How have courts-martial and military tribunals interpreted ‘manifestly illegal’ orders?
Executive summary
Courts-martial and military tribunals have settled on a dual obligation: service members must obey lawful orders but must refuse orders that are so clearly illegal that “a man of ordinary sense and understanding” would recognize them as unlawful — the so‑called “manifestly unlawful” standard [1][2]. Military practice and precedent hold that obedience is not a blanket defense; carrying out manifestly unlawful orders can produce individual criminal liability in U.S. military courts and international tribunals [3][4].
1. What “manifestly unlawful” means in practice
The phrase has been defined by U.S. military authorities and courts to mean an order that plainly contravenes the Constitution, federal law, or the laws of war — essentially orders that on their face command a crime or an atrocity, such as targeting civilians or mistreating detainees [1][5][3]. Repeated summaries of military law emphasize that an order is presumed lawful when issued by a superior but that presumption does not extend to “patently illegal” orders that direct criminal acts; the standard therefore hinges on obviousness to a reasonable person in the subordinate’s position [6][5].
2. How courts have applied the standard: landmark examples
The My Lai prosecutions, and specifically Lieutenant William Calley’s court‑martial, are canonical: the tribunal rejected Calley’s claim that he was merely following orders, finding either knowledge of illegality or that any ordinary person would have recognized the order as illegal [1][2]. Courts since have repeatedly cited that line: obedience cannot override clear legal prohibitions, and following an order that is manifestly criminal will not shield a subordinate from accountability [3][4].
3. Who decides lawfulness and where the burden falls
Under U.S. practice the lawfulness of an order is a question of law for the military judge to decide, not a discrete element the jury must determine as fact in Article 92 prosecutions, and courts routinely recognize a judicial role in resolving the legality of contested orders [6][7]. At the same time, the accused generally bears the practical burden of showing the order was manifestly unlawful or that he knew it to be unlawful if claiming “acting pursuant to orders” as a defense [5][8].
4. The operational dilemma: culture, training, and the risk of refusal
Military culture and conditioning to obey make refusal fraught; service members can face punishment for disobeying lawful commands while also being criminally exposed for obeying unlawful ones, a tension that courts and commentators repeatedly note and which complicates split‑second decisions in combat [9][10]. Legal guidance counsels seeking Judge Advocate advice when possible and warns that the “manifest” standard is high — hesitation or refusal can carry consequences even if, later, a court finds the order unlawful [8][11].
5. International law and the rejection of the “just following orders” defense
International humanitarian law and instruments such as ICRC commentary mirror domestic practice: a subordinate who knew or should have known the ordered act was unlawful cannot rely on superior orders to avoid responsibility, and the Nuremberg‑style defense has been explicitly repudiated in both customary and treaty‑based doctrine [4][2]. That alignment means that manifest illegality — typically framed around war crimes like willful killing of civilians or grave breaches of distinction and proportionality — exposes actors to both national courts‑martial and international prosecution [4][9].
6. Bottom line and implications for commanders and troops
The law as applied by courts‑martial creates a strict dichotomy: obey clear, lawful orders; refuse orders that are plainly criminal — but recognize that the line is fact‑intensive, judged by military judges and appellate courts, and operationally hazardous to determine in real time, which places heavy premium on training, command clarity, and prompt legal advice when orders appear to cross the line into manifest illegality [1][3][8]. Sources consulted consistently emphasize that the obligation to disobey manifestly illegal orders is legally settled, even as practical uncertainty and career risk persist for those forced to choose in the field [5][10].