The tensions that arise when unarmed black men are killed by police just won't go away. Rarely are the incidents caught on video, and rarely are police criminally charged.

This time is different. If you haven't seen the video, you should.

A North Charleston, South Carolina, officer is now charged with murder for coldly shooting Walter Lamar Scott in the back. Scott, who is black, was stopped for a broken taillight on Saturday. Scott ran off, and Officer Michael Slager, who is white, chased him firing his Taser, according to the report the officer filed. But the killing was captured on video by a bystander.

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Slager is seen firing several shots from about 15 to 20 feet away -- hitting Scott in the back. Slager handcuffed a dead or dying Scott before walking back to where the incident began. He retrieved what may have been the Taser he claimed Scott had taken from him and dropped it near the prone body. The officer provided no medical assistance.

This began as a routine traffic stop. Scott was unarmed. It was broad daylight. On the video, Slager's life does not appear to be threatened. Nor was the safety of anyone else.

According to relatives, Scott, 50, owed child support and may have run to avoid going to jail for the arrears. He didn't run very fast and didn't look like he could have gone very far. What's more, Slager had Scott's car and license plate number. If he didn't already have Scott's name and address, he could have gotten that from motor vehicle records and apprehended him at his home.

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More evidence might surface to change perceptions of events, but the video underscores a distillation of the sort of unjustified use of deadly force and disregard for black life claimed in many other police shootings. Under murkier circumstances, those claims most often fall on deaf ears.

In this case, it's clear why Slager was charged with murder and fired from his job. It's also clear why policing and race is an issue the nation must confront and resolve.