[furyg3]

It isn't very complicated from a military law perspective. The chain of command (following orders) has a lot more weight on it than a given solder's interpretation of military, constitutional, or international law.

If you believe you are being a given an order that is illegal and refuse, you are essentially putting your head on the chopping block and hoping that a superior officer (who outranks the one giving you the order) later agrees with you. Recent events have involved the commander in chief issuing the orders directly, which means the 'appealing to a higher authority' exit is closed and barred shut for a solider refusing to follow orders.

That doesn't mean a soldier isn't morally obligated to refuse an unlawful / immoral order, just that they will also have to pay a price for keeping their conscience (maybe a future president will give them a pardon?). The inverse is also true, soliders who knowingly follow certain orders (war crimes) are likely to be punished if their side loses, they are captured, or the future decides their actions were indefensible.

A punishment for ignoring a command like "execute those POWs!" has a good chance of being overruled, but may not be. However an order to invade Canada from the President, even if there will be civilian casualties, must be followed. If the President's bosses (Congress/Judiciary) disagree with that order they have recourse.

Unfortunately the general trend which continues is for Congress to delegate their war making powers to the President without review, and for the Supreme Court to give extraordinary legal leeway when it comes to the legality of Presidential actions.