The Uniform Code of Military Justice defines penalties for insubordination, treason, and cowardice. When ordered to fire upon others, the only defense a soldier has when refusing to do so is to claim that the order was "illegal". Soldiers may be executed for such refusal to obey orders.
Please revise the UCMJ to clarify that a soldier, in the absence of a declaration of war from Congress, is duty-bound to refuse to fire upon others except in self-defense. Essentially, unless Congress has declared war, no soldier should *ever* be court-martialed for refusing an order to kill.