The New Yorker published a long article earlier this year based on interviews with some of the US soldiers involved in the Abu Ghraib abuses, where prisoners were photographed in obscene situations. One reader wrote to the editor to complain: the reader was "outraged" at the lack of "moral outrage" in the article.

Writer Philip Gourevitch chuckles. "I was delighted", he says. "I'm not going to say, 'cry here', 'stamp your foot here' – I don't feel we can hold up cue cards.

"If you can't supply your own moral outrage to this material, there's really not much I can do for you."

The New Yorker article was an extract from his book, just published, Standard Operating Procedure: A War Story. The book is the result of an unusual collaboration. Filmmaker Errol Morris recorded hundreds of hours of interviews with the soldiers and officials who had been at Abu Ghraib; he shared these with Gourevitch, and Gourevitch has written a book to tie in with Morris's documentary film of the same title.

One vignette plucked, more or less at random, from that material is military policeman Javal Davis's account of what would happen when an interrogation team went to work on a prisoner:

"They put a sheet up over the door and for hours and hours and hours, all you would hear is screaming, banging, slamming, and just more screaming at the top of their lungs. When they were done, eight, 10 hours later, they'd bring the guy out, he'd be halfway coherent, or unconscious. You'd put him back in the cell and they'd say, 'OK, this guy gets no sleep. Throw some cold water on him. We'll be back for him tomorrow.'"

In person (over the phone from New York) as in print, Philip Gourevitch is understated but crisp.

"It's a pretty angry book," he says, as if he is surprised that anybody could miss that. "And because I knew I was writing an angry, absurd, outlandish story, I felt I had to rein in my own amplification of those things and just let the material carry it."

One of the strengths of his book is his refusal to judge his subjects.

"It's way too easy for all of us to assume that we would be the whistleblower, the good guy, the person who says, 'No.' I wanted to describe how a soldier in this war is caught in this incredibly claustrophobic, fearful climate, where they're given great encouragement – if not direct orders – and given pats on the head for the kind of treatment that we saw in these photos, for abusing prisoners, and how confusing that is for them."

He is sympathetic towards them, he says: "They were both instruments of a great injustice and, in their punishment, victims of a pretty great injustice: the burden for the crimes of a system that they had nothing to do with creating was placed entirely on them.

"After Nuremberg, there
was the argument that just following orders was a totally unacceptable excuse. Subsequently, in looking for political justice in the aftermath of Rwanda, Cambodia, Bosnia, the prevailing view was that the low-level hatchetman is held to a lower standard of guilt and punishment than the mastermind that might never have spilt blood directly. That's the way that political crimes are prosecuted throughout the world these days. It's the exact opposite of what we saw at Abu Ghraib."

Philip Gourevitch has previously written a seminal book on the 1994 Rwandan genocide, We Wish to Inform You That Tomorrow We Will Be Killed With Our Families (the title comes from a letter written by a group of Tutsi pastors to the Hutu head of their church, who failed to intervene to help them). In Rwanda, not only did the US fail to intervene, they also sought to dampen calls for intervention.

The Iraqi quagmire could be described as arising from an excess of intervention. For Philip Gourevitch, one element is constant, and it's where he finds his role: "The argument over intervention should be an argument about information, at the very least. Whether we're going to act or not act, the very least we should be is well informed."

Gourevitch's day job is as editor of the Paris Review, an illustrious, New York-based literary journal. Given the political urgency of his work, is there a danger that its pages, and those of the New Yorker, might limit his writing to a perceived elite audience?

"It's not elitist. It's not theoretical, it's not highbrow. It's an attempt to write in clean, plain English at a certain length and a certain level of detail. That's not elitist.

"To me, the journalistic imperative isn't compromised by trying to tell a story well, vividly and compellingly, it's served by it. What one is trying to do is make sure that the story that one presents is not merely a pile of crucial data, but is emotionally and morally vivid and accessible."