A quantum of force The consequences of m

Robert J. Kaminski, Robin S. Engel, Jeff Rojek, Michael R. Smith and Geoffrey Alpert

In a recent paper, researchers reported increases in the risk of citizen injury associated with police use of conducted energy devices (CEWs), a finding that is contrary to that reported in most previous studies. These authors speculate that the differences in findings when compared to other similar studies may

be due, in part, to the exclusion of routine CEW dart punctures as injuries by

Robert J. Kaminski is associate professor in the department of criminology and criminal justice, University of South Carolina. His research focuses on violence against the police, police use of force, less-lethal technologies, and the causes and prevention of officer and suspect line-of-duty injuries. His has published in a variety of journals, including Criminology, the American Journal of Public Health, Criminal Justice and Behavior, Crime and Delinquency, Homicide Studies, and Violence Against Women. Robin S. Engel, PhD is associate professor of criminal justice at the University of Cincinnati. Her research includes empirical assessments of police behavior, police/ minority relations, police supervision and management, criminal justice policies, criminal gangs, and violence reduction strategies. Previous research has appeared in Criminology, Justice Quarterly, Journal of Research in Crime and Delinquency, Journal of Criminal Justice, Crime and Delinquency, and Criminology and Public Policy. Jeff Rojek is assistant professor in the depart- ment of criminology and criminal justice at the University of South Carolina. His primary research interests are in the area of police officer and organizational behavior. His most recent publications have appeared in Criminology, Journal of Research in Crime and Delinquency, Crime and Delin- quency, and Police Quarterly. Dr Michael R. Smith is professor of criminal justice and vice provost

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at the University of Texas at El Paso. Prior to assuming his current position, he served as dean of the College of Liberal Arts and Social Sciences at Georgia Southern University and chair of the Department of Criminology and Criminal Justice at the University of South Carolina. Dr Smith is a former police officer and holds a JD from the University of South Carolina School of Law and a PhD in Justice Studies from Arizona State University. He has served as a principal or co-principal inves- tigator on many research and evaluation grants and contracts over his career. He has written extensively on racial profiling, use of force, and other critical issues at the intersection of law, public policy, and policing. His most recent publications have appeared in Criminology & Public Policy, the American Journal of Public Health, and Review of Policy Research. Geoffrey P. Alpert is a professor in the department of criminology and criminal justice at the University of South Car- olina. Dr Alpert has been conducting research on high-risk police activities for more than 30 years. He is currently working with Cal POST on their Vehicle Operations Training Advisory Council, and the Queensland Police Service and Griffith University in Brisbane, Australia. He is a member of the International Association of Chiefs of Police Research Advisory Committee. Correspondence to Robert J. Kaminski, Department of Criminology & Criminal Justice, University of South Carolina, Columbia, SC 29208, USA. E-mail: kaminskb@mailbox.sc.edu.

2 KAMINSKI ET AL.

other researchers, and they called on the research community to collectively agree on how CEW injuries should be operationalized. In this paper, we empir- ically demonstrate the differences in findings when routine CEW puncture wounds are included as citizen injuries and when they are not. Ultimately, we reject the authors’ measurement approach as inconsistent with how injuries associated with other types of force are routinely coded and measured.

Keywords police use of force; conducted energy weapons; citizen injuries

Introduction

One of the most consistently documented and researched behavior in policing is the use of force. Despite the litany of studies that have been conducted over the years to measure the types, frequency, and correlates of police coercion, there has been little consensus derived across academics and practitioners regarding many of the most fundamental issues surrounding the use of force by police. In contrast to this larger body of literature, however, recent findings regarding the use of one type of weapon —conducted energy weapons

(CEWs) 1 —have generated relatively consistent findings. Most recent studies of the use of CEWs by police have shown that they substantially reduce the num- ber and severity of injuries to citizens compared to other types of force and have similar effects on injuries to officers or are benign (Lin & Jones, 2010; MacDonald, Kaminski, & Smith, 2009; Smith, Kaminski, Rojek, Alpert, & Mathis, 2007; Taylor & Woods, 2010). Notably, the only two studies to date employing quasi-experimental designs bolster confidence in these results (MacDonald et al., 2009; Taylor & Woods, 2010).

These findings, however, have recently been called into question based on new findings reported by Terrill and Paoline (2011) in Justice Quarterly. Employing a nonexperimental design, these authors examined CEW usage in

Downloaded by [Robert Kaminski] at 16:06 14 May 2013 seven mid-to large-size US police agencies. Using different methods and mea- sures, they reported significant increases in citizen injuries involving the use of CEWs compared to other types of force across a majority of their statistical models. Terrill and Paoline highlighted the importance of their findings by not- ing that their study “is the first to report a fairly consistent increased risk between the use of CEWs and citizen injury,” leading them to suggest that “recent policy recommendations made by a number of researchers (MacDonald et al., 2009; PERF, 2005; Smith et al., 2007; Taylor & Woods, 2010) as to how or when to use CEWs, are premature” (Terrill & Paoline, 2011, p. 24). Yet, contrary to most prior studies, Terrill and Paoline’s measure of citizen injury included routine minor CEW punctures. They speculated that the differences in their findings when compared to other studies of similar size, scope, and

1. Conducted energy weapons are also known as electro-muscular disruption devices, electronic control devices, neuro-muscular incapacitation devices, and conducted electrical devices.

