A Conducted Energy Device (CED), commonly known as a Taser, is a tool designed for law enforcement to temporarily incapacitate a person using an electrical discharge. While categorized as “less-lethal,” CEDs can contribute to or directly cause death, though this outcome is uncommon relative to their frequent use. Understanding this risk requires examining the device’s electrical output and its interaction with the human body. The medical risks depend highly on the individual’s pre-existing health, the placement of the probes, and the circumstances of deployment.
How Conducted Energy Devices Work
A CED operates by delivering a high-voltage, low-amperage electrical pulse designed to override the body’s voluntary nervous system signals. Devices typically produce between 1,500 and 5,000 volts, allowing the current to efficiently puncture the skin’s resistance. However, the current flow is low and delivered in brief pulses, often lasting only tens of microseconds.
The primary objective is to achieve Neuromuscular Incapacitation (NMI) by causing involuntary, forceful contractions of the skeletal muscles. In the most common “probe mode,” two barbed probes are fired from the device, connecting to the target via thin wires. The electrical current travels between these two points, disrupting the central nervous system’s ability to control muscle movement. This temporary paralysis causes the person to fall, allowing for easier restraint.
The Primary Risk: Electrical Interference with the Heart
The most serious direct medical risk from a CED discharge is the potential for inducing ventricular fibrillation (VF), a fatal heart rhythm disturbance. VF occurs when the heart’s lower chambers quiver chaotically instead of beating in a coordinated manner, stopping the effective pumping of blood. The electrical pulse can directly stimulate the heart muscle, a phenomenon known as “electrical capture.”
The risk is elevated if the probes create an electrical pathway across the chest, especially near the heart. The electrical discharge can interrupt the heart’s natural rhythm during its most vulnerable period, the T-wave. The T-wave represents the repolarization phase of the heart’s electrical cycle, and an untimely shock during this period can trigger VF.
While the overall probability of a CED causing VF is statistically low, some analyses suggest a direct current flow across the heart could reach a 30% fibrillation risk in a theoretical “worst-case” scenario. The danger is highly dependent on the dart-to-heart distance and the vector of the current. The rapid onset of VF leads to sudden cardiac arrest, which is usually only reversible with immediate defibrillation.
Individual Factors That Increase Vulnerability
The outcome of a CED exposure varies widely because the electrical discharge interacts with an individual’s pre-existing physiological state. Individuals with underlying cardiac conditions are at a higher risk of experiencing a fatal arrhythmia. Conditions like cardiomyopathy, coronary artery disease, or Long QT syndrome make the heart more susceptible to electrical disruption.
The state of the body before deployment also plays a large role. Stimulant drug use, such as cocaine or methamphetamine, stresses the cardiovascular system, raising heart rate and blood pressure. This chemical stress, combined with the physical exertion of a struggle, elevates adrenaline levels, making the heart more volatile and prone to chaotic rhythms.
The combination of extreme agitation and underlying medical vulnerability creates a heightened physiological state that increases the likelihood of a catastrophic outcome. Studies note that drug use and mental illness are frequently associated with reported CED-proximate deaths. The device’s effect is often magnified by the subject’s already compromised or hyper-stimulated physical condition.
Causes of Secondary Fatalities
Not all fatalities associated with CED use are due to a direct electrical effect on the heart; many result from secondary complications. The sudden Neuromuscular Incapacitation (NMI) caused by the device can cause a person to fall immediately and uncontrollably. If the individual strikes their head on a hard surface during the fall, a severe or fatal head injury may result.
A complex cause of death often cited is metabolic collapse associated with “excited delirium.” This state is characterized by severe agitation, high body temperature, confusion, and an extreme surge in adrenaline. When a person in this state is physically restrained, including with a CED, the immense physical struggle can lead to severe metabolic acidosis and hyperthermia.
This metabolic collapse can overwhelm the body’s systems, leading to death independent of the electrical shock itself. While “excited delirium” is controversial and not universally recognized by major medical associations, the underlying physiological emergency—extreme agitation leading to fatal physiological stress—is a factor in many in-custody deaths where a CED was deployed.