Look BDB obviously FISA is the law. Ok. Now, you may or may not know of this law. Which basically says that, yes the POTUS can order a suspects phone to be tapped in a time of war. PROVIDING, that within 72 hours of the wire tap, a showing is made to the FISA Court and then the Court will issue a wire tap.
Ok, now I know this is hard to grasp, but W can't just order this on his own and not get the Courts approval. He's not a King.