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.
you seem awfully confident of that - in an environemnt where a court just granted geneva protection to terrorists, ignoring article 4 of the geneva agreement.
the bottom line - the court will do whatever it damn well pleases, and whatever political biases it has - will be reflected in the decision rendered. And if it does, and it rules against the administration - WHAT HAPPENS THEN? Do we shut the program down, does the president defy it (he won't)? Do we have the votes in the Senate to authorize it (we don't, just listen to Specter)?