Fatal traumatic brain injury with electrical weapon falls
Mark W. Kroll a, *
, Jiri Adamec b
, Charles V. Wetli c, 1
, Howard E. Williams d
a
Dept of Biomedical Engineering, University of Minnesota, California Polytechnical Institute, USA
b
Institute of Legal Medicine, LMU, Munich, USA
c
Chief Medical Examiner and Director of Forensic Sciences, Suffolk County, NY, USA
d
School of Criminal Justice, Texas State University, San Marcos, TX, USA
a r t i c l e i n f o
Article history:
Received 30 March 2016
Received in revised form
27 May 2016
Accepted 3 July 2016
Available online 5 July 2016
Keywords:
TASER
Arrest-related-death
Traumatic brain injury
Falls
Electrical weapons
CEW
ECD
a b s t r a c t
Introduction: While generally reducing morbidity and mortality, electrical weapons have risks associated
with their usage, including eye injuries and falls. With sufficient probe spread, an uncontrolled fall to the
ground typically occurs along with the possibility of a fatal brain injury.
Methods: We analyzed possible risk factors including running and elevated surfaces with established
head-injury criteria to estimate the risk of brain injury. We searched for cases of arrest-related or incustody
death, with TASER®
electrical weapon usage where fall-induced injuries might have contributed
to the death. We found 24 cases meeting our initial inclusion criteria of a fatal fall involving
electronic control. We then excluded 5 cases as intentional jumps, leaving 19 cases of forced falls. Autopsy
reports and other records were analyzed to determine which of these deaths were from brain
injury caused by the fall.
Results: We found 16 probable cases of fatal brain injuries induced by electronic control from electrical
weapons. Out of 3 million field uses, this gives a risk of 5.3 ± 2.6 PPM which is higher than the theoretical
risk of electrocution. The mean age was 46 ± 14 years which is significantly greater that the age of the
typical ARD (36 ± 10). Probe shots to the subject's back may present a higher risk of a fatal fall.
Conclusions: The use of electronic control presents a small but real risk of death from fatal traumatic
brain injury. Increased age represents an independent risk factor for such fatalities.
© 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.
1. Introduction
Arrest-related-death (ARD) is a well-recognized syndrome often
with no clear single pathological mechanism or obvious anatomical
or toxicological basis.1,2
Annually there are about 800 000 arrests in
which force is used in North America and approximately 800 ARDs
yielding a mortality rate of about 1:1000 for a law-enforcement
interaction associated with force.3,4
About 80% of resistant subjects
have co-morbidities of mental illness, drug abuse, or intoxication;
the majority have at least 2 of these.5
The conducted electrical weapon (CEW) is involved in a minority
of ARDs.2,6
The largest manufacturer, TASER International,
tracks the number of field uses based on sales and known usage
patterns.7
This is continuously updated on their website and reveals
2.98 million field uses as of January 2016 (https://www.taser.
com/lives-saved). There have also been 1.95 million CEW training
exposures for a total of ~5 million human CEW exposures.
Electronic control with the CEW has gained widespread acceptance
as the preferred force option due to suspect injury reduction.
Large prospective studies have consistently found suspect injury
rate reductions of about 65%.8,9
Of the 310 000 annual CEW field
uses, only 1 in 3500 is involved in an ARD vs. the baseline ARD rate
of 1:1000. This reduction in fatality rate is consistent with prospective
published data, which showed that 5.4% of CEW uses
“clearly prevented the use of lethal force by police.”10
It is also
consistent with a 2/3 reduction in fatal police shootings where CEW
usage is not overly restricted.11
The short-duration (50e100 ms) electrical pulses applied by
TASER CEWs (see Fig. 1) are intended to stimulate type A-a motor
neurons, which are the nerves that control skeletal muscle
contraction, but with minimal risk of stimulating cardiac muscle.
This typically leads to a loss of regional muscle control and can
result in a fall to the ground to end a potentially violent
* Corresponding author. Box 23, Crystal Bay, MN 55323, USA.
