A Conducted Energy Weapon (CEW), commonly known as a Taser, is a device law enforcement uses as a less-lethal option to gain control of a person. The device delivers an electrical charge intended to temporarily incapacitate a subject through muscular disruption. While these tools are designed to reduce the risk of serious injury compared to other force options, public concern remains about their potential to cause sudden death. Understanding this risk requires examining the science behind the device’s electrical output and the physiological effects on the nervous and cardiovascular systems.
The Mechanism of Neuromuscular Incapacitation
The intended effect of a CEW is Neuromuscular Incapacitation (NMI). This effect is achieved when the device fires two small probes into a subject’s body or clothing, completing an electrical circuit. NMI relies on sufficient probe spread to create a wide path for the current to engage a large number of motor nerves.
The electrical pulses delivered mimic and overwhelm the signals sent by the central nervous system to the muscles. This electrical interference forces muscles within the current path to contract rapidly and involuntarily. They lose the ability to coordinate movement or maintain balance, resulting in temporary, uncontrolled muscle lock-up, which is the primary mechanism for achieving physical control.
The device operates on high voltage but very low amperage; the voltage primarily serves to overcome the resistance of clothing and skin. The current, measured in milliamperes, dictates the physiological effect on the nerves and muscles. The typical electrical cycle lasts about five seconds, after which the incapacitation immediately ceases, allowing the subject to regain voluntary control.
Understanding the Electrical Current and Cardiac Risk
The main physiological danger from a CEW involves the potential for the electrical current to interfere with the heart’s natural rhythm. If the current pathway spans the chest area, it can pass near or through the heart muscle. This risk is present despite the CEW’s low-amperage output.
Scientific studies confirm the biological plausibility of the current inducing Ventricular Fibrillation (VF), a lethal heart rhythm. VF is a chaotic quivering of the heart muscle that prevents effective blood pumping. One mechanism involves “myocardial capture,” where the electrical pulses override the heart’s natural pacemaker, forcing it to beat at an extremely high, unsustainable rate that can degenerate into VF.
A separate danger arises if the CEW pulse hits the heart during the T-wave, a vulnerable moment of its cycle. An electrical impulse delivered during this brief window can trigger VF, even with a relatively small amount of current. While the overall risk in a healthy individual is statistically low, the potential for the device to cause a fatal arrhythmia is confirmed.
Situational Factors That Increase Risk
Fatalities associated with CEW use often stem from a combination of external and physiological factors present during the incident. These variables act as significant risk multipliers, complicating the subject’s medical state.
Pre-existing Conditions
One major factor is the presence of pre-existing or undiagnosed heart conditions, which make the heart more susceptible to electrical disruption. A heart with underlying disease may have a lower threshold for developing a fatal arrhythmia when exposed to the CEW current.
Drug Intoxication
Drug intoxication, particularly with stimulants like cocaine or methamphetamine, significantly increases the danger. These drugs place immense stress on the cardiovascular system by elevating heart rate and blood pressure, making the heart muscle more irritable. The combination of drug-induced stress and CEW electrical pulses creates a highly volatile physiological environment that can easily tip the subject into cardiac arrest.
Physical Exertion and Excited Delirium
Physical exertion is another powerful risk factor, often linked to excited delirium (ExD). A subject who has been violently struggling or actively resisting for an extended period is metabolically compromised. This extreme struggle can lead to severe metabolic acidosis and hyperthermia, which predispose the heart to failure. In these cases, the CEW application becomes one stressor in a cascade of events that culminates in sudden death, making it difficult to isolate the device as the sole cause.
Application Variables
Application variables also play a role in increasing the overall risk profile. Repeated or prolonged activation of the CEW, especially beyond the standard five-second cycle, increases the total electrical dose delivered. Furthermore, probe placement that results in a shorter electrical path directly across the chest heightens the risk of current affecting the heart.