For all who have participated here I suggest a good book : "Six Days" by Brendan DuBois available in US and UK publisher Little Brown. In hard cover - ISBN 0-316-85481-6 or in C format ISBN0-316-85477-8
Also a cautionary tale about homeland security!!!
I register as opposed to a national ID card.
Fer heaven's sake there are books out in general circulation about how to establish a different identity, fake IDs and even passports ... just for starters.
Even a voluntary card could be easily faked ... there's always someone who can find a way around any law or regulation if they're up to no good!