Related Rule
France
Practice Relating to Rule 154. Obedience to Superior Orders
France’s Disciplinary Regulations (1975), as amended, states that members of the military “have the duty to obey lawful orders”. 
France, Règlement de Discipline Générale dans les Armées, Decree No. 75-675 of 28 July 1975, replacing Decree No. 66-749, completed by Decree of 11 October 1978, implemented by Instruction No. 52000/DEF/C/5 of 10 December 1979, and modified by Decree of 12 July 1982, Ministère de la Défense, Etat-Major de l’Armée de Terre, Bureau Emploi, Article 6.
The Regulations further provides:
The subordinate shall not carry out an order to do something that is manifestly unlawful or contrary to the customs of war, the rules of international law applicable in armed conflicts, or duly ratified or approved international treaties. 
France, Règlement de Discipline Générale dans les Armées, Decree No. 75-675 of 28 July 1975, replacing Decree No. 66-749, completed by Decree of 11 October 1978, implemented by Instruction No. 52000/DEF/C/5 of 10 December 1979, and modified by Decree of 12 July 1982, Ministère de la Défense, Etat-Major de l’Armée de Terre, Bureau Emploi, Article 8(3).
France’s Code of Defence (2004), as amended in 2007, states:
Soldiers must obey the orders of their superiors … Nonetheless, they may not be ordered to undertake and they may not undertake any acts contrary to the laws [and] customs of war and to the international conventions. 
France, Code of Defence, 2004, as amended by Ordinance No. 2007-465 on 29 March 2007, Article L. 4122-1.
France’s Code of Defence (2004), as amended in 2008, states:
D.4122-2.When exercising the authority of a commander, the member of the military … [h]as the right and the duty to demand obedience from subordinates; he cannot order the performance of acts contrary to the laws, rules of international law applicable to armed conflicts and international conventions in force.
D.4122-3.As a subordinate, the member of the military … [s]hall not execute an order that prescribes the performance of an act evidently illegal or contrary to the rules of international law applicable to armed conflicts and the international conventions in force. 
France, Code of Defence, 2004, as amended in 2008, Article D4122-2 and D4122-3.