Akuperma, you said: “This is a big issue for goyim, since most western legal systems considering it a valid defense that someone is following orders with a possible exception only of one knows that the orders one is following were also illegal.”
I suppose the possible exception is the fundamental issue. Ignorance of the (clear and valid)law is not an excuse both in the religious and secular context. There is also a presumption of knowledge of the law.
In Germany, the law of following orders unconditionally may have been inherently tyrannical and therefore unbinding(see our declaration of independence for rationale).
The only real questions arise when 1. there is a disagreement as to the content of the law, or 2. the question isn’t whether the law was technically violated, rather, whether we found the right scapegoat. Receiving orders going against the law may be a mitigating excuse as to the punishment but don’t (in a civilian context) justify violation.
As far as whether the chain of command in a military context requires the soldier to follow orders unquestioningly, there are laws about that too. Soldiers are taught what they may or may not do. So long as the (secular) laws don’t violate basic principles
of decency (and/or the constitution), the law always trumps all.
In summary, the law always takes precedence, in every context, unless the law is fundamentally flawed.