84 Resource book on the use of force and firearms in law enforcement conditions known as positional asphyxia and acute behavioural disturbance.177 Because of the medical risks to a person who is restrained this way, limb restraints should only be used in exceptional circumstances and they should be easy to remove. In addition, ACPO states that any device adopted should be medically reviewed to minimize the potential of injury to the person.178 Metal limb restraints, such as leg cuffs or chains that connect the limbs with chains to handcuffs and belts, should be avoided. Soft restraints should always be preferred, in line with the Nelson Mandela Rules. There should be an absolute prohibition on weighted restraints, and also of nonadjustable ones such as fixed rings, leg irons, fetters or shackles. Hog-tying, that is tying someone’s hands and legs together at the back, should not be used given the unnecessary discomfort and suffering it causes, as well as the risk of asphyxiation it poses. Hog-tying may amount to cruel, inhuman and degrading treatment or punishment. Dogs and horses Description and use In law enforcement dogs are used either to search for people or goods (e.g. explosives, drugs), or as an instrument of force. This section will only look at using dogs as an instrument of force. Dogs are typically used to assist in the search, pursuit, apprehension and detention of a subject who is actively resisting his or her arrest or assaulting the official; to disarm a suspect armed with a firearm or other weapon; to guard and escort suspects after arrest; to defend against attack; and to protect members of the public and property.179 In some countries dogs can only be used against (alleged) offenders of serious violent crimes. In addition, dogs can be deployed as a deterrent in situations of general disorder. They can also be used to support cordons, escort marches/groups, assist with the dispersal of a crowd or to help arrest or detain someone.180 Dogs should not be used in an offensive role in a public order situation. Deployment of dogs in a public order situation is dependent on the tactical plan that has been drafted as a preparation for the event that clearly specifies what they are to be used for and under what conditions. Risks and how to mitigate these It is essential that the capabilities and limitations of using dogs are fully understood prior to their deployment. The dog(s) and their handler(s) need to be well-trained and the advice of the handler should be sought prior to deployment. The dog-handler combination should be certified. When deployed, dogs can be either muzzled or unmuzzled, on or off leash, each option obviously having a different impact and varying levels of risk. Dogs should be trained to “find-and-bark” rather than “find-and-bite”. 177  See PSNI Manual of Policy, Procedure and Guidance on Conflict Management, chapter 7: Limb restraints: http://www.psni.police.uk/chapter_7_-_limb_restraints.pdf 178  See ACPO Guidance on the Use of Limb Restraints, 2009: http://www.acpo.police.uk/documents/uniformed/2009/200905UNGLR01.pdf 179  See Anneke Osse, Understanding Policing: a Resource for Human Rights Activists, Amnesty International, the Netherlands, 2006; ACPO Police Dogs Manual of Guidance, 2011: http://www.dyfed-powys.police.uk/media/1817/ police_dog_manual_of_guidance_2011_foi_version.pdf 180  See College of Policing, Tactical options, 2014.