Here’s why the argument is so wrong that it can’t possibly be made with a straight face by anyone but the criminally insane or a Republican.
Whatever the AUMF is, it is not a Declaration of War. Only Congress can declare war, and that hasn’t happened since World War II. However, the Supreme Court has ruled that although the President cannot declare war he can recognize a state of war. So, let’s grant the President the benefit of the doubt and say that the facts add up to the United States being at war.
Now open your books to the FISA statute:
§ 1811. Authorization during time of war
Notwithstanding any other law, the President, through the Attorney General, may authorize electronic surveillance without a court order under this subchapter to acquire foreign intelligence information for a period not to exceed fifteen calendar days following a declaration of war by the Congress.
Get it? Even if Congress had declared war there would be a 15 day limitation on his ability to listen in on Americans’ conversations.
As the old song goes: “How long has this been going on?” A lot longer than 15 days.
“… and tell ‘em Big Mitch sent ya!”