One of the marks of a civil society is that private conduct is not governed by decree. The precise number of times that a husband and wife have sex has nothing to do with anyone other than them. It seems that President Karzai's Government in Afghanistan does not agree.

This week Mr Karzai signed legislation from the Afghan parliament that will legalise minority Shia family law applicable to 15 per cent of the nation's population. The laws state that “the wife is bound to preen for her husband, as and when he desires” and that “the husband... is bound to have intercourse with his wife every night in four nights”. A woman will not be permitted to leave the house without the permission of her husband and obedience to the man will be put into statute. So women are, once again, to be defined as chattels, told not just what they must do but how often they must do it.

It is not enough, it seems, that the fate of women should be defined by their subjugation to the man of the household. There is no reason to suppose that the relative enlightenment of the way that women are treated in public in Afghanistan since the Taleban's departure has yet altered a patriarchal culture in private. But it is quite another thing to enshrine such prejudice in statute.

Even if there were any religious authority for such a view, that religious authority would disqualify itself for consideration in the process of making such ludicrous suggestions. But, in fact, advocates will look in vain through the Koran in search of a passage that warrants treatment of this kind, still less the precision of the proposals.

Not that the Afghan Government is seeking religious justification. Mr Karzai's reasoning is less elevated than that. He is claiming simply that, pragmatically, this legislation is the price that he has to pay for victory in August's election. The laws have been framed expressly to appeal to Islamists in the Shia community as the Hazaras are the biggest bloc of potential swing voters.

Even if the Shia minority were persuaded into the political coalition on this basis, even if the policy were absolutely guaranteed to bring electoral success and even if the re-election of President Karzai were clearly better than any available alternative, none of this is remotely enough. There is no case, and can never be any case, for subjugation. The basic rights of women should not be subject to political horse trading. Indeed, that women could finally be afforded basic public respect after years of contempt under the Taleban was precisely the source of the early optimism for the Karzai regime. The sight of young girls going to school and their mothers voting in free elections was a joy to behold after years of gender tyranny. It did seem, for a fleeting moment, that the seeds of a genuine civil society were being sown. Clearly not.

This is not a return to the Taleban, of course. Women's rights in Afghanistan have improved significantly since the overthrow of the strict Sunni Islamist Government in 2001. The horrors committed against women in that period are still of a different order of magnitude. And yet, with this brazen attempt to head off the Taleban by embracing their putrid thinking, President Karzai is squandering what very little remains of his international support - and putting in jeopardy the commitment of international forces and funds working alongside his Government.