[mywittyname]

Presumably this evidence will eventually come to light through court proceedings. I'm not talking like one huge case, but through thousands of inconsequential small cases where an effort is not made to hide the data origin.

[JohnFen]

> Presumably this evidence will eventually come to light through court proceedings.

Probably not. Great effort is made to hide the use if NSLs. Instead, they engage in "parallel construction" -- reverse engineering a different way of getting the evidence they've collected, so they can use the evidence in court without revealing the NSL.