E-mail addresses: mark@kroll.name (M.W. Kroll), Jiri.Adamec@med.unimuenchen.de
(J. Adamec), charlesvwetli@gmail.com (C.V. Wetli),
howardewilliams@msn.com (H.E. Williams).
1
Retired.
Contents lists available at ScienceDirect
Journal of Forensic and Legal Medicine
journal homepage: www.elsevier.com/locate/jflm
http://dx.doi.org/10.1016/j.jflm.2016.07.001
1752-928X/© 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.
Journal of Forensic and Legal Medicine 43 (2016) 12e19
confrontation or suicide attempt.12,13
Electrical weapons are, after all, weapons and there are indeed
risks associated with their usage, including eye injuries and falls.
With sufficient probe spread (30 cm in the front or 20 cm in the
back) an uncontrolled fall to the ground is possible.12
The goal of
our research was to analyze the risks of such falls from both
analytical and epidemiological frameworks.
1.1. Biomechanics of head injury from a fall
The relationship between the physical parameters of a fall and
the risk of life-threatening injuries is complex and influenced by
many factors, such as the shape and material properties of the
object impacted, the exact fall kinematics, the individual anatomy,
and the biomechanical tolerance of various body tissues.
The most common relevant parameter is the head injury criterion
(HIC), based on the resultant head linear acceleration (or
deceleration) calculated with Eq. (1).
HIC ¼ max
8
><
>:
ðt2 À t1Þ
2
6
4
1
t2 À t1
Zt2
t1
aðtÞdt
3
7
5
2:59
>=
>;
(1)
where a(t) is the resultant head linear acceleration (as a function of
time) and t1 and t2 define the time interval that maximizes the HIC.
The duration, (t2 - t1) is typically taken as 36 ms or 15 ms and the
corresponding HIC-values are referred to as HIC36 or HIC15. Eq. (1)
can be simplified as follows. Take the average deceleration to the
2.5 power and multiply times the exposure time. The probability of
skull fracture (Abbreviated Injury Score ! 2) with a HIC15 ¼ 700 is
~30% for a mid-size male.
The energy equivalent head impact velocity (EEV) is a meaningful
reference comparison of biomechanical head loading and
defined as the head impact velocity that results from a fall if the
initial state of the body (the potential as well as the kinematic
energy of the head) is transformed in an undamped fall. In a person
initially standing still, it is the velocity of a free fall from the height
of the head center-of-gravity. With walking, running, or riding a
bicycle the EEV increases accordingly (see Fig. 2).
If a forward fall occurs with braced hip and knee joints (i.e. the
whole body tilts rigidly), the actual head impact velocity is well
approximated by the EEV. In case of free knee-joint landings, the
subject falls first on the knees and the tilting movement then occurs
from a lower position of the head (see Fig. 3); this leads to a slightly
lower head impact velocity and injury risk. Hajiaghamemar found a
minor reduction of both head impact velocity (6.5 msÀ1
vs.
6.7 msÀ1
, or 21 fps vs. 22 fps) and HIC15 (3300 vs. 4100) for forward
falls with free vs. locked knee joints.14
A much stronger effect was
observed in backward falls, where free hip movement leads to an
impact in the buttocks first and the head impact is the result of the
following tilting movement of the torso (see Fig. 4). The difference
between this scenario and a backward fall with stiff hips was dramatic,
giving a head impact velocity of 4.9 msÀ1
vs. 6.8 msÀ1
(16 fps
vs. 22 fps) and HIC15 of 1800 vs. 4100.
The biomechanical tolerance of different skull regions varies
substantially. While some facial bones can fracture well below
impact force levels of 3 kN, the calvarium is more stable and, at the
occiput, forces well above 10 kN can be tolerated.15e22
Forward falls
have lower risks of life-threatening injuries compared to backward
falls. A severe impact on the face causes fractures at moderate force
levels resulting in energy absorption and a reduction of the
resulting head acceleration similar to that seen with crush zones in
an automobile body. The higher stability of the occiput region leads
to higher accelerations and a higher risk of intracranial injuries
(contre-coup contusions with subdural hematoma).
