Related Rule
United States of America
Practice Relating to Rule 146. Reprisals against Protected Persons
Section E. Civilians in general
The US Air Force Pamphlet (1976), referring to Articles 4 and 33 of the 1949 Geneva Convention IV, states: “The protection against reprisals expressed in the Conventions … does not protect civilians who are under the control of their own country.” 
United States, Air Force Pamphlet 110-31, International Law – The Conduct of Armed Conflict and Air Operations, US Department of the Air Force, 1976, § 10-7(b)(2).
The US Air Force Commander’s Handbook (1980), under the heading “Persons and Things Not Subject to Reprisals”, lists a number of persons and objects protected under the 1949 Geneva Conventions against which it is prohibited to take reprisals, among which are “inhabitants of occupied territory”. The Handbook adds, however: “A Protocol to the 1949 Geneva Conventions would expand this list to include all civilians … The United States signed this Protocol in 1977, but has not yet ratified it. Consult the Staff Judge Advocate for further guidance.” 
United States, Air Force Pamphlet 110-34, Commander’s Handbook on the Law of Armed Conflict, Judge Advocate General, US Department of the Air Force, 25 July 1980, § 8-4(c).
The US Naval Handbook (1995) provides: “Reprisals may be taken against enemy armed forces, enemy civilians other than those in occupied territory, and enemy property.” 
United States, The Commander’s Handbook on the Law of Naval Operations, NWP 1-14M/MCWP 5-2.1/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 Transportation, US Coast Guard, October 1995 (formerly NWP 9 (Rev. A)/FMFM 1-10, October 1989), § 6.2.3.
The US Naval Handbook (2007) states: “Reprisals may be taken against … enemy civilians other than those in occupied territory”. 
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, § 6.2.4.
At the CDDH, the United States stated:
[The 1977 Additional Protocol I] had gone far to remove the deterrent of reprisals, for understandable and commendable reasons and in view of past abuses. In the event of massive and continuing violations of the [1949 Geneva] Conventions and [the 1977 Additional Protocol I], however, the series of prohibitions on reprisals might prove unworkable. Massive and continuing attacks directed against a nation’s civilian population could not be absorbed without a response in kind. By denying the possibility of such response and not offering any workable substitute, [the 1977 Additional Protocol I] was unrealistic and, in that respect, could not be expected to withstand the test of future armed conflicts. 
United States, Statement at the CDDH, Official Records, Vol. VII, CDDH/SR.58, 9 June 1977, p. 294, § 81.
In 1987, in submitting the 1977 Additional Protocol II to the US Senate for advice and consent to ratification, the US President announced his decision not to ratify the 1977 Additional Protocol I, stating, inter alia, that the 1977 Additional Protocol I “fails to improve substantially the compliance and verification mechanisms of the 1949 Geneva Conventions and eliminates an important sanction against violations of those Conventions”. 
United States, Message from the US President transmitting the 1977 Additional Protocol II to the US Senate for advice and consent to ratification, Treaty Doc. 100-2, 29 January 1987.
In 1987, the Deputy Legal Adviser of the US Department of State stated that the United States did not support “the prohibition on reprisals in article 51 and subsequent articles” and did not consider it part of customary law. 
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 Journal of International Law and Policy, Vol. 2, 1987, p. 426.
On the same occasion, another Legal Adviser of the US Department of State, explaining “the position of the United States on current law of war agreements”, stated:
Article 51 of Protocol I prohibits any reprisal attacks against the civilian population, that is, attacks that would otherwise be forbidden but that are in response to the enemy’s own violations of the law and are intended to deter future violations. Historically, reciprocity has been the major sanction underlying the laws of war. If article 51 were to come into force for the United States, an enemy could deliberately carry out attacks against friendly civilian populations, and the United States would be legally forbidden to reply in kind. As a practical matter, the United States might, for political or humanitarian reasons, decide in a particular case not to carry out retaliatory or reprisal attacks involving unfriendly civilian populations. To formally renounce even the option of such attacks, however, removes a significant deterrent that presently protects civilians and other war victims on all sides of a conflict. 
United States, Remarks of Judge Abraham D. Sofaer, 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, 22 January 1987, American University Journal of International Law and Policy, Vol. 2, 1987, p. 469.
According to an army lawyer who participated in the review of the 1977 Additional Protocol I by the US Joint Chiefs of Staff:
Article 51, paragraph 6, and article 52, paragraph 1, of [the 1977 Additional Protocol I] prohibit reprisals against the civilian population or civilian objects of an enemy nation, respectively. These provisions are not a codification of customary international law, but, in fact, a reversal of that law. The military review considered whether surrender of these rights would advance the law of war, or threaten the continued respect for the rule of law in war. It was concluded that removal of this legal right placed any further respect for the rule of law by certain nations in jeopardy …
The American review recognized the historic pattern for abuse of U.S. and allied prisoners of war by their enemies, and concluded that a broad reservation to the prohibition of reprisals contained in articles 51 and 52 of [the 1977 Additional Protocol I] was essential as a legitimate enforcement mechanism in order to ensure respect for the law of war. 
W. Hays Parks, “Air War and the Law of War”, Air Force Law Review, Vol. 32, 1990, pp. 94 and 97.
In its written statement submitted to the ICJ in the Nuclear Weapons case in 1995, the United States stated:
Various provisions of Additional Protocol I contain prohibitions on reprisals against specific types of persons or objects, including the civilian population or individual civilians (Article 51(6)) … These are among the new rules established by the Protocol that … do not apply to nuclear weapons. 
United States, Written statement submitted to the ICJ, Nuclear Weapons case, 20 June 1995, p. 31.
According to the Report on US Practice, during the review of the 1977 Additional Protocol I by the US Government prior to the decision on whether to seek its ratification, the discussion of the reprisal issue shifted from the need to deter attacks on civilians to the need to protect US prisoners of war by enforcing the 1949 Geneva Convention III. 
Report on US Practice, 1997, Chapter 2.9.