In his final lecture at Stanford University on Wednesday, Philip Zimbardo said abuses committed by Army reservists at Iraq's Abu Ghraib prison were not isolated incidents by rogue soldiers. Rather, sadism was the inevitable result of U.S. government policies that condone brutality toward enemies, he said.

Individual military personnel -- those who stripped prisoners and leashed them like dogs -- are only as culpable as the people who created the overall environment in which the soldiers operated, Zimbardo told undergraduates enrolled in introductory psychology.

"Good American soldiers were corrupted by the bad barrel in which they, too, were imprisoned," said Zimbardo, 73. "Those barrels were designed, crafted, maintained and mismanaged by the bad barrel makers, from the top down in the military and civilian Bush administration."

The professor blasted President Bush, former Secretary of Defense Donald Rumsfeld and other senior officials who said al-Qaida and Taliban captives would be considered "unlawful combatants" rather than "prisoners of war," a designation that would invoke the Geneva Convention.

Zimbardo said those officials "should be tried for the crimes against humanity."