The head impact velocity in falls from a standing position can
reach values exceeding 6 msÀ1
(20 fps).14,23
Such an impact on a
hard surface can cause severe or life-threatening injuries even on
flat ground. The EEV for a mid-size male (body height 1.75 m) for a
fall from a standing position (locked joints) is ~5.7 msÀ1
(19 fps). If
the subjects runs or rides with a speed of 5 msÀ1
(11 mph) and then
falls, the EEV reaches ~7.5 msÀ1
(25 fps). A fall from a standing
position on a platform 3 m above the head impact location results
in an EEV of ~9.5 msÀ1
(31 fps). The ability to break the fall with
coordinated arm movements prevents most fatalities from groundlevel
falls. Consistent with this, Thierauf et al. reported that the
majority of fatal ground-level falls featured an alcohol-intoxicated
subject.24
Injuries from ground-level falls are most commonly to
the skull vault while elevated-fall injuries tend to be found at the
skull base or cervical vertebrae.25
2. Epidemiological data
2.1. Methods
The inclusion criteria for our study were:
Fig. 1. X26 CEW during probe launch.
M.W. Kroll et al. / Journal of Forensic and Legal Medicine 43 (2016) 12e19 13
1. Arrest-related or in-custody (post confinement) incident
2. Death
3. Electronic control was used in the relevant incident
4. Decedent fell during the incident and the fall was forced by the
CEW
5. Traumatic brain injury (TBI) contributed to or caused the death
Co-author HEW maintains a database of worldwide CEWproximate
ARDs. It had 1030 cases (971 from USA) as of 1 Feb 2016.
This ARD database has been cross-checked with the TASER International,
Inc. internal ARD database and is continuously updated
with Internet news scans. Due to the high level of media interest in
ARDs, we feel that few, if any, cases are missing from this database.
Autopsies and law-enforcement investigative reports are regularly
requested and maintained. The HEW database has been used in
previous peer-reviewed publications.
There were 5 exclusions for the fall not being forced by the CEW
and 3 additional exclusions for the death not being caused by TBI.
2.2. Results: brief case summaries of 19 forced falls
Cases are listed from earliest incident. The Manner of Death and
autopsy findings are given when available. See Table 1 for further
details.
1. Officers responded to a disturbance call involving a man and
his son but the father was intoxicated and uncooperative. As
he walked away from officers toward the house, an officer
fired a CEW, striking the man in the back, causing him to fall
backwards and hit his head on concrete steps. The father was
transported to the hospital where he died 3 days later.
2. A woman called police claiming that her ex-boyfriend was
intoxicated and had assaulted her. When police arrived, the
man was uncooperative and implored officers to shoot him.
When he advanced on them, 2 officers fired their CEWs, each
striking the man in the chest. The man fell backward and
Fig. 2. Energy Equivalent Velocity (EEV) for head injury from standing or running.
Fig. 3. Forward fall with locked (left) and flexed (right) knees.
Fig. 4. Backward fall with locked (left) and flexed (right) hips.
M.W. Kroll et al. / Journal of Forensic and Legal Medicine 43 (2016) 12e1914
struck his head on the ground. Following surgery for head
injuries, he lapsed into a coma and died 2 days later.
3. Subject was attacking a woman in a pharmacy parking lot.
The man remained agitated and refused to cooperate with
police when they arrived. An officer deployed a CEW striking
the man in the back. The man fell and hit his head on the
pavement. He later died from his injuries in the hospital.
Autopsy found craniocerebral trauma with subdural hematoma
and his death was ruled an accident.
4. Sheriff's deputies attempted to arrest a parole violator on
outstanding warrants, but he fled on foot down the street.
During the chase, a deputy deployed a CEW, striking the man
in the back and causing him to fall face down on the pavement.
An ambulance took the man to a hospital where he
refused medical treatment so deputies then took him to jail.
The jail nurse ordered that the man be taken to a hospital 2
days later, where, about 5 h after arrival, he died from his fall
injuries. Autopsy found multiple skull fractures and epidural
and subdural hemorrhage. Tissues were positive for methamphetamine
and amphetamine. His death was ruled a
homicide.
