I think we're beyond this point now. There is no "what we are allowed to do" vs "what we are not allowed to do". From what we have seen in the past few months, it's now a matter of "do what we want to do" and if we can't do it then we'll interpret the law.
> (a) Introduce evidence that is the product of NSA surveillance
> (b) Literally manufacture probable cause to effect a search to generate introducible evidence
There is probably even a team at the NSA whose sole purpose is parallel construction!