I'm not arguing your point about the legality.
What I am saying is that the NSA (and the federal govt.) do things illegally all the time.
But since they have no real oversight...they don't get caught.
So the laws are meaningless to them.
Hell, if it weren't for Edward Snowden whistleblowing, we still wouldn't know that they were doing it.
And if you noticed...nobody at the NSA or any other federal agency has been prosecuted for what they are doing.
The only person in trouble is...Snowden.
That's how shit works when you are dealing with the United States federal govt.
