I have been following with interest the case of Lieutenant Ehren Watada. He has refused to go to Iraq, and is the first officer to do so. Initially, I felt he was completely in the wrong -- he is employed by the military and can't pick and choose his assignments.
But on further reflection, I have done a complete reversal. Officer Watada feels the war is illegal, as it was based on faulty and inflated intelligence information. As an officer, he committed to among other things, "refusing to participate in illegal military actions". We expect our soldiers to refuse any order that is illegal. Nuremburg pretty much ended the "just following orders" defense, and made it an obligation of all soldiers to consider their orders in view of their legality.
Officer Watada offered to serve in Afghanistan, so he is not using this as a dodge to avoid combat. He also offered to resign. Both offers were rejected. A military tribunal also refuses to hear any defense that involves using the legality of the war as a basis, effectively convicting Officer Watada before trial. He has vowed to fight all the way to the Supreme Court. But in the meantime, he will most likely serve 4 years in a military prison -- for doing his duty and taking his pledge seriously.