A/72/178 law. 5 In particular, the use of force by State agents is governed by the followin g cumulative principles: • Legality: any use of force must have a legal basis and pursue a lawful purpose . 6 • Necessity: force must only be used when, and to the extent, strictly necessary for the achievement of a lawful purpose. 7 • Proportionality: the harm likely to be inflicted by the use of force must not be excessive compared to the benefit of the lawful purpose pursued. 8 • Precaution: law enforcement operations must be planned, prepared and conducted so as to minimize, to the greatest extent possible, the resort to force and, whenever it becomes unavoidable, to minimize the resulting harm. 9 6. In order for the use of force by State agents to be lawful, full adherence to all of the above principles is required. A. Principle of legality 7. According to the principle of legality, any use of force by State agents must pursue a lawful purpose and must be based on and regulated by national law. 10 Lawful purposes typically include effecting the arrest or preventing the escape of a person suspected of having committed a crime, self-defence or defence of others against an unlawful threat of death or serious injury, or dispersing violent assemblies. A further parameter of legality is the equal treatment of all persons before the law in accordance with the principle of non-discrimination (see A/HRC/26/36, para. 74, and A/HRC/31/66, para. 15). States must provide express authority for the use of force in their national law and must regulate the matter in line with their obligations under international law. B. Principle of necessity 8. The principle of necessity requires that any use of force by State agents must be restricted to the least harmful means that can reasonably be expected to achieve the purpose pursued. Thus, law enforcement officials must apply non -violent means whenever possible and may use force only when, and only to the extent, strictly necessary to achieve a lawful purpose. 11 9. The principle of necessity has a qualitative, a quantitative and a temporal aspect. In qualitative terms, any use of force must be “unavoidable” in the sense that non-violent or other less harmful means remain ineffective or without any promise of achieving the desired purpose. 12 In quantitative terms, whenever the use of force __________________ 5 6 7 8 9 10 11 12 6/24 For an in-depth analysis of the use of force principles in law enforcement, see Nils Melzer, Targeted Killing in International Law (Oxford, Oxford University Press, 2008), pp. 83-239. See also A/HRC/26/36, paras. 59-73; A/HRC/31/66, paras. 50-66; International Committee of the Red Cross (ICRC), “Violence and the use of force”, September 2015, chap. 2; and Stuart Casey Maslen and Sean Connolly, Police Use of Force under International Law (Cambridge, United Kingdom, Cambridge University Press, 2017), chap. III. Code of Conduct, art. 8, and Basic Principles, principle 1. See also ICRC, “Violence and the use of force”, p. 17. Code of Conduct, art. 3, and Basic Principles, principle 4. Code of Conduct, art. 3, and Basic Principles, principle 5 (a). Basic Principles, principles 2, 3 and 5 (a) and (b). Ibid., principle 1. See also A/HRC/26/36, para. 56. Code of Conduct, art. 3, and Basic Principles, principle 4. Basic Principles, principles 4 and 5. 17-12326