Check this out. Britian’s Passport Office this week begins a trial program for personal identification cards.

Ten thousand Brits volunteered to carry cards similar to U.S. drivers licenses. The big difference: biometrics. Face measurements, iris scans or fingerprints qualify under the current trial.

A card-carrier always has the means to prove his or her identity. On the flip-side, all of that information is encoded in a magnetic strip and mounted on a card issued by the government.

The advent of this kind of identification in the United States is both inevitable and dangerous. Since the latter is scarier than the former, citizens need to make sure the implementation addresses civil liberty concerns.

For example, which kinds of information should the government collect and encode? Civil information, such as cross-border comings and goings and arrest records, seem appropriate enough. What about medical details? Financial records?

What balance of security and privacy is appropriate?

Lest readers think this is a British concern, U.S. companies have floated the idea of identification cards at least since 9/11. Typically, Americans approach it from a business standpoint - aiming to save travelers time at the airport and in other security-sensitive areas.

Whether such PIDs come as part of a government program, or through private enterprise (like Steven Brill’s VID), Americans need to ready themselves to have these discussions.