5. Officers responded to a call of a man pounding on a neighbor's
front door and making threats. When officers arrived,
they found the intoxicated subject back at his own home. He
came out on his front porch cursing and threatening the
officers. When officers moved to arrest him, the man tried to
walk back inside his front door where he claimed he had a
weapon. Two officers simultaneously fired CEWs, both
striking the man in his back. He fell backward, striking his
head on the concrete porch. He did not immediately appear
to have any injuries, but, as a precaution, an ambulance took
him to a local hospital. He died early the next morning. Autopsy
found subdural hematoma and temporal lobe contusions.
His death was ruled a homicide.
6. Police received a call of a man who had tried to break into an
automobile, but who then ran 1500 m after the vehicle's
owner confronted him. Officers then found the man carrying
a knife but he refused orders to drop the knife. An officer
discharged a CEW causing the man to fall backwards and
strike his head on the sidewalk. He was bleeding from the
head wound and never regained consciousness. Emergency
services was called for the bleeding and he was taken to a
hospital where he died. The autopsy found no skull fracture
or intracranial hemorrhage. The initial autopsy report listed a
hamartoma of mature cardiac myocytes (which is known to
be very arrhythmogenic). Toxicological analysis revealed a
blood alcohol concentration of 0.18% along with tetrahydrocannabinol
and its metabolites. The chief medical examiner
later changed the cause of death to electrocution from the
CEW. No molecular autopsy was performed for channelopathy
risk. Inquest expert testimony opined that the cause of
death was stress-induced ventricular fibrillation along with a
possible channelopathy.
7. Officer received calls of a naked man standing on the ledge of
a building, screaming at passersby, and swinging a long
florescent tube. When they arrived, officers found the
emotionally disturbed man on a 2nd story ledge. When efforts
to talk the man into coming down from the ledge failed,
an officer fired a CEW at him, causing him to fall head first
onto the sidewalk about 3 m below his feet for a ~5 m fall for
his head. He suffered an obvious head injury and died soon
thereafter. The autopsy report was not released but media
reports suggested that the autopsy was inconclusive. https://
www.youtube.com/watch?v¼Sg5RVq4m8xg
8. Officers confronted a man with bipolar disorder who had
sexually harassed a female clerk at a gasoline station. When
they asked for his identification in the parking area, he
knocked both officers to the ground and ran at the clerk, who
was now standing outside in front of the station. An officer
deployed his CEW, which struck the man in the back and
caused him to fall face-first onto a curb. When officers
completed handcuffing him, they realized the man was not
breathing and resuscitation efforts were unsuccessful. The
autopsy found bilateral fractures of the orbital plates, with
extensive right retrobulbar hemorrhage and concluded that
death was due to posttraumatic concussion. His death was
ruled an accident. The conclusion of forensic pathologist coauthor
CVW was different. He noted a lack of intracranial
injury along with a history of bipolar disorder and sudden
loss of vital signs, after being handcuffed, which is typical for
an excited delirium death.
9. During a routine traffic stop, the driver struck the deputy and
fled on foot. The deputy caught up to the man and deployed a
CEW hitting the man in the chest. The man fell face-down
Table 1
Cases analyzed.
# Age Race Elevation Posture Impact surface Head impact Probes Year Fatal TBI?
1 55 W BH Walking Concrete Back Back 2004 Prob
2 55 W BH Walking Trailer park Rear skull fracture 2 CEWs (4 probes) R & L chest 2007 Prob
3 59 W BH Standing? Pavement Back Back 2007 Yes
4 39 H BH Running Pavement Face Back 2007 Yes
5 49 W BH Walking Concrete Frontal and side impact 2 CEWs (4 probes) R back 2007 Yes
6 17 IC BH Standing Pavement Back Front 2008 No
7 35 H 3 m Standing Concrete sidewalk Front 2008 Prob
8 39 W BH Running Curb Face. Right forehead Back 2009 No
9 42 H BH Running Pavement Right orbit Front 2010 Yes
10 68 W >BH Standing in Trailer Cervical fracture Face 2011 No Cervical fracture
11 22 W BH Running Pavement Back Back 2011 Prob
12 61 B BH Bicycle Pavement Back Back 2011 Yes
13 57 B BH Standing Jail floor Back Both arms 2012 Yes
14 32 H BH Standing Pavement Back? 2014 Prob
15 23 B BH Running Street lamp pole Left Back? 2014 Yes
16 54 H 5 m Standing Sidewalk Frontal and Top Right arm 2014 Yes
17 57 O BH Standing Pavement 2015 Prob
18 62 W BH Standing Concrete Back Back 2015 Prob
19 33 B 2.5 m Climbing Back 2015 Prob
Note: Cases 6, 8, and 10 were excluded from statistical analysis as not being fall-induced traumatic brain injury. Case 11 was the only female. BH ¼ Body Height.
