One effect of the failed Christmas Day underpants bombing on NW Flight 253 to Detroit was to reveal how hard it is for counterterrorism bureaucracies to know, or do, anything about anyone. A leaked US Transport Security Agency document briefly required not only that passengers had been to the loo 61 minutes before their flight landed, but also that - with the exception only of heads of state and a single nominated companion - pat-down searches should be conducted at boarding gates, paying particular attention to the 'upper thighs and lower torso', a clear euphemism for underpants. So for at least a week any thinking terrorist would have had to find some other body part to strap his explosives to, and blow up his plane a little earlier than he might have liked. But the biggest disclosure was of the workings of America's post-9/11 terrorist database systems, the main component of which is the Terrorist Identities Datamart Environment, or TIDE.

LRB 28 January 2010 | PDF Download