For me, the problem lies in the central database, rather than the card. Hence the recent compromise between the Lords and Commons to include the biometrics in the database but not insist on a card is missing the point.

There are a number of quite fundamental issues with the database, from my point of view. Identifying a person by referring to the database and using the database to identify a person are two very different things. The analogy I use is that that it is difference between "if this person in front of me really you, they must have blue eyes" and "if the person has blue eyes, it must be you". Ok, the DNA sample takes something like 15 characteristics into account not just one, but its fundamentally the same. Moreover, you can't (easily) use the database to pick out likely suspects and then use it again to find which is the best fit - the mathematically inclined will remember Bayes Theorem here. It was the failure to understand Bayes Theorem and other probability manipulation that led to the mess with Sir Roy Meadows and I can't see a sudden mass improvement in sophisticated numeracy myself.

Then there is the fact that in forensic work you are looking at very small samples. That introduces the fact that we don't really know enough about how DNA can be transferred. For example: if you have dandruff and travel on public transport, how do you know where those flakes of your DNA will end up?

If you are innocent you have nothing to fear? It's not so simple.