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Review 2018-2019 - Volume 57

The Use of Force for Mission Accomplishment: A Pitfall in Contemporary Operations?*
HANNA BOURGEOIS**
PhD Fellow of the Research Foundation – Flanders (FWO) at the Leuven Centre for Global Governance Studies, KU Leuven
JEAN-EMMANUEL PERRIN***
Deputy Chief of the Military Department – International Institute for Humanitarian Law

Table of Contents
  1. Introduction
  2. Existing Legal Framework for the Use of Force for Mission Accomplishment
    1. Use of Force for Mission Accomplishment in the Conduct of Hostilities
    2. Use of Force for Mission Accomplishment Outside the Conduct of Hostilities
      1. Use of Lethal Force: Identifying the Scope of the Permissible Grounds for Deprivation
        of Life
      2. Use of Non-Lethal Force: Determining the Scope of Possible Actions
  3. The Relationship Between Self-Defence, Mission Accomplishment, and the Law Enforcement
    and Conduct of Hostilities Paradigms
  4. Do the Current Legal Regimes Provide for Useful and Sufficient Legal Grounds for the Use of Force
    for Mission Accomplishment?
  5. Conclusion
1
4
5
8

9
13

14

20
23

I. Introduction

States involved in contemporary military operations increasingly find themselves in an intermediate state of “neither peace nor war”. 1 Whereas during World War I, World War II, and the Cold War, States were primarily involved in inter-State conflicts in which they exhibited a combat-oriented mentality, the end of the Cold War introduced an era of intra-State conflicts. In these conflicts, multinational operations are regularly deployed to carry out complex missions in a volatile environment in the territory of third States, often in support of the authorities of these third States. In the course of these missions, military forces on the ground are confronted with a wide range of threats which frequently necessitate the use of defensive or even offensive force if they endeavour to accomplish the mission. However, it is not always clear whether they have the legal authorization to underpin such use of force. For example, the United Nations Security Council (UNSC) may provide a multinational operation with a mandate to protect

* The authors would like to thank J.F.R. Boddens Hosang, B. De Vidts, Y. Donders, J. Trampert, the general editors, and the anonymous peer reviewers for their insightful comments and suggestions on earlier drafts of this article. All errors and omissions remain our own. Back
** The author wishes to express her gratitude to the Amsterdam Center for International Law of the University of Amsterdam for supporting and welcoming her as a visiting researcher in the first months of 2019 while she was engaged in the writing of this article. Back
*** The author writes in his personal capacity and his views do not reflect any official position of the French Ministry of Armed Forces or of the International Institute for Humanitarian Law. Back
1 J-E. Perrin, ‘N’être ni en paix, ni en guerre… mais en Atari !’, Vol. 817 Revue de la Défense Nationale 2019, Formation et Commandement, pp. 89-93. Back


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civilians, promote and protect human rights, and support humanitarian assistance. Suppose that the force commander has been informed that insurgents have surrounded a village of 1200 residents and are intercepting all relief supplies. While the military forces taking part in the multinational operation are on their way to evacuate the village, they are confronted with the insurgents who are blocking the road leading to the village. In this scenario, the insurgents do not directly threaten the military forces, nor do they pose an imminent threat to the lives of citizens from the village in question. This kind of situation raises the question of to what extent the military forces can use force to accomplish their mission (i.e. the protection of civilians).

The use of force for mission accomplishment may be understood as force that is used to carry out a given mission, as defined in the Operational Plan (also known as the OPLAN). 2 This may potentially include the use of force beyond self-defence and for other reasons than just defensive purposes. The strategic objectives which are set forth in an OPLAN are subsequently embedded in the planning process at the operational and tactical level. For example, if a State is involved in heavy warfighting, the strategic objective may involve establishing superiority over the enemy’s armed forces and the subsequent defeat of the opposing party. The strategic objective of a non-combatant evacuation operation is to secure the exit of individuals, mostly nationals and close relatives, from a territory after the security conditions have seriously degraded and to bring them to safe havens by air, sea, or land. The level of force envisaged in such circumstances mainly depends on whether the evacuation is conducted in a permissive environment with the host State consent, or in a hostile context. The strategic objective of a United Nations (UN) peace operation which is carrying out a UNSC mandate may include the protection of civilians or support for the reestablishment of State authority throughout the country. To this end, UN peace operations are generally authorized to use “all necessary measures” in defence of the mandate under Chapter VII of the UN Charter.

Yet, irrespective of the strategic objective and the scope of the mandate, for the use of force in a specific case to be legal, it needs to comply with any additional body of domestic or international law that applies in the circumstances. 3 Legal doctrine commonly distinguishes between two different paradigms: the law enforcement paradigm, mainly derived from human rights law, 4 and the conduct of hostilities paradigm, mainly derived from international humanitarian law. 5 Depending on the circumstances, international humanitarian law and/or human rights law determine the outer limits of permissible use of force.

2 The OPLAN is a plan for the conduct of military operations which sets out the objectives to be achieved by the military operations and the manner in which it is envisaged that those objectives will be reached (see M. Zwanenburg, ‘North Atlantic Treaty Organization-Led’, in A. Nollkaemper et al. (eds.), The Practice of Shared Responsibility in International Law (Cambridge, Cambridge University Press, 2017), p. 651). Under the doctrine of the North Atlantic Treaty Organization (NATO), OPLAN means “[a] plan for a single series or connected operations to be carried out simultaneously or in succession”. It is usually based upon stated assumptions and “is the form of directive employed by higher authority to permit subordinate commanders to prepare supporting plans and orders”. The term designation “plan” is usually used instead of “order”. An OPLAN “may be put into effect at a prescribed time, or on signal, and then becomes the operation order”, see NATO, Glossary of Terms and Definitions, AAP-06, 2018, p. 91. Back
3 T. D. Gill, D. Fleck, W. H. Boothby, M. Benatar, R. Jorritsma, and International Society of Military Law and Law of War (eds.), Leuven manual on the international law applicable to peace operations (Cambridge, Cambridge University Press, 2017), Rule 12.2, p. 146. Back
4 When referring to human rights law, this article implies both international and regional human rights law. Moreover, it is important to highlight that the law enforcement paradigm may not only derive from human rights law, but also from domestic law. An analysis of the domestic legal systems falls, however, outside the scope of this article. Back
5 G. Gaggioli, The Use of Force in Armed Conflict: Interplay between the Conduct of Hostilities and Law Enforcement Paradigms, ICRC Outcome Report (Geneva, ICRC, 2013), p. 1. Nevertheless, as Gaggioli emphasizes in a more recent article, “while it could be said that the paradigms of the conduct of hostilities and law enforcement find their international legal bases in the legal regimes of [...] [international humanitarian law and human rights law], it would be an oversimplification to consider that the dichotomy between [...] [these two legal regimes] does neatly correspond to a dichotomy conduct of hostilities/law enforcement since [...] [international humanitarian law] includes both conduct of hostilities and law enforcement rules for the use of force”, see G. Gaggioli, ‘The Use of Force in Armed Conflicts Conduct of Hostilities, Law Enforcement, and Self-Defense’, in W. S. Williams et al. (eds.), Complex Battlespaces: The Law of Armed Conflict and the Dynamics of Modern Warfare (New York, Oxford University Press, 2019), p. 69. Back


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Nevertheless, questions remain as to the interpretation and implementation of these legal regimes and in particular the manner and circumstances in which force may be used for mission accomplishment. Returning to the example above, the level of violence which these military forces may face when trying to evacuate the villagers can prove to be rather high without reaching the level of a confrontation that could qualify as an armed conflict. This is usually the case when very localized events and situations tend to degenerate into an aggravated use of force, yet remain limited in time and space. When operating outside the conduct of hostilities, some States will allow the contingents that they have contributed to the mission to act in self-defence and defence of others, reaching a fairly high level of engagement compared to what other States may allow their contingents to do on the basis of the same principle of self-defence. After all, States use different approaches as to which type of threat can give rise to the use of (potentially) lethal force (hereinafter “lethal force”) in self-defence or the defence of others. Moreover, some States will allow their contingents to use force beyond self-defence to accomplish certain aspects of their mission, whereas other States would be rather hesitant to do so. To accomplish the mission, the level of violence could also necessitate a level of use of force that would neither fall within the scope of self-defence for some States, nor within the broader law enforcement legal framework for other States. In these different situations, the operational necessity to use force to accomplish the mission possibly clashes with the limits of the existing legal framework. The question then arises whether the law as it is still provides for enough leeway to effectively address the relevant threats or whether we should develop a new legal regime for the use of force for mission accomplishment in these specific situations.

Before considering this question, the present article intends to map, as a first step, the existing legal framework regarding the conditions for the use of force for the accomplishment of the mission (Section II). After all, as outlined above, States seem to take different approaches to the scope of actions that can be taken in certain situations. In this respect, two possible scenarios will be studied: the first one relating to the use of force in the conduct of hostilities, the second dealing with force used in situations which have no nexus with an armed conflict or which take place outside an armed conflict. In doing so, this article aims to elucidate to what extent (lethal) force can be used for mission accomplishment under both international humanitarian law and human rights law. In this regard, it is important to stress that the present article does not address questions related to the (il)legality of the use of force on the territory of a third State and the possible legal bases underlying such operations. 6 By contrast, this article analyses the scope of the legal regimes regulating specific instances of the use of force in such operations. In other words, it addresses the question of under which circumstances and in which manner military forces may use force against a particular objective or a particular person. Moreover, when discussing the human rights law framework, this article will mainly focus on the normative content of the right to life (as opposed to questions of applicability) and the possible grounds for the deprivation of someone’s life. For that purpose, the authors will interpret the relevant human rights treaties by using the rules and methods of interpretation as provided in Articles 31 and 32 of the 1969 Vienna Convention on the Law of Treaties (VCLT). 7 Case law from various human rights courts (including the European Court of Human Rights (ECtHR) and the Inter-American Court of Human Rights (IACtHR)) and international human rights mechanisms 8 (including the Human Rights Committee (HRC), the Inter-American Commission on Human Rights (IAComHR), and the African Commission on Human and Peoples’

6 Such legal bases range, for example, from the use of force in national self-defence to the use of force under Chapter VII of the UN Charter or with the consent of the host State. Back
7 Article 31(1) of the 1969 VCLT provides that “[a] treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose”. Article 32 of the 1969 VCLT sets forth that “[r]ecourse may be had to supplementary means of interpretation, including the preparatory work of the treaty and the circumstances of its conclusion, in order to confirm the meaning resulting from the application of article 31, or to determine the meaning when the interpretation according to article 31: (a) leaves the meaning ambiguous or obscure; or (b) leads to a result which is manifestly absurd or unreasonable”. Back
8 In this article, the term “international human rights mechanisms” designates both international and regional human rights mechanisms. Back


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Rights (AComHPR)) will be illustrative in this regard. In addition, other instruments issued by these international human rights mechanisms, such as their general comments on the right to life, or resolutions or reports issued by the UNSC, the UN Secretary-General, and the Special Rapporteur on Extrajudicial, Summary or Arbitrary Executions (Special Rapporteur), are used.

After discussing the existing legal framework, this article will clarify the relationship between the notions of self-defence and mission accomplishment on the one hand and the law enforcement and conduct of hostilities paradigms on the other hand (Section III). Not only does practice indicate that there is a lack of clarity as to where self-defence ends and mission accomplishment begins, how these two notions relate to the law enforcement and conduct of hostilities paradigms is also disputed. Subsequently, before concluding, this article will evaluate the extent to which human rights law and international humanitarian law provide sufficient space for the necessary use of force required for the fulfilment of the mission in contemporary operations (Section IV). Towards this end, different options are considered as to how the applicable legal framework could meet the operational necessity in contemporary operations.

