It's not just a matter of "bad apples" and lack of training, as this story from this morning's Guardian illustrates. US forces were taught torture techniques:

"The attitude that was communicated started from the highest levels and was sent on down the chain. It created an overall climate in which adversaries were dehumanised, the distinction between suspect and known perpetrator was effaced, and the overall message was that international law or domestic niceties get in the way of doing quote 'what we had to do', said Rosa Ehrenreich Brooks, formerly a senior adviser on human rights to the State Department. "When that is the message from the top it enables all sorts of bad behaviour."