Hard though it is to believe, Barack Obama may be facing an issue with bigger consequences for the US than any already on his desk: whether officials from the previous administration – perhaps up to and including George W. Bush – should be prosecuted for violating domestic and international laws on torture.

This debate began in earnest when Mr Obama agreed to release “torture memos” written by Bush administration officials. Mr Obama had hoped to draw a line under the issue. The effect was the opposite. In the fight that has broken out the stakes are huge.