Maybe departments should try teaching the cops to always know their target...
Sounds like a good idea, but I think it fails to recognize the complexities which an officer encounters in arriving at an apparently active crime scene. Consider a hypothetical scenario:
Officer arrives on scene, responding to 911 call saying that a madman is holding someone at gunpoint. As he cautiously approaches from the side (he doesn't want to startle the guy with the gun from behind, but he'd be foolish to approach from the direction where the gun is pointed), he sees a guy pointing a gun at a seemingly innocent, unarmed person sitting on the ground. The guy with the gun is shouting something, but the officer can't clearly understand him. (There's some background noise, and the shouting gun-holder is somewhat incoherent because he's upset.) The officer needs to gain control of the situation, and make sure the only person on the scene with a gun out is himself, plus any uniformed backup who might show up. He shouts at the guy with the gun to put it down. The guy with the gun hasn't realized the officer has arrived, he turns slightly out of surprise, and is shot once through the heart by the officer, who saw the guy with the gun turning it on him.
Who's at fault?
The officer knew his target. There was a random guy he didn't know pointing a gun at an unarmed person, and then it looked like the gunman was starting to point his gun at the officer.
The gunman had stopped a crime in progress. His wife was being threatened by a guy with a knife. He pulled his gun. He would've shot the guy with the knife, but the guy dropped the knife as our hero reached for his gun (it's now out of sight behind him) and started blubbering like a baby. Guy with a gun hesitated at first, and then didn't think he'd be justified any more in shooting the guy who used to have a knife, once he was sitting on the ground pleading for his life. He didn't trust this guy who just assaulted his wife, so he was still covering the guy on the ground. He'd had a huge adrenaline rush from being in fear for his wife's life. He had tunnel vision, and didn't see or hear the officer arrive on the scene at first. When he suddenly realized that someone was shouting at him to put the gun down, he was startled, and started to turn toward the sound.
A very sad situation for everyone involved. The only partial winner is knife guy, who deserved to be shot for what he was trying to do. Hopefully he'll spend some time in prison, but he'll come out of it alive. Our hero, who may very well have saved his wife's life, is dead. The officer will discover to his horror that he shot a well-intentioned person who was just trying to protect an innocent person. The gunman's wife just saw her husband shot dead in front of her. To one degree or another, everyone we care about loses in this scenario.
Sure, this situation may sound contrived, but it's just one example of the countless ways in which an officer might be justified in shooting someone who really didn't deserve to get shot. To answer my question from above, fault lies with the guy with the knife, who's initial violence started the sequence of events which led to the death of our hero, the guy with the gun.
I am not a lawyer, LEO, or in any other profession of relevance to this thread. I have no personal axe to grind in this discussion, other than having a license to carry. I just don't think there are any simple, one-size-fits-all solutions to the problem being discussed.
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-twency
(Incidentally, I am not using the term "our hero" sarcastically. A person who protects his or her family from harm is indeed a hero. I simply used the term to help distinguish the participants, and to indicate that even heros can get dead, sometimes for reasons that don't seem fair or right.)