What it could do if employed correctly Kevin is catch someone who is not who they say they are. Works like this I go and get my new passport have my fingerprints taken, recent photograph, plus what ever other measure you want to include on it but retinal scan information is the best. That information is all stored away in a database at the Passport Office, or where ever.

Now for whatever reason somebody steals my new passport and doctors it. Then buys an airline ticket in my name and travels on my passport. The passenger manifest has been transmitted ahead with electronic files covering all passenger information. For arguements sake this guy is travelling to the US. On receipt of the manifest US Immigration request photographs and fingerprint data for verification. As each of the passengers files through and hands over their passport the guy behind the desk calls up my photo from the UK passport office - it won't match and the fingerprints won't match - Now the US Immigration Service might not know this guy, he might not be on any data base as a known felon or terrorist - but they do know that he is up to no good and they do have him.