Tasers work by using electrical pulses to disrupt the voluntary control of muscles, thereby temporarily incapacitating people.
They fire two small dart-like electrodes, which in most taser models stay connected to the main unit by wire.
The electrodes are propelled by small compressed nitrogen charges, similar to those in some air or paintball guns.
The manufacturer, Taser International, says the pulses sent through the electrodes ‘mimic the electrical signals used within the human body to communicate between the brain and the muscles.’
The artificial pulses interfere with this natural communication, quickly rendering the person temporarily unable to control their movements.
Taser International likens it to static on a telephone line, which passes without permanent damage.
In an interview with SBS News, Professor Cavazzini from the Australian National University explains that the millisecond pulses of electricity are specifically designed to target motion muscles and not cardiac muscles.
He says the electrical pulses can cause breakdown of muscle tissue, release of toxins and change in blood acidity, but they are all within the levels normally seen in human exercise, even when the taser is used repeatedly.
Although the voltage involved is very high, the current (measured in amps) is very low and pulsed rather than constant, which Taser International says makes it much less dangerous than a domestic electricity supply, which has a low voltage but high continuous current.
Tasers have become extremely popular among police forces worldwide. Nearly every officer in the United States carries one.
A study by the US National Institute of Justice concluded that ‘there is no conclusive medical evidence in the current body of research literature that indicates a high risk of serious injury or death’, but does add this only applies ‘in healthy, normal, non-stressed, non-intoxicated persons.’
They’re also used across Australia, although are not carried as standard by all police officers.
Taser International asserts that they are a safe alternative to lethal weapons.
But critics say if someone’s body has already been affected by illness, alcohol or drugs, for example, the cumulative effect of that, and the changes in the body’s function made by the taser, can be too much for the body to take.
They say over 700 deaths worldwide can be linked to people who’d been tasered.
The American Civil Liberties Union is among those calling for them to be banned until further safety tests are carried out.
Others also criticise a lack of testing. For example, a new study by the American Heart Association found evidence that the electrical pulses from tasers can cause heart attacks.
Campaigners, such as Truth… not Tasers and Portland Copwatch, also say police are now using them too often, including on people who haven’t even committed a crime.
The high-profile Braidwood Inquiry in Canada, which followed the death of a man at Vancouver Airport, concluded that tasers should only be used in the face of an imminent bodily threat.
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