On reaching office, US President Barack Obama said “we need to look forwards not backwards” on the Bush administration’s torture programme. As a result, there have been no prosecutions on his watch. But the past keeps reaching back to grab him. On Tuesday Dianne Feinstein, chair of the Senate intelligence committee and a stalwart defender of America’s spies, accused the Central Intelligence Agency of blocking her staff’s investigations into its so-called “enhanced interrogation techniques”. She also accused it of illegally breaking into Senate computer systems. Ms Feinstein’s impassioned speech risks a constitutional showdown between America’s first branch of government and the executive. Although both are Democrats, the breach between Mr Obama and Ms Feinstein is getting dangerously wide. The past can no longer be kept under wraps. It is time for Mr Obama to declassify all material related to the CIA’s torture programme.

The case for transparency is compelling. When he was campaigning for office, Mr Obama eloquently set out the moral damage the US had suffered as a result of torture. Not only had it breached the Geneva convention by its resort to “waterboarding”, mock executions, secret renditions and the like. It had also traduced the US constitution. Whatever intelligence the US had gained from torture – and that remains hotly contested – was outweighed by its reputational damage. After taking office, Mr Obama immediately proclaimed an end to torture. But he drew a line at holding the CIA to account for its actions. That decision was untenable. More than a year ago Ms Feinstein’s committee completed a 6,300-page report on the CIA’s torture programmes. It has yet to see the light of day. Mr Obama says he wants it declassified. Yet he has given the CIA an effective veto over its publication.

Ms Feinstein’s revelations make it imperative he declassifies it straight away. By its own admission, the CIA has broken into the Senate’s data systems and tried to remove evidence of an internal inquiry into torture – the “Panetta report” ordered by the then CIA director. The agency has also tried to stymie Ms Feinstein’s staff by recommending they be criminally prosecuted. This breaks the CIA’s ban on domestic spying and breaches the US separation of powers. Some are even calling for the resignation of John Brennan, the CIA director. That would be premature. But suppressing the Senate’s investigation is no answer.