One feels a great deal of sympathy for the guy, and can understand him. So what is justice for him?
What's justice for his family? What then is justice for the Afghani's who had friends and family members killed? What is justice for the Afghanistan state, who has already been shown to be a very weak puppet? What is justice for the American government, who must do something?

Lt. Calley got 3.5 years of house arrest for the massacre of 347 Vietnamese. If one reads the history one can feel a good deal of sympathy for Calley, a weak person feeling pressure from above and below, over his head, friends dying and feeling the scorn and derision of his superiors. A pathetic man in an emotional vise.

And the enormity of his crime indicates he should have been shot. Period.

What is justice in this case? I don't know, but I know it won't be done. I think an Afghani court would come closest. One cannot massacre 16 people like that no matter what the circumstances.

Let's see what the US does to the Major in the Fort Hood shooting, where he killed 13 Americans.

http://en.wikipedia.org/wiki/Fort_Hood_shooting