A couple of quotes:

From the infamous torture memos:

In order to respect the Presdient's inherent constitutional authority to manage a military campaign, 18 U.S.C. § 2340A (the prohibition against torture) must be construed as inapplicable to interrogations undertaken pursuant to his Commander-in-Chief authority. ...

As this authority is inherent in the President, exercise of it by subordinates would be best if it can be shown to have been derived from the President's authority through Presidential directive or other writing.

And here's Dubya, while delivering his final ultimatum to Saddam:

... all Iraqi military and civilian personnel should listen carefully to this warning: Do not destroy oil wells, a source of wealth that belongs to the Iraqi people. Do not obey any command to use weapons of mass destruction against anyone, including the Iraqi people. War crimes will be prosecuted, war criminals will be punished and it will be no defense to say, "I was just following orders."

Torture is a war crime.

I was reminded of this by watching Control Room, the documentary on al-Jazeera's coverage of the Gulf War -- and Centcom's staff's reactions to al-Jazeera. The film also quotes Rumsfeld denouncing the Iraqi Army's showing of video of American prisoners as violation of the Geneva Conventions...