IC ¼ Indigenous Canadian. Prob ¼ most likely TBI but autopsy not available. A blank space represents an unknown datum.
M.W. Kroll et al. / Journal of Forensic and Legal Medicine 43 (2016) 12e19 15
onto the pavement. After handcuffing him, the deputy
noticed the man was in an altered mental state. An ambulance
transported him to the hospital, but, despite surgery,
he died the next morning. Autopsy found frontal skull fractures
and subdural hemorrhage. His death was ruled a
homicide.
10. An elderly man (age 68) was involved in a disturbance with
his landlord. When police arrived, the man had locked
himself in a trailer and refused to come out. Believing he was
armed, officers cut into the trailer. One officer fired a CEW at
the man, hitting him in the face and causing the man to fall
and injure his neck. An ambulance transported him to a
hospital where he died from complications of his injuries 7
days later. Media reported that the autopsy found the cause
of death to be “spinal cord injury due to cervical spine fractures
due to blunt face and neck injury.”
11. A state highway officer arrested a woman for fleeing the
scenes of 2 separate collisions within an hour. When he took
her out of his patrol vehicle at the station, she ran. The officer
deployed a CEW striking the woman in the back while she
was still handcuffed, causing her to fall head-first onto the
pavement. She was taken to a hospital where she remained
in a coma until she died 725 days later. No autopsy was
performed. As seen on the video, the escapee was running
and the horizontal velocity increased the resulting head
impact velocity; the feet and the buttocks decelerated
rapidly on the tarmac. Because of the friction, the inertia
caused a rotation of the upper body and head. She was
initially higher than the head impact location (running down
a slight slope) and the fall was uncontrolled as no selfprotection
measures can be observed. The tarmac is
extremely hard and the impact in the occipital region (the
woman spun as she fell) resulted in very high linear accelerations
of the head. Brain contusions (more pronounced in
frontal region than the occipital), subdural hematoma and
skull fracture are expected but no autopsy was performed.
https://www.youtube.com/watch?v¼mpV7qqhxZ_4
12. While investigating a citizen report about an intoxicated
man on a bicycle, an officer observed an elderly (age 61) man
pedaling down the street and putting something into his
mouth. When the man refused to stop, the officer got out of
his vehicle and deployed a CEW to the man's back, causing
him to fall from the bicycle and hit his head on the pavement.
The man, who had a history of seizures and a craniotomy,
died the next day. According to media reports, the autopsy
found the cause of death to be blunt force trauma to the head.
13. A county jail inmate was in a fight and a jailer applied a CEW
to him. The man fell backward onto the floor, striking his
head. The jail nurse initially treated him for a small cut to his
head, but 90 min later he was transported to a local hospital
where he died 4 days later. Autopsy found subdural and
subarachnoid hemorrhage.
14. When police conducted a routine traffic stop, the driver
exited the vehicle and ran. One officer deployed a CEW,
causing the man to fall backward onto the ground. Whether
he hit his head, during the fall, is in dispute. Other officers
arrived and used additional force to get the man into custody.
The officers took the man to a local hospital where he spent 5
days before his release. After 7 days, he complained of severe
headaches and returned to the hospital where he died of
head injuries after an additional 5-day stay. Cause of death
was blunt craniocerebral trauma.
