ESSEX PAPER 3: INITIAL GUIDANCE ON THE INTERPRETATION AND IMPLEMENTATION OF THE UN NELSON MANDELA RULES While a distinction is often made between the use of force, arms, firearms and restraints, and specific standards are applicable to them, a number of principles apply to all uses of force and other coercive measures. These are: •  principle of legality •  principle of necessity •  principle of proportionality •  relevance of classification, prisoner file management, conflict prevention and dynamic security •  documentation of use •  training •  accountability. In order to be permissible the use of force or arms must be ‘used only in exceptional circumstances, when strictly necessary as specified by law’.422 The experts recommended policymakers provide written regulations setting out which different force options can (and cannot) be used, the criteria for their deployment and the risks that accompany their use. Providing clear guidance on different use of force options has been shown to influence significantly their use in practice.423 The principle of necessity means that force or arms should be used ‘only when less extreme means are insufficient’ to achieve the objective. Basic Principle 4 of the BPUFF states that law enforcement officials shall ‘as far as possible, apply non-violent means before resorting to the use of force and firearms’ and may use them ‘only if other means remain ineffective or without any promise of achieving the intended result’. Basic Principle 5 uses the term ‘unavoidable’,424 and the Special Rapporteur on Torture refers to the concept of ‘last resort’.425 The experts stressed that factors such as a sufficient prisoner-staff ratio and adequate training of officers play a role when determining the necessity of such an intervention. They further recalled the relevance of conflict prevention and mediation as alternatives to physical intervention.426 The experts noted that the use of force, arms and/or restraints may increase rather than decrease the number and severity of incidents. As captured in the 2010 Survey of the UN and other best practices in the treatment of prisoners in the criminal justice system: Special Rapporteur on Torture report 2013, A/68/295, para. 58. 422  For example, when the Dallas Police implemented a more ‘restrictive’ policy on conducted energy weapons, the use of these weapons ‘dropped significantly’ (Stephen Bishopp, David Klinger and Robert Morris, ‘An Examination of the Effect of a Policy Change on Police Use of TASERs’, Criminal Justice Policy Review, Vol. 26 No. 7, October 2015, p. 737) 423  Basic Principle 5 of the Basic Principles on the Use of Force and Firearms by Law Enforcement Officials. 424  Special Rapporteur on Torture report 2013, A/68/295. para. 58. 425  Rule 38(2) in this context as it encourages, ‘to the extent possible, conflict prevention, mediation or any other alternative dispute resolution mechanism’ (although in the context of disciplinary measures), and of Rule 76(c) which encourages the use of the concept of dynamic security. (See Chapter 2, Prison management – Dynamic security and conflict prevention.) 426  Penal Reform International and the Essex Human Rights Centre | 108