Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 47. Attacks against Persons Hors de Combat
The UK LOAC Manual (2004) states: “A person who is recognized or who, in the circumstances, should be recognized to be hors de combat shall not be made the object of attack.” 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 5.6.
In its chapter on enforcement of the law of armed conflict, the manual notes:
Additional Protocol I extends the definition of grave breaches to include the following:
b. any of the following acts, when committed wilfully, in violation of the relevant provisions of the protocol, and causing death or serious injury to body or health:
(5) making a person the object of attack in the knowledge that he is hors de combat. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 16.25.
The UK Geneva Conventions Act (1957), as amended in 1995, punishes
any person, whatever his nationality, who, whether in or outside the United Kingdom, commits, or aids, abets or procures the commission by any other person of, a grave breach of … [the 1977 Additional Protocol I]. 
United Kingdom, Geneva Conventions Act, 1957, as amended in 1995, Section 1(1).
In 2010, in its closing submissions to the public inquiry into the circumstances surrounding the death of Baha Mousa and the treatment of those detained with him by UK armed forces in Iraq in 2003, the UK Ministry of Defence stated:
12. The treaties setting out rules of IHL are supplemented by rules of customary international law (CIL), i.e. rules which are recognized as binding by States, even though they do not appear in treaty texts. … [I]n relation to the rules described below the Government accepts that they reflect CIL. It is suggested that the rules which are of most relevance to this inquiry are:
12.1. … Attacking persons who are recognised as hors de combat is prohibited. A person hors de combat is: (a) anyone who is in the power of an adverse party; ... provided he or she abstains from any hostile act and does not attempt to escape.
12.2. Thus, as persons in the power of UK forces the detainees all fell within the definition of persons hors de combat and could not be attacked provided that they abstained from any hostile act and did not try to escape. 
United Kingdom, Ministry of Defence, Closing Submissions to the Baha Mousa Public Inquiry on Modules 1–3, 25 June 2010, §§ 12, 12.1 and 12.2, p. 28.
The Ministry of Defence also stated regarding common Article 3 of the 1949 Geneva Conventions more generally: “On its face this protection is restricted to armed conflicts not of an international character. However, it is understood to apply in all forms of armed conflict as part of customary international law to set out the irreducible minimum standard.” 
United Kingdom, Ministry of Defence, Closing Submissions to the Baha Mousa Public Inquiry on Modules 1–3, 25 June 2010, § 10.2, p. 10.
The UK Military Manual (1958) provides:
It is forbidden to kill or wound an enemy who, having laid down his arms, or having no longer the means of defence, has surrendered at discretion, i.e., unconditionally … A combatant is entitled to commit acts of violence up to the moment of his surrender without losing the benefits of quarter. 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 119.
The manual also states: “Even if a capitulation is unconditional, the victor has nowadays no longer the power of life and death over his prisoners, and is not absolved from observing the laws of war towards them.” 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 476.
The UK LOAC Pamphlet (1981) provides that it is forbidden “to kill or wound someone who has surrendered, having laid down his arms, or who no longer has any means of defence”. 
United Kingdom, The Law of Armed Conflict, D/DAT/13/35/66, Army Code 71130 (Revised 1981), Ministry of Defence, prepared under the Direction of The Chief of the General Staff, 1981, Section 4, p. 12, § 2(b); see also Annex A, p. 44, § 12 and p. 47, § 10(f).
The Pamphlet also states: “Shipwrecked persons may not be made the object of attack.” 
United Kingdom, The Law of Armed Conflict, D/DAT/13/35/66, Army Code 71130 (Revised 1981), Ministry of Defence, prepared under the Direction of The Chief of the General Staff, 1981, Section 7, p. 26, § 2.
