> The FBI isn't typically allowed to do that without a warrant, which would require probably cause. They or the NSA could do it anyway, but the evidence would n

> The FBI isn't typically allowed to do that without a warrant, which would require probably cause. They or the NSA could do it anyway, but the evidence would never be let into court. At least some law enforcement has a track record of acquiring evidence one way and, once they know what the resulting evidence should be, reconstructing it in a court-admissable way.