II. Existing Legal Framework for the Use of Force for Mission Accomplishment

When discussing the legal framework for the use of force for mission accomplishment, it is important to distinguish between the rules and principles of human rights law on the one hand and international humanitarian law on the other. International humanitarian law regulates the use of force for mission accomplishment in the conduct of hostilities. 9 Lethal force for mission accomplishment is, however, also indirectly guided by human rights law in such situations. 10 Force which has no clear nexus with an ongoing armed conflict or which is used outside an armed conflict is mainly governed by the human rights law framework. 11

9 In its most recent General Comment No. 36 on Article 6 of the International Covenant on Civil and Political Rights on the Right to Life, the UN Human Rights Committee (HRC) vaguely indicated that for international humanitarian law to apply a nexus should exist between the use of lethal force and any specific theatre of hostilities. In particular, it noted that “rules of international humanitarian law may be relevant for the interpretation and application of article 6 when the situation calls for their application” (emphasis added), see HRC, General Comment No. 36 (2018) on article 6 of the International Covenant on Civil and Political Rights, on the right to life, UN Doc. CCPR/C/GC/36, Advanced unedited version, 30 October 2018, § 64. Although the HRC did not take the opportunity to take a clear stance on the distinction between the conduct of hostilities and the law enforcement paradigms, it has already indicated in earlier reports that international humanitarian law only applies to the use of force which has a clear nexus with the armed conflict, see e.g. HRC, Concluding observations on the fourth periodic report of the United States of America, UN Doc. CCPR/C/USA/CO/4, 23 April 2014, § 9. By taking this position, the HRC followed the earlier approach taken by the AComHPR in its General Comment No. 3 on Article 4 of the African Charter on Human and Peoples’ Rights on the Right to Life in which it stated that “[i]nternational humanitarian law on the conduct of hostilities must only be applied during an armed conflict and where the use of force is part of the armed conflict. In all other situations of violence, including internal disturbances, tensions or riots, international human rights rules governing law enforcement operations apply”, see AComHPR, General Comment No. 3 on the African Charter on Human and Peoples’ Rights: The Right to Life (Article 4) , Adopted during the 57th Ordinary Session of the AComHPR held from 4 to 18 November 2015 in Banjul, The Gambia, § 32. See also discussion by V. Todeschini, ‘The Human Rights Committee’s General Comment No. 36 and the Right to Life in Armed Conflict’, Opinio Juris, 21 January 2019, http://opiniojuris.org/2019/01/21/the-human-rights-committees-general-comment-no-36-and-the-right-to-life-in-armed-conflict/ (unless indicated otherwise, all URLs cited were last accessed on 12 September 2019). Back
10 According to the HRC, “[l]ike the rest of the Covenant, article 6 [of the ICCPR] continues to apply also in situations of armed conflict to which the rules of international humanitarian law are applicable, including to the conduct of hostilities”, see HRC’s General Comment No. 36 on the Right to Life, UN Doc. CCPR/C/GC/36, supra note 9, § 64. The AComHPR has also indicated that the right to life continues to apply during armed conflict, see AComHPR’s General Comment No. 3 on the Right to Life, supra note 9, § 13. Back
11 As mentioned above, the law enforcement paradigm may not only derive from human rights law, but also from domestic law. An analysis of the domestic legal systems falls, however, outside the scope of this article. Back


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1. Use of Force for Mission Accomplishment in the Conduct of Hostilities

A State that decides to engage in an international or non-international armed conflict against an enemy chooses to resort to a potentially high level of violence which is regulated in the first place by international humanitarian law. 12 Such a high level of violence may prove to be necessary to guarantee, for example, the integrity of its own territory, the protection of its vital interests or the security of its own population. Achieving such goals may require the defeat of one’s opponents through the use of force, including the use of lethal force, that can reach levels of intensity and duration without equivalent in peacetime.

The use of lethal force for mission accomplishment is influenced by the right to life, a right which was initially proclaimed in the Universal Declaration of Human Rights (UDHR). 13 The right to life is considered a non-derogable right and therefore applicable at all times. 14 Nevertheless, this non-derogable nature must be understood in the context that permissible grounds for the deprivation of life are already built into treaty law and commonly accepted principles and practices. 15 This does not imply that a person can be deprived of the protections promised by the right. 16 It only means that someone can be deprived of his or her life in certain restrictive situations consistent with the right to life. 17 For example, Article 6(1) of the 1966 International Covenant on Civil and Political Rights (ICCPR) provides that the deprivation of life does not violate the right to life when it results from the use of force which is not arbitrary. Article 6(1) of the ICCPR is a rule of customary international law which implies that it also binds States that are not party to the ICCPR. 18 Moreover, this instrument does not only apply when a State operates within its own territory, but in principle also applies when it is exercising extraterritorial jurisdiction over people. A State has extraterritorial jurisdiction over people either when it exercises sufficient territorial control over territory abroad where these people find themselves, or when it exercises authority or power over an individual, even if the operation in question is conducted outside its territorial control. 19 Similarly to Article 6(1) ICCPR, Article 4(1) of the 1969 American Convention

12 The rules of international humanitarian law equally apply to all parties to the conflict, either as a matter of treaty or as a matter of customary international law. Back
13 Article 3 of the Universal Declaration of Human Rights, UNGA Res. 217 A(III), 10 December 1948. Back
14 As will be discussed below, a number of human rights treaties include a specific provision on the right to life and most, but not all, explicitly state that no derogation can be made from this right. For example, Article 6 ICCPR, Article 4 of the ACHR, Article 4 of the ACHPR, and Article 2 of the ECHR protect the right to life (full reference to the ACHR and the ACHPR: American Convention on Human Rights: Pact of San José, Costa Rica, San José, 22 November 1969, Vol. 1144 No. 17955 U.N.T.S. 1979, pp. 144-212; African Charter on Human and Peoples’ Rights, Banjul, 27 June 1981, OAU Doc. CAB/LEG/67/3 rev. 5, Vol. 21 No. 1 I.L.M. 1982, pp. 58-68). Article 4(2) ICCPR and Article 27(2) ACHR explicitly state that no derogation can be made from this right to life. Article 15(2) ECHR sets forth that “[n]o derogation [shall be made] from Article 2 [of the ECHR], except in respect of deaths resulting from lawful acts of war, or from Articles 3, 4 (paragraph 1) and 7 [of the ECHR]” (emphasis added). According to Doswald-Beck, “lawful acts of war” refer to international armed conflicts, see L. Doswald-Beck, ‘The Right to Life in Armed Conflict: Does International Humanitarian Law Provide All the Answers?’, Vol. 88 No. 864 I.R.R.C. 2006, p. 883. The ACHPR does not explicitly provide for a derogation clause. Back
15Fighting at the Legal Boundaries: Controlling the Use of Force in Contemporary Conflict (New York, Oxford University Press, 2016), p. 459. Back
16 M. E. O’Connell, ‘The Law on Lethal Force Begins with the Right to Life’, Vol. 3 No. 2 Journal on the Use of Force and International Law 2016, pp. 205-209, p. 206. Back
17 Id. , p. 206. Back
18 Article 6(1) of the ICCPR indicates that “[e]very human being has the inherent right to life” (emphasis added). The qualification of this right as being “inherent” serves to indicate its customary nature. See also Gaggioli, ‘The Use of Force in Armed Conflicts Conduct of Hostilities, Law Enforcement, and Self-Defense’, supra note 5, p. 65. Back
19 N. Melzer and G. Gaggioli, ‘Conceptual Distinction and Overlaps Between Law Enforcement and the Conduct of Hostilities’, in T. Gill et al. (eds.), The Handbook of the International Law of Military Operations (Oxford, Oxford University Press, 2015, 2nd ed.), p. 66. The applicability of human rights obligations through extraterritorial jurisdiction is now accepted by most States. Nevertheless, it remains disputed when a State is exercising extraterritorial jurisdiction. In light of Article 2(1) ICCPR, each State Party to the ICCPR undertakes to respect and ensure the rights under Article 6 ICCPR to all individuals who are within its territory and subject to its jurisdiction. According to the HRC, this concerns all persons over whose enjoyment of the right to life the State exercises power or effective control, including “persons located outside any territory effectively controlled by the State, whose right to life is nonetheless impacted by its military or other activities in a direct and reasonably foreseeable manner”, see General Comment No. 36 on the Right to Life, UN Doc. CCPR/C/GC/36, supra note 9, § 63. According to Austria and Germany, this approach goes, however, beyond the established interpretation of the extraterritorial application of the ICCPR, see Austrian comments on the Draft General Comment on Article 6 of the International Covenant on Civil and Political Rights (ICCPR), on the right to life, undated, p. 2 and Submission from Germany on the draft General Comment on Article 6 of the International Covenant on Civil and Political Rights – Right to life, 6 October 2017, § 21. The US does not accept the extraterritorial application of human rights obligations in its entirety. It has consistently held that the ICCPR applies only to individuals who are both within the territory of a State Party and subject to its jurisdiction, see Observations of the United States of America On the Human Rights Committee’s Draft General Comment No. 36 On Article 6 - Right to Life, § 13, 6 October 2017. The submissions can be found on the following website: https://www.ohchr.org/EN/HRBodies/CCPR/Pages/ GC36-Article6Righttolife.aspx. For case law on the extraterritorial application of the ICCPR, see e.g. HRC, Sergio Euben Lopez Burgos v. Uruguay, Communication No. R.12/52, UN Doc. Supp. No. 40 (A/36/40) at 176 (1981), 29 July 1981, §§ 12.1-12.3; and HRC, Celeberti de Casariego v. Uruguay, CCPR/C/13/D/56/1979, 29 July 1981, § 10.3. Back


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on Human Rights (ACHR) and Article 4 of the 1981 African Charter on Human and Peoples’ Rights (ACHPR) provide that no one shall be arbitrarily deprived of his or her life. 20 For the use of force not to be arbitrary, it must find its legal basis in a rule of international law or more protective domestic law provisions. During the conduct of hostilities, the assessment of what constitutes an arbitrary deprivation of the right to life is to be determined by reference to the rules of international humanitarian law. 21

In international armed conflicts, the rules of international humanitarian law allow for the use of lethal force for mission accomplishment, provided that, among others, the principles of distinction, precaution in the attack, and prohibition of excessive collateral damage are respected. 22 Hence, in accordance with the principle of distinction, international humanitarian law allows for the use of force directed at military

20 The AComHPR accepts that the ACHPR applies extraterritorially when “the State has jurisdiction or otherwise exercises effective authority, power, or control over either the perpetrator or the victim (or the victim’s rights), or exercises effective control over the territory on which the victim’s rights are affected, or whether the State engages in conduct which could reasonably be foreseen to result in an unlawful deprivation of life”, see AComHPR’s General Comment No. 3 on the Right to Life, supra note 9, § 14. With respect to the possible extraterritorial application of the ACHR, Article 1(1) of the ACHR sets forth that “[t]he States Parties to this Convention undertake to respect the rights and freedoms recognized herein and to ensure to all persons subject to their jurisdiction the free and full exercise of those rights and freedoms, [...]”. For case law of the IACtHR on the extraterritorial application of the ACHR in which the test adopted seems to be one of effective control over a person, see e.g.: IAComHR, Petition Victor Saldaño v. Argentina, Report No. 38/99, 11 March 1999, § 17. Back
21 The ICJ observed in the Nuclear Weapons case that “[t]he test of what is an arbitrary deprivation of live [...] then falls to be determined by the applicable lex specialis, namely, the law applicable in armed conflict which is designed to regulate the conduct of hostilities”, see ICJ, Legality of the Threat or Use of Nuclear Weapons, 8 July 1996, I.C.J. Rep. 1996, Advisory opinion, p. 556, § 25. Similarly, the IAComHR has used international humanitarian law to determine whether persons had been arbitrarily deprived of their right to life in situations amounting to an armed conflict, see IAComHR, Jean Carlos Abella Argentina (Martha Francisca Fernández de Burgos and Eduardo Salerno v. Argentina) , Case 11.137, Report No. 55/97, OEA/Ser.L/V/II.98 Doc. 7 rev. at 271 (1997), § 161; and IAComHR, Riofrío Massacre Colombia (Corporación Colectivo de Abogados “José Alvear Restrepo v. Colombia) , Case 11.654, Report No. 62/01, OEA/Ser.L/V/II.111 Doc. 20 rev. at 758 (2000), 6 April 2001, § 54. The AComHPR has also indicated that the right to life needs to be interpreted with reference to the rules of international humanitarian law, see AComHPR’s General Comment No. 3 on the Right to Life, supra note 9, §§ 13 and 32. For a discussion on the applicability of the right to life during an international armed conflict, see also P.J., Rowe, The Impact of Human Rights Law on Armed Forces (Cambridge; New York, Cambridge University Press, 2006), pp. 134-161. For a more general discussion on how international humanitarian law has become a source of human rights law, see G. Oberleitner, ‘Humanitarian Law as a Source of Human Rights Law’, in D. Shelton (ed.), The Oxford Handbook of International Human Rights Law (Oxford ; New York, Oxford University Press, 2013), pp. 275-294. Back
22 The principle of distinction is for example codified in Articles 48, 51(2), and 52(2) of AP I, whereas Article 51(4) of AP I prohibits indiscriminate attacks. The principle of precaution in attack can be found in Article 57(1) of AP I. The prohibition of excessive collateral damage is, conversely, set out in Article 51(5)(b) of AP I. For an analysis of the customary nature of these rules, see J-M. Henckaerts and L. Doswald-Beck (eds.), ICRC Study on Customary International Humanitarian Law, Volume I: Rules (Cambridge; New York, Cambridge University Press, 2005), Rule 1. The parties to the conflict must at all times distinguish between civilians and combatants. Attacks may only be directed against combatants. Attacks must not be directed against civilians, pp. 3-5; Rule 11. Indiscriminate attacks are prohibited, pp. 37-38; Rule 14. Proportionality in attack, pp. 46-48; and Rule 15. In the conduct of military operations, constant care must be taken to spare the civilian population, civilians and civilian objects. All feasible precautions must be taken to avoid, and in any event to minimise, incidental loss of civilian life, injury to civilians and damage to civilian objects, pp. 51-52. Back


