Thanks Tom, I'd subscribe to a scheme where warranted intercepts happened without the ability for dragnet surveillance to happen. The paper doesn't really address the problems of data storage and retention (it says rightly this is a different issue, which is true, but I happen to think it's a huge problem - and vulnerability). In addition, there's the issue of how do they target people and their associates. Unfortunately, there's quite a lot of evidence that this is done on an unreasonable basis, at least at times. The paper is at Catching Bandits and only bandits - dedis.cs.yale.edu/dissent/papers/bandits.pdf
Yup I'm all for surveillance that prevents physical harm (theft rape murder terrorism) and even some others but when they store or use that data for other things which is bound to happen once they have it my issues start. (official or not, let's face it, people have a track record of breaking the rules.)