15. An officer deployed a CEW on a shoplifting suspect who had
fled the store. The man fell to the ground, but he got up and
tried to flee again. The officer again applied the CEW, and the
man fell forward striking the left side of his head on a light
pole. The man was unconscious when he arrived at the
hospital via ambulance. He never regained consciousness,
and he died from his injuries 13 days later. Autopsy found
multiple cerebral contusions. His death was ruled an
accident.
16. A mentally ill man climbed atop a billboard and was
threatening to jump off. When responding officers failed to
talk him down, they called for SWAT officers. When SWAT
officers arrived, the man climbed down from the billboard
onto the roof of a building. As officers approached him,
however, he began to again climb a ladder back up to the
billboard. An officer deployed his CEW with a probe striking
him in the right arm. (The other probe injury was not located
at autopsy.) The man fell from the ladder and then fell headfirst
onto the sidewalk, missing the airbag rescue teams had
placed for him. He was transported to a hospital where he
died. Autopsy found skull fracture and subdural hematoma.
Tissues were positive for cocaine and cocaine metabolite. His
death was ruled an accident.
17. Police received calls about a group of people fighting with
weapons in the parking lot of an auto body shop. Police found
a man wielding a crowbar. When he refused orders to drop
the crowbar, an officer deployed a CEW. The man fell to the
ground striking his head on the pavement. He was transported
to a hospital where he had surgery for a head injury,
but his condition deteriorated, and he died 2 days later. Autopsy
was not released: however, the death certificate gave a
cause of death as blunt force craniocerebral trauma. His
death was ruled a homicide.
18. Police received a call from an elderly (age 62) man who reported
a disturbance with his son. He told dispatchers that he
had a gun and had already fired 3 rounds. When officers
arrived, they confronted the man, who refused to comply
with their orders to get on the ground. An officer deployed a
CEW into the man's back, causing him to hit the back of his
head when he fell to the concrete driveway. He was treated
and released from a hospital for the laceration to his head.
However, he died 8 days later from complications of injuries
sustained in the fall. According to litigation filings, the autopsy
found the cause of death to be “blunt force head
trauma.”
19. When officers stopped a vehicle, a passenger jumped out of
the vehicle and fled on foot. Officers gave chase and found
the man trying to climb a cement wall behind a business. An
officer deployed a CEW, striking the man in the back, and
causing him to fall head-first from the 2.5 m wall. He was
transported by ambulance to a hospital where he died. According
to media reports, the autopsy found the cause of
death was “head and neck trauma resulting from the fall.”
2.3. Results: analysis
We found 24 initial cases from screening for fatal falls involving
electronic control. See Fig. 5 for classification details. Based on the
investigative reports and autopsies, we classified 5 cases as
“intentional” as they were either suicides or escape attempts. These
cases are summarized in the Appendix and will not be analyzed
here.
For the 19 “forced” falls, we obtained 11 full autopsy reports and
5 autopsy summaries from litigation filings, police reports, a death
certificate, or news accounts directly quoting from the report. Of
the remaining 3 cases there were 2 cases (#1 and 2) with sufficient
incident detail from litigation filings, police reports, or news
M.W. Kroll et al. / Journal of Forensic and Legal Medicine 43 (2016) 12e1916
accounts to support a classification of an electrical-weapon forced
fall. Case #11 did not receive an autopsy but her highly-publicized
case has no causal controversy and is well-supported by a lengthy
incident video.
Of the 19 forced-fall cases, we excluded another 3 as not being
due to TBI. Subject #6 fell backwards onto pavement and was
immediately bleeding from a laceration. Even though he never
regained consciousness, he had no brain injuries at autopsy. The
inquest consensus was that this was a stress-induced cardiac
arrhythmia in a subject with a proarrhythmic cardiomyopathy
(hamartoma), high alcohol levels, and a possible channelopathy.
The primary acute stressors were probably running 1500 m, fear of
arrest, electrical shock from the CEW, and the traumatic shock of
the head impact. In a sense, one could argue that the external head
injury, therefore, contributed to the death. We found this hypothesis
tenuous and did not classify him as a fall-induced death.
