Ross Anderson mentions some of the problems of the biometric identification techniques, so beloved of Tony Blair and David Blunkett and their pending ID card information system disaster, in his terrific book Security Engineering. For example iris scanners can be defeated by photographs or printed contact lenses. There are also systems issues eg. if one biometric technique, such as iris scanning, becomes the standard and everyone uses it, then terrorists can get Tony Blair's or George Bush's (but not David Blunkett's) from high quality photographs put out by their PR people! Fingerprint scanners don't work so well with the elderly or manual workers. Iris scanners don't work so well with dark eyed people such as Asians. That instantly raised questions relating to discrimination and racism. And the bad guys will get good ID anyway, through identity theft, forgery, having genuine IDs issued by overworked or even a small number of incompetent or corrupt government employees or by social engineering (my ID got stolen can you give me a temporary one while I'm waiting for the new one to come through?). Maybe if Blair , Blunkett and co. had a paint-by-numbers version of Ross's book read to them as a bedtime story, they might think twice about blowing mountains of taxpayers money on stupid ID schemes, in an attempt to create the illusion that they are 'doing something' about terrorism, immigration, benefit fraud, public services, social cohesion, parking fines, TV licenses, etc., etc, etc..