THE CONSEQUENCES OF COUNTING ENERGY WEAPON PUNCTURES AS INJURIES

design may be due to the inclusion of minor dart punctures as “injuries,” and further articulated several reasons why they departed from previous approaches regarding the measurement of citizen injury associated with CEWs. They concluded by recommending that the research community collectively decide how to better operationalize CEW-related injuries.

Given the importance of police use of force, and that Terrill and Paoline’s findings are contrary to those reported in previous research studies, their approach merits additional consideration and attention from researchers. We therefore consider the consequences of including routine CEW-related punctures as measures of citizen injuries. First, we review the prior literature surrounding use of force and specifically CEW usage, including Terrill and Paoline’s most recent contribution. Using data from a large West-coast law enforcement agency, we next empirically demonstrate the differences in findings when routine puncture wounds are included as citizen injuries compared to when they are not. In direct contrast to Terrill and Paoline, we argue that our findings regarding CEW-related citizen injury (when properly measured) are consistent with the majority of previous empirical research find- ings. We conclude with a discussion of the practical and policy implications of including routine CEW punctures in measures of citizen injuries. We also revisit prior measurement decisions in the use of force literature and note how Terrill and Paoline have previously departed from conventional measures of police use of force and now citizen injury. Ultimately, we reject these authors’ measurement approach as inconsistent with how injuries associated with other types of force are routinely coded and measured, and we discuss the negative consequences that such an overly expansive view of injuries may have on the development of future technologies designed to reduce injuries and save lives.

Police Use of Force and Conducted Energy Devices Downloaded by [Robert Kaminski] at 16:06 14 May 2013

The use of physical force by police has been a matter of great debate and controversy for decades. From Westley’s (1953) initial characterization of police use of force as violence to Bittner’s (1985) observation that the core of the police role in society is the nonnegotiable use of coercive force, the conceptualization and study of police use of force is often a central compo- nent of criminal justice research. Over the years, successful attempts at reducing police use of force and the resulting harms associated with it have included changes in laws, legislation, policies, training, and practice (Fyfe, 1988). And most recently, law enforcement officials have turned to the use of less-lethal technologies (e.g. CEWs and pepper spray) as weapons of choice to reduce citizen and officer injuries when force must be used to control resistant criminal suspects (MacDonald et al., 2009; Taylor, Alpert, Kubu, Woods, & Dun- ham, 2011).

CEWs have been used by law enforcement since at least the 1980s. They are handheld devices that use compressed nitrogen to launch two or four

4 KAMINSKI ET AL.

(depending on the manufacturer and device) tiny barbed darts tethered to a power source by insulated wires that project outward to maximum distances of 15-35 feet. CEWs also have a “touch-stun” mode used for pain compliance. When the darts attach to clothing or penetrate the skin, they deliver short electric pulses with very low average current that interrupts the electrical sig- nals from the central nervous system to the peripheral body, typically leading to neuro-muscular incapacitation (Kroll & Ho, 2009). Although some law enforcement agencies purchased Stinger Systems’ Ò CEWs, Taser International Ò has been the market leader supplier (US Department of Justice, 2009).

The introduction of CEWs as a use-of-force alternative significantly shifted the use-of-force landscape. Although early models of the TASER Ò were not widely adopted during the 1980s, in part because they were less effective than newer models (Meyer, 2009), the number of law enforcement agencies employ- ing 100 or more sworn officers adopting CEWs grew substantially following the

marketing of the TASER Ò model M-26 TM in 1999. According to the Bureau of Statistics, only 14.5% of agencies deployed CEWs in 2000. This percentage

tripled by 2003 (43.9%) and as of 2007, 74.9% of agencies deployed CEWs (Law Enforcement Management and Administrative Statistics, 2006, 2003, 2011).

CEW Effectiveness An initial consideration regarding CEWs is their ability to successfully incapaci-

tate resistant and combative subjects so that they can be brought under control by arresting officers. The early seven-watt versions of CEWs were less effective than current models and were often ineffective against suspects under the influence of Phencyclidine (PCP) or in a state of excited delirium (Meyer, 2009). Other assessments found CEWs to be effective between 50 and 85% of the time (Donnelly, 2001), while more recent evaluations by Taser International Ò and individual law enforcement agencies reported CEWs were

Downloaded by [Robert Kaminski] at 16:06 14 May 2013 effective between 80 and 94% of the time (White & Ready, 2007, 2010). Inde- pendent research on CEW effectiveness has also reported high levels of suc- cessful incapacitation of resistant suspects, albeit the reported percentages are lower than those reported by CEW manufacturers. For example, research conducted by Mesloh, Henych, Hougland, and Thompson (2005) demonstrated that the use of CEWs was immediately effective (with no further suspect resis- tance) in 67.7% of the 400 random sampled use-of-force reports from the Orange County Sheriff’s Office in 2001-2003. Delayed effectiveness was reported in 9.6% of the reports and ineffectiveness on first application in 22.7% of the reports. The main reasons for failure were missed shots, suspects wear- ing baggy clothes, or loosened probes. Subsequent analyses of use-of-force reports from the Orange County Sheriff’s Office and the Orlando Police Department in 2001-2005 reported 59.8% effectiveness without further suspect resistance (Mesloh, Henych, & Wolf, 2009). Importantly, both studies reported that CEWs were more effective than all other types of force at ending suspect

THE CONSEQUENCES OF COUNTING ENERGY WEAPON PUNCTURES AS INJURIES

resistance on first application; these findings are similar to those reported by Meyer (2009).

