PART III.  INSTRUMENTS OF FORCE Law enforcement agencies should therefore ensure that they only use RCAs which are scientifically tested and that they review the impact of their use. In cases where the riot agent is found to have long-lasting effects, an analysis needs to determine whether long-term effects can be prevented through better supervision and training or whether the use of a particular type of riot control agent should be discontinued.186 Chemical irritants in a handheld device are widely used by law enforcement officials around the world. This is usually placed at the lower end of the scale of force and in most countries law enforcement officials have broad discretion over its use. Such devices are employed at close range where the suspect is sprayed in the face in order to temporarily disable or disorient him or her. It can be used for up to 4 metres but optimum accuracy will be achieved over a distance of 1.25 to 2 metres. The PSNI manual, for example, states that the spray should not be used under following circumstances: • At a distance of less than one metre • In an enclosed area (e.g. a car) • On a subject who is restrained or handcuffed • As a crowd dispersal tactic (due to the possibility of other officers and innocent bystanders being affected) • In all aforementioned cases, “officers must be prepared to justify not only their use of the spray, but also their decision to use it in these circumstances”. It can take up to one minute before its effects are noticeable, and they can last for hours. Risks and how to mitigate these The use of chemical irritants entails the risk of harming oneself or others, including other law enforcement officials.187 A chemical irritant is not always effective and may lead to more resistance or aggression on the part of the subject. It should not be used against someone who is armed as it may lead to him or her to start firing indiscriminately. As the PSNI manual states that “if the firearm is merely close at hand, the spray may be useful in preventing a subject actually arming themselves. Because of the extreme dangers, use in such circumstances should be carefully considered”. It should not be used against someone who is driving, either. These sprays can be used against violent offenders, other than those armed with firearms or similar remote injury weapons, where failure to induce “immediate” incapacitation would increase risks to all those present at the scene. In Northern Ireland, the PSNI acknowledge that the handheld sprays are open to abuse, and therefore their manual starts with stating that any abuse of these devices may amount to assault and lead to further internal or external investigations. Tear-gas cartridges and grenades are designed to be used for dispersing groups that present an immediate and direct threat and when conventional methods of policing have been tried and have failed, or are unlikely to succeed. 186  OHCHR, Human Rights and Law Enforcement, A Manual on Human Rights Training for Law Enforcement Officials, 2017, chapter 5. 187  See also OHCHR, Human Rights and Law Enforcement, A Manual on Human Rights Training for Law Enforcement Officials, 2017, chapter 5 (Human Rights and Use of Force). 87