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One type is a conductive energy device (CED) which fires projectiles that administer the shock through a thin, flexible wire. Other electroshock weapons such as stun guns, stun batons, and electroshock belts administer an electric shock by direct contact. A shockround is a piezo-electric tip for a projectile that generates and releases electric charge on impact.
Jack Cover, a NASA researcher, began developing the Taser in 1969. By 1974, Cover had completed the device, which he named after his childhood hero Tom Swift ("Thomas A. Swift's electric rifle"). The Taser Public Defender used gunpowder as its propellant, which led the Bureau of Alcohol, Tobacco and Firearms to classify it as a firearm in 1976. John Cover's patent was adapted by Nova Technologies in 1983 for the Nova XR-5000, their first non-projectile hand-held style stun gun. The XR-5000 design was widely copied as the source for the compact handheld stun gun used today.
Electroshock weapon technology uses a temporary high-voltage low-current electrical discharge to override the body's muscle-triggering mechanisms. The recipient is immobilized via two metal probes connected via wires to the electroshock device. The recipient feels pain, and can be momentarily paralyzed while an electric current is being applied. It is reported that applying electroshock devices to more sensitive parts of the body is even more painful. The maximum effective areas for stun gun usage are upper shoulder, below the rib cage, and the upper hip. High voltages are used, but because most devices use a non-lethal current, death does not usually occur. The resulting "shock" is caused by muscles twitching uncontrollably, appearing as muscle spasms.
The internal circuits of most electroshock weapons are fairly simple, based on either an oscillator, resonant circuit (a power inverter), and step-up transformer or a diode-capacitor voltage multiplier to achieve an alternating high-voltage discharge or a continuous direct-current discharge. It may be powered by one or more batteries depending on manufacturer and model. The output voltages without external "load" (which would be the target's body) are claimed to be in the range of 50 kV up to 8 MV, with the most common being in the 200 to 300 kV range. The output current upon contact with the target will depend on various factors such as target's resistance, skin type, moisture, bodily salinity, clothing, the electroshock weapon's internal circuitry, discharge waveform, and battery conditions.
Manufacturers' instructions and manuals shipped with the products state that a half-second shock duration will cause intense pain and muscle contractions, startling most people greatly. Two to three seconds will often cause the recipient to become dazed and drop to the ground, and over three seconds will usually completely disorient and drop the recipient for at least several seconds. TASER International warns law enforcement agencies that "prolonged or continuous exposure(s) to the TASER device’s electrical charge" may lead to medical risks such as cumulative exhaustion and breathing impairment.
Because there was no automatic stop on older model Taser guns, many officers have used it repeatedly or for a prolonged period of time, thus potentially contributing to suspects’ injuries or death. The current X26 model automatically stops five seconds after the trigger is depressed and then the trigger must be depressed again to send another "shock". The trigger can be held down continuously for a longer shock or the device can be switched off before the full five seconds have elapsed.
Mobile phone-style stun gun
Taser International has developed a long-range wireless electro-shock projectile called XREP (eXtended Range Electro-Muscular Projectile), which can be fired from any 12-gauge shotgun. It contains a small high-voltage battery. Its range is currently 30 metres (98 ft), but the U.S. Department of Defense, which has funded development of the technology, expects delivery of a 90 metres (300 ft) range projectile of this type from the company in 2007. An XREP projectile was controversially used by British police during the 2010 Northumbria Police manhunt  It subsequently transpired that the XREP has never been officially approved for use in the United Kingdom and the weapon system was provided unrequested to the police at the scene directly by the civilian company which distributes Taser International's products in the UK. The company's licence to provide Taser systems was afterwards revoked by the Home Secretary Theresa May.
The Leyden Gun is another long-range electric shock weapon being developed by Nova Technologies in cooperation with Oleg Nemtyshkin. This weapon uses simple needles rather than barbed darts and these do not stick to the target but instead administer a single jolt from a high-voltage capacitor. Range is 30 meters, the same as the XREP.
A stun belt is a belt that is fastened around the subject's waist, leg, or arm that carries a battery and control pack, and contains features to stop the subject from unfastening or removing it. A remote-control signal is sent to tell the control pack to give the subject an electric shock. Some models are activated by the subject's movement.
The United States uses these devices to control prisoners. One type is the REACT belt. Some stun belts can restrain the subject's hands and have a strap going under the subject's groin to stop him from rotating the belt around the subject's waist and trying to deactivate it. Stun belts are not generally available to the public.
The larger baton-style prods are similar in basic design to an electric cattle prod. It has a metal end split into two parts electrically insulated from each other, or two thin projecting metal electrodes about 2.5 centimetres (0.98 in) apart, at an end of a shaft containing the batteries and mechanism. At the other end of the shaft are a handle and a switch. Both electrodes must touch the subject. In some types the sides of the baton can be electrified to stop the subject from grasping the baton above the electrodes.
