Dianne Feinstein and the US Senate intelligence committee have produced a brave and damming report on torture by the CIA. It will go some way in preventing the use of torture, yet there is more to be done.

Her findings offered no real surprises: waterboarding and other techniques of torture were authorised for use by the CIA in the summer of 2002, approval came from the top, the techniques were ineffective and there was much lying and deception. The report focuses on the CIA, yet as I discovered during research for my 2008 book Torture Team, the legal approvals she homed in on had other nefarious consequences: you can follow the authorisations of July and August 2002 through to the torture and other abuses that occurred at the instance of the US defence department and then migrated onwards to Iraq. There is a seamless trail from terrible legal opinions to the appalling images of abuse at Abu Ghraib prison and to the shaming of America.

My work focused on the role of senior Bush administration lawyers in the authorisation of the torture, dubbed by the New Yorker as ‘the Bush Six’. But for their efforts none of this would have happened: lawyers are the ultimate guardians of legality and constitutionality, and if they are complicit, if they fail to act independently and fearlessly to speak truth to power, then we might as well give up on the rule of law.