1. United States
2. Letter

This letter is submitted to address a fundamental and enduring tenet of military service under the law: the duty of all service members to obey only lawful orders, and their corollary duty to refuse any order deemed unlawful. This principle is not merely a matter of military ethics but is explicitly codified and enforced through the Uniform Code of Military Justice (UCMJ). The UCMJ establishes the bedrock requirement for obedience. For instance, Article 92 states that any service member who "violates or fails to obey any lawful general order or regulation" shall be punished. Similarly, Article 90 and Article 91 establish that the offense of willful disobedience applies only to the failure to execute a lawful command given by a superior. The essential criterion for the entire military justice system is the lawfulness of the order. As defined by military law and reinforced by the Manual for Courts-Martial (MCM), an order is unlawful if it "clearly and palpably illegal," such as one requiring the commission of a crime, a violation of the U.S. Constitution, or a violation of the laws of war. It is a non-delegable professional obligation for every service member to assess the legality of an order. The duty to refuse an unlawful order is absolute and stems from the responsibility of every person subject to the UCMJ to uphold the law. Crucially, a military member who carries out an order that he or she knows or reasonably should know to be illegal remains individually accountable under the UCMJ and can be subject to court-martial. The source of the order does not grant immunity from prosecution. Maintaining this clear, bright line between lawful and unlawful orders is vital for ensuring the discipline, professionalism, and legal integrity of the United States Armed Forces, regardless of who is issuing the command. It's sometimes difficult for a service member to know when an order is unlawful, but if it is CLEARLY illegal, and they still carry out the order, they can, will, and have been, prosecuted. See, for example, Lieutenant William Calley Jr. in the Viet Nam war, and also the Nuremberg trials, where "I was just following orders" was generally not a defense. If you don't make any illegal orders, you've got nothing to worry about. If you're unsure about the legality of an order, then don't make it. Problem solved.