The UK LOAC Manual (2004) states:
“A person who is recognized or who, in the circumstances, should be recognized to be hors de combat shall not be made the object of attack.” A person is hors de combat if:
a. “he is in the power of an adverse Party”;
b. “he clearly expresses an intention to surrender”; or
c.“he has been rendered unconscious or is otherwise incapacitated by wounds or sickness, and therefore is incapable of defending himself”;
“provided that in any of these cases he abstains from any hostile act and does not attempt to escape.” 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 5.6.
The manual further states:
The Hague Regulations 1907 are now recognized as part of customary law. Those regulations provide that the following acts are “especially forbidden”:
c. to kill or wound an enemy who, having laid down his arms, or having no longer means of defence, has surrendered at discretion. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 16.27.
Under the UK ICC Act (2001), it is a punishable offence to commit a war crime as defined in Article 8(2)(b)(vi) of the 1998 ICC Statute. 
United Kingdom, ICC Act, 2001, Sections 50(1) and 51(1) (England and Wales) and Section 58(1) (Northern Ireland).
The Eck case (The Peleus Trial) before the UK Military Court at Hamburg in 1945 concerned the sinking, during the Second World War, of a Greek steamship by a German U-boat on the high seas and the subsequent killing of shipwrecked members of the crew of the Greek boat. Four members of the crew of the German U-boat were accused of having violated the laws and usages of war by firing and throwing grenades on the survivors of the sunken ship. The Court held that there was no case of justifiable recourse to the plea of necessity when the accused killed by machine-gun fire survivors of a sunken ship, in order to destroy every trace of sinking and thus make the pursuit of the submarine improbable. In summing up, the Judge Advocate underlined that it was a fundamental usage of war that the killing of unarmed enemies was forbidden as a result of the experience of civilized nations through many centuries. He also stated that to fire so as to kill helpless survivors of a torpedoed ship was a grave breach of the law of nations. He added that the right to punish the perpetrators of such an act had clearly been recognized for many years. The accused were found guilty of the war crimes charged. 
United Kingdom, Military Court at Hamburg, Eck case (The Peleus Trial), Judgment, 20 October 1945.
In the Renoth case before the UK Military Court at Elten in 1946, the accused, two German policemen and two German customs officials, were accused of committing a war crime for their involvement in the killing of an Allied airman whose plane had crashed on German soil. After he had emerged from his aircraft unhurt, the pilot was arrested by Renoth, then attacked and beaten, before Renoth shot him. All the accused were found guilty. 
United Kingdom, Military Court at Elten, Renoth case, Judgment, 10 January 1946.
In the Von Ruchteschell case before the UK Military Court at Hamburg in 1947, the accused was charged, inter alia, of having continued to fire on a British merchant vessel after the latter had indicated surrender. He was found guilty on that count. The central question concerned the ways of indicating surrender. The Court noted that, even if the accused did not receive a signal of surrender, he could still be convicted because he “deliberately or recklessly avoided any question of surrender by making it impossible for the ship to make a signal”, which constituted a violation of the customary rules of sea warfare. 
United Kingdom, Military Court at Hamburg, Von Ruchteschell case, Judgment, 21 May 1947.
In 1982, in reply to a question in the House of Commons, the UK Prime Minister stated that, following the sinking of an Argentine cruiser by a UK warship during the war in the South Atlantic, another UK warship returning to the area where the sinking had occurred was instructed not to attack warships engaged in rescuing the survivors. 
United Kingdom, Letter of the Prime Minister in reply to a question asked in the House of Commons on the subject of the Falkland Islands situation, 1982, BYIL, Vol. 55, 1984, p. 595, § 13.
A training video on IHL produced by the UK Ministry of Defence illustrates the rule that “it is forbidden to kill or wound anyone who has laid down arms”. 
United Kingdom, Ministry of Defence, Training Video: The Geneva Conventions, 1986, Report on UK Practice, 1997, Chapter 2.1.
In 1991, before the UK Parliamentary Defence Committee, the officer commanding the UK forces in the Gulf War confirmed that the rules of engagement were modified in order to minimize casualties when it was realized that the Iraqis were seeking to surrender (the initial rules of engagement were to destroy the enemy). The plan was adjusted to encourage surrender rather than resistance. 