The forensic pathologist co-author (CVW) disagreed with the
original medical examiner cause of death (TBI from the fall) in case
#8 as the subject had only orbital fractures without any intracranial
injury. Subject #10 died from a cervical fracture and, thus, TBI (if
any) was not considered to be a contributor to his death. Thus, we
excluded cases #6, 8, and 10 from our statistical analysis.
We found 16 cases of fatal TBI from falls most likely forced by
electronic control. Out of 3 million field uses, this gives a risk of
5.3 ± 2.6 PPM. The mean age was 46 ± 14 years which is significantly
greater than the age of the typical ARD. Strote reported a
mean age of 35.6 (median 36), Stratton reported 32.1 ± 6.4 years,
and Ho reported 35.7 ± 9.8 years.6,26,27
(p ¼ 0.0002 vs. Ho with
n ¼ 162).6
There were 6 whites, 5 Hispanics, 4 blacks, and 1 South
Asian in our series.
Only 3 were elevated in any way. Case #7 was standing on a 2nd
floor ledge (3 m), #16 was on a rooftop (5 m) and #19 was climbing
over a 2.5 m concrete wall. Thus 13 of the cases had no elevation.
Only 5 subjects were moving rapidly. Case #12 was riding a
bicycle while 4 others were running. Only 3 subjects were walking
while 8 were either standing or climbing. Of the 16 cases, 6 suspects
were fleeing police and were not armed. Taking police and media
reports as accurate, 5 subjects were armed and 6 represented a
threat to themselves, police or another party.
Probe locations were known for 14 of the 16 included cases.
They were in the back for 9 of these 14 cases. Bozeman reported
that 37% (628/1703) of CEW probes land in the back.28
This difference
was barely statistically different from our 9/14 fraction
(p ¼ 0.034 by Chi-square) suggesting a possibly increased mortality
risk with probe deployments to the back. However, Bozeman
published his data in 2009, the same year that the major manufacturer
modified their training suggestions to encourage more
back deployments.29
This confounding variable mitigates against
any conclusions regarding probe-deployment locations.
3. Discussion
We believe that this paper represents the first methodical
analysis of the death risk from falls induced by electronic control.
Fox and Payne-James first reported that the majority of “definite or
probable” deaths strongly associated with electronic control were
the 8 cases of fatal falls that they found.30
Mangus reported 2
serious non-fatal head injuries from CEW deployments: (1) basilar
skull fracture, right subarachnoid hemorrhage, and left-sided
epidural hemorrhage necessitating craniotomy and (2) a concussion,
facial laceration, comminuted nasal fracture, and orbital floor
fracture.31
The warnings of the largest CEW manufacturer appear to be
consistent with our results. They warn against use on elevated
subjects; we found 3 such deaths. They warn against use on
running or bicycling subjects; we found 5 such subjects. With
hindsight, one could say that strictly following these warnings
could have prevented 8 of the 16 fatalities, which is ½ of the cases.
Such utopian reasoning, of course, does not suggest a viable control
alternative for the officer at the time of the incident.
The unexpected finding was the increased age for the subjects.
This is consistent with other studies finding that the mortality risk
from head injury increases with age.32,33
Due to the CEW using an electrical current, the primary concern
in the media and some peer-reviewed literature has been the
possibility of electrocution. There have been 12 published case reports
suggesting a potential cardiac arrest link giving an incidence
of 4 PPM.34e39
Such assertions have always been made without
mention (or apparent consideration) of the relatively low outputs
of these devices. CEW pulses deliver <110 microcoulombs of
charge, far less than that required for transcutaneous pacing,
making any cardiac effects (much less VF) highly unlikely.40,41
Low
average CEW currents of <2 mA are comparable to TENS painblocking
units.42
CEWs deliver < 2 W of power, which can be
contrasted with the 100 W used in internal cardiac RF ablation and
the 2.5 W IEC limit for electric fences.43
In fact, current CEWs satisfy
all relevant electrical safety standards including those for the
electric fence.44,45
None of the published electrocution-alleging
case reports have stood up to careful scrutiny.46
It appears that
the risk of a fatal head or neck injury far exceeds the hypothetical
risk of electrocution which has been estimated at ~ 0.3 PPM.47
4. Limitations
A prospective experimental study would generate superior data
compared to our retrospective data. However, an experiment d
designed to cause people to fall to determine what injuries or fatalities
can be generated d would have difficulty obtaining ethical
approvals.
