Quick-footed criminals hoping to avoid the debilitating shock of a police stun gun could soon be facing a more exacting foe--the "electric bullet." Stun guns, like the Taser, fire small spears joined to the hand piece with wires. The spears discharge an electric shock and incapacitate the target, but such weapons have a limited range of up to about 30 feet. The United States Department of Homeland Security is seeking alternatives with broader uses, like light lasers or guns firing electric bullets to combat all manner of felons. (The military, meanwhile, is developing so-called nonlethal weapons such as a millimeter...