United Kingdom, Minutes of Evidence taken before the Parliamentary Defence Committee, 8 May 1991, Defence Committee’s Tenth Report, 1991, § 86.
In 2003, in reply to a written question in the House of Commons, the UK Secretary of State for Defence wrote:
The Coalition have dropped approximately 32 million–33 million leaflets aimed at Iraqi citizens, mainly combatants, but also civilians.
Those aimed at combatants include instructions on how to surrender, including adopting a non-offensive posture, raising a white flag, stowing weapons, and parking combat vehicles in a square formation.
In addition, the Coalition have used radio and loudspeaker broadcasts to convey specific surrender instructions to combatants. 
United Kingdom, House of Commons, Written answer by the Secretary of State for Defence, Hansard, 10 April 2003, Vol. 403, Written Answers, col. 351W.
In 2010, in its closing submissions to the public inquiry into the circumstances surrounding the death of Baha Mousa and the treatment of those detained with him by UK armed forces in Iraq in 2003, the UK Ministry of Defence stated:
12. The treaties setting out rules of IHL are supplemented by rules of customary international law (CIL), i.e. rules which are recognized as binding by States, even though they do not appear in treaty texts. … [I]n relation to the rules described below the Government accepts that they reflect CIL. It is suggested that the rules which are of most relevance to this inquiry are:
12.1. … A person hors de combat is: (a) anyone who is in the power of an adverse party; ... provided he or she abstains from any hostile act and does not attempt to escape.
12.2. … Thus, as persons in the power of UK forces the detainees all fell within the definition of persons hors de combat. 
United Kingdom, Ministry of Defence, Closing Submissions to the Baha Mousa Public Inquiry on Modules 1–3, 25 June 2010, §§ 12(1)–(2), p. 28.
The UK Military Manual (1958) provides:
A commander may not put his prisoners of war to death because their presence retards his movements or diminishes his power of resistance by necessitating a large guard, or by reason of their consuming supplies, or because it appears that they will regain their liberty through the impending success of the forces to which they belong. It is unlawful for a commander to kill prisoners of war on grounds of self-preservation. This principle admits of no exception, even in the case of airborne or so-called commando operations …
Whether a commander may release prisoners of war in the circumstances stated in the text is not clear … If such a release be made, it would seem clear that the commander should supply the prisoners with that modicum of food, water and weapons as would give them a chance of survival. 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 137, including footnote 1.
The UK LOAC Manual (2004) states:
“When persons entitled to protection as prisoners of war have fallen into the power of an adverse Party under unusual conditions of combat which prevent their evacuation as provided for in Part III, Section I, of the Third Convention, they shall be released and all feasible precautions shall be taken to ensure their safety.” … This rule covers cases such as commando operations or long-range reconnaissance patrols in enemy held territory. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 5.8.
In its chapter on air operations, the manual states:
12.64. Although it is forbidden to “kill or wound an enemy who, having laid down his arms, or having no longer means of defence, has surrendered at discretion”, in air-to-air combat, surrender is usually impracticable and occurs very infrequently.
12.64.1. In the special circumstances of air-to-air combat the continuation of an attack after an indication by the opponent of a wish to surrender is not inconsistent with the rule in paragraph 12.64 as the enemy pilot who remains in his aircraft cannot be said to have “laid down his arms” or to have “no longer a means of defence”. However, if the surrender is offered in good faith and in circumstances that do not prevent enforcement, for example, when the engagement has not taken place over enemy territory, it must be respected and accepted. Surrenders of enemy aircraft and crews should not be discouraged because not only is a psychological advantage gained, but an enemy aircraft and defecting aircrew can provide intelligence which, if promptly and properly evaluated, may be of inestimable benefit to operations planning.
