主题：假如骚乱发生在别国…… -- 无所事事

But many who have seen the video think it is anything but exculpatory. It raises questions about aspects of the story police told in the immediate aftermath of the shooting — Powell does not appear to charge the police with his knife held high, and he is shot when he is farther away than two or three feet, for instance.

It's more than just that, though. The events on the video happen quickly, but they also happen slowly. Powell does not move like a man who poses a threat. There is no evidence that anyone felt threatened before the police arrived. Even when he advances on police, he walks, rather than runs. He swings his arms normally, rather than entering into a fighting stance.

Powell looks sick more than he looks dangerous. But the police draw their weapons as soon as they exit their car. They begin yelling at him to stop. And when they begin shooting, they shoot to kill — even continuing to shoot when Powell is motionless on the ground. There is no warning shot, even. It does not seem like it should be so easy to take a life.

The police arrive and instantly escalate the situation. They don't seem to know how to stop Powell, save for using deadly force. But all Powell had was a steak knife. If the police had been in their car, with the windows rolled up, he could have done little to hurt them. It is impossible not to wonder what would have happened if the police didn't have deadly force on their hips, if all they had were tasers or batons. It is impossible not to wonder what would have happened if the police had simply never shown up at all.

It is easy to criticize. It is easy to watch a cell phone video and think of all the ways it could have gone differently. It is easy to forget that the police saw a mentally unbalanced man with a knife advancing on them. It is easy to forget that 20 seconds only takes 20 seconds. It is easy to forget that police get scared. It is easy not to ask yourself what you might have done if you had a gun and a man came at you with a knife.

But there is still something wrong with that video. There is something wrong that the video seems obviously exculpatory to the police and obviously damning to so many who watch it. The dispute over the facts in the Michael Brown case offers the hope that there is a right answer — that Wilson either did clearly the right thing or clearly the wrong thing. The video of the Powell case delivers a harder reality: what the police believe to be the right thing and what the people they serve believe to be the right thing may be very different.

This man needed help. He had a knife, but he also, clearly, had an illness. After watching the video, Vox's Amanda Taub said, "I keep thinking about the times when I have called 911 because I have encountered a mentally ill person in public who seems unsafe. I don't know how I would live with it if this had been the result." There has to have been a way that police could have protected Kajieme Powell rather than killed him.