First tested in the early 1970s, the Taser was successfully marketed two decades later by brothers Rick and Tom Smith, who lost friends to gun violence and saw the electric shock-discharging weapon as a “non-lethal” alternative to bullets. This compelling documentary follows the Taser’s evolution as a law enforcement tool while examining the hundreds of deaths that have occurred due to its use and whether it makes police more likely to use “lethal force.” 95 min.