The compact handheld stun guns are smaller (about the size of a TV remote or calculator). The original XR-5000 design in 1983 had the electrodes spread farther apart to make the noisy electric arc between the electrodes as a more visible warning. Some such devices are available disguised as other objects, such as umbrellas, cell-phones or pens.
Some models are built into long flashlights also designed to administer an electric shock with its lit end's metal surround (which is split into halves insulated from each other).
Due to increased interest in developing non-lethal weapons, mainly from the U.S. Military, a number of new types of electroshock weapon are being researched. They are designed to provide a "ranged" non-lethal weapon.
The electrolaser is a prototype weapon that uses a laser to create a conducting ionized channel through the air.
Prototype electroshock guns exist that replace the solid wire with a stream of conductive liquid (e.g., salt water), which offers the range of a Taser (or better) and the possibility of multiple shots. See Electrified water cannon. According to the proponents of this technology, difficulties associated with this experimental design include:
Another design, announced by Rheinmetall W&M as a prototype in 2003, uses an aerosol as the conductive medium. The manufacturers called it a "Plasma Taser"; however, this is only a marketing name, and the weapon does not use plasma. According to the proponents of this technology, problems associated with this design include:
Because of the use of electricity and the claim of the weapon being non-lethal, controversy has sprouted over particular incidents involving the weapon and the use of the weapon in general. In essence, controversy has been centered on the justification of the use of the weapon in certain instances, and, in some cases, health issues that are claimed to be due to the use of the weapon.
Tests conducted by the Cleveland Clinic found that Tasers did not interfere with pacemakers and implantable defibrillators. A study conducted by emergency medicine physicians at the University of California, San Diego (UCSD) Medical Center showed no lasting effects of the Taser on healthy test subjects. However, Taser International no longer claims the devices are "non-lethal", instead saying they "are more effective and safer than other use-of-force options".
Currently, Tasers are programmed to be activated in automatic five second bursts, although the officer can stop the energy charge at any time by engaging the safety switch. The charge can also be prolonged beyond five seconds if the trigger is held down continuously. The operator can also inflict repeated shock cycles with each pull of the trigger as long as both barbs remain attached to the subject. The only technical limit to the number or length of the electrical cycles is the life of the battery, which can be ten minutes or more.
Repeated bursts by a Taser can be lethal as evidenced by the death of the Polish immigrant Robert Dziekanski in the Vancouver, BC airport where he died after the RCMP officer, in spite of his training, repeatedly stunned him with a Taser.
The study  done by Pierre Savard, Ing., PhD., Ecole Polythechnique de Montreal, et al., for the Canadian Broadcasting Corporation (CBC), indicated that the threshold of energy needed to induce deadly ventricular fibrillation decreased dramatically with each successive burst of pulses; however, one pulse may provide enough energy to induce deadly ventricular fibrillation in some cases. The threshold for women may be less.
Although the Taser is a programmable device, the controlling software does not limit the number of the bursts of pulses and the time between bursts while the trigger is held down continuously, or the number of times the shock cycles can be repeated. Thus the design does not adequately reduce the likelihood that the victim's heart enters into a deadly ventricular fibrillation.
Electroshock weapons have been made illegal in Germany by supplement 2 WaffG if they do not carry an official seal of approval demonstrating they do not constitute a health risk. As of July, 2011, no such seal has been issued to any device on the market. According to § 40 Abs. 4 WaffG, the German federal police may approve of exceptions though. Such a special approval for purchase, ownership and carrying was in effect until 31 December 2010. As of 1 January 2011, only devices carrying the PTB's seal of approval are legal. Previous owners may keep their devices, but cannot carry or sell them. Electroshock weapons effective over a distance, like airtasers, have been completely outlawed in Germany since 1 April 2008.
The United Nations Committee against Torture reports that the use of Tasers can be a form of torture, due to the acute pain they cause, and warns against the possibility of death in some cases.   The use of stun belts has been condemned by Amnesty International as torture, not only for the physical pain the devices cause, but also for their heightened abuse potential, due to their perceived "harmlessness" in terms of causing initial injuries, like ordinary police batons do. Amnesty International has reported several alleged cases of excessive electroshock gun use that possibly amount to torture. They have also raised extensive concerns about the use of other electro-shock devices by American police and in American prisons, as they can be (and according to Amnesty International, sometimes are) used to inflict cruel pain on individuals.
Tasers may also not leave the telltale markings that a conventional beating might. The American Civil Liberties Union has also raised concerns about their use, as has the British human rights organization Resist Cardiac Arrest.