A National ID Card

Imagine this:

A National ID card has a thumbprint and your signature. To use it, you sign, and your thumbprint is taken on a digital scanner. This information is compared with what's on the card. If the thumbprint is the same and the signature matches, a hash of the information on the card is sent back to the big NID database, which either says back "yep, this card is valid" or "nope, it's not." Then, access is granted. Of course, if either of the checkpoints failed at first, access would be denied, as it would if the NID database returned a "nay".

They'd also have pictures on them, I'm sure.

Not that I'm arguing for/against a National ID card. But I can see how they could be, properly implemented, a very strong safeguard against identity theft.