White and Ready (2007) examined 243 CEW uses by NYPD emergency service unit personnel on persons who were in an agitated state (e.g. under the influ- ence of drugs and mentally ill) that presented a danger to themselves or others for the years 2002-2004. They found that suspects were reported as being inca- pacitated 84.7% of the time, but that of those initially incapacitated, 21.3% continued to resist (calculated from Table 2, p. 182). If one considers contin- ued resistance as less than “effective,” the effectiveness rate would be 63.4%, which is similar to other studies. In a follow up study, White and Ready (2010) used multiple regression analyses to examine CEW effectiveness of 375 CEW deployments by the NYPD during 2002-2005. Of suspects initially incapacitated, 33.0% continued to resist and of suspects not incapacitated (e.g. due to CEW failure), 10.9% continued to resist. The authors found that suspect body weight greater than 200 lb, a distance of three feet or less, alcohol or drug intoxication, violence directed towards officers, CEW misses, and use of other less-lethal devices were all significant predictors of continued suspect resistance. Interestingly, other variables, such as suspect race, gender, and mental status were unrelated to reported CEW effectiveness.

CEWs, Deaths, and Deadly Force One of the major concerns of police use of CEWs is sudden in-custody death

following exposure. According to Amnesty International, 500 subjects died following exposure to CEWs in the USA since 2001 (Trimel, 2012). Sudden in-custody death during police confrontations is not a new phenomenon and these outcomes have been variously attributed to positional asphyxia, exposure to pepper spray (oleoresin capsicum, OC), prolonged violent struggle, excited delirium syndrome, drug intoxication, cardiovascular dis-

Downloaded by [Robert Kaminski] at 16:06 14 May 2013 ease, or other factors (Chan, Vilke, Neuman & Clausen, 1997; DiMaio & DiMaio, 2006; Petty, 2004; Reay, Fligner, Stilwell, & Arnold, 1992; Roeggla, Roeggla, Moser, & Roeggla, 1999). The difficulty, of course, is determining whether less-lethal weapons such as OC and CEWs cause or contribute to sudden in-custody deaths, or whether these deaths would have occurred even in the absence of exposure to these weapons.

Several medical-based studies have attempted to determine the contribu- tion of CEWs to injury and in-custody deaths following exposure. Two studies involved medical screenings and record reviews of 1,627 exposed subjects (Bozeman et al., 2009; Eastman et al., 2007). Eastman et al. (2007) examined 426 exposed subjects and found all nonfatal injuries were minor, though there was one death. This subject had a core body temperature of 107.4 and was intoxicated on cocaine, and likely would have died even without the shock from a CEW (White & Ready, 2009). Bozeman and colleagues (2009) examined 1,201 exposed subjects, and reported that the vast majority (99.75%) suffered

6 KAMINSKI ET AL.

no injuries or only superficial injuries. Although there were two fatalities, upon autopsy it was concluded the deaths were unrelated to CEW exposure.

Several retrospective mortality reviews were conducted by medical researchers who examined hundreds of autopsy and toxicology reports of persons who died proximate to CEW exposure. Many subjects were found to

be intoxicated on drugs, suffered from cardiovascular disease, and/or were in a highly-agitated state at the time of exposure (excited delirium). The general conclusion from this body of research was that CEWs are not a common cause or contributor to sudden in-custody death (Kornblum & Reddy, 1991; Strote & Hutson, 2006; Swerdlow, Fishbein, Chaman, Lakkired- dy, & Tchou, 2009; US Department of Justice, 2011). An exception is a study by Zipes (2012), who reviewed eight cases of CEW-proximate deaths and concluded that CEWs can cause cardiac dysrhythmias and sudden death, though this study has been challenged on a number of grounds (see, e.g. Vilke, Chan, & Karch, 2013). Furthermore, although the vast majority of CEW-proximate deaths have been attributed to causes other than CEWs, Amnesty International reported that CEWs contributed to or caused more than 60 deaths as determined by medical examiners (Trimel, 2012). Further, some subjects without any apparent risk factors have also died following CEW exposure (US Department of Justice, 2011). Clearly, the deployment of

a CEW by law enforcement personnel should not be taken lightly. While the focus of research on CEWs has been on their contribution or potential contribution to in-custody deaths (Kaminski, 2009), relatively little empirical research has examined the potential of CEWs to reduce citizen fatalities and the use of lethal force by police. Given the deterrent and inca- pacitation effects of CEWs and other less-lethal weapons such as OC, however, it is likely that their use early on during resistive and violent encounters prevents further escalation and the need for the use of deadly force by police in some cases (Mesloh, Henych, Hougland, & Thompson, 2005; Thomas et al., 2010; White & Ready, 2007, 2010). For example, Taser International Ò reports

Downloaded by [Robert Kaminski] at 16:06 14 May 2013 that as of October 2012, police use of CEWs saved over 97,000 people from potential death or serious bodily injury (http://www.taser.com/taser-prod- ucts-save-lives). Likewise, several law enforcement agencies reported large reductions in the use of lethal force by its officers following the introduction of CEWs (see, e.g. Smith et al., 2009), though there have been some excep- tions (Amnesty International, 2004; Thomas et al., 2011). However, these sim- ple pre-post CEWs research designs suffer from a number of threats to internal validity and are often not the product of independent research (Adams & Jenn- ison, 2007; Alpert & Dunham, 2010; Campbell & Stanley, 1966; Kaminski et al., 1998; Smith et al., 2009; Taylor & Woods, 2010).

