Personally I think ID cards have all sorts of advantages and no serious disadvantages. BUt the idea that they'll stop terrorism is ridiculous. If the terrorist is British, he'll have the card. KIf he isnt, he'll have a passport with a visa if needed. Theyre usueful in loads of normal boring circumstances - proving your 18 in a pub, instead of a passport in the EC, collecting parcels, medical records in an emergency - helping sort out identity fraud. All sorts of day-to-day things. But they won't stop terrorism and they won't ever be 100% secure