Rule 154. Every combatant has a duty to disobey a manifestly unlawful order.
Volume II, Chapter 43, Section D.
State practice establishes this rule as a norm of customary international law applicable to orders given in both international and non-international armed conflicts.
This rule flows from the duty to respect international humanitarian law (see Rule 139) and is also a corollary of the rule that obeying a superior order is not a defence of a war crime, if the subordinate should have known that the act ordered was unlawful because of its manifestly unlawful nature (see Rule 155). In finding that superior orders, if manifestly unlawful, cannot be a defence, several courts based their judgements on the fact that such orders must be disobeyed.
Besides the practice related to the defence of superior orders, practice specifying that there is a duty to disobey an order that is manifestly unlawful or that would entail the commission of a war crime is contained in the military manuals, legislation and official statements of numerous States.
This rule is confirmed in national case-law.
This practice, together with the fact that a subordinate who commits a war crime pursuant to an order which is manifestly unlawful cannot invoke that order as a defence and remains guilty of that crime (see Rule 155), means that there is a duty to disobey such an order.
With respect to the position of a combatant who disobeys an order that is unlawful, but not manifestly so, practice is unclear. Many countries specify in their military law that it is the duty of all subordinates to obey “lawful” or “legitimate” orders and that not to do so is a punishable offence.
Although this could be interpreted as implying that subordinates must not obey unlawful orders, no practice was found stating such an obligation. Some practice was found providing for a right to disobey an unlawful order.
Disobedience of an unlawful order should not entail criminal responsibility, under domestic law, as subordinates only have a duty to obey lawful orders.
As mentioned above, this rule flows from the duty to respect international humanitarian law (see Rule 139) and is also a corollary to the rule that obeying a superior order is not a defence of a war crime, if the subordinate should have known that the act ordered was unlawful because of its manifestly unlawful nature (see Rule 155), both of which apply equally to State armed forces and to armed opposition groups. However, no specific practice was found to confirm this conclusion, as the military manuals, national legislation and case-law referring to this rule relate essentially to members of State armed forces.