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objectives, but not at civilian objectives. Along the same lines, international humanitarian law permits the use of lethal force against lawful military targets (e.g. combatants or civilians directly participating in hostilities), but outlaws such use of force against persons hors de combat by sickness, wounds, detention or any other cause, or against civilians not taking a direct part in hostilities. 23 International humanitarian law does not, however, recognize the status of “combatant” in non-international armed conflicts. Common Article 3 of the 1949 Geneva Conventions only sets forth that persons not taking active part in the hostilities, including members of armed forces who have laid down their arms and those placed hors de combat, cannot be killed. How this gap in international humanitarian law must be filled has already been the subject of fierce debates, but remains outside the scope of this article. 24

Any lethal force against a person which violates international humanitarian law is to be considered an arbitrary deprivation of life, as well as a war crime in most cases. 25 Accordingly, a direct attack against a civilian, an indiscriminate attack which does not distinguish between military objectives and civilians or civilian objects, and an attack against military objectives causing excessive loss of civilian life all constitute violations of the right to life.

It follows that human rights law and international humanitarian law allow for considerable leeway for the use of force for mission accomplishment in the conduct of hostilities. The recognition of the lawfulness of the use of lethal force during coalition operations in Afghanistan and in Iraq, which have been characterized as international armed conflicts at the very beginning of hostilities and as non-international armed conflicts a few months later, has not posed any substantial difficulties. For example, little criticism was voiced concerning the implementation of the air operations and the targeting of individuals recognized as combatants or civilians taking a direct part in hostilities, or the targeting of military objectives as defined in Article 52(2) of the 1977 Additional Protocol I (AP I). 26 On the other hand, accidental air strikes on protected targets have been widely reported and commented on, as was the case with the air strikes carried out by the United States (US) that hit the Médecins sans Frontières (MSF) hospital in Kunduz, Afghanistan, on 3 October 2015, resulting in the death of 42 people, including 38 MSF patients and staff. 27

Nonetheless, in the context of an armed conflict, the political authority may wish to limit the use of force for mission accomplishment to preserve the possibility for the adversary to return to the negotiating table and facilitate a de-escalation of hostilities. In this respect, even though there is a legal authority to

23 See Articles 41(1) and 51(2) and (3) of AP I. For a discussion on the customary nature of these rules, see Henckaerts et al., supra note 22, Rule 1. The parties to the conflict must at all times distinguish between civilians and combatants. Attacks may only be directed against combatants. Attacks must not be directed against civilians, pp. 3-5; and Rule 47. 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; (b) anyone who is defenceless because of unconsciousness, shipwreck, wounds or sickness; or (c) anyone who clearly expresses an intention to surrender; provided he or she abstains from any hostile act and does not attempt to escape, pp. 164-165. Back
24 For further reading, see e.g. D. Kretzmer, A. Ben-Jehuda, and M. Furth, ‘Thou Shall not Kill’: The Use of Lethal Force in Non-International Armed Conflicts, Vol. 47 Israel Law Review 2014, pp. 191-224; N. Melzer, Interpretive Guidance on the Notion of Direct Participation in Hostilities under International Humanitarian Law (Geneva, ICRC, 2009); and M. Hlavkova, ‘Reconstructing the Civilian/Combatant Divide: A Fresh Look at Targeting in Non-International Armed Conflict, Vol. 19 No. 2 J.C.S.L. 2014, pp. 251-278. Back
25 According to the ICRC Study on Customary International Humanitarian Law, State practice has established the rule that murder is prohibited as a norm of customary international law applicable in both international and non-international armed conflicts, see Henckaerts et al., supra note 22, Rule 89. Murder is prohibited, pp. 311-314. This implies, inter alia, that “[t]he prohibition of “arbitrary deprivation of the right to life” under human rights law [...] also encompasses unlawful killing in the conduct of hostilities”, see id. , p. 313. Back
26 Article 52(2) of AP I defines military objectives as “objects which by their nature, location, purpose or use make an effective contribution to military action and whose partial or total destruction, capture or neutralisation, in the circumstances ruling at the time, offers a definite military advantage”. Back
27 V.J. Blue, ‘Kunduz Hospital Attack’, [no date available], https://www.msf.org/kunduz-hospital-attack-depth. Back


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use lethal force under international humanitarian law, the political directives and orders given to the strategic command can impose a limitation on the use of this force. Thus, the decision might be to limit the use of lethal force against combatants to situations in which they engage in hostile acts or hostile intentions likely to compromise the proper accomplishment of the mission. For example, a State may itself exclude the lethal targeting of combatants belonging to the regular armed forces of an enemy country as long as their activities do not disrupt the ongoing operations. The constraint imposed on the military command is therefore, in this case, not of a legal nature but of a political one.

2. Use of Force for Mission Accomplishment Outside the Conduct of Hostilities

In principle, human rights law does not prohibit military forces from using force under the law enforcement paradigm. Circumstances may for example require the use of force in self-defence, in defence of others, or for the achievement of tasks, purposes, and objectives as consented to by the host State 28 or as set out in a mandate of a competent organ of an international organization conducting the operation (e.g. the UNSC). 29 Yet, any use of force outside the conduct of hostilities has to comply with the applicable body of domestic or international law that applies in the circumstances.

To understand to what extent human rights law leaves room for the use of force for mission accomplishment, this article will first discuss the exact scope of the permissible grounds for the deprivation of life and reveal how much room it leaves for the use of lethal force for mission accomplishment. Second, the possibility for non-lethal force for mission accomplishment will be examined.

28 Provided that the consent of the host State relates not only to access to the territory, but also to the tasks, purposes, and/or objectives that the mission can perform. Back
29 Gill et al, supra note 3, Rule 12.2, p. 146 (it is to be noted, however, that Rule 12.2 does not make a reference to the consent of the host State). Back


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A. Use of Lethal Force: Identifying the Scope of the Permissible Grounds for Deprivation of Life

Lethal force is affected by the right to life. Article 6(1) of the ICCPR, Article 4(1) of the ACHR, and Article 4 of the ACHPR set forth that the deprivation of someone’s life does not violate his or her right to life when it results from force which is not “arbitrary” in nature (see Section II.1). These articles do not stipulate, however, when force is “arbitrary”. The HRC and the AComHPR specify in their respective general comments on the right to life that “arbitrariness” should be interpreted with reference to the elements of appropriateness, justice, predictability, reasonableness, necessity, and proportionality. 30 The HRC also adds the principle of “due process of law” to the list. 31 These general comments are not legally binding instruments, but are nevertheless authoritative interpretations of the relevant human rights treaties.

Article 2(2) of the 1950 European Convention on Human Rights (as amended) (ECHR) provides for more detailed grounds for the possible deprivation of someone’s life. In particular, it determines that the “[d]eprivation of life shall not be regarded as inflicted in contravention of this Article when it results from the use of force which is no more than absolutely necessary: (a) in defence of any person from unlawful violence; (b) in order to effect a lawful arrest or to prevent the escape of a person lawfully detained; (c) in action lawfully taken for the purpose of quelling a riot or insurrection”. 32 Also the UN Basic Principles for the Use of Force and Firearms set forth an exhaustive list of circumstances under which lethal force can be used. In particular, Article 9 of these UN Basic Principles holds that officials are prohibited from using firearms “except in self-defence or defence of others against the imminent threat of death or serious injury, to prevent the perpetration of a particularly serious crime involving grave threat to life, to arrest a person presenting such a danger and resisting their authority, or to prevent his or her escape, and only when less extreme means are insufficient to achieve these objectives”. 33 In a footnote to the UN Basic Principles, it is specified that the rules also apply to military personnel when such persons “exercise police powers”. 34 These principles are a soft law instrument and thus not legally binding in nature. Yet, according to former Special Rapporteur Philip Alston, the substance of Article 9 reflects binding international law. 35 Moreover, since a very large number of States were involved in their development and adoption, there is near universal consensus on their content. 36 Both human rights courts

30 HRC’s General Comment No. 36 on the Right to Life, UN Doc. CCPR/C/GC/36, supra note 9, § 12; and AComHPR’s General Comment No. 3 on the Right to Life, supra note 9, § 12. Back
31 General Comment No. 36 on the Right to Life, UN Doc. CCPR/C/GC/36, supra note 9, § 12. Back
32 Emphasis added. The ECHR may apply extraterritorially when State Parties to the ECHR exercise authority outside their territory. Article 1 of the ECHR provides that “[t]he High Contracting Parties shall secure to everyone within their jurisdiction the rights and freedoms defined in Section I of this Convention”. See e.g. case law of the ECtHR on the extraterritorial application of the ECHR during military presence and/or military intervention outside the territory of State Parties: ECtHR, Bankovic and Others v. Belgium and Others, Appl. No. 52207/99, 12 December 2001, Decision as to the admissibility, §§ 54-82; ECtHR, Issa and Others v. Turkey, Appl. No. 31821/96, 16 November 2004, Judgment, §§ 65-82; ECtHR (Grand Chamber), Behrami and Behrami v. France and Saramati v. France, Germany and Norway, Appl. No. 71412/01 and 78166/01, 2 May 2007, Decision as to the admissibility, 133-136; ECtHR (Grand Chamber), Al-Skeini and Others v. the United Kingdom, Appl. No. 55721/07, 7 July 2011, Judgment, §§ 130-150; ECtHR (Grand Chamber), Al-Jedda v. the United Kingdom, Appl. No. 27021/08, 7 July 2011, Judgment, §§ 74-86; ECtHR (Grand Chamber), Hassan v. the United Kingdom, Appl. No. 29750/09, 16 September 2014, Judgment, §§ 74-80; ECtHR (Grand Chamber), Jaloud v. the Netherlands, Appl. No. 47708/08, 20 November 2014, Judgment, §§ 137-156; and ECtHR, Loizidou v. Turkey, Appl. No. 15318/89, 18 December 1996, Judgment, §§ 137-156. Back
33 Article 9 of the Basic Principles on the Use of Force and Firearms, Adopted by the Eighth United Nations Congress on the Prevention of Crime and the Treatment of Offenders, Havana, Cuba, 27 August to 7 September 1990. Back
34 Id., fn. 1. Back
35 UNGA, Interim Report of the Special Rapporteur, Philip Alston, on Extrajudicial, Summary or Arbitrary Executions, UN Doc. A/61/311, 5 September 2006, § 35. Back
36 Id., § 35. For a detailed overview of the development of the UN Basic Principles for the Use of Force and Firearms, see also N. S. Rodley and M. Pollard, The Treatment of Prisoners Under International Law (New York, Oxford University Press, 2011, 3rd ed.), pp. 495-508. Back


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and international human rights mechanisms also mention them as part of the normative framework and rely on them to interpret the articles on the right to life. 37

At first sight, the articles on the right to life as incorporated in the main human rights treaties seem to diverge. Yet, when reviewing the treaty-based jurisprudence and practice, it becomes clear that the material scope of the right to life under the ECHR on the one hand and under the ICCPR, the ACHR, and the ACHPR on the other, is not fundamentally different. 38

