In olden days (before the first world war, that is) the traveller simply pulled his boots on and went. The idea that he might need a piece of paper to prove to foreigners who he was would not have crossed his mind.

Alas, things have changed. In the name of security (spies then, terrorists now), travellers have to put up with all sorts of inconvenience when they cross borders. The purpose of that inconvenience is to prove that the passport’s bearer is who he says he is.

The original technology for doing this was photography. It proved adequate for many years. But apparently it is no longer enough. At America’s insistence, passports are about to get their biggest overhaul since they were introduced. They are to be fitted with computer chips that have been loaded with digital photographs of the bearer (so that the process of comparing the face on the passport with the face on the person can be automated), digitised fingerprints and even scans of the bearer’s irises, which are as unique to people as their fingerprints.

A sensible precaution in a dangerous world, perhaps. But there is cause for concern. For one thing, the data on these chips will be readable remotely, without the bearer knowing. And—again at America’s insistence—those data will not be encrypted, so anybody with a suitable reader, be they official, commercial, criminal or terrorist, will be able to check a passport holder’s details. To make matters worse, biometric technology—as systems capable of recognising fingerprints, irises and faces are known—is still less than reliable, and so when it is supposed to work, at airports for example, it may not. Finally, its introduction has been terribly rushed, risking further mishaps. The United States want the thing to start running by October, at least in those countries for whose nationals it does not demand visas.

More here.