Related Rule
United States of America
Practice Relating to Rule 65. Perfidy
Section B. Killing, injuring or capturing an adversary by resort to perfidy
The US Field Manual (1956) states:
It is especially forbidden to kill or wound treacherously individuals belonging to the hostile nation or army …
[Article 23(b) of the 1907 Hague Regulations] is construed as prohibiting assassination, proscription, or outlawry of an enemy, or putting a price upon an enemy’s head, as well as offering a reward for an enemy “dead or alive”. It does not, however, preclude attacks on individual soldiers or officers of the enemy whether in the zone of hostilities, occupied territory, or elsewhere. 
United States, Field Manual 27-10, The Law of Land Warfare, US Department of the Army, 18 July 1956, as modified by Change No. 1, 15 July 1976, § 31.
The US Air Force Pamphlet (1976) provides: “It is especially forbidden … to kill or wound treacherously individuals belonging to the hostile nation or army.” 
United States, Air Force Pamphlet 110-31, International Law – The Conduct of Armed Conflict and Air Operations, US Department of the Air Force, 1976, § 8-2.
The Pamphlet also states:
Article 23(b) [of the 1907] Hague Regulations … prohibits the killing or wounding treacherously of individuals belonging to a hostile nation or army, whether they are combatants or civilians. This article has been construed as prohibiting assassination, proscription, or outlawry of an enemy, or putting a price upon an enemy’s head, as well as offering a reward for an enemy “dead or alive”. Obviously, it does not preclude lawful attacks by lawful combatants on individual soldiers or officers of the enemy. 
United States, Air Force Pamphlet 110-31, International Law – The Conduct of Armed Conflict and Air Operations, US Department of the Air Force, 1976, § 8-6(d).
The US Manual for Military Commissions (2007), Part IV, Crimes and Elements, includes in the list of crimes triable by military commissions:
USING TREACHERY OR PERFIDY.
a. Text. “Any person subject to this chapter who, after inviting the confidence or belief of one or more persons that they were entitled to, or obliged to accord, protection under the law of war, intentionally makes use of that confidence or belief in killing, injuring, or capturing such person or persons shall be punished, if death results to one or more of the victims, by death or such other punishment as a military commission under this chapter may direct, and, if death does not result to any of the victims, by such punishment, other than death, as a military commission under this chapter may direct.”
b. Elements.
(1) The accused invited the confidence or belief of one or more persons that they were entitled, or obliged to accord, protection under the law of war;
(2) The accused intended to betray that confidence or belief;
(3) The accused killed, injured or captured one or more persons;
(4) The accused made use of that confidence or belief in killing, injuring or capturing such person or persons; and
(5) The conduct took place in the context of and was associated with armed conflict.
c. Comment.
(1) Ruses of war are legitimate so long as they do not involve treachery or perfidy on the part of the belligerent resorting to them. They are, however, forbidden if they contravene any generally accepted rule.
(2) The line of demarcation between legitimate ruses and forbidden acts of perfidy is sometimes indistinct, but the following examples indicate the correct principles. It would be an improper practice to secure an advantage of the enemy by deliberate lying or misleading conduct which involves a breach of faith, or when there is a moral obligation to speak the truth. For example, it is improper to feign surrender so as to secure an advantage over the opposing belligerent thereby. So similarly, to broadcast to the enemy that an armistice had been agreed upon when such is not the case would be treacherous. On the other hand, it is a perfectly proper ruse to summon a force to surrender on the ground that it is surrounded and thereby induce such surrender with a small force.
(3) Treacherous or perfidious conduct in war is forbidden because it destroys the basis for a restoration of peace short of the complete annihilation of one belligerent by the other.
(4) One may commit an act of treachery or perfidy by, for example, feigning an intent to negotiate under a flag of truce or a surrender or feigning incapacitation by wounds or sickness or feigning a civilian, non-combatant status or feigning a protected status by the use of signs, emblems, or uniforms of the United Nations or a neutral State or a State not party to the conflict.
d. Maximum punishment. Death, if the death of any person occurs as a result of the improper use of the treachery or perfidy. Otherwise, confinement for life. 
