[drcube]

Because they're not the police. And the jails are already full.

[mikeash]

Also the criminal justice system doesn't accommodate evidence obtained through the NSA's methods.

[dllthomas]

Until they lie about how they got it.

http://en.wikipedia.org/wiki/Parallel_construction

[mikeash]

Even then, that's way too much effort to go through to convict a car thief or other similarly small stuff.

[dllthomas]

Unless there's some other reason they want to nail that car thief, probably, yeah.

[mikeash]

That's an interesting thought. Some terrorist is in the US and planning something, but they don't want to give away their intel. So do a bit of parallel construction and tip off the local cops to some relatively small crime he's committed in the course of everything....

Or substitute "whistleblower" or "inconvenient politician" for "terrorist" if you prefer.

[dllthomas]

Or even "ex-" or "rival".