PART III.  INSTRUMENTS OF FORCE • Always ensure that only experienced and trained LEOs are allowed to launch riot control agents. • Always document the use of riot control agents, including type, amount and reason for use of force. • Always conduct effective investigations and apply accountability measures into and for misuse of riot control agents and analyse the cause of any shortcomings of standard operating procedures, trainings or orders. Another use of chemical irritants is a tear gas or pepper spray that is shot or thrown into a confined area to conduct an arrest of a person who can reasonably be expected to have firearms ready for use, or otherwise poses a great threat to life or limb. In such instances, the use of the chemical is meant to prevent the subject from firing a gun, detonating a bomb or otherwise creating an imminent threat of death or serious injury. Tactically this is a risky option, as gas can be relatively slow to incapacitate an individual, allowing the suspect to cause harm as long as the effects have not set in. It is also difficult to estimate the exact dosage required, because if the dosage used is too high, it may be lethal, and if it is too low, it may fail to incapacitate the suspect. Due to unpredictability, any use of chemical irritants should be monitored, for example by the National Human Rights Institution (NHRI), including on its long-term medical effects.190 WHEN TO USE TEAR GAS? a In The Netherlands, during riots in a small village which totally overwhelmed the police, it was decided not to use tear gas because there were insufficient riot police to “go forward”, because there were many under-aged youngsters, and also because the riots took place in an area where many people lived so there was a great risk it would cause harm to the residents who had nothing to do with the riots. Indeed, tear gas should not be used in every situation to disperse a crowd, even when it is rowdy, and its use should always be based on a careful analysis of the situation at hand. a Otto M. J. Adang and Tom van Ham, “Contextual and Individual Factors Determining Escalation of Collective Violence: Case Study of the Project X-Riot in Haren, the Netherlands”, British Journal of Criminology, 5 April 2015. Water cannon Description and use A water cannon is exactly what the name implies: a cannon that “fires” a large volume of water over dozens of metres. It is used in some countries to disperse a violent crowd, to control the movement of a crowd, or to keep a crowd at a distance. Indeed, “the mere presence of a water cannon can have a deterrent effect and experience from Northern Ireland demonstrates that water cannons are often deployed without being employed”.191 190  See Omega Research Foundation, Briefing for the Special Rapporteur on extrajudicial, summary or arbitrary executions on the Use of Lethal Force during Arrest, 2011. 191  See ACPO and College of Policing, National Water Canon Asset, 2014: https://www.london.gov.uk/sites/ default/files/ACPO%20Water%20Cannon%20Briefing%20Document,%20Jan%202014_0.pdf 89