Aircraft in distress
12.66. If it is clear that an enemy aircraft is disabled beyond recovery and is unable to continue and will not resume combat, or indeed is unarmed, and its immediate destruction would offer no military advantage then the attack must be broken off to allow its crew and passengers to evacuate.
12.66.1. A topic very closely related to that of surrender in the air is whether an attack should be continued against a disabled aircraft. The rule of the law of armed conflict forbidding the killing or wounding of an enemy who is hors de combat is difficult to apply in the context of aerial warfare. Sometimes pilots simulate disability or loss of control. It is frequently necessary in aerial combat to pursue to destruction an enemy aircraft apparently in distress because of the impossibility of verifying its condition. Despite its apparent condition the aircraft may not have lost the use of all its offensive systems. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, §§ 12.64–12.64.1 and 12.66–12.66.1.
With regard to “downed” airmen in enemy-held territory, the manual states:
12.68. On land, a “downed” airman from an aircraft in distress must be afforded a reasonable opportunity to surrender before the attack upon him is resumed. Clearly if the “downed” airman is incapacitated he is hors de combat and the general rule will apply. The attack may be resumed immediately if he offers violence, attempts to escape or if, suffering no incapacity, he is in territory controlled by his own forces. The pilot who has crash-landed his aircraft and is attempting to complete its destruction or the destruction of any part of his or its equipment is committing a hostile act and may be attacked immediately.
Combat rescue of downed aircrew on land
12.69. The use of, for example, military assets to rescue aircrew who have been “downed” on territory under the control of the enemy is a combat activity. It is therefore legitimate for an enemy in such circumstances to attack the rescuers or by some other means to impede or prevent the rescue activity. However, that would not apply in the case of medical personnel, units or transports collecting the sick or wounded, see chapter 7.
12.69.1. The mere fact that a rescue service saves enemy personnel as well as its own does not entitle it to immunity from attack. Once taken prisoner, such enemy personnel should be accorded all the rights of a prisoner of war, at least until their status has been determined. Arguably, any communication by downed aircrew with their national authorities constitutes a hostile act, which would at that point justify an attack upon that aircrew. Such justification may also arise from other conduct indicating that the downed individual is seeking to continue the fight.
Combat rescue at sea
12.70. A “downed” airm[a]n at sea falls within the definition of “shipwrecked” so that he must not be attacked if he refrains from hostile acts.
12.70.1. Although it can be argued that search and rescue by aircraft used exclusively for rescuing airmen “downed” at sea in areas either not controlled by friendly forces or not occupied by enemy forces should be regarded as a protected activity under the provisions of Geneva Convention II 1949, it has been the general practice not to afford such protection. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, §§ 12.68–12.70.1.
In its chapter on prisoners of war, the manual states: “It is unlawful to kill prisoners of war on grounds of self-preservation or because holding them would impede or endanger military operations.” 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 8.32.
(emphasis in original)
Upon signature of the 1977 Additional Protocol I, the United Kingdom stated: “The word ‘feasible’ means that which is practicable or practically possible, taking into account all circumstances at the time including those relevant to the success of military operations.”  
United Kingdom, Declarations made upon signature of the 1977 Additional Protocol I, 12 December 1977, § b.
Upon ratification of the 1977 Additional Protocol I, the United Kingdom stated that it understood the term “feasible” as used in the Protocol to mean “that which is practicable or practically possible, taking into account all circumstances ruling at the time, including humanitarian and military considerations”. 
United Kingdom, Reservations and declarations made upon ratification of the 1977 Additional Protocol I, 28 January 1998, § b.
The Report on UK Practice cites a former director of the UK Army Legal Services who stated that UK soldiers were not required to risk their own lives in granting quarter. He added that it may not be practicable to accept surrender of one group of enemy soldiers while under fire from another enemy position. Capture was to take place when circumstances permitted. 
Report on UK Practice, 1997, Notes on a meeting with a former Director of Army Legal Services, 19 June 1997, Chapter 2.1.