(Pulls up stool...)
Ok, this is a very interesting and pertinent debate.
As members of the military, we are required to consider every order we receive and check that it is legal. When satisfied with the legality, we will go ahead and implement.
AFAIK, the legal position for orders is as follows:
Illegal orders are those that will break the customary laws of war, and those codified in the 4 Geneva Conventions (1948), the two Additional Protocols (1977) and for those states that have signed up, the Rome Statute of the International Criminal Court (1998). (The ICC statute in Article 8 outlines what crimes it will prosecute.) In addition, the ICC also has jurisdiction over all nationalities for crimes committed in states which have joined the ICC.
As has already been pointed out, Nuremberg onwards enshrined two principles that matter here: individual criminal responsibility and inadmissibility of superior orders. In other words, it is up to you to satisfy yourself that the orders are legal and you have a hard time claiming that orders meant that it was ok.
In this case, the issue is this: if the war is illegal (a state responsibility issue) can the orders (individuals' responsibility) to fight it be legal?
Those (including me) who think that GW2 was illegal, mostly do so because there was no second resolution explicitly authorising the use of force. As a result, whatever you think of Saddam Hussein's regime (in my case, that it was a brutal dictatorship), US/UK et al forces were engaged in aggression, or in Nuremberg's terms, Crimes Against Peace. The crime of aggression can theoretically be tried in the ICC; it is the subject of dispute as to what it means, but in customary and ICC law, aggression is a crime.
So, if any order to commit a crime is illegal, then orders to commit aggression - what Nuremberg called "the ultimate crime" - must be illegal, and ignored; which is why I guess the grown ups had a little chat with the PM and the Attorney General before GW2 to ensure that they were legally defensible. (Pity that virtually every other international lawyer thought that the rationale was bizarre, and worse, b0ll0cks.)
On this basis, where does our happy chappy medic fit in? The question of whether there is a war or not going on seems nonsensical to me: there is clearly an insurgency going on and lots of people are dying violent deaths - if looks, walks and talks like a duck, then it's probably a duck: this looks like a war. Under the 1977 Second Additional Protocol (AP II), the laws of war include civil wars, so the law applies.
On this basis, we have a war, and a coherent case can be made that it's one we started illegally. Therefore, does our happy chappy medic, having served two tours out there, come back and looked at the law, realised that the orders he's been given are illegal, now have a case?
The answer must be yes.
But will he win? Much more difficult, because the argument that orders to commit aggression are illegal hasn't (
AFAIK) been tried recently. So the good Flt Lt is making important legal history. Personally, and based on no more evidence than is in the press, I think that he's got a good chance; and if he does win, we're all beneficiaries, as it will make politicians much less likely to launch aggressive wars.
None of which answers Desparado and others.... should you stand by your mates?
S41