You did not read my post. Yes, you are correct that the law does not apply to Atta and bin Laden. But you don't know who it is until after you've intercepted the phone call. All you know is that it's an al Qaeda number calling a US number. It could be Atta, and you could be safe in intercepting the call.
But it might not be Atta. It might be you who answers the phone, in which case, it's a crime under the statute to intercept the call. So the only way to avoid violating the statute for certain is to refrain from taking the call at all, no matter who it is.
No it's not a crime. If I answer a call from Osama, of course the govt can listen in. They've always been allowed to listen in. They already will have gotten authorization to tap Osama's phone so whoever he calls is fair game.
The difference is that they can't tap my phone, if I'm a citizen, becuase my number was on some list somewhere, and then listen in on every call that I make to someone, at least without a warrant.
The FISC court will alwys grant the warrant if it's as serious a situation as you make it out to be. The problem is that by bypassing FISC and Congress the govt is implicitly admitting that if we really knew what was going on, it might not be considered legal so they have to keep it secret.
The govt, I think, is playing "six degrees of separation" with AQ. Let's say they found some laptop when they got KSM that had a bunch of numbers on it. One of those numbers was for Ahmed in Brooklyn. The govt could easily and instantly get a warrant to tap Ahmed's phone and could listen in immediately to any call involving him.
What I think they're doing, and no one knows becuase they're keeping the whole thing secret, is an able danger style data mining op. Once they have Ahmed's #, they basically come up with a whole list of #s that AHmed may have called for whatever reason, it could be his accountant, the pizza guy, his girlfriend, his buddies from work, whoever. I think they're using this to then say that all those people may be involved with AQ via Ahmed and since we have no way of knowing we need to tap their phones. They cut out FISC becuase in that situation, they might not approve such an openended request.
In any event, we can't really judge what went on until we have more information about who was involved, who was spied on, etc... And we may never know that. But I still contend that there was no reason for the govt to go beyond the established procedures. The 72hr rule takes care of any emergency that may pop up.