For lethal force to be necessary, it must be “strictly unavoidable”, “strictly necessary”, or “absolutely necessary” to achieve a legitimate aim. 39 In the first place, this imposes a duty upon State agents, be it policemen or soldiers, to minimize the need to use lethal force. 40 In this regard, State agents do not only have a negative obligation not to provoke situations in which they could use force, but also a positive obligation to take all reasonable measures to prevent escalation of a situation that might otherwise require the use of lethal force (“escalation of force procedure”). 41 In other words, lethal force must constitute a method of last resort that can only be used if lesser means (such as the arrest of a person) are not available or manifestly unreasonable. This duty to minimize the need for the use of lethal force does not, however, imply a general duty to retreat. 42 In his 2006 Report on extrajudicial, summary or arbitrary executions, former Special Rapporteur Philip Alston specified that “the use of lethal force may prove strictly unavoidable when [giving suspects the opportunity to surrender and employ a graduated resort to force] would unduly risk death or serious harm to law enforcement officers or other persons”. 43 He added that “there are circumstances in which an immediate recourse to lethal force is strictly necessary to prevent an even greater loss of life. In most such situations, this necessity is the result of a threat’s imminence. [...] When a criminal is already in the process or visibly on the verge of using a weapon, there can be little doubt regarding the inevitability of violence if immediate recourse to lethal force is not taken”. 44 According to former Special Rapporteur Christophe Heyns, determining whether a threat is “imminent” or “immediate” is “a matter of seconds, not hours”. 45 Support for the principle that lethal force must constitute a method of last resort can also be found in case law of the HRC, the IACtHR, the AComHPR, and the ECtHR. For example, in Suarez de Guerrero v. Colombia, the HRC considered the intentional killing of alleged kidnappers by police to be a violation of Article 6(1) of the

37 See e.g. IACtHR, Case of Montero-Aranguren et al. (Detention Center of Catia) v. Venezuela, Series C No. 150, 5 July 2006, Judgment, §§ 68-69; IACtHR, Case of the Landaeta Mejías Brothers et al. v. Venezuela, Series C No. 281, 27 August 2014, Judgment, § 131; IAComHR, Fifth Report on the Situation of Human Rights in Guatemala, OEA/Ser.L/V/II.111, Doc. 21 rev., 6 April 2001, § 50; IAComHR, Corumbiara Massacre v. Brazil, Case 11.556, Report No. 32/04, 11 March 2004, § 172; AComHPR, Noah Kazingachire, John Chitsenga, Elias Chemvura and Batanai Hadzisi (represented by Zimbabwe Human Rights NGO Forum) v. Zimbabwe, Communication 295/04, 22 October 2013, §§ 87, 110, 112, 114; ECtHR (Grand Chamber), Case of Nachova and Others v. Bulgaria, Appl. No. 43577/98 and 43579/98, 6 July 2005, Judgment, §§ 71 and 96; and HRC’s General Comment No. 36 on the Right to Life, UN Doc. CCPR/C/GC/36, supra note 9, § 12. See also J. A., Hessbruegge, Human Rights and Personal Self-Defense in International Law (New York: Oxford University Press, 2017), p. 97; and N. Melzer, Targeted Killing in International Law (New York, Oxford University Press, 2008), p. 119. Back
38 It is worth highlighting, however, that case law does not always differentiate clearly between necessity and proportionality. See also Melzer, supra note 37, pp. 118-120. Back
39 Melzer identifies this as “qualitative necessity”, see id., pp. 101 and 116. Back
40 Hessbruegge, supra note 37, p. 146. Back
41 Id. Back
42 Id. Back
43 UN Economic and Social Council, Commission on Human Rights, Civil and Political Rights, Including the Questions of Disappearances and Summary Executions, Report of the Special Rapporteur, Philip Alston, on Extrajudicial, Summary or Arbitrary Executions, Sixty-second session, item 11(b) of the provisional agenda, UN Doc. E/CN.4/2006/53, 8 March 2006, § 48 (emphasis added). Back
44 Id. , § 49. Back
45 UNGA, HRC, Report of the Special Rapporteur, Christof Heyns, on Extrajudicial, Summary or Arbitrary Executions, UN Doc. A/HRC/26/36, 1 April 2014, § 59. Back


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ICCPR because the police had not given them any opportunity to surrender. 46 The IACtHR held on similar grounds that Ecuador had violated Article 4 of the ACHR in Zambrano Vélez et al. v. Ecuador. 47 In particular, the IACtHR found that there was no evidence which demonstrated that State agents who had participated in the operation had attempted to use less lethal means of intervention. 48 In Kazingachire and Others v. Zimbabwe, the AComHPR argued that since the person fleeing from the police was not armed, he did not pose any immediate threat to the safety of the police officers or any other member of the public. 49 Hence, a lower level of force would have been sufficient to restrain or apprehend the person in question. 50 Also in Bakan v. Turkey, the ECtHR confirmed that firearms should only be employed as a last resort. 51 In McCann and Others v. the United Kingdom, the ECtHR accepted that the soldiers honestly believed that it was “absolutely necessary” to shoot the suspects in order to prevent them from detonating a bomb and causing serious loss of life. 52 Yet, given that there was a lack of appropriate care in the control and organization of the arrest operation, the ECtHR was not persuaded that the killing of the three terrorists constituted a use of force which was no more than “absolutely necessary” in defence of others. 53 According to the ECtHR, the term “absolutely necessary indicated that a stricter and more compelling test of necessity must be employed from that normally applicable when determining whether State action is “necessary in a democratic society” under Articles 8(2), 9(2), 10(2), and 11(2) of the ECHR. 54 In particular, the force used must be strictly proportionate to the achievement of the aims set out in Article 2(2)(a), (b), and (c) of the ECHR. 55 The ECtHR has, however, occasionally departed from that strict standard given that its application is sometimes impossible. For example, both in Finogenov and Others v. Russia and Tagayeva and Others v. Russia, the ECtHR confirmed that it is conscious of the difficulties that States face in protecting their population from the threats posed by terrorism and the risks of hindsight analysis. 56 Therefore, it held that the absolute necessity test formulated in Article 2 of the ECHR is bound to be applied “with different degrees of scrutiny, depending on whether and to what extent the authorities were in control of the situation and other relevant constraints inherent in operative decision-making in this sensitive sphere”. 57

If the use of force is inevitable, the amount of force must not exceed the minimum that is necessary to respond to the threat and force can only be used as long as it is still necessary to achieve the legitimate

46 HRC, Husband of Maria Fanny Suarez de Guerrero v. Colombia, Communication No. R.11/45, UN Doc. Supp. No. 40 (A/37/40) at 137 (1982), 9 April 1981, Decision as to admissibility, § 13.2. See also HRC’s General Comment No. 36 on the Right to Life, UN Doc. CCPR/C/GC/36, supra note 9, § 12. Back
47 IACtHR, Case of Zambrano Vélez et al. v. Ecuador, Series C No. 166, 4 July 2007, Judgment, § 108. See also IAComHR, Armando Alejandre Jr. and Others v. Cuba, Case 11.589, Report No. 86/99, 29 September 1999, § 42; and IACtHR, Case of Barrios Family v. Venezuela, Series C No. 237, 24 November 2011, Judgment, §§ 67-68. Back
48 IACtHR, Case of Zambrano Vélez et al. v. Ecuador, Series C No. 166, 4 July 2007, Judgment, § 108. Back
49 AComHPR, Noah Kazingachire, John Chitsenga, Elias Chemvura and Batanai Hadzisi (represented by Zimbabwe Human Rights NGO Forum) v. Zimbabwe, Communication 295/04, 22 October 2013, § 119. Back
50 Id. , § 119. Back
51 ECtHR, Bakan v. Turkey, Appl. No. 50939/99, 12 June 2007, Judgment, § 51. See also ECtHR (Grand Chamber), Case of Nachova and Others v. Bulgaria, Appl. No. 43577/98 and 43579/98, 6 July 2005, Judgment, § 108. Back
52 ECtHR (Grand Chamber), McCann and Others v. the United Kingdom, Appl. No. 18984/91, 27 September 1995, Judgment, § 200. Back
53 Id. , § 213. Back
54 Id. , § 148. Back
55 Id. , § 148. Back
56 ECtHR, Case of Finogenov and Others v. Russia, Appl. No. 18299/03 and 27311/03, 20 December 2011, Judgment, § 212; and ECtHR, Case of Tagayeva and Others v. Russia, Appl. No. 26562/07 and 6 other applications, 13 April 2017, Judgment, § 481. Back
57 ECtHR, Case of Tagayeva and Others v. Russia, Appl. No. 26562/07 and 6 other applications, 13 April 2017, Judgment, § 481. For a similar reasoning, see ECtHR, Case of Finogenov and Others v. Russia, Appl. No. 18299/03 and 27311/03, 20 December 2011, Judgment, §§ 213-214. Back


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aim. 58 According to the HRC, “the amount of force applied cannot exceed the amount strictly needed for responding to the threat”. 59 In Suarez de Guerrero v. Colombia, the HRC condemned for example that one of the alleged kidnappers had been shot several times after she had already died from a heart attack. 60 In Rickly Burrell v. Jamaica, the HRC noted that the alleged hostage taker had been shot after the warders were already released, making the use of force no longer necessary. 61 The IACtHR ruled in Zambrano Vélez et al. v. Ecuador that the use of lethal force by State agents against persons who no longer represent a threat, such as individuals held in custody by the authorities, would be a flagrant violation of Article 4 of the ACHR. 62 In Güleç v. Turkey, the ECtHR accepted that force may be justified to quell a riot or insurrection, but considered that in the circumstances of the case the use of a very powerful weapon to disperse the demonstrators was not “absolutely necessary” to pursue that aim. 63

The use of lethal force is disproportionate if the nature or scale of the actual threat does not justify the (potential) deprivation of life. 64 A legitimate objective for the use of lethal force is for example self-defence or to effect the arrest of dangerous persons. But, the intentional (as opposed to incidental) use of lethal force is permissible only if it is absolutely or strictly necessary to protect life from imminent threat. It follows that lethal force cannot be used intentionally to for example effect a lawful arrest or prevent the escape of a person who is not posing an imminent threat to life. Unlike the human rights treaties referred to above, Article 9 of the UN Basic Principles for the Use of Force and Firearms has included this caveat by explicitly holding that “intentional lethal use of firearms may only be made when strictly unavoidable in order to protect life”. 65 As previously mentioned, the UN Basic Principles are not legally binding, but nevertheless have a considerable impact upon the interpretation of the right to life. For example, both the HRC, the AComHPR, and the IACtHR have explicitly confirmed that the intentional use of lethal force is only legitimate to protect life. 66 The ECtHR has also adopted this approach, despite the fact that Article 2(2) of the ECHR does not directly suggest this. As mentioned

