Robinson: What does it take to get a cop punished for killing an unarmed black man?

Watch the video. Walter Scott, unarmed and slow of foot, tries to run away. Police officer Michael Slager calmly fires five rounds into Scott’s back. Later, Slager approaches Scott’s body, not to give first aid but apparently to plant evidence of a struggle that never took place.

Now tell me: How cheap is black life in these United States of America? A jury in North Charleston, South Carolina, could not agree that Slager committed a crime, forcing the judge in the case to declare a mistrial. Prosecutors quickly announced they will try Slager again. In the optimistic view, this week’s stunning result, or non-result, means justice deferred rather than justice denied. I’m trying to be an optimist, but at the moment it’s not easy.

Tell me: What does it take to get a police officer punished for killing an unarmed black man in cold blood?

The whole thing is on video, people.

A passerby named Feidin Santana used his mobile phone to capture Scott’s final minutes. An immigrant from the Dominican Republic, Santana gave lengthy testimony at Slager’s trial.

”You ask yourself, what if there was no video? What if I wasn’t there? Would we have gotten this far in this trial?” Santana asked in an ABC News interview after the mistrial was announced. “That’s the way justice is over here, and we have to understand it. But it’s a little bit disappointing.”

Santana’s phrase “over here” refers to the nation that fancies itself a beacon of freedom and equality.

The fatal encounter took place April 4, 2015, when Slager, who is white, pulled Scott over for having a busted brake light. African-Americans and Hispanics are used to such petty, harassing traffic stops. White Americans, perhaps not so much.

Slager testified that he feared for his life; Scott, he claimed, had wrestled away his Taser and was trying to use it on him. But Santana, who saw the whole thing, said there was no struggle - and the video appears to show Slager placing the Taser next to Scott’s body, as if it had been in the dead man’s possession. If he did stage the crime scene, the officer demonstrated full awareness of his own culpability. Again, I ask, what does it take?

Even if you want to believe Slager’s unsupported account of a struggle, no one can dispute the fact that Scott was running away when Slager gunned him down. A heavyset 50-year-old with no weapons, running as if through molasses, is hardly a clear and present danger to society. Having a broken light on one’s car is hardly a capital offense. Yet Slager shot Scott five times. In the back.

Nearly half the population of North Charleston is black; Slager’s jury included 11 whites and just one African-American. Notes from the jury to the judge, who is African-American, suggest there may have been one lone holdout who would not vote to convict Slager of murder or manslaughter. That’s how the system works, and the outcome of Slager’s next trial may be different. But still.

One miscarriage of justice, caused by one stubborn juror, would be easier to swallow if not for all the rest. Eric Garner, approached by police on Staten Island for selling loose cigarettes, was choked to death - again on video - but none of the officers involved has been charged. Tamir Rice, a 12-year-old boy, was playing with a toy gun; a police officer shot him dead within seconds of arriving on scene but faced no charges. Michael Brown was unarmed when a police officer stopped him in Ferguson, Missouri; the officer fired his weapon 12 times, killing Brown, but a grand jury failed to indict him.

No one should wonder why the Black Lives Matter movement is so relevant and necessary. It will remain so until black lives do, in fact, matter. And conservatives who claim to champion individual liberty against abusive state power should be the movement’s most avid supporters.

Slager also faces federal charges for allegedly violating Scott’s civil rights. That prosecution was delayed pending the completion of the state trial; now that there is to be a second state trial, presumably the federal case will be put off once again.

So it will likely fall to Sen. Jeff Sessions, R-Alabama - President-elect Donald Trump’s pick for attorney general - to decide whether to move forward with a trial in federal court. Sessions was once denied a federal judgeship because of racist remarks he had made; friends and supporters say that’s all ancient history. We shall see.

Eugene Robinson is a columnist for the Washington Post.