Google says geofence warrants make up one-quarter of all US demands
Being a spy is only getting harder.  I remember reading a few years back how biometric scanning meant the CIA spy could not enter CountryX as a Textiles importer one week and a Olive salesman the next.  They had to bribe people at the passport office into fixing their biometrics etc.Now this sort of thing must make it almost impossible. You can't even leave your mobile at home accidentally - that would trip alarm bells, especially if your contact does it at the same lunch hour.Spying seems to be a necessary part of how States understand one another.  If human level intelligence work simply gets blown apart by technology then yeah we can keep track on what the other side is doing, but so very often we want to know why.