What’s the Evidence Mass Surveillance Works? Not Much

[Commentary] Current and former government officials have been pointing to the terror attacks in Paris as justification for mass surveillance programs. CIA Director John Brennan accused privacy advocates of “hand-wringing” that has made “our ability collectively internationally to find these terrorists much more challenging.” Former National Security Agency and CIA director Michael Hayden said, “In the wake of Paris, a big stack of metadata doesn’t seem to be the scariest thing in the room.” Ultimately, it’s impossible to know just how successful sweeping surveillance has been, since much of the work is secret. But what has been disclosed so far suggests the programs have been of limited value. Here’s a roundup of what we know.