United States, Manual for Military Commissions, published in implementation of the Military Commissions Act of 2006, 10 U.S.C. §§ 948a, et seq., 18 January 2007, Part IV, § 6(17), pp. IV-13 and IV-14.
The US Naval Handbook (2007) states:
Improperly using protective signs, signals, and symbols … to injure, kill, or capture the enemy is an act of perfidy. Such acts are prohibited because they undermine the effectiveness of protective signs, signals, and symbols and thereby jeopardize the safety of noncombatants and the immunity of protected structures and activities. 
United States, The Commander’s Handbook on the Law of Naval Operations, NWP 1-14M/MCWP 5-12.1/COMDTPUB P5800.7, issued by the Department of the Navy, Office of the Chief of Naval Operations and Headquarters, US Marine Corps, and Department of Homeland Security, US Coast Guard, July 2007, § 12.2.
The US Manual for Military Commissions (2010), Part IV, Crimes and Elements, includes in the list of crimes triable by military commissions:
USING TREACHERY OR PERFIDY.
a. Text. “Any person subject to this chapter who, after inviting the confidence or belief of one or more persons that they were entitled to, or obliged to accord, protection under the law of war, intentionally makes use of that confidence or belief in killing, injuring, or capturing such person or persons shall be punished, if death results to one or more of the victims, by death or such other punishment as a military commission under this chapter may direct, and, if death does not result to any of the victims, by such punishment, other than death, as a military commission under this chapter may direct.”
b. Elements.
(1) The accused invited the confidence or belief of one or more persons that they were entitled, or obliged to accord, protection under the law of war;
(2) The accused intended to betray that confidence or belief;
(3) The accused killed, injured or captured one or more persons;
(4) The accused made use of that confidence or belief in killing, injuring or capturing such person or persons; and
(5) The conduct took place in the context of and was associated with hostilities.
c. Comment.
(1) Ruses of war are legitimate so long as they do not involve treachery or perfidy on the part of the belligerent resorting to them. They are, however, forbidden if they contravene any generally accepted rule.
(2) The line of demarcation between legitimate ruses and forbidden acts of perfidy is sometimes indistinct, but the following examples indicate the correct principles. It would be an improper practice to secure an advantage of the enemy by deliberate lying or misleading conduct which involves a breach of faith, or when there is a moral obligation to speak the truth. For example, it is improper to feign surrender so as to secure an advantage over the opposing belligerent thereby. So similarly, to broadcast to the enemy that an armistice had been agreed upon when such is not the case would be treacherous. On the other hand, it is a perfectly proper ruse to summon a force to surrender on the ground that it is surrounded and thereby induce such surrender with a small force.
(3) Treacherous or perfidious conduct in war is forbidden because it destroys the basis for a restoration of peace short of the complete annihilation of one belligerent by the other.
(4) One may commit an act of treachery or perfidy by, for example, feigning an intent to negotiate under a flag of truce or a surrender or feigning incapacitation by wounds or sickness or feigning a civilian, non-combatant status or feigning a protected status by the use of signs, emblems, or uniforms of the United Nations or a neutral State or a State not party to the conflict.
d. Maximum punishment. Death, if the death of any person occurs as a result of the improper use of the treachery or perfidy. Otherwise, confinement for life. 
United States, Manual for Military Commissions, published in implementation of Chapter 47A of Title 10, United States Code, as amended by the Military Commissions Act of 2009, 10 U.S.C, §§ 948a, et seq., 27 April 2010, § 5(17), pp. IV-14 and IV-15.
Under the US War Crimes Act (1996), violations of Article 23(b) of the 1907 Hague Regulations are war crimes. 
United States, War Crimes Act, 1996, Section 2441(c)(2).
