If I was arguing against the administration I believe I would take up the points the attorney general must swear to, specifically :
(B) there is no substantial likelihood that the surveillance will acquire the contents of any communication to which a United States person is a party;
I think the adminstration could defend against this sort of legal attack successfully but it would be the most challenging part.
If Al Qaeda is a foreign power (a substantial if) and if the (let's say) US citizen on the US end of the telecon is conspiring with or a member of Al Qaeda, is that US citizen still a US person for purposes of this statute?