Recent medical studies hail the safe use of conducted energy weapons

By Darrell L. Ross, Ph.D.

The use of the TASER®, conducted energy weapons (CEWs) has increased in popularity among law enforcement and correctional agencies. Presently over 8,000 law enforcement departments utilize them (TASER International, 2007). However, since there have been a number of sudden deaths and injuries of arrestees following deployment of the TASER, numerous concerns have emerged regarding the safe use of the device. Questions regarding the safety of CWEs have prompted several research projects. Because the use of the TASER has increased over the use of oleoresin capsicum and impact weapons, a review of recent research is important.

In 2005 the Canadian Police Research Centre released a report entitled, “Review of Conducted Energy Devices,” which analyzed 15 studies regarding the medical safety of the use of CEWs. Their research did not present evidence that implicated a causal relationship between the use of CEWs and death; that existing studies indicate that the risk of cardiac harm to subjects from CEW is very low; and the impact of CEWs on respiration, pH levels, and other associated physical effects, offers a plausible theory on the possible connection between deaths, CEWs use, and people exhibiting the symptoms of excited delirium. The researchers concluded that CEWs are effective tools with a low risk of harm to the subject.

In 2006 Stroke and Huston, published a medical case series article which analyzed 37 autopsy reports of decedents who died after exposure to the TASER® from 2001 to 2005. All of the subjects were men, ranging between the ages of 18 to 50 years. Cardiovascular disease was found in 54%, illegal substances were found by toxicology screening in 78%, and 86% within that group were found to have been using stimulants. Excited delirium was determined in 76% of the cases. The use of the TASER was considered a potential or contributory cause of death in 27%. This research was the largest and the second study to analyze autopsy reports of those exposed to CEW applications. Kornblum and Reddy (1991) studied 16 deaths after the use of the TASER and found no causal factor of death associated with its use. Stroke and Huston concluded that those that died after the use of the TASER are individuals who were already at a high risk for sudden deaths, particularly those who are exhibiting extreme agitation, those with a history of stimulant drug use, and those with preexisting heart disease.

Ho et al. (2006) performed a medical study for TASER International which assessed the effects of the TASER on human subjects.  The researchers were unable to detect, following a 5 second TASER exposure in a healthy population, any induced dysrthymias or cardiac cellular damage that could be related to sudden death, They did report, however, blood pH, and metabolic acidosis could increase the risk of cardiac arrest.

Chan et al. (2006) exposed 32 subjects to a 1.5 second cycle shock to the TASER. Prior to exposure, the subjects’ baseline measurements were taken. All of the subjects were monitored for six hours after the exposure. They found no evidence of hypoxemia or hypoventilation. Further, they found a moderate increase in respiratory rate for ten minutes but found no significant clinical changes in cardiovascular rates. Changes in blood levels were not evidenced.

Orange County Sheriff Kevin Beary slumps to the ground while being held by Dr. Louis Rueda, left, and sheriff's Lt. Dave Ogden, right, after being hit with a taser gun at the Orange County Sheriff's Training Facility in Orlando, Fla., in June 2004. Beary invited the media to the event as part of the training given to members of the Taser Review Committee. (AP Photo/Peter Cosgrove)
Bouton et al. (2006) exposed 21 law enforcement academy cadets to one, 5 second TASER application and monitored their physiological stress, ventilatory and blood pH for one hour after exposure. Baseline measurements were taken prior to the TASER application. The main finding of the research indicated that a 5 second TASER application did not cause clinically significant physiological stress. Respiratory rates increased mildly for a brief time. Changes in ventilatory and blood measures increased no more than what is expected during moderate exercise. The researchers concluded that a 5 second TASER exposure did not cause clinically significant indications of physiological stress that could be causally linked to sudden death.

Ross (2007) analyzed 47 autopsy reports from 20 states from 1999 to 2006 of individuals who died after exposure to the TASER. Of these incidents, 85% occurred in a street arrest situation and 15% occurred in jail. All of the decedents were men, 54% were white, and the average age was 35 years. Heart disease was found in 85%, 65% had an enlarged heart, and 35% exhibited other internal organ abnormalities. On average the TASER was applied in 2 cycles of 5 second intervals. In 75% of the cases the cause of death was due to cardiac arrest due to drugs and excited delirium and 10% of the deaths were caused by acute exhaustive mania. No direct linkage to the use of TASER was correlated to the cause of death.

Ross (2007) also analyzed 75 police agency reports from 22 states on the applications of the TASER in 34,000 arrests from 2002 to 2006. Of these arrests the TASER was deployed in 6,010 or 18%. The agencies reported that suspect injuries decreased by 66%, minor injuries were sustained in 35% of the arrests, and officer injuries declined by 58%. The effective rate of the use of the TASER was observed in 94%. On average lethal force incidents declined by 48%, excessive force lawsuits declined by 52%, citizen complaints declined by 52%, and no deaths were reported.

The most recent medical study researching the injury potential of using the TASER was performed by Bozeman et al. (10/2007) from the Wake Forest Medical School. The Department of Justice funded the study for the purpose of performing the first large, independent study which assessed the injury and severity of injury after exposure to the TASER. A multicenter cohort study was conducted at six police agencies across the country. All arrestees exposed to the TASER were included in the study from July 2005 to June 2007 which totaled 962. A tactical physician at each agency reviewed police records and medical records for each case.

Injuries were classified as mild (outpatient treatment), moderate (short-term inpatient treatment), or severe (long-term inpatient treatment). Subjects mean age was 32 years and 94% were male. The mean number of shocks delivered was 1.6 in the probe mode and 1.8 in the drive stun mode. Findings of the research reveal that: 99.7% of the subjects sustained no injuries or mild injuries; skin punctures from the TASER probes, contusions and lacerations account for 98.5% of mild injuries; and the back, chest and the abdomen/pelvis areas represented 76% of the body impact areas. During the study, two in-custody deaths occurred. Neither death occurred immediately after the TASER was deployed and the autopsy showed that both deaths were unrelated to the TASER. Only 3 cases (0.3%) were classified as severe requiring hospitalization, including: 1 case of rhabdomolysis, 1 case of cerebral contusion, and 1 case of epidural hematoma. The researchers concluded that the findings support the safety of TASER use by law enforcement.

While these studies do not represent all medical research on the subject they do reveal emerging significant findings. All but one of the studies involved independent research. What is important about these studies is that they have moved past studying the effect of the TASER on animals and have researched its impact on humans. The Bozeman et al., Ross, and Ho et al. studies analyzed incidents from actual field applications. The Bozeman et al. study is particularly noteworthy as it applied a longitudinal design with multiple sites with almost 1,000 suspects. The study shows that the injury potential of using the TASER is statistically insignificant supporting its safe usage.

The collective findings of all of these studies support the fact that the TASER is not causally linked to sudden deaths of suspects, that there is an extremely low risk of injury to a suspect, and that there is no evidence that it causes cardiovascular effects linking it to sudden death. This is not to suggest that the TASER is totally risk free. While rare, there have been limited significant injuries sustained after the use of the TASER. These studies, however, are important as they underscore the initial development of the TASER, in that it was designed to safely control resisting subjects by decreasing the injury potential for the subject and the officer. Officers using the TASER are encouraged to closely follow their training, policy, and use of force legal standards in a continued effort to maximize its continued safe application.


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