On the other hand, 99.7 percent of people who are tasered suffer no serious injuries, according to a May report from the National Institute of Justice. "The risk of human death due directly or primarily to the electrical effects of CED application has not been conclusively demonstrated," says the report.
A growing number of police departments have begun to limit Taser use, imposing stricter policies for use or even taking the instruments out of officers' hands. Memphis, San Francisco, and Las Vegas police departments have all opted out of Taser use recently, amid growing questions about the level of threat necessary to justify electrocuting someone with 50,000 volts delivered through barbed bolts.
"Because of the criticism and the deaths, there's been a lot of people backing off of Tasers," says Samuel Walker, a professor emeritus at the University of Nebraska at Omaha, who studies police accountability. "The fact is, a lot of departments are taking some very positive, proactive steps to ensure accountability, and controlling Tasers is one of part of doing that," he says. But in other departments, he adds, "they're using it much too broadly and recklessly, where it isn't appropriate."