The 8-1 ruling by the law lords that the detention of foreign terrorist suspects without trial breaches the European Convention on Human Rights is an unprecedented rebuff to the Government. Rarely on an issue so central to national policy has the highest appeal court in the land rejected the Government’s case in language so damning. Lord Bingham of Cornhill said that the measures “unjustifiably discriminate” against foreign nationals and Baroness Hale of Richmond said these “draconian” measures were unaccept-able. Would it be more acceptable to the judges to deport the suspects immediately to Algeria or elsewhere, where a far rougher form of justice would be meted out?

The law lords do not constitute a supreme court; unlike in the US, they do not have primacy over Parliament and the executive. The Government, therefore, is under no constitutional obligation to release the nine men still detained in Belmarsh. Indeed, Charles Clarke, in one of the most vexed issues to face a secretary of state on his first day in new office, said measures would remain in force until the law were reviewed. But the moral pressure of the judgment is formidable. Mr Clarke made clear that he would go back to Parliament in the new year and would, meanwhile, be looking at his options.

They are stark. No one could sensibly argue that detention without trial is edifying, but it is an extraordinary measure whose use remains extremely limited. The judges have identified obvious contradictions without providing a coherent remedy. To expel the detainees to their countries of origin would contravene undertakings under the convention not to send people back if they faced torture or death. To put them on trial would be impossible without detailing the intelligence against them, thus probably compromising other surveillance operations or using evidence such as telephone taps or confessions obtained overseas under torture which are inadmissible.

Mr Clarke must address several interlocking questions. The first is transparency. The present periodic review of the cases by the Special Immigration Appeals Commission is unsatisfactory — although it has led to the release of one man — because both its workings and findings are secret. The alternative, which David Blunkett said a month ago he was considering, is a special court, sitting without a jury, to consider all terrorist cases. This would avoid accusations of discrimination as well as restrict publication of sensitive intelligence evidence. The security services have already suggested their support.

The second issue is proportionality. The lords did not dispute that the Government can decide what constitutes a national emergency, but said its response was disproportionate. This veers into political, rather than judicial, contention, however. The judgment aside, the stridency of the judges’ language creates an unfortunate suspicion that the vehemence of their opposition was influenced by previous confrontations with this Government.

Finally, Mr Clarke must review asylum policy. To the extent that the detainees prefer detention to repatriation, they are still offered protection. But no policy that poses a danger to national security as well as leading to an evident transgression of legal principles can be right. Britain should seek not an exemption from the convention but a fundamental review of its workings.