Papers and Evidence

A reader posted a link to Douglas Zipes’s 2014 article, “TASER Electronic Control Devices Can Cause Cardiac Arrest in Humans,” published in Circulation. Its stated purpose is “to present information to support the conclusion” that the TASER X26 can cause cardiac arrest. This paper is best understood as an evidence-based argumentative essay or narrative review, but not as original empirical research, a systematic review, or proof that Tasers caused the reported deaths. At the time it was published, Circulation paired it with Kroll and colleagues’ contrary article, “TASER Electronic Control Devices and Cardiac Arrests: Coincidental or Causal?” The literature itself later described the two papers as “polarized opinions.”

The human-death argument in this paper relies heavily on causal reconstruction from a small, outcome-selected case series. This paper cherry picked eight cases already displaying the outcome sought by the study’s author, then worked backwards from that point to support the author’s previously held opinion. People subjected to Tasers in real encounters may simultaneously have:

• Severe physical exertion and sympathetic activation
• Stimulant intoxication
• Underlying cardiac disease
• Restraint or impaired ventilation
• Trauma
• Delayed recognition and resuscitation
• A pre-existing medical crisis that prompted police contact

Without an appropriate comparison group, these alternative causes cannot be reliably separated from the electrical exposure. Close timing strengthens suspicion, but it does not by itself identify which factor caused the arrest.

There is also a denominator problem. Studying eight concerning cases can show that a proposed phenomenon might have occurred. It cannot estimate risk without knowing how comparable exposed people fared or how often similar arrests occurred without TASER exposure.

The paper begins with the conclusion it intends to support and selects and interprets evidence toward that end. It’s also noted that the author, Zipes, works as a paid plaintiffs’ expert in litigation involving TASER, which creates a relevant potential allegiance conflict. That does not invalidate his arguments, but it should be considered when assessing case selection and interpretation. It disturbs me that the author doesn’t disclose that in the paper itself. Other issues making me believe it can’t be relied upon includes the use of opinion phrases:

•  I think
•  In my opinion
•  all in-custody deaths after ECD shocks are not likely a direct result of the shock, a number probably are.
• should,
• in all likelihood,

Those sorts of phrases just aren’t used in evidence based medicine. Evidence, not opinion, is what drives these papers.

Turning to the cited works in the footnotes, he uses three of his own previous opinion pieces, a blog, and articles, and letters to the editor from several newspapers as evidentiary support for this paper. Hardly unbiased and not primary source material.

The opposing literature also has significant industry relationships, so the counter-paper should not automatically be treated as neutral either. Research in this area has notably been associated with competing legal and commercial interests.

Had I turned in a paper like this for one of my own classes, my professor would have likely given it a C-. This isn’t anything I would run around citing as evidence of anything. It reads like a paper written by an industry shill (the legal profession needs ‘experts’ to give opinions in front of gullible juries) to establish his bona fides.

This is a paper arguing from biological plausibility, animal experiments, limited human observations, and cherry-picked forensic cases that TASER-induced cardiac arrest is possible to support his career as an ‘expert witness’ for lawyers wanting to cash in from suing Taser.

Meanwhile, there are studies out there showing Taser shocks are not out there causing fatalities.

In one study of 1,201 actual Taser uses, 178 involved anterior probe configurations potentially capable of producing a transcardiac vector. There were no immediate deaths or apparent fatal dysrhythmias—including in the transcardiac group. The statistical upper bound for an immediate fatal event in the entire cohort was approximately 0.3%, not literally zero. Bozeman et al.

Other consecutive field cohorts have similarly found very few serious outcomes. A systematic Bayesian analysis combining three cohorts found one death among 2,728 exposures, but could not necessarily attribute that death directly to the weapon. Its authors estimated a likely mortality risk of roughly 2–5 deaths per 10,000 exposures, while emphasizing that the data were too limited for precision and should not be mechanically applied to individual cases. Rich and Brophy systematic review

A 2021 systematic review examined 33 human experimental studies. They generally found few acute adverse effects apart from dart wounds and did not show clinically important arrhythmias. But the review also identified serious limits:

• Subjects were usually healthy and physically fit.
• Exposure was generally only five seconds.
• Real-world high-risk populations were poorly represented.
• No long-term outcomes were studied.
• Many studies had elevated risk of bias.
• About half were at least partially manufacturer-funded.

The authors therefore concluded that observed risk was low in the studied populations, but that the studies could not establish safety for intoxicated, medically vulnerable, highly agitated, or physiologically exhausted people—the population of greatest concern. 2021 systematic review

A structured review of 37 human studies found no evidence of dangerous physiological changes, cardiac ischemia, or immediate or delayed dysrhythmias after exposures of up to 15 seconds. It concluded that an otherwise alert, asymptomatic patient generally does not require routine ECG testing or prolonged cardiac monitoring solely because of Taser exposure. Emergency-medicine review

The highest risk of injury from a Taser shock isn’t the shock itself, it’s the effects of the shock. There are numerous cases where Taser shocks have resulted in environmental injuries such as falls from height. Tasers have a low but nonzero capacity to cause death. Fatalities through falls and environmental trauma are clearest. Direct electrical induction of ventricular fibrillation appears biologically possible and may explain a small number of cases, but it is not demonstrated as a common field outcome. Existing safety studies substantially constrain the likely frequency but do not exclude rare events, especially in vulnerable people, chest-probe placements, prolonged or repeated discharges, or complicated restraint situations.

The rate of injury from various types of force:

Force method	All included studies	Higher-quality studies	Typical injury pattern

OC/pepper spray

20.2%

6.0%

Eye, skin and airway irritation; usually transient

Taser/CEW

24.5%

26.8%

Dart punctures, abrasions and fall injuries; serious injury uncommon

Baton/club

30.4%

40.7%

Contusions, lacerations and fractures

Hands-on physical force

59.4%

31.4%

Contusions, sprains, fractures and restraint-related injury

Police dog

43.4%

95.7%*

Deep bites, tissue, vascular and nerve damage

As you can see, injuries from hands on force, dogs, and batons all exceed those from Tasers. Only chemical spray injuries happened less frequently, and those come with their own risks and don’t really work on intoxicated individuals, especially when dealing with Meth and Cocaine intoxication.