摘要：Objectives. We investigated the effect of the use of less-lethal weapons, conductive energy devices (CEDs), and oleoresin capsicum (OC) spray on the prevalence and incidence of injuries to police officers and civilians in encounters involving the use of force. Methods. We analyzed data from 12 police departments that documented injuries to officers and civilians in 24 380 cases. We examined monthly injury rates for 2 police departments before and after their adoption of CEDs. Results. Odds of injury to civilians and officers were significantly lower when police used CED weapons, after control for differences in case attributes and departmental policies restricting use of these weapons. Monthly incidence of injury in 2 police departments declined significantly, by 25% to 62%, after adoption of CED devices. Conclusions. Injuries sustained during police use-of-force events affect thousands of police officers and civilians in the United States each year. Incidence of these injuries can be reduced dramatically when law enforcement agencies responsibly employ less-lethal weapons in lieu of physical force. Police officers are disproportionately affected by intentional injuries in the workplace. 1 Although incidents of use of force by police officers account for less than 2% of the estimated total of police and civilian contacts (official interaction between any person and an officer), the prevalence of injury to civilians and officers in these situations is high. 2 – 8 Police departments in the United States are increasingly providing officers with less-lethal weapons to control suspects who physically resist arrest. The limited body of research on risk factors associated with injury during use-of-force incidents suggests that suspects have a greater likelihood of sustaining an injury when officers use canines, impact weapons (e.g., batons), or other physical force than when they use less-lethal weapons like conducted energy devices (CEDs) or chemical irritants like oleoresin capsicum (OC), also known as pepper spray. 9 – 13 Less-lethal weapons have been accused of causing unnecessary injuries to and deaths of civilians. 14 , 15 CEDs and OC spray are routinely used by police officers and have been the focus of these accusations. 16 , 17 Police officers in more than 7000 law enforcement agencies in the United States now use CEDs, and use of OC spray is nearly universal. 18 , 19 Medical research indicates that most deaths associated with these weapons are the result of positional asphyxia, pre-existing health conditions, or drug-related factors. 20 , 21 CEDs appear to be relatively safe when used on healthy individuals in clinically controlled research settings, 22 – 34 but these weapons are not risk free. For example, CEDs may increase one's chance of secondary head injuries from falls. 35 – 37 Because of a lack of rigorous epidemiological studies, it remains unclear whether less-lethal weapons produce harmful effects among individuals at risk for police use of force, such as persons intoxicated by illicit drugs and physically struggling with the police. A review of police and medical records of suspects exposed to a CED shock during a 2-year period found that less than 1% received moderate injuries, and only 1 suspect (0.1%) received severe injuries. 38 Few rigorous studies have examined the effect of policy decisions to adopt less-lethal weapons on the incidence of injuries to suspects and officers. Several studies have suggested that adoption of less-lethal weapons has led to substantial reductions in assaults on officers and injuries to suspects but have either failed to control for the level of resistance by the suspect or other important circumstances 39 – 41 or have relied on simple comparisons of injury rates before and after the introduction of less-lethal weapons. 42 – 44 These studies suffer from a number of potential methodological problems, including regression to the mean and a lack of sufficient control variables. Also, because research in this area has been sponsored by law enforcement agencies, lack of independence has been a point of contention. 15 , 17 , 45 Use of force by police involves multiple types of force, so it is critical to assess the independent contribution of less-lethal weapons on the prevalence and incidence of injury to the suspects and officers involved. Injury from police use-of-force incidents continues to be a public health problem affecting tens of thousands of people in the United States each year. We investigated whether use of less-lethal weapons was associated with the likelihood of injuries to suspects and officers during police–civilian use-of-force incidents after statistical control for other important aspects of the events. Relying on administrative data collected by 12 police departments across the United States (collected from 1998 through 2007), we investigated whether the use of CEDs or OC spray was associated with the odds of injury to officers and suspects in use-of-force cases. Because an association between use of these weapons and injury could result from selection effects, whereby events that require these weapons' application by police are more serious than those that do not, we tested for such an effect by examining whether these associations remained after control for important confounders including physical force used by the police; relative physical resistance from suspects; age, race, and gender of suspects; differences in departmental policies restricting use of force by the police; and average agency differences in the prevalence of use of force. Finally, to assess the effect that an agency's decision to adopt CEDs has on the incidence of injury to suspects and officers, we examined data from 2 cities in which monthly data were available for periods before and after adoption of this less-lethal weapon.