A more rigorous prospective study of CEW use on mentally-ill subjects by Ho, Dawwes, Johnson, Lundin, and Miner (2007) that used data self-reported

by law enforcement agencies submitted to Taser International Ò estimated that CEWs were deployed in nearly 50% of encounters in which deadly force

would have been justified. While they cannot prove a counterfactual, they

THE CONSEQUENCES OF COUNTING ENERGY WEAPON PUNCTURES AS INJURIES

estimated that 1,100 lives were potentially saved over a six-year period because of the availability of CEWs. A prospective study of 426 CEW field uses in a large US city concluded that the availability of CEWs clearly prevented police use of lethal force in 5.4% or 23 encounters (Eastman et al., 2008). However, in another pre-post test study, Lee et al. (2009) examined CEW use in 50 of 123 police agencies surveyed in California (40% response rate) and found that CEWs were not associated with a decrease in firearm-related deaths. Given the variability in findings, additional research is needed to better assess the relationship between CEW use and police use of deadly force and civilian fatalities, preferably through studies employing quasi-experimental designs.

CEWs and Nonfatal Officer and Suspect Injuries Among the reasons law enforcement agencies adopt less-lethal weapons such

as CEWs is to gain compliance from resistive and combative suspects while reducing the likelihood of injury and the severity of injury to officers and suspects (Thomas et al., 2011). A central question, therefore, is whether or not CEWs are effective in gaining compliance and reducing injuries and the severity of injuries.

With the widespread adoption of CEWs during the 2000s, many law enforce- ment agencies have since reported substantial reductions in officer and suspect injuries, but these studies were not independent and relied on overly simplistic pre-post test comparisons. Using more sophisticated research designs and statistical methods, several independent studies have since been conducted, with the majority reporting that the use of CEWs significantly reduced injuries to suspects and/or officers as well as the severity of injuries to suspects (Lin & Jones, 2010; MacDonald et al., 2009; Paoline, Terrill, & Ingram, 2012; Smith et al., 2007; Taylor & Woods, 2010). Further these studies reported that the

Downloaded by [Robert Kaminski] at 16:06 14 May 2013 risk of moderate to severe harm from the use of CEWs was quite low. Several studies, however, were correlational, cross-sectional, or relied on statistical controls for potential rival explanations and therefore could not support causal inferences (Kaminski, 2009; Terrill & Paoline, 2011). 2

Two studies, however, are noteworthy because they employed quasi-experi- mental designs that reduce many of the threats to internal validity (Campbell & Stanley, 1966). Studies conducted by MacDonald et al. (2009) and Taylor and Woods (2010) reported substantial and statistically significant reductions in injuries to both officers and suspects in several law enforcement agencies. Specifically, MacDonald et al. (2009) examined 108 months of pre-post CEW-adoption data (1998-2006) and 60 months of pre-post CEW-adoption data (2002-2006) in the Orlando (FL) and Austin (TX) police departments, respec-

2. Although a detailed discussion is beyond the scope of this paper, a recent study questioned the objectivity of industry-funded studies on the safety of CEWs (Azadani et al., 2011).

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tively. Using count regression models to estimate injury incident rates, MacDonald et al. found in Orlando that the average monthly incidence of suspect injuries decreased by 53% after adopting CEWs while the rate of officer injuries declined by 62%. The adoption of CEWs by the Austin Police Depart- ment was associated with 30 and 25% reductions in the average monthly rates of suspect and officer injuries, respectively.

Likewise, Taylor and Woods (2010) compared four years of pre-post CEW adoption data from seven law enforcement agencies with six matched agencies that did not adopt CEWs. Examining a variety of injury outcomes, they found that CEW adoption was associated with lower rates of officer injuries, the severity of suspect injuries, and injuries to suspects and officers requiring medical attention. In summary, the bulk of the available evidence strongly indicates that CEWs are associated with reductions in the frequency and sever- ity of injury to officers and civilians.

The Terrill and Paoline (2011) Study Despite the research findings reported above, Terrill and Paoline (2011)

recently summarized this body of research as indicating that “the relation- ship between CEWs and citizen injuries is unclear” (2011, p. 6). These researchers further critiqued this body of research by noting that previous studies: (1) did not adequately control for other types of force; (2) did not control for additional factors that might account for injuries; and (3) did not adequately test the impact of CEWs “beyond one simple reference category” (2011, pp. 6-7). To address these concerns, Terrill and Paoline analyzed 13,913 use-of-force cases across seven police departments. Of these use-of-force incidents, 2,607 (18.7%) involved the use of CEWs. Further, the authors reported that of the 13,913 use-of-force incidents, 4,447 (31.9%) involved an injury to the citizen. More specifically, citizens

Downloaded by [Robert Kaminski] at 16:06 14 May 2013 were injured in 41.2% of CEW-only incidents and 47% of CEW plus other types of force incidents, compared to only 28.9% of nonCEW incidents. A series of logistic regression models comparing CEW usage to other types of force demonstrated that even after controlling for some officer and citizen demographics, along with some forms of citizen behavior, the bivariate findings (that CEWs resulted in a greater likelihood of citizen injury compared to other types of force) held in seven of the eight estimated models. Supplemental analyses also demonstrated that CEW usage was significantly associated with a greater likelihood of citizen injury, even when injury was measured as a scaled variable (i.e. no injury, bruises/ abrasions, lacerations, and broken bones) and as a hospitalization dichoto- mous variable.

