How is this practical?
How can it be more practical to collect every single piece of data which passes through the internet, mobile phones and other media as opposed to targetting people already under suspicion?
The sheer volume of information, and the fantastic ability of our government to lose or "misplace" a lot of what it already has, means I'm not too concerned about our Jacqui listening in on my dirty phone calls, more that a terrorist (or worse, a marketing bod) on a train could suddenly pick up a hard-disk telling him how much KY-Jelly I bought last month, along with the rest of the country.
Besides, I'm just going to start using yoghurt pots and string - far safer!
Biting the hand that feeds IT
