OK, and when FISA refuses to grant blanket constitutional authority for them - then what? then where are we? try and think a couple of moves ahead.
They won't grant a blanket Constitutional Authority but they will rule as they've ruled before that the President has the Constitutional Authority to conduct foreign surveillance and then the critics will still yell that this isn't one of them.
Since their say is non-binding, they do the program anyway. This is simple, why make it harder just to scare yourself.