Yet, as with all studies, Terrill and Paoline’s measurement of key variables likely influenced their findings. In particular, their measurement of citizen injury departs from most previous research and common practice regarding

THE CONSEQUENCES OF COUNTING ENERGY WEAPON PUNCTURES AS INJURIES

CEW usage and reporting. Specifically, Terrill and Paoline’s measure of citizen injury was based on officers’ perception and reporting of injuries on official reports (and these reports varied across sites). As they noted:

There was little to no direction in the policy guidelines to designate the criteria individual officers were to apply to determine whether a citizen was injured other than the officer’s perception of injury or complaint of injury by the citizen. According to queries with officials across the sites, each offi- cer using force was provided the discretionary power to determine injury, based on his/her assessment, as to whether the force he/she used caused such. Thus, the injuries analyzed as part of this inquiry are considered inju- ries by police personnel, as opposed to a determination made by the authors. (2001, p.10)

Thus, there was likely little consistency in the reporting of injuries, with some officers in some departments documenting dart punctures and minor burns from CEWs as lacerations or abrasions (and therefore included in Terrill and Paoline’s dichotomous injury measure), while other officers did not report these minor wounds as injuries. It appears that in their scaled injury variable, Terrill and Paoline categorized these minor wounds as either minor injuries (abrasions) or moderate injuries (lacerations). Unfortunately, we could not dis- cern if their findings would change if they had used the more common measure of citizen injury that did not include these types of minor wounds. Also note that these types of minor wounds were not included for uses of force other than CEWs. For example, Terrill and Paoline indicated in a footnote that simi- lar minor “injuries” resulting from the use of chemical sprays were likely not captured in their study, because officers may not perceive skin inflammation or eye irritation and the resulting blurring and burning sensation as injuries (2011, p. 15). Based on findings generated using this more expanded measure of citizen injury, Terrill and Paoline called on the “research community” to “collectively decide how to operationalize police-inflicted injuries as a result

Downloaded by [Robert Kaminski] at 16:06 14 May 2013 of CEW usage, especially in light of the practical implications of our research” (2011, p. 28).

In summary, based on previous studies, we know the following about police use of CEWs. First, current versions of CEWs are highly effective at incapaci- tating subjects when appropriately deployed, but estimates of the rates of effectiveness vary based on how effectiveness is defined. While CEWs are not risk-free, the risk of death or serious injury from CEW exposure appears to be very low. Further, there is some evidence that CEWs have reduced police use of deadly force and civilian fatalities, though to date the findings are mixed. The vast majority of studies show that CEWs are associated with reductions in police and/or suspect injuries as well as the severity of injuries among suspects. This research has been recently called into question by Terrill and Paoline (2011), with claims that the associated reductions reported in police and suspect injuries during use of force incidents involving CEWs are likely due to improper measurement and operationalization of key constructs (in this

10 KAMINSKI ET AL.

case, injuries). This core fundamental question regarding the appropriate measurement of CEW-induced injuries is the subject of our inquiry below.

Data and Methods

Data for our analyses are from one of the 12 police agencies that previously provided data for a study conducted by Smith et al. (2009) (see also MacDonald

et al., 2009). 3 This agency is selected because it provides a data-set containing

a large number of use-of-force incidents and the detail necessary to assess the consequences of counting and not counting CEW punctures on suspect injury rates and predictors of injury in regression models. We include only CEW punc- tures because touch-stun mode is infrequently applied and there are only three reported CEW-related burns. The data-set contains information on the types of force used by each officer in a given incident. The data also include an indica- tor of whether or not a suspect sustained an injury and if so the type (e.g. abra- sion, laceration, puncture wound, and broken bone) and severity of the injury sustained, as well as several control variables. Information on 2,477 use-of- force incidents that occurred 1 January 2005-31 December 2005 is included.

Measures and Descriptive Statistics Four dependent variables, displayed in Table 1, examine the effects of exclud-

ing and including CEW dart punctures as injuries sustained during use-of-force incidents —two dichotomous outcomes measuring injury/no injury and two

trichotomous outcomes measuring injury severity. 4 The first dichotomous measure (labeled BiInjury-1) excludes CEW punctures to approved targets (i.e. not counted as an injury), and is coded 1 if one or more suspects were injured in an incident and 0 otherwise. As shown, 31.7% of the force incidents

Downloaded by [Robert Kaminski] at 16:06 14 May 2013 involve an injury to a suspect when dart punctures are excluded as a measure of injury. Punctures to unapproved targets, such as the head, face, or groin, however, are included as injuries. The second dichotomous variable (labeled BiInjury-2) includes CEW punctures to approved targets as injuries, increasing the injury rate from 31.7 to 35.7% or an increase of 98 injury events (examin- ing CEW incidents only, the injury rate increases from 32.3 to 81.1%). Regarding the trichotomous outcomes, counting CEW punctures does not change the rate of major injuries, but does increase the minor injury rate from

3. Due to the original data sharing agreement, we are obligated to keep the identity of the agency confidential. The agency selected, however, is a large law enforcement agency in the United States.

4. Bruises, sprains, scrapes and soft tissue damage are classified as minor injuries, except when including CEW punctures to approved targets; in which case these are included as an injury for the dichotomous measure and a minor injury for the trichotomous measure. Fractures, lacerations, dog bites, concussions, gunshot wounds, and puncture wounds to the head, face or groin (unapproved targets) are classified as major injuries for both measures.

