Hook this up into the facial recognition tech they're in no doubt are already using, and then you could also collect data from people's social profiles, ensure they vote for the right parties and generally don't get into trouble like opposing mainstream political ideas and such things.

I've spent a whole of 15 seconds thinking about this and I don't foresee a single drawback here, lets just try it and see if we can prevent future crimes 100%, because then the future will have been saved.