When Barack Obama starts to redeem campaign promises to ban torture, close Guantánamo Bay and put the US’s “war on terror” on a sounder legal footing, it will be Eric Holder, his nominee for attorney-general, who will shoulder most of the burden.

Mr Holder is also be likely to come under pressure to step up prosecutions of white-collar criminals amid the worst financial crisis in two generations. But his most important task will be to convince observers that he is acting as the nation’s top lawyer rather than as a cipher for the president.