the Congress says so: "outlawing waterboarding rests with Congress."
So to hell with international law and every relevant historical opinion and precedent. According to the Spector doctrine, unless the moral cowards in the US Congress can pass a veto-proof, signing-statement-immune law explicity forbidding it, the president of the United States can use any form of "enhanced interrogation" technique he wants. This whole gang should be hung as war criminals.

All those that think waterboarding isn't torture should be subjected to the procedure for the same period of time as it took to get reliable information on those prisoners who got to experience the technique. If after that they still think it's just fun and games, at least they will be speaking from personal experience.

Actually, torture doesn't get reliable information; that isn't its purpose, which is to terrorize and get confessions to anything the victim thinks will get the torturers to stop.