ESSEX PAPER 3: INITIAL GUIDANCE ON THE INTERPRETATION AND IMPLEMENTATION OF THE UN NELSON MANDELA RULES close range).442. ‘Serious reservations’ have also been raised about the ‘the use of irritant gases443 [especially the alleged use of teargas] in confined spaces, as it may entail health risks and cause unnecessary suffering’.444 The experts recalled Basic Principle 2 of the BPUFF, which requires law enforcement agencies to ‘develop a range of means as broad as possible and equip law enforcement officials with various types of weapons and ammunition that would allow for a differentiated use of force and firearms’. These should include the development of non-lethal incapacitating weapons, while carefully controlling the use of such weapons and evaluating them to ‘minimize the risk of endangering uninvolved persons’.445 Where prison officials are provided with arms, Rule 82(3) is unambiguous in that officers should be trained in their use (see above). In this context, Basic Principle 20 calls for special attention to ‘ethics and human rights, (...), to alternatives to the use of force and firearms, including the peaceful settlement of conflicts, (... and) methods of persuasion, negotiation and mediation, as well as to technical means, with a view to limiting’ their use. Where arms are used in places of detention, they should be stored safely, with access only to those entitled and clear records (e.g. signing in and out of arms), providing accountability for the use of weapons. Use of firearms The commentary to Article 3 of the Code of Conduct emphasises that ‘the use of firearms is considered an extreme measure’ and that ‘Every effort should be made to exclude the use of firearms’. Situations which may prompt the use of firearms are described in Basic Principle 9 as ‘selfdefense or defense 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, (…) or to prevent his or her escape’. 446 However, the Essex group emphasised that a particular threshold applies for the use of lethal force, which can only ever be applied ‘when strictly necessary to protect a life’.447 The Basic Principles also clarify that ‘intentional lethal use of firearms’ may only be used ‘when strictly unavoidable in order to protect life’. Impact projectiles can be fired from a wide variety of weapons, and projectiles can be made of wood, rubber, plastic or other materials (e.g. fabric bags weighted with lead shot). Single and multiple projectiles can be fired including, for example, balls, segments, blocks or cylinders of wood, plastic or rubber (often referred to as ‘rubber bullets’). On impact they are designed to cause blunt trauma (i.e. non-penetrating trauma); however, they often cause serious injuries including lacerations, broken bones, concussion, head injuries or internal organ damage (Omega Research Foundation, Tools of torture and repression in South America: Use, manufacture and trade, June 2016, p. 16). 442  Chemical irritants are designed to deter or disable an individual, by producing temporary irritation of the eyes and upper respiratory tract. The most commonly used chemicals include CN or CS (commonly called tear gas) and OC/ Pepper and PAVA (commonly called pepper spray). Chemical irritants are delivered through hand-held aerosol sprays, hand-thrown grenades, weapon- launched projectiles/grenades, as well as via water cannon. (Omega Research Foundation, Tools of torture and repression in South America: Use, manufacture and trade, June 2016, p. 18).  443  For example, the UN Subcommittee on Prevention of Torture, has expressed “serious reservations about the use of irritant gases in confined spaces, as it may entail health risks and cause unnecessary suffering” (SPT Report on visit to Brazil, CAT/OP/BRA/1, para. 128.) 444  Principle 3 of the UN Basic Principles on the Use of Force and Firearms by Law Enforcement Officials. 445  Principle 9 of the UN Basic Principles on the Use of Force and Firearms by Law Enforcement Officials. The case of ‘arrest’ was not included here as not relevant in the detention context. 446  Principle XXIII (2) of the Principles and Best Practices on the Protection of Persons Deprived of Liberty in the Americas. 447  Penal Reform International and the Essex Human Rights Centre | 112