Police agencies began buying the stun guns in large quantities in 1999 and again in 2003 when the company reduced the product's size and weight. They are now used in more than 8,000 law-enforcement agencies across the country and are spreading into the US military.

a growing number of coroners across the country have cited Tasers as a contributing factor in accidental deaths. These and other questions about their safety have led some police departments to ban their use. They've also prompted an inquiry by the US Securities and Exchange Commission into claims the company has made about safety studies. In addition, the company's stock - formerly one of the market's best performers - has plunged.

Resembling a small pistol, the stun guns use nitrogen cartridges to propel darts into the body, delivering a 50,000-volt shock. Lasting several seconds, the shock immobilizes a person, thereby allowing officers to take control of the situation.

167 cases in the United States and Canada of death following a police Taser strike since September 1999. In 27 cases, medical examiners said Tasers were a cause, a contributing factor or could not be ruled out in someone's death. In 35 cases, coroners and other officials reported the stun gun was not a factor