PRESIDENT Obama took two difficult decisions this past week - both connected with the treatment of terrorist suspects and both involving him in a substantial change of mind. Firstly, he decided to oppose the release of newly discovered photographs of US troops abusing prisoners at Baghdad's Abu Ghraib prison in 2004. Originally he had supported the release of the pictures in the interests of open government but after listening to the advice of his top generals he reversed his decision. Secondly, he decided that military trials of some twelve suspected terrorists held at Guantanamo Bay should go ahead; again this was a reversal of the position he had taken during his election campaign and it drew criticism from civil rights groups. However, the prisoners will now be able to choose their own lawyers and evidence based on hearsay or obtained by extreme interrogation will not be allowed - in each case a fundamental revision of previous procedures. In all elections potential leaders cannot avoid making promises that lack detailed information about the background to the issue; if they achieve office they face the alternative of sticking stubbornly to their promise despite what they have subsequently learned or admitting that they were wrong and publicly changing their mind. The latter is the most difficult course but Obama has taken it in each case - and also made sure the public were given his reasons for doing so.