58 Melzer labels these two aspects as “quantitative necessity” and “temporal necessity” respectively, see Melzer, supra note 37, pp. 101 and 116. Back
59 General Comment No. 36 on the Right to Life, UN Doc. CCPR/C/GC/36, supra note 9, § 12. Back
60 HRC, Husband of Maria Fanny Suarez de Guerrero v. Colombia, Communication No. R.11/45, UN Doc. Supp. No. 40 (A/37/40) at 137 (1982), 9 April 1981, Decision as to admissibility, §§ 13.2 and 13.3. Back
61 HRC, Rickly Burrell v. Jamaica, Decision as to the admissibility, Communication No. 546/1993, UN Doc. CCPR/C/53/D/546/1993 (1996), 4 April 1995, Decision as to admissibility, § 9.5. Back
62 IACtHR, Case of Zambrano Vélez et al. v. Ecuador, Series C No. 166, 4 July 2007, Judgment, § 108. See also IACtHR, Case of Barrios Family v. Venezuela, Series C No. 237, 24 November 2011, Judgment, §§ 67-68; and IACtHR, Case of Montero-Aranguren et al. (Detention Center of Catia) v. Venezuela, Series C No. 150, 5 July 2006, Judgment, § 68. Back
63 ECtHR, Güleç v. Turkey, Appl. No. 54/1997/838/1044, 27 July 1998, Judgment, §§ 71 and 73. Back
64 Melzer, supra note 37, pp. 101 and 117. Back
65 Emphasis added. Article 9 of the UN Basic Principles seems to refine the conditions and modalities for the use of lethal force in law enforcement operations also in another way. Instead of referring to “the use of force and firearms” (as it does in the more general Article 4 of the UN Basic Principles for the Use of Force and Firearms which provides that “[l]aw enforcement officials, in carrying out their duty, shall, as far as possible, apply non-violent means before resorting to the use of force and firearms”), it specifically refers to the “use of firearms”. In doing so, it confirms that all uses of firearms against people should be considered (potentially) lethal. This position was also adopted by the AComHPR in Kazingachire and Others v. Zimbabwe (see AComHPR, Noah Kazingachire, John Chitsenga, Elias Chemvura and Batanai Hadzisi (represented by Zimbabwe Human Rights NGO Forum) v. Zimbabwe, Communication 295/04, 22 October 2013, § 120). See also analysis by Melzer, supra note 37, p. 203. Back
66 HRC’s General Comment No. 36 on the Right to Life, UN Doc. CCPR/C/GC/36, supra note 9, § 12. For the views of the AComHPR, see AComHPR, Noah Kazingachire, John Chitsenga, Elias Chemvura and Batanai Hadzisi (represented by Zimbabwe Human Rights NGO Forum) v. Zimbabwe, Communication 295/04, 22 October 2013, §§ 120-122; AComHPR’s General Comment No. 3 on the Right to Life, supra note 9, § 27. See also case law of the IACtHR in which the Court explicitly refers to the permissible grounds for deprivation as set out by the UN Basic Principles for the Use of Force and Firearms: IACtHR, Case of Barrios Family v. Venezuela, Series C No. 237, 24 November 2011, Judgment, §§ 67-68; IACtHR, Case of Montero-Aranguren et al. (Detention Center of Catia) v. Venezuela, Series C No. 150, 5 July 2006, Judgment, § 69; and IACtHR, Case of the Landaeta Mejías Brothers et al. v. Venezuela, Series C No. 281, 27 August 2014, Judgment, § 131. Back


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above, Article 2(2) of the ECHR provides that there is no violation of the right to life when it results from the use of force which is no more than absolutely necessary in order to defend oneself or others from unlawful violence or when carrying out certain law enforcement tasks. However, both in Nachova and Others v. Bulgaria and in Kakoulli v. Turkey, the ECtHR held that “the legitimate aim of effecting a lawful arrest can only justify putting human life at risk in circumstances of absolute necessity” whereby the person to be arrested poses a “threat to life or limb” and is “suspected of having committed a violent offence”, even if a “failure to use lethal force may result in the opportunity to arrest the fugitive being lost”. 67 Nevertheless, Article 2(2) of the ECHR does not only concern the use of intentional lethal force, but also any use of force which may result, as an unintended outcome, in the deprivation of life. 68 In this respect, the use of force must be no more than “absolutely necessary” for the achievement of one of the purposes set out in Article 2(2) of the ECHR.

On a final note, there is a positive obligation upon States to take all necessary measures to prevent arbitrary deprivation of life. This may include the adequate planning and controlling of an operation as to minimize the need to resort to lethal force or a duty to report, review, and investigate lethal or life-threatening incidents. 69

B. Use of Non-Lethal Force: Determining the Scope of Possible Actions

Not all force for mission accomplishment is lethal in nature. Military forces can use non-lethal force for the achievement of tasks, purposes, and objectives as set out in a mandate 70 in so far as it complies with the principles of necessity, proportionality, and precaution. For force to be necessary, State agents may not have provoked the situation in which they can use force. They are also under the obligation to use all reasonable measures to prevent escalation of a situation that might otherwise require the use of force. Whenever possible, an appropriate warning should be given before resorting to the use of force. If force is unavoidable, the amount of force must not exceed the minimum that is necessary to respond to the threat and force may only be used as long as the threat exists. Proportionality implies that the damage caused to the party posing the threat must not be excessive in relation to the intensity of the damage that party caused initially. 71 Last but not least, the principle of precaution requires for example that operations

67 ECtHR (Grand Chamber), Case of Nachova and Others v. Bulgaria, Appl. No. 43577/98 and 43579/98, 6 July 2005, Judgment, § 95; and ECtHR, Case of Kakoulli v. Turkey, Appl. No. 38595/97, 22 November 2005, Judgment, § 108 (emphasis added). In these cases, the ECtHR is using the language of necessity to refer to proportionality. See also ECtHR, Case of Finogenov and Others v. Russia, Appl. No. 18299/03 and 27311/03, 20 December 2011, Judgment, § 220; ECtHR, Case of Vasil Sashov Petrov v. Bulgaria, Appl. No. 63106/00, 10 June 2010, Judgment, § 48; and ECtHR, Case of Karandja v. Bulgaria, Appl. No. 69180/01, 23 September 2014, Judgment, § 59. Back
68 See ECtHR (Grand Chamber), McCann and Others v. the United Kingdom, Appl. No. 18984/91, 27 September 1995, Judgment, § 148; ECtHR, Stewart v. United Kingdom, Appl. No. 10044/82, 10 July 1984, Decision as to the admissibility, § 15; ECtHR, Huohvanainen v. Finland, Appl. No. 57389/00, 13 March 2007, Judgment, § 97; and ECtHR (Grand Chamber), Ramsahai and Others v. The Netherlands, Appl. No. 52391/99, 15 May 2007, Judgment, §§ 286-289, as also discussed by Hessbruegge, supra note 37, p. 97. Back
69 HRC’s General Comment No. 36 on the Right to Life, UN Doc. CCPR/C/GC/36, supra note 9, § 13. For case law of the IACtHR on the principle of precaution, see e.g. IACtHR, Case of Montero-Aranguren et al. (Detention Center of Catia) v. Venezuela, Series C No. 150, 5 July 2006, Judgment, § 79-84; and IACtHR, Case of Zambrano Vélez et al. v. Ecuador, Series C No. 166, 4 July 2007, Judgment, § 108. See also IAComHR, Armando Alejandre Jr. and Others v. Cuba, Case 11.598, Report No. 86/99, 29 September 1999, § 88-90. For case law of the ECtHR on the obligation to plan and control the operation, see e.g. ECtHR, Bubbins v. the United Kingdom, Appl. No. 50196/99, 17 March 2005, Judgment, § 136; and ECtHR, Huohvanainen v. Finland, Appl. No. 57389/00, 13 March 2007, Judgment, § 94. For case law of the ECtHR on the procedural obligation, see e.g. ECtHR (Grand Chamber), McCann and Others v. the United Kingdom, Appl. No. 18984/91, 27 September 1995, Judgment, § 161; and ECtHR (Grand Chamber), Al-Skeini and Others v. the United Kingdom, Appl. No. 55721/07, 7 July 2011, Judgment, § 163. Back
70 Such a mandate can be provided for by the host State or by a competent organ of an international organization conducting the operation (e.g. the UNSC). Back
71 Gill et al, supra note 3, Rule 12.3, p. 147. Back


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are adequately planned and conducted so as to avoid or at least minimize the need to resort to the use of force.

Moreover, any such use of force will have to comply with any additional body of law that applies in the circumstances. 72 If non-lethal force is used in a situation which is not addressed by applicable domestic or international law, the mandate shall in principle constitute an adequate legal basis for the degree of force it permits in the circumstances it specifies. 73 In the absence of a reference to the possibility to use force for mission accomplishment in the mandate, such force can only be lawfully used to the extent it complies with applicable law. 74

Nowadays, there are several operations that are carried out by individual States or international organizations (e.g. by the UN, North Atlantic Treaty Organization (NATO), the European Union (EU) or the African Union (AU)) within the framework of a mandate that do not require the use of lethal force for mission accomplishment. These operations may include, for example, post-conflict stabilization operations or missions to train and advise the armed forces of a third State. In these cases, there is no adversary identified. To the contrary, the operation is conducted in close collaboration with the governmental and law enforcement authorities of the host State which continue to exercise their law enforcement powers over the territory. Only protective measures for certain sensitive installations or infrastructures should, for example, be adopted. Under all circumstances, the use of force follows a logic of graduated response and absolute necessity, with adherence to the principles enacted in this regard.

III. The Relationship Between Self-Defence, Mission Accomplishment, and the Law Enforcement and Conduct of Hostilities Paradigms

Before assessing whether human rights law and international humanitarian law provide for useful and sufficient legal grounds for the use of force for mission accomplishment, we should first clarify the relationship between the following notions: self-defence, mission accomplishment, and the law enforcement and conduct of hostilities paradigms. Not only does practice indicate that there is a lack of clarity as to where self-defence ends and mission accomplishment begins, how these two notions relate to the law enforcement and conduct of hostilities paradigms is also a subject of discussion.

Rules of Engagement (ROE) 75 usually distinguish between the use of force for mission accomplishment and the use of force in self-defence. 76 Yet, according to the US Operational Law Handbook:

72 Id. , Rule 12.2, p. 146. Back
73 Id. Back
74 Id. , Rule 12.3, p. 148 and Rule 12.4, p. 149. Back
75 According to the UN Department of Peacekeeping Operations and the UN Department of Field Support, ROE “provide the authority for the use of force as well as directions to operational commanders delineating the parameters within which force be used”, see UN Department of Peacekeeping Operations / Department of Field Support, DPKO/DFS Guidelines: Use of Force by Military Components in United Nations Peacekeeping Operations, Ref. 2016.24, p.4. Back
76 The Standing Rules of Engagement issued by the Chairman of the Joint Chiefs of Staff of the US (SROE) state that the purpose of rules of engagement is “to provide implementation guidance on the application of force for mission accomplishment and the exercise of self-defense”, see US Joint Chiefs of Staff, Chairman of the Joint Chiefs of Staff, Standing Rules of Engagement for US Forces, Document CJCSI 3121.01B, 13 June 2005, Enclosure A. Standing Rules of Engagement for US Forces, p. 86, § 1(a). See also NATO, Military Committee, MC 362/1, NATO Rules of Engagement, 30 June 2003 (this document is “NATO Unclassified”), p. 4, § 7 and p. 5, § 10(d) (on file with J-. E. Perrin); EU, EU Concept for the Use of Force in EU-led Military Operations, 4 December 2009 (this document is “EU Restricted”), p. 24, §§ 52-53 and p. 25, §§ 54-54 (on file with J-. E. Perrin). Back


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[T]he line between action for mission accomplishment and action in self-defense is not always clear. Distinctions between mission accomplishment and self-defense, and between offensive and defensive operations, may vary based on the level of command, array of forces, and circumstances on the ground. 77
This is, however, not the only reason why the dividing line between use of force in self-defence and mission accomplishment is blurred and causes problems of legal interoperability. Another reason is that States have different views on the scope of self-defence. This discrepancy is most clearly reflected in the way the concepts of “hostile act” and “hostile intent” are understood. In the US military doctrine, the Standing Rules of Engagement (SROE), for instance, consider that the triggering act for self-defence is a hostile act or a demonstrated hostile intent. A hostile act is understood as “[a]n attack or other use of force against the United States, US forces or other designated persons or property”. 78 Hostile intent is understood as “[t]he threat of imminent use of force against the United States, US forces or other designated persons or property”. 79 These same triggering acts also apply to the use of force used directly to “preclude or impede the mission and/or duties of US forces, including the recovery of US personnel or vital US [government] property” and thus to the use of force for mission-accomplishment. 80 The determination of whether the use of force against US forces is imminent is principally based on “an assessment of all facts and circumstances known to US forces at the time and may be made at any level”. 81 That being said, imminent “does not necessarily mean immediate or instantaneous”. 82 The notions of hostile act and hostile intent and the understanding of what is “imminent” constitute an integral part of the US concept of self-defence and provide for a justification for the use of force in self-defence to an extent that would exceed self-defence in the view of most States.

