He has served two combat missions in Iraq and Afghanistan. He is described by friends as a devout Christian who prays before every meal and carries a copy of the US constitution in his pocket. And while serving at Camp Mercury near the Syrian border in Iraq, he observed horrifying abuse of prisoners, in testimony that was released last week by Human Rights Watch.

He has testified to habitual beatings to the face and body before interrogation, the pouring of burning chemicals on prisoners’ faces, routine shackling in positions that led to physical collapse, forced exercises that led prisoners to lose consciousness, and stacking prisoners in pyramids in the same mode as Abu Ghraib.

These abuses occurred before, during and after the Abu Ghraib scandal broke. Fishback testified that commanders directed and condoned the abuse. “I would be told, ‘These guys were IED (improvised explosive device) trigger men last week.’ So we would f*** them up. F*** them up bad . . . But you gotta understand, this was the norm.”

Prisoners were apparently called “PUCs”, for “Persons Under Control”. Another sergeant testified: “Everyone in camp knew if you wanted to work out your frustration you show up at the PUC tent. In a way it was sport. One day (another sergeant) shows up and tells a PUC to grab a pole. He told him to bend over and broke the guy’s leg with a mini-Louisville slugger, a metal bat. As long as no PUCs came up dead, it happened. We kept it to broken arms and legs.”

Fishback finally decided to take a stand when he saw Donald Rumsfeld testify to the Senate on television that the Iraq war was subject to the Geneva conventions. He went to his superiors and told them he believed that what was going on was a clear, continuing violation. They ignored him and told him his career would suffer if he persisted in his complaints.

But Fishback went all the way to the secretary of the army and Senate aides. Finally one man responded: Senator John McCain, another war hero, who endured five years of torture by the Vietcong.

Fishback’s letter to McCain is a poignant illustration of what has happened to America these past three years: “Some argue that since our actions are not as horrifying as Al-Qaeda’s we should not be concerned . . . Others that clear standards will limit the president’s ability to wage the war on terror. Since clear standards only limit interrogation techniques, it is reasonable for me to assume that supporters of this argument desire to use coercion to acquire information from detainees. This is morally inconsistent with the constitution and justice in war. It is unacceptable.”

Of course it is unacceptable. But we have presidential memos dating from 2002 exempting the US military from the Geneva conventions in the war against Al-Qaeda and somehow those exemptions “migrated” to the war in Iraq. It is now beyond dispute that the abuses were condoned, enforced and tolerated by commanders throughout the war zone.

We know, for example, that the general in charge of Guantanamo, where torture was formally permitted, was told to Guantanamo-ise Abu Ghraib in the early stages of the insurgency. The notion that the widespread abuse was the invention of a few “bad apples” on the night shift in one prison is preposterous. Reports of inhumane treatment can now be found throughout Iraq and Afghanistan involving hundreds of prisoners, with 36 confirmed deaths in interrogation.

This summer Republican Senators McCain and Lindsey Graham have tried to pass legislation laying down clear guidelines for humane interrogation of prisoners. Behind the scenes Vice-President Dick Cheney has threatened to veto any such attempt to curtail presidential power in wartime. Alberto Gonzales, the man who helped craft the memos redefining torture to meaninglessness, is now attorney-general of the United States. The one sane, principled man who objected to the policy change, Colin Powell, got the boot.

Even now, while the administration insists that it doesn’t condone torture, its definition of what is permitted short of “torture” is murky. In written answers to a senator’s inquiry, leaked last week to The Washington Post, a key official in the White House counsel’s office who helped craft the new policy, Timothy Flanigan, gave nonanswers to clear questions.

He was asked if “water-boarding” was inhumane. “Water-boarding” entails tying a prisoner to a wooden plank and immersing his head in water to the moment of drowning, saving him at the last second, and then repeating this terrifying process again and again. Flanigan replied that “whether a particular interrogation technique is lawful depends on the facts and circumstances”. Without knowing these, “it would be inappropriate for me to speculate about the legality of the techniques you describe”.

Suddenly you understand what has been going on. The Bush administration has abandoned the Geneva conventions for the war against the Taliban and Al-Qaeda on the grounds that they are not legitimate warriors as defined by Geneva. And Flanigan is nominated to be Gonzales’s deputy at the Justice Department. You can’t make this up.

In the US military, responsibility goes directly up the chain of command, even if the commanders are unaware of misconduct. But Fishback shows that they were fully aware and condoned it. US law, international treaties and military law have all been junked.

Last Thursday a judge finally ruled that the remaining photos and tapes from Abu Ghraib will be released, and Bush administration memos specifically related to torture will be made public. There will be appeals, but we will soon be reminded of what really went on: rape and murder.

One wonders when the American public will demand accountability for the abandonment of civilised warfare in their own military and by their own president, who is after all commander-in-chief and ultimately responsible.

Fishback is now sequestered at Fort Bragg, North Carolina, being interrogated by military officials. From all we know of Fishback he will not crack under pressure. He wrote something to McCain that still rings in my ears: “If we abandon our ideals in the face of adversity and aggression, then those ideals were never really in our possession. I would rather die fighting than give up even the smallest part of the idea that is ‘America’.”

Alas, I fear a large part of that idea has already been abandoned — by a president who swore an oath to uphold it.

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