[Myrddin]

Good observation with respect to knowing when and where an item was used, but being unable to assure the user was the actual owner of the ID.

I'm reminded of the technique of cutting off a tracking collar from an animal and hanging it on the back end of an 18 wheel truck. It would be dead simple to pass "terrorist" ids to ignorant individuals with permission to use them as a diversionary tactic.

[Travis McGee]

Absolutely. But in the end, even the use of such diversionary tactics can flag groups.