This broad concept of self-defence is partially reflected in the current NATO ROE as set out in MC 362/1. 83 But, unlike in the US doctrine, the concepts of “hostile act” and “hostile intent” do not relate to self-defence. Instead they refer to situations in which there is a coercive act or intent by another actor in situations other than self-defence. 84 The sample ROE include the “33 series” ROE which mainly concern defensive use of force and the “42 series” ROE which describe the offensive use of force. The “33 series” ROE include for example provisions on the use of force to accomplish the mission and thus to prevent any interference with the mission or to defend forces from other Member States, 85 areas where the troops are active, or property that is used in the accomplishment of the mission. 86 The “42 series” ROE are provisions that focus on attacks in response to a hostile act or hostile intent. 87 In this context, the act of laying an improvised explosive device could for example be qualified as a hostile act. Also for other States the concepts of “hostile act” and “hostile intent” do not relate to self-defence. For these

77 M. D. Kouba (ed.), Operational Law Handbook (International and Operational Law Department, The Judge Advocate General’s Legal Center & School, U.S. Army, 2017, 17th ed.), p. 79. Back
78 US ROE, supra note 76, p. 89, § 3(e). Back
79 Id. , p. 89, § 3(f). Back
80 Id. , p. 89 §§ 3(e) and (f). Back
81 Id. , p. 89, § 3(g). Back
82 Id. Back
83 NATO MC 362/1, supra note 76. Back
84 J. F. R. Boddens Hosang and T. D. Gill, ‘Soldier Self-Defense Symposium: Netherlands Views on Self-Defence for Military Personnel’, Opinio Juris, 29 April 2019, https://opiniojuris.org/2019/04/29/soldier-self-defense-symposium-netherlands-views-on-self-defence-for-military-personnel%EF%BB%BF/. Back
85 NATO uses the term “extended self-defence” to describe the right of troops from one Member State to assist in the defence of troops from another Member State in the event of an (imminent) attack, see T. Gill, C. Marchand, J. F. R. Boddens Hosang, and P. Ducheine, General Report for the 19th Congress of the International Society for Military Law and the Law of War Held at Quebec, 1-4 May 2012, May 2012, https://www.ismllw.org/wp-content/uploads/2018/11/1_QUEBEC.pdf, p. 49. Back
86 NATO MC 362/1, supra note 76, p. 5, § d, and p. A-13. Back
87 Id. , p. 5 and pp. A-19 and A-1-1. Back


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States, the terms similarly relate to situations which trigger the use of offensive force, as opposed to the use of force for mission accomplishment which is rather defensive in nature.

Thus, defensive use of force for mission accomplishment is the domain where potential overlaps might appear between some States’ definition of self-defence and the need of other States for specific authority given by these ROE. Depending on how broadly or narrowly the right to self-defence is interpreted, a varying number of additional rules are needed for such use of force for mission accomplishment. If a State has for example adopted a very broad view of self-defence, it will not need a great number of additional rules dealing with defensive use of force for mission accomplishment. For example, for a threat to be imminent from the perspective of the US, it does not necessarily have to be an immediate or instantaneous threat. This significantly widens the scope of self-defence. For States that have adopted a very narrow interpretation of self-defence, the use of force in such situations will require additional rules dealing with mission accomplishment. These additional rules require a solid basis in applicable law. After all, ROE reflect lawful use of force within the outer limits imposed by applicable law, but do not create any right to use force. Moreover, the use of force beyond self-defence needs to be authorized not only legally but also politically, usually by the highest political authorities, whether national (e.g. Head of State or Head of government) or multinational (North Atlantic Council for NATO).

To accommodate existing disparities in domestic laws and regulations with regard to the use of force in self-defence and to enable some level of uniformity of response to threats occurring in multinational operations, the EU has adopted the concept of “confirmatory ROE”. 88 This concept of confirmatory ROE addresses specific categories of actions, which for some States would constitute self-defence whilst for other contributing States such actions would need to be specifically authorized as part of the mandate, i.e. covered by specific ROE. 89 An example of such a situation would be the use of force to defend property, since this is one of the points on which national views diverge. 90 Where one contingent in an EU mission would need additional authorization and implementation of ROE to have a legal and lawful authorization to use force in the given circumstances, other contingents for which the use of force is already authorized on the basis of their domestic laws and regulations would not need the ROE in question, but would also not be impeded by it. 91 This explains why the EU labelled it as “confirmatory ROE”: they confirm the right to use force in self-defence, 92 while leaving the use of force in response to hostile acts and hostile intent outside the frame of self-defence.

The challenge of differentiating between self-defence and mission accomplishment is also reflected in the practice of the UN. Already in the 1970s, the UN started to adopt more expansive interpretations of self-defence for UN peace operations, thereby not only anticipating the use of force in personal self-defence and defence of others, but also including the notion of “defence of the mandate”. 93 On 11 April 1964, the UN Secretary-General issued a note in which it clarified that “self-defence” includes “(a) the defence of United Nations posts, premises and vehicles under armed attack; [and] (b) the support of other personnel of the United Nations Peacekeeping Force in Cyprus (UNFICYP) under armed attack”. 94 One of the examples in which the UNFICYP troops where authorized to use force was “attempts by

88 EU Concept for the Use of Force in EU-led Military Operations, supra note 76. See also the discussion by J. F. R. Boddens Hosang, ‘Rules of Engagement. Rules on the Use of Force as Linchpin for the International Law of Military Operations’, Dphil thesis, University of Amsterdam, 2017, p. 56. Back
89 EU Concept for the Use of Force in EU-led Military Operations, supra note 76. Back
90 Boddens Hosang, supra note 88, p. 57. See also Gill et al., supra note 85, pp. 39-40. Back
91 Boddens Hosang, supra note 88, p. 57. Back
92 Id.. Back
93 See also discussion by B. Oswald, ‘Soldier Self-Defense Symposium: The Evolution of the UN Doctrine of Self-Defence in UN Peacekeeping’, Opinio Juris, 1 May 2019, http://opiniojuris.org/2019/05/01/soldier-self-defense-symposium-the-evolution-of-the-un-doctrine-of-self-defence-in-un-peacekeeping/. Back
94 UNSC, Note by the Secretary-General, UN Doc. S/5653, 11 April 1964, § 18. Back


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force to prevent them from carrying out their responsibilities as ordered by their commanders”. 95 By adopting this approach, the UN Secretary-General clearly went beyond the generally accepted approach of the principle of personal self-defence. Nonetheless, both the UN Secretary-General and the UNSC reinforced this extensive approach of self-defence at a later stage. 96 Only after the end of the Cold War, the UNSC detached the concept of self-defence from defence of the mandate. In particular, the President of the UNSC stated that the UNSC has the right to “authorize all means necessary for United Nations forces to carry out their mandate and the inherent right of United Nations forces to take appropriate measures for self-defence”. 97 Simultaneously, the UNSC started giving UN peace operations “robust” mandates by “authorizing them to “use all necessary means” to deter forceful attempts to disrupt the political process, protect civilians under imminent threat of physical attack, and/or assist the national authorities in maintaining law and order”. 98 In this regard, it is to be stressed that if a UN peace operation is authorized to use all necessary means to deter forceful attempts to disrupt the political process, 99 this may indeed require the use of force beyond self-defence or defence of others. Yet, if a UN peace operation receives a mandate from the UNSC to use all necessary means to protect civilians from the imminent threat of physical violence, 100 its strategic objective is the protection of civilians. Hence, any use of force to protect civilians from the imminent threat of physical violence may not only be considered use of force in defence of others but also use of force for mission accomplishment.

By recognizing that UN forces not only have the inherent right to take appropriate measures for self-defence but may also take all necessary means to carry out their mandate, the UNSC gave missions the permission to proactively use force in defence of their mandates. This new approach recognizes the need for the use of force for mission accomplishment alongside the possibility to use force in personal self-defence and defence of others. 101 But the UN did not clarify which legal regime regulates the use of force in such instances and what the limits are to this “legitimate” use of force beyond self-defence for mission accomplishment. This can be problematic. After all, in general it is the applicable legal regime that determines the outer limits of permissible use of force. In principle, neither States nor international organizations can broaden the possibilities in which force can be used under human rights law or international humanitarian law, unless the UNSC authorized lawful derogation thereof pursuant to Article 103 of the UN Charter. Article 103 of the UN Charter provides that “in the event of a conflict between the obligations of the Members of the United Nations under the present Charter and their obligations under any other international agreement, their obligations under the present Charter shall prevail”. One of the obligations that results from this authority is provided for in Article 25 of the Charter, namely “to accept and carry out the decisions of the Security Council in accordance with [...] the Charter”. Although Article 103 of the UN Charter is marked by uncertainties as to its precise scope

95 Id.. Back
96 The UN Secretary-General held that the troop belonging to the Second United Nations Emergency Force (UNEF II) “shall not use force except in self-defence. Self-defence would include resistance to attempt by forceful means to prevent it from discharging its duties under the mandate of the Security Council”, see UNSC, Report of the Secretary General on the Implementation of Security Council Resolution 340 (1973), UN Doc. S/11052/Rev. 1, 27 October 1973, § 4(d). In UNSC Res. 467 concerning the United Nations Interim Force in Lebanon (UNIFIL), the UNSC reaffirmed that “self-defence would include resistance to attempts by forceful means to prevent it from discharging its duties under the mandate of the Security Council”, see UNSC Res. 467, 24 April 1980, pream. § 6. Back
97 UNSC, Provisional Verbatim Record of the Three Thousand Two Hundred and Twenty-First Meeting, UN Doc. S/PV.3225, 28 May 1993, p. 3 (emphasis added). Back
98 UN Department of Peacekeeping Operations and Department of Field Support, The United Nations Peacekeeping Operations: Principles and Guidelines, 2008, p. 34 (so-called “Capstone Doctrine”). Back
99 See for example UNSC Res. 1592, 30 March 2005; USC Res. 1649, 21 December 2005; and UNSC Res. 1756, 15 May 2007. Back
100 See for example UNSC Res. 1545, 21 May 2004; UNSC Res. 1592, 30 March 2005; UNSC Res. 1996, 8 July 2011; and UNSC Res. 2100, 25 April 2013. Back
101 Watkin, supra note 15, p. 469. Back


