Where exactly up the chain of command does the legality of the persons rank stop mattering?
If I'm an E-1 and an "E-2" who I along with tens-of-millions of others suspect is an infiltrator or a spy gives me an order I do nothing? I have no reason to doubt the lawfulness of the order? No recourse?
If I do have recourse with an E-2 what about an O-1? If an O-1 why not the alleged commander-in-chief?
Again, where does the need to certify legitimacy stop?