THE CONSEQUENCES OF COUNTING ENERGY WEAPON PUNCTURES AS INJURIES

Table 1 Descriptive statistics for variables used in the analysis Variable

Description Code N % BiInjury-1

One or more suspects injured —CEW punctures not counted 0 —no 1,687 68.3 1 —yes

783 31.7 BiInjury-2

One or more suspects injured —CEW punctures counted 0 —no 1,589 64.3 1 —yes

881 35.7 TriInjury-1

Severity of suspect injury —CEW punctures not counted 0 —none 1,687 68.3 1 —minor

708 28.7 2 —major

75 3.0 TriInjury-2

Severity of suspect injury —CEW punctures counted 0 —none 1,589 64.3 1 —minor

806 32.6 2 —major

75 3.0 CEW

Conducted energy device —with or without other type of force 0 —no 2,271 201 1 —yes

91.9 8.1 CEW-only

Conducted energy device without other force 0 —no 2,406 66 1 —yes

97.3 2.7 CEW+

Conducted energy device with other force 0 —no 2,337 135 1 —yes

94.5 5.5 Non-CEW

Non-CEW force —with or without use of CEW 0 —no 136 2,336 1 —yes

5.5 94.5 OC

Pepper spray 0 —no 1,414 1,058 1 —yes

57.2 42.8 Soft-Hands

Physical control holds without weapons 0 —no 1,174 1,298 1 —yes

47.5 52.2 Hard-Hands

Strikes of any kind without weapons 0 —no 1,823 649 1 —ye

73.7 26.3 Takedowns

Throws, sweeps, tackles, etc. 0 —no 1,448 1,024 1 —yes

58.6 41.4 Hobble

Suspect handcuffed and ankles held together by restraint device

0 —no 2,245 227 1 —yes

90.8 9.2 Other force

Canine, teargas, impact munitions, baton controls, etc. 0 —no 2,243 229 1 —yes

90.7 9.3 Assault

One or more suspects assaulted/battered one or more officers 0 —no 1,417 1,073 1 —yes

56.9 43.1 >1 officer

Two or more officers involved in incident 0 —no 949 1,523 1 —yes

38.4 61.6 >1 suspect

Two or more suspects involved in incident 0 —no 2,296 176 1 —yes

92.9 7.1 Female

Female suspect involved in incident 0 —no 2,162 303 1 —yes

87.7 12.3 Mixed race

Two or more suspects of different race/ethnicity 0 —no 2,445 20 1 —yes

Downloaded by [Robert Kaminski] at 16:06 14 May 2013

Impaired One or more suspects impaired by drugs and/or alcohol 0 —no 1,811 654 1 —yes

73.5 26.5 Note. Number of observations = 2,477.

28.7 to 32.6%, and decreases the no injury category from 68.3 to 64.3% (exam- ining CEW incidents only, the minor injury rate increases from 27.9 to 76.6%). We also include three measures of CEWs to assess their effects on injuries. CEW is coded 1 if a CEW was deployed, regardless of whether or not another type of force was also used (8.1%) and 0 otherwise. CEW Only is coded 1 if the only force used was a CEW (2.7%) and 0 otherwise, and CEW + is coded 1 if a CEW was used and one or more other types of force also was used (5.5%) and 0 otherwise. NonCEW is coded 1 if force other than a CEW was used (94.5%) and

0 otherwise.

12 KAMINSKI ET AL.

Other officer use-of-force related control variables are coded similarly. These include measures of: OC (used in 42.8% of force incidents); Soft-Hands (i.e. any physical control holds without the use of a weapon, such as grabbing, holding, and joint locks, used in 52.2% of force incidents); Hard-Hands (i.e. any strikes without a weapon, such as punching, kicking, kneeing, and elbow- ing, used in 26.3% of force incidents); Takedowns (e.g. throws, tackles, sweeps and swarms, used in 41.4% of force incidents); Hobble (i.e. restraint device in which a suspect’s hands are handcuffed and ankles are held together, used in 9.2% of force incidents); and Other Force (collapsed category including less frequent types of force, such as canines, teargas, impact munitions, baton strikes, and soft baton controls, used in 9.3% of force incidents). Note that CEWs are the least used tactic by this police agency (8.1% of force incidents), likely due in part because not all officers within this agency were issued CEWs during the time of the study.

Several additional dichotomous controls included account for the level of violence directed at police, the number of officers and suspects involved in the encounters, and the gender and racial/ethnic composition of the partici- pants. Specifically, as reported in Table 1 43.1% of incidents involved one or more suspects assaulting or battering one or more officers; 61.6% of incidents involved two or more officers; 7.1% of incidents involved two or more suspects; 12.3% of incidents involved one or more female suspects; .8% of incidents involved suspects of different race/ethnicity; and 26.5% of incidents involved one or more suspects who were perceived to be impaired by drugs and/or alco- hol (26.5%). 5

Analysis

Following Terrill and Paoline (2011), we assess the effect of CEWs on citizen injuries, noting our differences in how injury is measured (including and excluding CEW punctures). We first estimate four models in a series of eight

Downloaded by [Robert Kaminski] at 16:06 14 May 2013 binary logistic regressions (Table 2) using the various CEW measures described above, along with the control variables. Each model is estimated twice; once excluding routine CEW punctures as injuries and a second time including punc- tures as injuries. For example, Model 1.1 in Table 2 excludes routine CEW punctures as injuries, while Model 1.2 includes them.

The first two sets of models (Models 1.1-2.2) use the dummy variables CEW (CEWs used whether or not other types of force also used) and nonCEW (the use of any force other than a CEW whether or not a CEW also used). In addi- tion, to test whether the effect of CEWs on injury is dependent on whether or not force other than a CEW is also used in a given incident, an interaction term between CEW and nonCEW is added to the second set of models (Models 2.1 and 2.2). Our expectation for the set of models without the interaction term

5. Due to the data sharing agreement with the law enforcement agencies, officer demographic characteristics are not available (Smith et al., 2009).

