31 7.3.7 In general, chemical irritants should not be used in confined spaces, such as prison cells,93 where there is no viable exit or adequate ventilation, owing to the risk of death or serious injury from asphyxiation. Low cross-contamination irritants (e.g. PAVA) may be better suited to this application. 7.3.8 Chemical irritants that contain hazardous levels of active agents shall not be used. Where an irritant is found to have had long-term negative effects on individuals, it should be determined whether these effects may be prevented through better supervision and training of law enforcement officials or whether the use of the particular type of agent should be discontinued. Associated chemicals (for example, combustion products from pyrotechnic devices) may also have toxic effects. Accordingly, any toxic effects of active or associated chemicals should be assessed and tested. Law enforcement agencies should use irritants with the lowest level of toxicity that is still likely to be effective. 7.4 CONDUCTED ELECTRICAL WEAPONS (“TASERS”) 94 UTILITY AND DESIGN 7.4.1 Conducted electrical weapons are typically used to deliver pulses of electrical charge that cause the subject’s muscles to contract in an uncoordinated way, thereby preventing purposeful movement. This effect has been termed “neuromuscular incapacitation”. The charge is delivered through metal probes that are fired towards the subject but which remain electrically connected to the device by fine wires. During the period of uncoordinated muscle activity, law enforcement officials are able to intervene to restrain the subject using conventional methods, such as handcuffs. Many models use compressed nitrogen to fire two darts that trail electric cable back to the weapon’s handset. When the darts strike the human body, pulses of highvoltage charge pass down the cable.95 OHCHR, Human Rights and Law Enforcement: A Manual on Human Rights Training for Law Enforcement Officials, chap. 5. 94 TASERTM is a market-leading brand of conducted electrical weapon. The term “taser” is sometimes used generically to describe this type of weapon. 95 One manufacturer of a conducted electrical weapon claimed that only 1,200 volts enter the victim’s body; see US Court of Appeals (Ninth Circuit), Bryan v. McPherson, Opinion (Case No. 08–55622), 28 December 2009, para. 2 and note 4. 93