This is called "a fishing expedition" and is wildly unconstitutional in the US.
>The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
Besides I wasn't talking about the USA when I said this. I was remembering a conversation I once had with a person who worked as a technician in a telephone exchange.
Yes, it is wildly unconstitutional, but in practice don't the courts endorse the asinine "it's not a search unless we find something" argument from the NSA?
Power always just finds a way to rationalize what it wants to do.
>The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.