The release to British custody of four remaining British detainees in Guantanamo Bay was promised, the Foreign Secretary said yesterday, after “intensive and complex discussions” with US officials. Yet the task Britain’s police and courts will face on their arrival is hardly unfamiliar. It is to reconcile the daunting and often competing demands of security and justice.

It will be fascinating to hear from Moazzam Begg, Feroz Abbasi, Richard Belmar and Martin Mubanga their stories of what took them to war-torn Afghanistan, which was not a popular tourist destination at the time. They have already paid a price at the US naval base in Cuba, and while justice has been delayed, it has yet to be denied. The delay between detention and due process is as unfortunate in these four cases as in the approximately 400 others still unresolved at Guantanamo, as the US Supreme Court explicitly recognised last year. But the long wait is not merely vindictiveness. It is the result of an entirely legitimate quandary, by no means restricted to the US, over what limits to a terror suspect’s rights are reasonable in the changed world bequeathed by the September 11 atrocities. Those attacks rendered the machinery of Western justice little short of obsolete. Three years on, it has been modernised.

When the first five British detainees of the Guantanamo camp returned to London last March, they were questioned and swiftly released without charge. Their fate offered a stark contrast to that of four French nationals returned by the US to France in August only to be re-arrested under French anti-terrorism laws that allow suspects to be held for up to three years without trial and interrogated at length with no defence lawyers present. No trials have been scheduled; nor has the French public demanded any.

Is Britain’s anti-terrorism legislation naive by comparison? That view has been bolstered in some quarters by credible reports of other former Guantanamo detainees returning immediately to terrorism on their release, leading in one case to the kidnapping of two Chinese engineers working on an aid project in Pakistan. But recidivism is not an argument against fair trials. In the fight against terrorism it is, rather, a reminder that the presumption of innocence carries a cost too high to ignore. It is too soon to say whether Britain’s judicial system has so far favoured that presumption at the expense of public safety, but it is not too late to show that, in the next four cases from Guantanamo, the courts can in fact guarantee both security and civil rights.

Ensuring national security is now unquestionably an international task, and the amended Terrorism Act 2000 reflects this priority. Specifically, it allows UK prosecutions for alleged terrorist acts committed anywhere in the world. Such prosecutions may be complicated by the need to protect intelligence sources and the inadmissibility of some of their evidence, but it is not impossible for entire trials to be held in camera, and the range of terrorist offences for which charges can be brought is now wide enough to prosecute “untouchable” ringleaders on apparently technical grounds. There are fewer loopholes, in short, for terrorism’s Al Capones. Closing them was necessary, and if current laws are properly and judiciously enforced they can provide a defence against terrorism and a defence of basic liberties.