What in principle would justify the scope of the surveillance revealed by the Snowden leak? Would it be enough, for example, if it could be shown that a specific potential act of terrorism had been prevented by, and could only have been prevented by, the full breadth and depth of what we now have learned is the playing field of the security services?
We should hesitate before we stray off the touchline. The idea that public safety, the safety of the innocent, is an absolute which trumps every other consideration, is tacitly abandoned in the way we live.
Nobody would be killed on the roads if the speed limit were 10 miles an hour. Flying would be safer if airport security demanded body searches with no exceptions and the examination of every item in every piece of luggage. On the matter of surveillance in general we have, without much discussion, learned to live with almost blanket surveillance by CCTV in our towns and cities. As a result thousand of crimes, including murder, have been solved and perhaps many more prevented. But how many more would there have been if we doubled the number of cameras, or increased them tenfold, a hundredfold?
Between that and the surveillance we are now talking about there is a qualitative as well as a quantitative difference which hardly needs pointing out. The cameras are in public places, they are not in our houses or our cars or even in our gardens. By contrast, the world of surveillance operated by the people we pay to guard us exceeds the fevered dreams of the Stasi.