Dianne Feinstein actually said...

I have found that the implementation has been reasonable in scope and tailored to the needs of our intelligence and law enforcement communit...

This is a very broad power. When used directly, the individual would know about it. In this case, they would have no recourse to court.

It is my hope that this will allow Justice and FBI employees to spend more time conducting intelligence investigations than passing papers t...

It seems to me that asking for an AUSA to sign off takes us back to the world where the answer to terrorism was criminal prosecution.