Two Explanations

There are two credible explanations for the horror of seeing the United States military turned into a band of thugs more suited to Milosevic's Serbia than a democratic liberator. The first is that there was direct authorization from the top, or near top, of the civilian and military hierarchy. Someone, after all, must have authorized this:

"Many of the American Special Operations soldiers wore civilian clothes and were allowed to grow beards and long hair, setting them apart from their uniformed colleagues. Unlike conventional soldiers and marines whose Iraq tours lasted 7 to 12 months, unit members and their commanders typically rotated every 90 days.
Task Force 6-26 had a singular focus: capture or kill Mr. Zarqawi, the Jordanian militant operating in Iraq. "Anytime there was even the smell of Zarqawi nearby, they would go out and use any means possible to get information from a detainee," one official said."

Who is that official? Was he responsible? Did he say who sanctioned this? But there's that telling phrase: "Any means possible." Suddenly you see the meaning of the phrase "military necessity" signed by president Bush. We also have all the John Yoo-approved techniques:

"At the outposts, some detainees were stripped naked and had cold water thrown on them to cause the sensation of drowning, said Defense Department personnel who served with the unit.
In January 2004, the task force captured the son of one of Mr. Hussein's bodyguards in Tikrit. The man told Army investigators that he was forced to strip and that he was punched in the spine until he fainted, put in front of an air-conditioner while cold water was poured on him and kicked in the stomach until he vomited."

Induced drowning, hypothermia, repeated beatings, the torture of relatives of intelligence targets: we have seen all these already multiple times. They are always the same techniques, almost as if someone had figured them out and trained people in them. But that couldn't have happened, could it? We don't know. We do know that the Pentagon's Steven Cambone tried to stop it, which implies the second explanation, which is that there were elite military units beyond the control of the Pentagon and the law, let alone the Geneva Conventions, who felt they had been allowed to enter the twilight zone.

Cambone's efforts seem to have come up empty, by the way. We have the far-right Christianist, general William Boykin, telling Cambone on March 17, 2004, that he had "found no pattern of misconduct with the task force." (Boykin was the man who declared the Iraq war one between his God and the God of Islam. He suffered no discipline for that comment.) So the alternative explanation is simply a complete breakdown in the chain of command. Other agencies - even CIA officials some of whom had been trained to abuse inmates at Gitmo - tip-toed around this black hole. They acted as if they knew someone had sanctioned it; or that no one dared stop it; or that these troops were empowered to do whatever they wanted.