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and the effects it may generate, 102 it is beyond doubt that the provision can never be invoked to justify a violation of a peremptory norm of international law. 103 In other words, an authorization to take “all necessary measures” has to be interpreted and implemented in such a manner that is compatible with ius cogens. In the event of a conflict between a UNSC Resolution and a peremptory norm, the latter will prevail. 104 As a non-derogable and fundamental right in any society which is incorporated in virtually every major human rights law instrument, the right to life is a rule of ius cogens. 105 Thus, any lethal
102 First, it remains disputed whether an “authorization” falls within the scope of “obligations under the UN Charter”. Second, there is discussion about the scope of “obligations under other international agreements” and notably whether this only concerns treaties between Member States, or also other obligations (e.g. under customary international law). Third, there is disagreement about when exactly a “conflict” occurs between the “obligations under the UN Charter” and “obligations under other international agreements”. However, a discussion of these matters goes beyond the scope of the present article. For case law on the question whether an authorization under a UNSC Resolution may supersede an obligation under the ECHR, see e.g.: United Kingdom House of Lords, R (on the application of Al-Jedda) v. Secretary of State for Defence, UKHL 58 (2008), International Law in Domestic Courts 832 (UK 2007), 12 December 2007, Appeal Judgment, §§ 26-39 (Lord Bingham); §§ 115-118 (Lord Rodger); §§ 131-135 (Lord Carswell); §§ 151-152 (Lord Brown) (for an in-depth analysis of the Al-Jedda case before the House of Lords (now the Supreme Court of the United Kingdom), see also A. Sari, ‘The Al-Jedda Case Before the House of Lords’, Vol. 13 Journal of International Peacekeeping 2009, pp. 181-96); ECtHR (Grand Chamber), Al-Jedda v. the United Kingdom, Appl. No. 27021/08, 7 July 2011, Judgment, §§ 97-109; ECtHR (Grand Chamber), Case of Al-Dulimi and Montana Management Inc. v. Switzerland, Appl. No. 5809/08, 21 June 2016, Judgment, §§ 135-149; and ECtHR (Grand Chamber), Nada v. Switzerland, Appl. No. 10593/08, 12 September 2012, Judgment, §§ 170-171. For legal literature discussing Article 103 of the UN Charter, see e.g. International Law Commission, Fragmentation of International Law: Difficulties Arising from the Diversification and Expansion of International Law. Report of the Study Group of the International Law Commission. Finalized by Martti Koskenniemi, UN Doc. A/CN.4/l.682, 13 April 2006, pp. 166-181; R. Kolb, ‘Does Article 103 of the Charter of the United Nations Apply Only to Decisions or Also to Authorizations Adopted by the Security Council’, Vol. 64 Zeitschrift für ausländisches öffentliches Recht und Völkerrecht 2004, pp. 21-35; J. R. Leiæ and A. Paulus, ‘Chapter XVI. Miscellaneous Provisions, Article 103’, in B. Simma et al. (eds.), The Charter of the United Nations: A Commentary (Oxford, Oxford University Press, 2012, 3rd ed.), pp. 2110-2137; R. H. Lauwaars, ‘The Interrelationship between United Nations Law and the Law of Other International Organizations International Law’, Vol. 82 Michigan Law Review 1984, pp. 1605-1607; R. Liivoja, ‘The Scope of the Supremacy Clause of the United Nations Charter’, Vol. 57, No. 3 I.C.L.Q. 2008, pp. 583-612; N. Krisch, ‘Chapter VII. Action with Respect to Threats to the Peace, Breaches of the Peace, and Acts of Aggression’, in B. Simma et al. (eds.), The Charter of the United Nations: A Commentary (Oxford, Oxford University Press, 2012, 3rd ed.), pp. 1262 and 1340; N.D. Sarooshi, The United Nations and the Development of Collective Security: the Delegation by the UN Security Council of its Chapter VII Powers (Oxford, Oxford University Press, 1999, Repr ed.), pp. 149-151; V. Gowlland-Debbas, ‘The Limits of Unilateral Enforcement of Community Objectives in the Framework of UN Peace Maintenance’, Vol. 11 E.J.I.L. 2000, pp. 361-383, pp. 370-371; R. McLaughlin, ‘The Legal Regime Applicable to Use of Lethal Force when Operating under a United Nations Security Council Chapter VII Mandate Authorising All Necessary Means’, Vol. 12 J.C.S.L. 2007, pp. 389-418, pp. 389-402; B. Fassbender, ‘The United Nations Charter As Constitution of the International Community’, Vol. 36 Columbia Journal of Transnational Law 1998, pp. 529-618, pp. 577-578 and 590-594; and A. Orakhelashvili, ‘The Acts of the Security Council: Meaning and Standards of Review’, in A. von Bogdandy et al. (eds.), Max Planck Yearbook of United Nations Law (Leiden, Koninklijke Brill, 2007), pp. 149-151. Back
103 Peremptory norms of international law, also referred to as ius cogens, are higher rules of public international law which protect those values and interests which are fundamentally important to the international community as a whole, see A. Orakhelashvili, ‘The Impact of Peremptory Norms on the Interpretation and Application of United Nations Security Council Resolutions’, Vol. 16 E.J.I.L. 2015, pp. 59-88, p. 62. Back
104 See ICJ, Case Concerning Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v Yugoslavia (Serbia and Montenegro), Order, 13 September 1993, I.C.J. Rep. 1993, p. 32, Separate Opinion of Judge Sir Lauterpacht, p. 440 (Judge Lauterpacht argued the following: “The concept of jus cogens operates as a concept superior to both customary international law and treaty. The relief which Article 103 of the Charter may give the Security Council in case of conflict between one of its decisions and an operative treaty obligation cannot - as a matter of simple hierarchy of norms - extend to a conflict between a Security Council resolution and jus cogens. Indeed, one only has to state the opposite proposition thus - that a Security Council resolution may even require participation in genocide - for its unacceptability to be apparent”). See also further case law as referred to by Leiæ et al., supra note 102, p. 2119, fn. 53. Back
105 For further support, see also HRC’s General Comment No. 36 on the Right to Life, UN Doc. CCPR/C/GC/36, supra note 9, § 68; AComHPR’s General Comment No. 3 on the Right to Life, supra note 9, § 5; UN Economic and Social Council, Report on the Protection of Human Rights in Chile, Thirty-seventh session, agenda item 12, UN Doc. A/37/564, 4 November 1982, § 22; P. W. Gormley, ‘The Right to Life and the Rule of Non-Derogability: Peremptory Norms of Jus Cogens’, in. B. G. Ramcharan (ed.), The Right to Life in International Law (Dordrecht; Boston, M. Nijhoff, 1985), pp. 121 et seq.; L. Hannikainen, Peremptory Norms (Jus Cogens) in International Law: Historical Development, Criteria, Present Status (Helsinki, Finnish Lawyers Pub. Co, 1988), pp. 514-520; C. Heyns and T. Probert, ‘Securing the Right to Life: A Cornerstone of the Human Rights System’, EJIL! Talk, 11 May 2016, https://www.ejiltalk.org/securing-the-right-to-life-a-cornerstone-of-the-human-rights-system/; K. Parker, ‘Jus Cogens: Compelling the Law of Human Rights’, Vol. 12 No. 2 Hastings International and Comparative Law Review 1989, pp. 411-464, pp. 431-432; I. Couzigou, ‘The United Nations Security Council Sanctions and International Human Rights’, Vol. 10 No. 3 Vienna Journal on International Constitutional Law 2016, p. 304; E. M. K. Uhlmann, ‘State Community Interests, Jus Cogens and Protection of the Global Environment: Developing Criteria for Peremptory Norms’, Vol. 11 No. 1 Georgetown International Environmental Law Review 1998, pp. 101-136, pp. 129-130; and E. Klein, ‘Establishing a Hierarchy of Human Rights: Ideal Solution or Fallacy’, Vol. 41 No. 3 Israel Law Review 2008, pp. 477-488. p. 482. However, not all authors agree, see e.g. T. Weatherall, Jus Cogens: International Law and Social Contract (Cambridge, Cambridge University Press, 2015), Chapter 11, [page numbers not available in online version]. Back


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force that has no clear nexus with an ongoing armed conflict or that is used outside an armed conflict by State agents must comply with the rules and principles of human rights law discussed above, such as necessity, proportionality, and precautions to take all necessary measures to prevent arbitrary deprivation of life. 106 By contrast, in the event of a conflict between a UNSC Resolution and an obligation which is not peremptory in nature and is imposed by a human rights law or international humanitarian law treaty, the UNSC Resolution will prevail.

It is not only important to understand where self-defence ends and mission accomplishment begins, but also to grasp their relationship with the law enforcement and conduct of hostilities paradigms. The San Remo Handbook on Rules of Engagement explicitly distinguishes between self-defence, law enforcement, and mission accomplishment. It holds that “[b]roadly speaking, during peacetime, the use of force is permitted in self-defence, in the exercise of law enforcement authority, and to accomplish operations or missions specifically authorised by a higher national authority or other governing body, such as the U.N. Security Council”. 107 In other words, it recognizes the operational necessity of having rules which explicitly permit the use of force for mission accomplishment. The aforementioned human rights law treaties and non-binding UN Basic Principles for the Use of Force and Firearms, conversely, do not explicitly refer to the use of force to accomplish the mission. The ECHR and the UN Basic Principles for the Use of Force and Firearms do make a distinction between (i) use of lethal force in personal self-defence and defence of others and (ii) use of lethal force to carry out law enforcement tasks. “Law enforcement tasks” should be distinguished from missions which operate under the “law enforcement paradigm”. Military operations which carry out “law enforcement tasks” only concern missions which are tasked with maintaining or restoring public security, rule of law, and internal order (either on the basis of a UNSC mandate or the consent of the host State). By contrast, the law enforcement paradigm can be understood as a paradigm which not only concerns the use of force for law enforcement in the strict criminal sense, but more broadly the use of force to exercise authority or power over individuals, objects, or territory. 108 It concerns for example the use of military force as a last resort in the context of a contemporary multinational operation deployed in a situation short of armed conflict.

As mentioned above, legal doctrine commonly distinguishes between two paradigms, being the law enforcement paradigm (mainly derived from human rights law) and the conduct of hostilities paradigm (mainly derived from international humanitarian law) (see Section I). Under both paradigms, use of force for mission accomplishment can be used, be it under different conditions. International humanitarian law generally allows for the use of force against legitimate targets to accomplish a mission provided that, among others, the principles of distinction, precaution in the attack, and prohibition of excessive collateral damage are respected (see section II.1). Under human rights law, military forces can use force to achieve tasks, purposes, and objectives as consented to by the host State or as set out in a

106 Assuming one accepts that the obligations under human rights law apply to the given situation (see inter alia the discussion on the extraterritorial application of human rights law treaties in fn. 19, 20, and 32. Back
107 International Institute of Humanitarian Law, Sanremo Handbook on Rules of Engagement (San Remo, International Institute of Humanitarian Law, 2009), p. 4. Back
108 Boddens Hosang, supra note 88, pp. 264-265; and Watkin, supra note 15, p. 460. Back


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mandate of a competent organ of an international organization conducting the operation, provided that the principles of necessity, proportionality, and precaution are respected. Yet, when the force is lethal in nature, it can only be used if such force is “strictly unavoidable”, “strictly necessary”, or “absolutely necessary” to achieve a legitimate aim. A legitimate aim for the use of lethal force is for example to defend others or to quell an insurrection. When lethal force is used intentionally, it can, however, only be used to protect one’s own life or the lives of others from imminent threat.

In contrast to the concept of mission accomplishment, self-defence is merely a subset of the law enforcement paradigm. 109 Although self-defence and international humanitarian law may well co-exist, they should not be conflated. 110 Neither should self-defence be considered a “third paradigm” alongside the conduct of hostilities and law enforcement paradigms. 111 Any use of force that has a clear nexus with an armed conflict is governed by the rules and principles of international humanitarian law. Resorting to self-defence is such occasions would be unnecessary or even inapplicable. 112

IV. Do the Current Legal Regimes Provide for Useful and Sufficient Legal Grounds for the Use of Force for Mission Accomplishment?

Unlike international humanitarian law, human rights law appears to be less adapted to govern situations in which multinational operations are, for example, charged with carrying out complex missions in a volatile environment where they face “transnational” threats posed by organized armed groups. To understand why, we must go back to its origin. International and domestic human rights law came into place to restrict the “internal” resort to force by State authorities against their own citizens in order to maintain or restore public security, the rule of law, and internal order (also identified as law enforcement tasks). 113 Hence, States did not necessarily aim to use human rights law to regulate the use of force in response to “transnational” security threats. In contrast, international humanitarian law was initially developed to limit the impact of “external” inter-State warfare. Thus, instead of focusing on the imposition of limits on the use of force by State agents against its own civilians, States mainly aimed to regulate humanitarian issues in time of armed conflicts and limit the detrimental effects of armed conflict. While international humanitarian law recognizes the need for the authorization of a more permissive use of force, which increases the risk of collateral damage, 114 the level of force permitted under human rights law is much lower and collateral death and injury is far less accepted. Moreover, human rights law is more generally threat or conduct based, 115 as opposed to international humanitarian law which is more generally status based. 116 The latter regime permits belligerent parties to use lethal force against legitimate targets as a first resort. Under the former regime, the use of military force in

109 Gaggioli, ‘The Use of Force in Armed Conflicts Conduct of Hostilities, Law Enforcement, and Self-Defense’, supra note 5, pp. 87 and 106. Back
110 Id., p. 80. Back
111 Id., p. 87. Back
112 Id., p. 81. Back
113 Gaggioli, The Use of Force in Armed conflict: Interplay between the Conduct of Hostilities and Law Enforcement Paradigms, supra note 5, p. 7; and Watkin, supra note 15, pp. 450-451. Back
114 Watkin, supra note 15, p. 449. Back
115 For example, if a civilian threatens to use lethal force against a police officer in a law enforcement situation, the police officer can use lethal force in self-defence against that civilian on the basis of the threat that civilian is posing to the police officer’s life. Back
116 For example, if an individual is a soldier of the armed forces of the adversary, lethal force can be used against him or her on the basis of his or her status, provided that, among others, the principles of precaution in the attack and prohibition of excessive collateral damage are respected. Nevertheless, the use of force under international humanitarian law is also often threat or conduct based. For example, when a civilian is taking a direct part in hostilities, lethal force can be used against this civilian on the basis of his or her conduct. See also Watkin, supra note 15, p. 448. Back


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response to a certain threat should in principle occur only as a last resort, after the exhaustion of all alternatives and in strict obedience to the rule of law and preservation of human life.

