Barack Obama's decision to revive the system of military tribunals at Guantánamo Bay will inevitably, and correctly, be branded a U-turn, that most unwelcome reproach for any politician. In fact, he is probably making the best of a very bad job.

In theory, there is no reason why the few people who will face the tribunals should not be tried by civilian courts on the US mainland, where they would enjoy greater legal safeguards. The civil system, after all, managed to deal with Zacharias Moussaoui, the so-called 20th hijacker of 9/11.

Both as candidate and president, Obama has described the military tribunal system as deeply flawed. In reality, any move by the Obama administration to move the prisoners into the regular court system would almost certainly unleash a public and congressional storm that could delay the process even longer.

The White House has concluded that the most practical solution is to go ahead with revamped tribunals, with additional safeguards for defendants, including a ban on all evidence obtained through harsh interro­gation tech­niques.

The essence now is speed. As the president has pointed out repeatedly, no Guantánamo inmate has yet been convicted of anything, even though some have been held for six years or more. Many of the 241 who remain may well be innocent of any offence. This is a shocking indictment of American justice, in any guise.

More than once, the Supreme Court has indicated its disapproval of such inordinate delays, and of the legal limbo – outside the purview of the Geneva Conventions – in which the detainees are trapped.

But an obvious deadline is available. The president is committed to closing the prison by January. That should allow sufficient time for the tribunals to get started.

Fewer than 20 people are likely to face them, including Sheikh Khalid Mohammed and others accused of organising the 9/11 attacks.

If there is any further delay, and Guantánamo Bay is shut on schedule, there would be no alternative to moving the defendants on to the mainland and into US domestic courts, exactly the outcome the administration wishes to avoid.

With Guantánamo closed, the rest of the 241 detainees, most of them very small fry, could be transferred to other countries, or simply released. A line would finally be drawn under a saga that has brought shame, rather than additional security, to America.