There is no national database that records data in such incidents,
so secondary sources are the only sources of information available
to identify the relevant cases. When primary sources of data, such
as autopsy reports, were available, we used them. However, autopsy
and police reports are not available in all states, depending on
each state's public information laws. Police reports, autopsy reports,
and news accounts are also subject to bias.
We also note that the sampling frame is less rigorous than we
would prefer. However, there is no practical alternative. We spent
Fig. 5. Case report processing flowchart.
M.W. Kroll et al. / Journal of Forensic and Legal Medicine 43 (2016) 12e19 17
significant time searching open records sources trying to identify
cases for this study. We limited our examination to those cases
when the electrical weapon caused someone to fall, and that fall
resulted in a fatality. Those instances are rare, but they are critically
important to understanding the risks of using such weapons.
Medical records are not available to us to study the effects of this
force on people who suffered non-fatal injuries, and the effects on
people d who did not fall d add nothing to the understanding of
the risks of fatal falls once the rate is calculated, as we did.
5. Conclusions
The use of electronic control presents a small (5.3 ± 2.6 PPM) but
real risk of death from fatal traumatic brain injury. This risk exceeds
the theoretical risk of electrocution. Increased age represents an
independent risk factor for such fatalities.
Disclosures
MWK & CVW have been expert witnesses in law-enforcement
litigation. MWK is a member of the TASER corporate and scientific
advisory board who partially funded this work. HEW is a retired
Police Chief.
Appendix. Excluded cases
These cases were judged to involve intentional jumps, either for
escape or suicide. The CEW was not judged to have caused the fall.
1. Officers received a call of a naked man behaving bizarrely at an
apartment building. When officers arrived, they found a 26year-old
man climbing on the balconies of the apartment
building, jumping from balcony to balcony. The man broke a
window to an apartment and began stabbing himself in the
thigh with a shard of glass. An officer attempted to use a CEW to
subdue the man, but it appeared to have no effect. The man then
either jumped or fell from a 4th floor balcony to the sidewalk
below. He was taken to a hospital where he died the next day
from a closed head injury. Autopsy found numerous cranial and
skull injuries along with methamphetamine. His death was
ruled an accident.
2. Police received a call of a man running in and out of traffic.
When officers arrived, they found a 35-year-old man sitting on
the wall of a highway overpass threatening to jump. For 3 h
police tried to talk the man down from the wall. When negotiations
broke down, an officer tried to subdue the man with a
CEW. The attempt failed, and the man jumped about 30 m to the
pavement below and died at the scene. Autopsy found multiple
internal and external injuries with no TASER probes penetrating
the skin. His death was ruled a suicide.
3. Police received a call of a suicidal man threatening to jump from
a bridge. Police arrived and found a 28-year-old man standing
on the bridge edge. The officers spent about 20 h negotiating
with the man. When the man stepped away from the edge of the
bridge, an officer attempted to subdue him with a CEW, but the
CEW did not disable the man. Instead, he jumped over the
railing and died when he hit the rocks below.
4. Officers went to the home of a 21-year-old man to arrest him on
warrants. As the officers approached him, the man dove through
a closed 2nd story window. To prevent his escape, an officer
deployed a CEW, striking him in the back as he was diving
through the window. The probes were only 6 cm apart and thus
achieved no muscle control. He struck his head on the pavement
below and died 4 days later. The autopsy was not released, but
litigation allegations cited multiple skull fractures and brain
injury. An appeals-court decision noted that the death was due
to “massive brain trauma.”
5. Police had been searching for a suspect in a murder. They found
him perched on a boulder on a cliff. They negotiated with the
34-year-old man for 3 h. Police tried to subdue the man with
less-lethal munitions and a CEW. Their efforts failed, and the
man jumped to the ground 14 m below. He died at the scene.
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