How TASER devices can cause incapacitation

Posted by Anthony Carli on 3/20/18 11:00 AM

TASER devices utilize a process called “neuro muscular incapacitation”, or NMI, to immobilize potential threats. Today, we explore how TASER devices harness electricity to override the nervous system.

Purple Backpack TASER Pulse

How does NMI work?

  • TASER technology is designed to use electrical pulses similar to those in your body’s nervous system to cause stimulation that affects the sensory and motor nerves.
  • Neuro Muscular Incapacitation (NMI) occurs when a TASER device is able to cause involuntary stimulation of both the sensory nerves and the motor nerves which may interfere with the attacker's ability to utilize the affected muscles. It is not dependent on pain and can be effective on subjects with a high level of pain tolerance.
  • Previous generations of generic stun guns could primarily affect the sensory nerves only, resulting in pain compliance. An attacker with a very high tolerance to pain (e.g., a drug abuser, person in serious psychological distress, or a trained, focused fighter) may not be affected by the pain or might be able to fight through the pain of a traditional stun gun.
  • A TASER device may cause NMI if probes are within sufficient proximity to complete a circuit, the probes have a sufficient spread, and an adequate circuit is completed and maintained.

How does a TASER CEW achieve NMI?

  • NMI requires two points of electrical contact plus a completed and maintained circuit. Electricity needs one place to flow in and another to flow back out. This can be achieved by either:
    • Two probes embedded in the body or sufficiently close to the body in order to close the circuit. Due to the electrical arcing, a probe can affect a person even if it is embedded in clothing and not touching the person, so long as the probe is no more than an inch a way


  • One or both probes embedded in the body or sufficiently close to the body (such as within one inch) with a drive-stun follow up to close the circuit.

What are the different types of NMI?

  • Incapacitation of voluntary muscles:
    • Probes are separated by 12 or more inches. This means there is 7 or more feet of distance between you and the target.
    • Enough muscle tissue exists between and around the probes to allow an electrical circuit to be completed, and the desired effect of NMI to occur.
  • Limited incapacitation of small or isolated muscle groups:
    • Probes are separated by fewer than 12 inches. This often means there is fewer than 7 feet of distance between you and the target.
    • Limited amount of muscle tissue exists between the probes to cause sufficient incapacitation. However, it may still have limited effect on the target. For example, if a leg was struck, it could impact the attacker's ability to move her/his leg.
    • As a backup, you may drive the front of the TASER device into the attacker's body, creating a third point of contact that would result in more widespread incapacitation. This only works when there is already one point of contact that has successfully attached to the body.

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