I'm sorry, you're missing the point. it's the individual who has to make the decision. He/she can't rely on anyone else.
Lest you think this is an elitist opinion, I can assure that, post the Clegg case and others, it was always forcibly put even by the regiment NCO during firearm training that the written ROE provided were only for guidance and we should all know our responsibilities and rights, as we could well end up having to justify our actions in a court of law.
If an order is illegal, the individual is bound under law and regulation to refuse to obey it. If it is legal he should obey. If there are those who believe that they cannot abide by that, the have a moral obligation to make their point known now, not when they may be placing the lives of others at risk.