The US is a signatory to the Geneva Conventions, and our Constitution makes ratified treaties the law of the land.
What constitutes torture was well hashed out after World War II and is embedded in the Geneva Conventions. There is no lack of clarity there.
A Justice Department dedicated to enforcing the law would have no choice but to go after the law-breakers; it is not a low-profile crime. Only a Justice Department which places ideology and party loyalty ahead of the law could let this reprehensible policy go unchallenged.
Mukasey appears well on his way to confirmation. So be it. He'll have to make a very important personal choice when he reports to work. If he chooses poorly, he may find himself prosecuted along with all the other lawbreakers.