American democracy is based on the optimistic notion that all three branches of government will not do the wrong thing, all at the same time. The president and even Congress might step over the line – but if they do, the US Supreme Court is there to restore the rule of law over the mistakes of men.

For six years, President George W. Bush and Congress – with the acquiescence of the Democrats – have colluded to violate the rights of those detained in the name of fighting terrorism. First, Mr Bush authorised indefinite detention without trial, and then last year Congress endorsed the notion that suspected terrorists could be held on the faintest suspicion of danger, without even minimal access to the courts to protest their detention. Now the Supreme Court has the chance to overrule the worst excesses of the other two branches, and reaffirm that detainees at Guantánamo Bay in Cuba have the constitutional right to challenge their confinement in court.