THE CONSEQUENCES OF COUNTING ENERGY WEAPON PUNCTURES AS INJURIES

(Models 1.1 and 1.2) is that CEW will be inversely associated with the odds of suspect injury when routine punctures are excluded as injuries, but will be positively associated when punctures are included as injuries. Regarding the sets of models including the interaction term (Models 2.1 and 2.2), we hypoth- esize that the injury-reducing effects of CEWs generally observed in the litera- ture will depend on whether or not other types of force are used. Here, we expect the interaction term to be positive and significant regardless of whether or not punctures are counted as injuries.

In the second and third sets of models (Models 3.1-4.2), the summary mea- sure of nonCEW force is replaced with the specific types of nonCEW force used by officers (e.g. OC, Hard Hands, etc.). The first set of models (Models 3.1 and

3.2) test the effect of CEW when excluding and including routine dart punc- tures as injuries, respectively. We expect CEWs to be inversely related to the odds of injury when punctures are excluded (Model 3.1) and positively related when they are included in the measure (Model 3.2).

The models in the final set (Models 4.1 and 4.2) are similar except that we substitute CEW Only (incidents in which the only reported force was a CEW) and CEW + (incidents in which a CEW and one or more other types of force were used). In Model 4.1 (excluding punctures), we expect CEW Only to be inversely associated with the odds of injury and CEW + to be positively associated. In Model 4.2 (punctures included as injuries), we expect both CEW Only and CEW + to be positively associated with the odds of suspect injury.

A second series of eight models is estimated to assess the effect of CEWs on the severity of injury when punctures are excluded and included as forms of injury. These results are presented in Tables 3 and 4. Following the same basic framework, the sets of models in Table 3 use the summary measure of nonCEW force, while the sets of models in Table 4 use the specific types of nonCEW force in place of the summary measure. Expectations regarding the effects of CEWs are the same as with the binary logistic regression results, except that

Downloaded by [Robert Kaminski] at 16:06 14 May 2013 we are modeling the odds of the severity of injury rather than the odds of injury.

We initially used ordered logistic regression to estimate the severity of injury models; however, tests of the proportional odds assumption indicated that at least one variable in every model failed to meet the assumption (Long, 1997). 6 To avoid incorrect inferences, we instead use the generalized ordered logistic regression model, which relaxes the proportional odds assumption and allows the effects of the relevant independent variables to vary over the cut points or thresholds of the dependent variable (Williams, 2006).

6. The ordered logistic regression model produces a single coefficient for each independent variable, with the important assumption that the effects are the same across all of the categories of the dependent variable, i.e., that the slopes are parallel to one another or equivalently that the odds are proportional. When violated, alternative models must be considered See Long (1997, pp. 140–145) for a more thorough explication.

14 KAMINSKI ET AL.

Results

Binary Logistic Regression Results We begin with a discussion of the binary logistic regression output, displayed

in Table 2. As expected, use of a CEW when punctures are excluded as injuries (Model 1.1) significantly decreased the odds of suspect injury (OR = .57, p 6 .01), while Model 1.2 shows that use of a CEW when punctures are included as injuries significantly increased the odds of suspect injury (OR = 5.18, p 6 .001). In short, the specific measurement of injuries matters in these mod- els. As shown in Models 2.1 and 2.2, the effect of CEWs on injury depends on whether or not other types of nonCEW force are used, regardless of whether or not punctures are included. In other words, the odds of injury are greatest in incidents where officers deployed a CEW and used some other type(s) of force. This suggests that these incidents are somehow unique in their injury potential (e.g. incidents in which nonCEW types of force failed to allow officers to gain control of suspects or that the CEW failed and thus other types of force were needed). Note, however, the effect is substantially larger when punctures are excluded (OR = 23.42, p 6 .001), compared to when they are included (OR = 4.92, p 6 .001).

Table 2 Binary logistic regression models of suspect injury Variable

Model 2.2 Model 3.1 Model 3.2 Model 4.1 Model 4.2 CEW

Model 1.1

Model 1. 2 Model 2.1

– – – CEW only

0.39 ⁄⁄⁄ 0.39 ⁄⁄⁄ 0.39 ⁄⁄⁄ Soft hands

1.17 1.15 1.14 1.16 Hard hands

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Hobble

0.73 0.67 ⁄ 0.75 Other force

0.47 ⁄⁄⁄ 0.46 ⁄⁄⁄ 0.47 ⁄⁄⁄ Mixed race

0.19 2 ⁄⁄⁄ 0.20 ⁄⁄⁄ 0.19 ⁄⁄⁄ 0.19 ⁄⁄⁄ Pseudo R

0.08 0.14 0.09 0.14 0.19 0.23 0.19 0.23 Notes. ⁄ p < .05, ⁄⁄ p < .01, ⁄⁄⁄ p 6 .001; coefficients are odds ratios; pseudo-R 2 = McFadden’s.

Model 1.1 = punctures not counted, non-CEW force types collapsed.Model 1.2 = punctures counted, non-CEW force types collapsed. Model 2.1 = punctures not counted with interaction term, non-CEW force types collapsed. Model 2.2 = punctures counted with interaction term, non-CEW force types collapsed. Model 3.1 = punctures not counted, specific force types. Model 3.2 = punctures counted, specific force types. Model 4.1 = punctures not counted, CEW only, specific force types. Model 4.2 = punctures counted, CEW only, specific force types.

