Get back to me when the dawn comes.
Hint ... read some U.S. history. Preferably about the Civil War, and the Second World War, and the presidential authority in conducting those wars.
Also The Clintoon administrations holdings and pronouncements on presidential authority as it pertains to the War Powers Act.
Now out, damn spot!
Powerline has listed about 5 various cases that determined that eavesdropping on the enemy's communications is a constitutional right of the POTUS.
There is no case law that finds the President must seek a warrant; there are several cases that have determined he does not.
Congress can not infringe on the inheirant rights of either of the other branches of government.
Suppose Congress passed a law that required the President to not grant a pardon unless it was first reviewed by a special secret "pardon court" that made sure it was proper. Such a law would be an unconstitutional infringement on the right of the President to grant pardons, and no law passed by Congress can do that. So if the President then issued a pardon without following that "pardon court" process, would he be acting above the law? Nope.
The FISA law centers on domestically intercepted communications between a criminal suspect within the US. Many (if not all) of these intercepted Al Quada communications are not even subject to review by the FISA court because the court has no jurisdiction. The POTUS would not need a court warrant to intercept those electronic communications that happen to terminate into the US any more than a commander in Iraq would need a court order before he could examine the cell phone or laptop contents of a captured enemy combatant.
Those that ask "Why didn't he go to the FISA court anyway, because he could get approval up to 72 hrs?" might as well ask why he didn't go to, say, the Ohio Supreme court or some other body who also had no authority to decide the matter. The merits of the situation does not apply to FISA.