for a shapely fee offering to draw one up anyway. There is already a campaign, fronted by the Ealing vicarage rape victim Jill Seward, to include consent forms in packets of condoms. One entrepreneur claims to have invented the “consent condom”, printed with the statement “Yes, I agree to have sex with you”, complete with a space for a woman’s thumb print. He admits that they might prove a passion killer.

Of course the messy business of sexual affairs is not really susceptible to strict codes and legal surveillance. Yet these reforms will demean both sexes in the eyes of the law. Rape law increasingly treats women like the child victims of abuse, considered incapable of giving consent and in need of special protective measures. For their part, men are now to be treated more like unconscious animals, who can be punished even though they were unaware that they were doing anything wrong.

Whatever happened to the idea of consenting adults?