THE CONSEQUENCES OF COUNTING ENERGY WEAPON PUNCTURES AS INJURIES

Models 3.1-4.2 in Table 2 substitute the specific types of nonCEW force used by officers for the summary measure. In Model 3.1, CEW is not significantly, inversely associated with the odds of injury when punctures are excluded, but given the statistically insignificant effect (p = .779) and a coefficient near 1.0 (OR = 1.05), we conclude that the effects of CEWs are benign and neither decrease nor increase the odds of injury. When punctures are included as inju- ries in Model 3.2, however, we observe large and statistically significant increases in the odds of suspect injury (OR = 14.39, p 6 .001).

Consistent with our expectations, Model 4.1 shows that the effect of CEWs without other types of force and the use of a CEW in conjunction with other types of force reduces injuries; although the effects fail to attain statistical significance (OR = .64, p = .254 and OR = 1.24, p = .308, respectively). When punctures are included as injuries (Model 4.2), however, the use of a CEW alone and the use of a CEW in conjunction with other types of force signifi- cantly increase the odds of suspect injury (OR = 18.41, p 6 .001 and OR = 12.20, p 6 .001, respectively).

Generalized Ordered Logistic Regression Results Models 1.1-2.2 in Table 3 repeat the analysis for the corresponding models in

Table 2, except we model the severity of injury using generalized ordered logis- tic regression. Note that for ease of display, redundant coefficients equal across the cut points of the dependent variable are not repeated. As expected, when punctures are excluded from the injury measure (Model 1.1), CEWs reduce the odds of both minor and major injury (versus no injury) and the odds of major injury (vs. no or minor injury) (OR = .57, p 6 .01). However, when punctures are included (Model 1.2), CEWs increase the odds of minor/major injury (OR = 5.35, p 6 .001), but dramatically decrease the odds of major injury (OR = .14, p 6 .001). This indicates that the effect of counting routine punctures on the relationship between CEW use and the magnitude of suspect injury is an increase

Downloaded by [Robert Kaminski] at 16:06 14 May 2013 in the odds of minor injuries rather than more serious injuries. Models 2.1 and 2.2 include the interaction between CEW and nonCEW usage. Similar to the binary logistic model results, regardless of whether or not punc- tures are included, the effect of CEWs on injury depended on whether or not other types of force are also used. Model 2.1 shows that the odds of minor/ major injury increased substantially, as did the odds of major injury when other types of force are used in conjunction with CEWs (OR = 26.06, p 6 .001). Similar results are obtained in Model 2.2, except the effects of the interaction term differed across the cut points. Specifically, the use of other types of force in conjunction with a CEW increase the odds of minor/major injury (OR = 4.70, p 6 .001), but the effect on major injury is much higher in magnitude (OR = 71.07, p 6 .001).

Models 1.1-2.2 in Table 4 substitute the specific types of nonCEW force for the summary measure of nonCEW force used in Table 3. When punctures are

16 KAMINSKI ET AL.

Table 3 Generalized ordered logit models of severity of suspect injury collapsing non-CEW force types

Model 2.1 Model 2.2 Variable

Model 1.1

Model 1.2

Injury P 2 Injury P 3 Injury P 2 Injury P 3 CEW

Injury P 2

Injury P 3

Injury P 2 Injury P 3

0.41 – 0.42 ⁄⁄⁄ – Mixed race

Notes. The coefficients for Injury P 2 correspond to the logit formed from the two categories (major injury + minor injury) and no injury; the coefficients for Injury P 3 correspond to the logit formed from the two categories (major injury) and (minor injury + no injury); ⁄ p < .05, ⁄⁄ p < .01,

⁄⁄⁄ p 6 .001; coefficients are odds ratios; pseudo-R 2 = McFadden’s.

Model 1.1 = punctures not counted, non-CEW force types collapsed. Model 1.2 = punctures counted, non-CEW force types collapsed. Model 2.1 = punctures not counted with interaction term, non-CEW force types collapsed. Model 2.2 = punctures counted with interaction term, non-CEW force types collapsed.

Table 4 Generalized ordered logit models of severity of suspect injury using specific force types

Model 2.2 Variable

Injury P 3 Injury P 2 Injury P 3 CEW

Injury P 2

Injury P 3

Injury P 2

Injury P 3

Injury P 2

– – CEW only

0.40 ⁄⁄⁄ – Soft hands

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Hard hands

0.76 – Other force

1.57 0.47 ⁄⁄⁄ 2.14 Mixed race

Notes. The coefficients for Injury P 2 correspond to the logit formed from the two categories (major injury + minor injury) and no injury; the coefficients for Injury P 3 correspond to the logit formed from the two categories (major injury) and (minor injury + no injury);

⁄ p < .05, ⁄⁄ p < .01, ⁄⁄⁄ p 6 .000; coefficients are odds ratios; pseudo-R 2 = McFadden’s. Model 1.1 = punctures not counted.

Model 1.2 = punctures counted.Model 2.1 = punctures not counted, CEW only. Model 2.2 = punctures counted, CEW only.

THE CONSEQUENCES OF COUNTING ENERGY WEAPON PUNCTURES AS INJURIES

excluded in the injury measure (Model 1.1), CEWs neither increase nor decrease the odds of injury when other specific force types are controlled (OR = 1.09, p = .627). When punctures are included in the injury measure (Model 2.1), CEW increase the odds of minor/major injury (OR = 14.49, p 6 .001), but not the odds of major injury (OR = .92, p = .839). Again, this indicates that the effect of CEWs increases the odds of minor injury rather than more serious types of injury, when the injury measure includes puncture wounds.