The TASER and How It Works

Electrical stun guns or neuromuscular incapacitating devices are increasingly being used by law enforcement to subdue suspects. The TASER is the most popular kind of these devices (TASER International, Inc., Scottsdale, AZ).¹ Its name is an acronym for the Thomas A. Swift Electric Rifle; the product was invented in the USA by Jack Cover, a NASA researcher, in the 1960s.² Different models of these devices have been introduced by the manufacturer. Among these, two models (M26c and X26c) are the ones most commonly used by police.³ A newly-introduced model, the X3, is capable of firing three cartridges in a "semi-automatic" mode.⁴ Moreover, TASER International has produced a model for civilians called the C2.⁵

The TASER resembles a handgun; however, instead of bullets, it ejects barbs which attach to the victim’s clothing or skin.

Then, a high-frequency, high-voltage, low-amplitude current is delivered via these barbs, causing involuntary muscle contraction and neuromuscular incapacitation.^1,2 Typically, this painful current stops suspects abruptly and drops them immediately to the ground. The TASER can also be deployed by holding it directly against the suspect’s body. This is called “drive stun” or “dry TASERing,” and is intended to cause pain without incapacitating the target.⁶

Although TASERs are acknowledged to be a safer alternative to firearms, there is some evidence that suggests the TASER might not be safe enough to be used widespread by law enforcement officials.¹

The TASER Debate

Even though many studies and reports have been published regarding the TASER’s safety, there is still no consensus. Some studies suggest that the TASER can directly pace the heart into ventricular fibrillation (VF). In North America, over 440 deaths have been reported immediately following TASER use.⁷ Two mechanisms have been previously proposed for inducing VF with electrical currents⁸: 1) Delivering a high-charge shock into the T-wave during the cardiac cycle; and 2) Delivering a lower level current for a longer time (e.g., 1–5 seconds). Current electrical safety standards are based on this knowledge. Kroll et al have presented another mechanism by which VF can be induced. This third newly presented mechanism involves the delivery of a continuous current causing high-rate cardiac capture. This eventually decreases the cardiac output, leading to ischemia and ultimately lowering the threshold of VF to the level at which the continuous current can induce VF.⁸ In summary, if the TASER could capture and pace heart muscle, there are several ways that VF could be induced.