A common reaction to the NSA disclosures has been, “Meh, it’s just metadata.” Unfortunately, the issues are perceived as being overly technical and as a result it is difficult to explain to the man-in-the-street, let alone your Aunt Millie, how the collection of metadata is a threat and why everyone should care.
As Bruce Schneier has pointed out, lot of people have effectively demolished the argument that metadata collection needn’t concern us but the arguments are subtle and hard to convey succinctly. Schneier comes to the rescue with a pithier argument: metadata equals surveillance.
He says suppose you hire a detective to eavesdrop on someone by planting bugs and tapping the target’s phone. The fruit of that endeavor would be the details of the target’s communications. That’s the data.
Now suppose that the detective instead followed the target around and discovered what he did, where he went, who he talked to, and what he purchased. That’s the metadata. What the detective is doing in the second case is surveilling the target. The difference between the detective and the government is that the government is putting everyone under surveillance. That’s something that should concern every citizen.