The US Military Commissions Act (2006), passed by Congress following the Supreme Court’s decision in Hamdan v. Rumsfeld in 2006, amends Title 10 of the United States Code as follows:
§ 950v. Crimes triable by military commissions
“ …
“(b) OFFENSES.—The following offenses shall be triable by military commission under this chapter at any time without limitation:
“ …
“(17) USING TREACHERY OR PERFIDY.—Any person subject to this chapter who, after inviting the confidence or belief of one or more persons that they were entitled to, or obliged to accord, protection under the law of war, intentionally makes use of that confidence or belief in killing, injuring, or capturing such person or persons shall be punished, if death results to one or more of the victims, by death or such other punishment as a military commission under this chapter may direct, and, if death does not result to any of the victims, by such punishment, other than death, as a military commission under this chapter may direct. 
United States, Military Commissions Act, 2006, Public Law 109-366, Chapter 47A of Title 10 of the United States Code, 17 October 2006, p. 120 Stat. 2629, § 950v(b)(17).
The US Military Commissions Act (2009) amends Chapter 47A of Title 10 of the United States Code as follows:
§ 950t. Crimes triable by military commission
“The following offenses shall be triable by military commission under this chapter at any time without limitation:
“ …
“(17) USING TREACHERY OR PERFIDY.—Any person subject to this chapter who, after inviting the confidence or belief of one or more persons that they were entitled to, or obliged to accord, protection under the law of war, intentionally makes use of that confidence or belief in killing, injuring, or capturing such person or persons shall be punished, if death results to one or more of the victims, by death or such other punishment as a military commission under this chapter may direct, and, if death does not result to any of the victims, by such punishment, other than death, as a military commission under this chapter may direct. 
United States, Military Commissions Act, 2009, § 950t(17).
In its Country Reports on Human Rights Practices for 1996, in a section entitled “Use of Excessive Force and Violations of Humanitarian Law in Internal Conflicts”, the US Department of State noted that, in Uganda, “newspapers reported that [a rebel leader] offered bounties for the killing of prominent Ugandan military personnel, including the Minister of State for Defence”. 
United States, Department of State, Country Reports on Human Rights Practices for 1996, United States Government Printing Office, Washington D.C., 30 January 1997.
The US Presidential Executive Order 12333 of 1981 provides: “No person employed by or acting on behalf of the United States Government shall engage in, or conspire to engage in, assassination.” 
United States, Executive Order 12333, 4 December 1981, CFR, 1981 Comp. (1982), p. 213.
In 1987, the Deputy Legal Adviser of the US Department of State, referring to Article 37 of the 1977 Additional Protocol I, affirmed: “We support the principle that individual combatants not kill, injure, or capture enemy personnel by resort to perfidy.” 
United States, Remarks of Michael J. Matheson, Deputy Legal Adviser, US Department of State, The Sixth Annual American Red Cross-Washington College of Law Conference on International Humanitarian Law: A Workshop on Customary International Law and the 1977 Protocols Additional to the 1949 Geneva Conventions, American University Journal of International Law and Policy, Vol. 2, 1987, p. 425.
In 1989, in a memorandum of law, the Office of the Judge Advocate General of the US Department of the Army concluded:
The clandestine, low visibility or overt use of military force against legitimate targets in time of war, or against similar targets in time of peace where such individuals or groups pose an immediate threat to United States citizens or the national security of the United States, as determined by the competent authority, does not constitute assassination or conspiracy to engage in assassination, and would not be prohibited by the proscription in [Executive Order] 12333 or by international law. 
United States, Department of the Army, Office of the Judge Advocate General, Memorandum of Law: Executive Order 12333 and Assassination, 2 November 1989, The Army Lawyer, Pamphlet 27-50-204, December 1989, p. 4.
In 1991, in response to an ICRC memorandum on the applicability of IHL in the Gulf region, the US Department of the Army stated that its practice was consistent with the prohibition of killing, injuring or capturing an adversary by resort to perfidy contained in Article 37 of the 1977 Additional Protocol I. 
United States, Letter from the Department of the Army to the legal adviser of the US Army forces deployed in the Gulf region, 11 January 1991, § 8(J), Report on US Practice, 1997, Chapter 2.8.