Well, tazers can kill people.  So can pepper spray, rarely.  Allergic reaction to capiscum and all that.  If a cop kills somebody while using supposedly sublethal implements like tazers or pepper spray his legal positoin can get very dicey.  After all, obviously he didn't think the situation merited the use of lethal force, and yet somebody died!<br/><br/>And tazers, as you poiint out, do not always stop people.  I once saw a video clip of a deranged naked man trying to break down the door to a daycare center.  The cops tazed him three times at the door.   He kept getting up.  Then they dogpiled on him.  He was lucky.  I'm sure  the only reason the cops didn't shoot him was their certainty that small children were in the line of fire.