Nevertheless, in contemporary situations, the question arises whether proactive force (i.e. force against a threat which is not necessarily imminent in nature) may be used to accomplish missions. For instance, when intelligence gathering is able to assess, with a high level of certainty, that individuals are planning an attack in the distant future which will have a clear nexus with an international armed conflict, international humanitarian law leaves room for a number of acts. If these individuals are civilians taking a direct part in hostilities, lethal force can be used against them on the condition that the persons are, at the time of attack, actively engaged in the conduct of hostilities. If these individuals are members of a recognized and identified organized armed group, status based lethal force can be used against them, even irrespective of any intelligence as to the group’s plans. However, if this attack has no clear nexus with an armed conflict or takes place outside an armed conflict, we must question whether we can consider the planning and deliberation of the attack in the distant future to be an imminent threat to life and limb which absolutely necessitates lethal force. 117 When observing the conditions set forth above, it seems highly unlikely that the threat may qualify as an imminent threat to life which immediately necessitates lethal force. Moreover, even if the threat can be qualified as such, it may be extremely difficult to identify which members of the organized armed group are posing this threat. In reality, the threat posed by an organized armed group is often an overall threat which goes beyond an individualized threat at the point of attack. Nonetheless, to successfully accomplish the mission, this threat may require a more proactive use of force to neutralize the threat before it manifests itself.

At this stage, we need to consider the different possible options that would allow us to effectively address such situations that have no clear nexus with an armed conflict or that take place outside an armed conflict.

The first option is to develop a new legal framework which allows for the possibility to use lethal force for mission accomplishment in situations which do not necessarily rise to the level of an international or non-international armed conflict but are nevertheless volatile in nature. This option can be referred to as “the third paradigm” (alongside the conduct of hostilities paradigm and the law enforcement paradigm), by which a UNSC Resolution could for example authorise the use of lethal force to successfully carry out the mandate, even where such use of force is not in self-defence or has a clear nexus with an armed conflict. 118 Both “traditional” law enforcement situations and conduct of hostilities situations are governed by their own set of specific rules. Instead of simply superimposing legal regimes developed for other purposes, one may argue it is time to reflect on the conceptualization of a sui generis specific legal framework to regulate individual rights and rules for the use of force for mission accomplishment in situations that fall below the threshold of an armed conflict but in which forces are confronted with considerable transnational or humanitarian security threats.

Last May 2018, the Supreme Court of Israel dismissed a petition brought by a group of Israeli non-governmental organizations (NGOs) in which they addressed the ROE governing the use of force by Israeli security forces in the arena of the security barrier between the Gaza strip and Israel. 119 In order to explain its position, the Israeli Government came up with a “legal innovation” giving some substance to the de facto existence of a third paradigm. In particular, it claimed that there is a separate law

117 Id., p. 456. Back
118 McLaughlin, supra note 102, pp. 391-392. Back
119 Supreme Court of the State of Israel, Yesh Din – Volunteers for Human Rights v. The IDF Chief of Staff, HCJ 3003/18 and HCJ 3250/18, 24 May 2018, Judgment, English translation available at https://supreme.court.gov.il/sites/en/Pages/FullCase. aspx?&CaseYear=2018&CaseNumber=3003. Back


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enforcement regime embedded in international humanitarian law. 120 This regime is “inspired by,” but not similar to, the law enforcement regime known under human rights law. 121 Lieblich translated part of the Israeli government’s response in which they argued the following:
[W]ithin the framework of the [...] [international humanitarian law]-law enforcement paradigm, potentially lethal force can be used when there is concrete threat to life or limb. This threat can be posed by a single individual, or by masses of individuals. Resort to force must be subject to several conditions: the use of non-lethal measures to address the threat has been exhausted… there is necessity to use potentially lethal force to address the threat (meaning, there are grounds to assume that use of force is required at the time to address the threat before it materializes, even if the danger itself is not immediate), [and force must be proportionate]. 122
Although the Israeli Supreme Court never scrutinized the relevant ROE itself, it unanimously dismissed the petition through which the NGOs sought to invalidate any ROE that empower the Israeli security forces to use lethal force against protestors in Gaza unless they pose an imminent and actual threat to life. 123 The third paradigm proposed by the Israeli government differs from the third paradigm discussed above. Where the Israeli government suggests that two distinct paradigms co-exist within the framework of international humanitarian law, the third paradigm suggested above concerns a paradigm which would exist alongside the conduct of hostilities paradigm and the law enforcement paradigm and would be governed by a sui generis legal regime.

Nonetheless, the development of any kind of “third paradigm” seems to be fraught with uncertainty and may result in the impermissible use of force against individuals. It is nevertheless our duty to at least reflect on the conditions of deconfliction of domestic and international legal orders and reconciliation of the principles of human rights law and international humanitarian law, without the risk of imposing unrealistic obligations on the forces contributed by States. As argued by McLaughlin, in order to contain such a risk, “any assertion that there exists a nascent third paradigm […] is unhelpful unless it details precisely what aspects of law governing the use of lethal force operate by force of law within that paradigm, and how it is that they can be said to be applicable as a matter of law”. 124 That being said, there is little doubt that States involved in hybrid transnational actions are already taking the necessary initiatives to regain their strategic freedom. They do so through the adoption of domestic legislative measures extending, for example, the conditions of use of force in peacetime, at the risk of creating strong inconsistencies with other rules laid down in international law.

The second possible option would consist of accepting the existing legal framework, but interpreting the permissible grounds for the deprivation of life in a less stringent manner. The existing legal framework may be exerted as such as to provide for the necessary flexibility to match current legal requirements with actual operational constraints. The attainment of such flexibility could for example involve a return to the initial rule that “no one shall be arbitrarily be deprived of his or her life” as provided for under Article 6(1) of the ICCPR, Article 4(1) of the ACHR, or Article 4 of the ACHPR without adopting the strict approach that intentional use of lethal force may only be used to protect life (see above, Section II.2.A). The permissible grounds for the deprivation of life could be interpreted in such a way that military forces could intentionally use necessary and proportionate lethal force for the achievement of tasks, purposes, and objectives as consented to by the host State or as set out in a mandate of a competent organ of an international organization conducting the operation. Another possibility may include the

120E. Lieblich, ‘Collectivizing Threat: An Analysis of Israel’s Legal Claims for Resort to Force on the Gaza Border’, Just Security, 16 May 2018, https://www.justsecurity.org/56346/collectivizing-threat-analysis-israels-legal-claims-resort-force-gaza-border/. Back
121 Id. Back
122 Id. Back
123 Supreme Court of the State of Israel, Yesh Din – Volunteers for Human Rights v. The IDF Chief of Staff, HCJ 3003/18 and HCJ 3250/18, 24 May 2018, Judgment, § 2, see link supra note 119. See also E. Chachko and Y. Shany, ‘The Supreme Court of Israel Dismisses a Petition Against Gaza Rules of Engagement’, Lawfare, 26 May 2018, https://www.lawfareblog.com/supreme-court-israel-dismisses-petition-against-gaza-rules-engagement. Back
124 McLaughlin, supra note 102, p. 409. Back


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development of a concept of anticipatory self-defence, defence of others or defence of the mandate. This could reconcile the use of force as described in both existing legal paradigms with the operational needs for flexibility in the use of force for mission accomplishment. Last but not least, the possibilities to derogate from certain human rights as referred to for example in Article 15 of the ECHR could be extended. In particular, it could be considered to allow for the derogation from the right to life under certain circumstances. Yet, unless these initiatives find strong support in both jurisprudence and practice, these different possibilities continue to expose States to the restrictive decisions by human rights courts and international human rights mechanisms. Moreover, in line with what has been said with respect to the first option, the adoption of such a pliable set of rules may lead to manipulation depending on the needs of the moment and hence in the impermissible use of force against individuals.

The third option consists of accepting the existing legal framework and the strict limits it poses to the use of force for mission accomplishment, while simultaneously exploring the use of possible non-lethal means. Under the current legal framework, intentional use of lethal force can only be used against imminent threats which absolutely necessitate the use of such force to protect life. Nevertheless, there are still many possible ways to use force which are not lethal in nature. As stated above, in principle, necessary and proportionate force which is not lethal in nature can be used to achieve tasks, purposes, and objectives as consented to by the host State or as set out in a mandate of a competent organ of an international organization conducting the operation, provided that it complies with any additional body of applicable law (see Section II.2.B). Let us return to the initial example of the non-combatant evacuation operation discussed in the introduction whereby insurgents attempted to raise a blockade on a road which was vital for the evacuation of the identified civilians to a secure location. When there is no clear nexus with an armed conflict, the forces belonging to the multinational operation will not be able to intentionally use lethal force to get through the road blockade or prevent armed groups from raising the blockade unless it is absolutely necessary to protect their own life or the life of others. The forces can, however, always undertake a number of other actions to enable the evacuation of the villagers. For example, they could employ non-lethal options such as tear gas, baton rounds or pellets, intercept and arrest individuals intentionally threatening the swift accomplishment of the mission, or try to circumvent the road blockade. If the situation escalates to the extent there is a need to protect life against imminent threat, the military forces are authorized to use intentional lethal force to respond to this threat. Having said this, many States and their armed forces are still confronted with a number of difficulties in this regard. First, it requires enhanced legal training of legal advisers and increased awareness among the military command to identify whether the conduct of hostilities paradigm or the law enforcement paradigm applies to a given situation. Second, in the drafting process of ROE, the conditions under which the relevant rules apply, need to be clearly identified. In other words, they need to allow for a clear distinction between the conduct of hostilities paradigm or the law enforcement paradigm. Third, it requires a flexible way of thinking, extensive training of forces, and adequate preparation of military operations to quickly switch from one paradigm to the other and respect the relevant legal constraints on the use of force for mission accomplishment as the situation requires.

V. Conclusion

States are increasingly deploying troops in volatile situations that do not necessarily rise to the level of an international or non-international armed conflict, but which do present the troops with a threat significant enough that it can severely impede the successful accomplishment of the mission. In such situations, legal advisers are frequently asked to what extent (lethal) force can be used. After all, it remains often unclear in which manner and circumstances force may be used and where self-defence stops and mission accomplishment begins. Some States interpret the right to self-defence rather broadly in their respective domestic laws and regulations and will allow their contingents to use force in self-defence reaching a fairly high level of engagement. Other States have adopted a rather strict interpretation of the right to self-defence. Their forces will have to be provided with ad hoc authority expressed in the form of specific mission accomplishment ROE when the use of force exceeds their domestic interpretation of self-defence. Having said that, although States or regional organizations can adopt more narrow approaches of self-defence, the outer limits of permissible use of force are



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nevertheless determined by the relevant legal regimes. In other words, neither States nor international organizations can broaden the possibilities in which force can be used under human rights law or international humanitarian law, unless the UNSC authorized lawful derogation thereof pursuant to Article 103 of the UN Charter.

Any force which has a clear nexus with an ongoing armed conflict is mainly governed by international humanitarian law. Once operating outside the conduct of hostilities, the use of force is mainly governed by human rights law. Unlike international humanitarian law, human rights law considerably restricts the use of force which is lethal in nature. Therefore, we considered whether the law as it is still provides for enough margin to effectively govern contemporary conflicts or whether we should develop a “third paradigm” (alongside the conduct of hostilities paradigm and the law enforcement paradigm) to fill the gap.

It is doubtful that clarity will be given in the near future on the potential emergence of a third paradigm for the use of force, which would allow the use of force – including lethal force not only as a last resort – below the threshold of an armed conflict and beyond self-defence. Moreover, the possibility for States to develop permissible grounds for the deprivation of life in a less stringent manner is also an option, but would nevertheless continue to expose these States to the restrictive decisions by human rights courts and institutions. Besides, both options may lead to abusive and hence impermissible use of force against individuals. Meanwhile, there is still the possibility to go a long way with accepting the existing legal framework and the strict limits it poses to the use of force for mission accomplishment, while simultaneously exploring the use of possible non-lethal means. This option still leaves some room for action when operating below the threshold of an international or non-international armed conflict. Military forces can use non-lethal force to achieve tasks, purposes, and objectives as set out in the mandate in so far as it complies with the principles of necessity, proportionality, and precaution, as well as any additional body of law that applies in the circumstances. This may, for example, involve the use of non-lethal force for patrol, control, dispersion, interception or arrest. While such non-lethal means can be used in the first place to accomplish the mission, lethal force can still be used intentionally if the situation escalates to the extent there is a need to defend oneself or others against the imminent threat to life.



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