As Michael O'Leary noted earlier, there are both legal aspects and there are ethical aspects to the events.
Retired AF Guy, the legal issue here is that the Canadian Code of Service Discipline clearly states that members of the CF are bound also by the Criminal Code of Canada, anywhere they may operate - worldwide. So while there are arguments for differentiating between civilian and military ethics, there cannot be for applicability (or not) of civilian and/or military law...it is necessarily by today's CSD an "and".
Timbits raised some interesting points, and as I continue to mull this issue over in my mind as to whether justice was done or not, or was too harsh or not, I too though of some situations that could pose, in light of the 'letter of the law' (of Armed Conflict):
a) A sniper's first shot disables a combatant at range to a degree that the combatant appears not to IMMEDIATELY pose a threat. Does the sniper take a second shot to despatch the target, or does he/she check fire as now the target appears to be, at least in the short-term, 'hors de combat'?
b) Similar situation to that of 2Lt Semrau, but the Canadian soldier with the ANA considers giving the combatant a shot (or more) of morphine from his (or say a nearby TCCC-trained/kitted Cdn soldier). What if enough morphine was given (without highly-trained med knowledge) knowing there might be high possibility of overdosing the injured combatant? Could heavy dosage, knowing its potential fatality, be considered any better than shooting, given use of morphine as either a painkiller, or potential or deliberate fatal action? Should only a single dose be given to the injured fighter? Might such an action at least be able to be portrayed as "assisting/rendering medical aid" even if some might consider doing it to essentially euthanize the mortally-wounded fighter?
This isn't meant to propose "what could he have done" for this case in particular, but note, as have others, some situations that pose a challenge to the ethical and legal conduct of our soldiers operating abroad.
Regards
G2G