Errol Morris's minutely researched film about the appalling treatment of prisoners in Abu Ghraib, and the notorious photographs that came to light in 2004, was made long enough ago to seem slightly secondhand by now. It says nothing that the more modestly produced Taxi to the Dark Side - which was about torturing prisoners in Afghanistan - didn't say in spades.

Added to that, this fine documentarist's attempt to tart up his film so that it gets a wider release is not entirely successful. There's an overweaning score from Danny Elfman, much swishing camerawork from robert Chappell and robert richardson, and a sense that Morris himself stares rather too long at the American GIs who produced those awful snaps.

In particular, he stares, without comment, at lynndie England, the private first class who is seen grinning inanely at the piled-up Iraqi bodies, and at Staff Sergeant Charles Granier, who ordered the fatal photos and with whom she was in love. If these wretched grunts are worth castigating, how much more culpable are those who either ordered such behaviour or did nothing to stop it?

Morris is never unfair, unlike certain other American documentarists, and this is still an important slice of film evidence which will shortly be published as a book. But this is not his best film. It's too polished by half.