New Study Explores Risk Of Death From CEW-Induced Falls

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A new study of fatalities associated with controlled electrical weapons (CEWs) finds that falls producing traumatic brain injury are by far the greatest mortality risk to suspects from these control devices. But even that risk is miniscule.

Out of some 3,000,000 field uses, a research team could document only 16 cases in which fatal brain injuries resulted from uncontrolled falling after CEW deployment. That’s one in every 187,500 applications–“a real risk of death” but “small,” the researchers note.

Compared to subjects who die from other arrest-related causes, those who are killed by falls tend to be significantly older, with those sustaining probe shots to the back possibly most vulnerable, the researchers found.

Although “an uncontrolled fall to the ground typically occurs with a sufficient probe spread, fatal falls from CEW deployment “are rare,” the study concludes, “but they are critically important to understanding the risks of using such weapons.” And some falls, the researchers point out, may be preventable.

The research, believed to be the first of its kind, was led by Dr. Mark Kroll, an adjunct professor of biomedical engineering at the University of Minnesota and the California Polytechnical Institute and a member of TASER International’s scientific advisory board. His team included an expert in legal medicine and death from blunt trauma and falls, a forensic pathologist, and a CJ professor with a law enforcement background.


To find relevant cases, the group screened two thoroughly maintained databases of arrest-related and post-confinement deaths, looking for incidents in which:

  • subjects fell during an arrest or in-custody encounter
  • the fall was “forced” by a CEW, and
  • traumatic brain injury from the fall “contributed to or caused” the resulting fatality.

Out of 1,030 incidents in which circumstances included a CEW discharge, they isolated only 16 deaths that fit their criteria (plus one other in which the cause of death was a cervical spinal fracture), after reviewing autopsy and police reports, litigation filings, death certificates, and/or news accounts. Each is described with salient detail in the study. All but one were males.


The cases include falls in which subjects, often intoxicated, hit their head on concrete steps, on the ground, on the floor, on a sidewalk, on pavement, on a curb, on a driveway, on a light pole, and on a concrete porch.

Three fell from an elevated position: one from a second-floor ledge, one from a roof, and one while climbing over a high wall. Five subjects were “moving rapidly” when they fell; riding a bicycle or running. Three were walking, eight standing or climbing.

The study includes stick-figure illustrations of the various types of falls that occurred and the velocity of head impact generated, from a crumpling to the knees to a rigid, full-body pitch. “Forward falls have lower risks of life-threatening injuries compared to backward falls,” Kroll writes.

In almost all cases, death occurred after some delay and usually in a hospital, in one case after the subject remained in a coma for 725 days.


From their findings, Kroll’s team offers several practical take-aways for trainers and patrol officers:

  • The average age of those killed was 46, “significantly greater than the age of the typical” arrest-related decedent, suggesting an enhanced vulnerability for falling in older subjects. “The mortality risk from head injury increases with age,” the study notes.
  • The researchers were able to identify the CEW probe locations in 14 of the 16 brain-damaged subjects. In nine cases (64%), they were in the back, “suggesting a possibly increased mortality risk with probe deployments” to that part of the body.
  • Perhaps most important, the study calls attention to warnings from TASER International, the largest CEW manufacturer. Kroll writes: “They warn against use on elevated subjects [and against] running or bicycling subjects….

“With hindsight, one could say that strictly following these warnings could have prevented 8 of the 16 fatalities, which is xBD of the cases.” He concedes, however, that this is “utopian reasoning,” in that involved officers may not have had a “viable control alternative.”


In an email to Force Science News, Kroll put the risk of CEW-induced falling in statistical perspective.

“Fatal head injury [from such a fall] is an exceedingly unusual event,” he writes, “and the study demonstrates that 99.9994% of electronic control incidents do not result in fatal brain injury.

“Electronic weapons continue to be the most studied law enforcement force option and there is no study that has found that other force options are less injurious. Control [alternatives] such as baton strikes, physical grounding, and tackling likely have higher rates of fatal brain injury.”

What Kroll calls “unscientific smoke” from the media and plaintiffs’ attorneys has focused on the alleged risk of electrocution by CEWs. But the slim risk of death by traumatic brain injury from falling “far exceeds [even] the theoretical risk of electrocution, which has been estimated at about 1 in 3,000,000,” he writes.

“It certainly exceeds the demonstrated risk of electrocution, as there has yet to be an actual documented case.”

Click here for a free abstract of this study, “Fatal traumatic brain injury with electrical weapon falls,” published in the Journal of Forensic & Legal Medicine. At this site you can also link to a full paper for a fee.

Dr. Kroll can be reached at: mark@kroll.name

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