San Francisco Chronicle: Fear can cause police officers to incorrectly perceive events, says John Powell, the director of UC Berkeley's Haas Institute for a Fair and Inclusive Society.

Take the case of Stephon Clark, the unarmed 22-year-old black man killed by two Sacramento police officers last month. In police body cam footage, you can hear the officers yelling "gun" before they open fire.

Police apparently mistook his cell phone for a gun.

"So the police may in fact have thought this person had a weapon," Powell told me. "That has nothing to do with the person. It has to do with implicit bias that says every black person is dangerous and therefore I'm prepared, unconsciously, to see a black person as dangerous and with a gun."

The newest revelations about the shooting raise questions about the police account that they opened fire as Clark moved toward them. According to an independent autopsy, of the eight gunshot wounds Clark sustained, six of them hit him in the back, one on his arm and one in the leg. The two officers fired 20 rounds.

Still, if a police officer can show an "objectively reasonable" fear of an imminent threat to his or her life, a standard set by the U.S. Supreme Court in 1989, the use of deadly force is justified.

What Powell tells us we're looking at is fear by police officers and others based in implicit bias, the stereotypes that affect our judgment in an unconscious manner.

"Fear of people who are slightly outside the norm whether they're gay, whether they're black, whether they're transgender — that's justification for killing someone? That's completely crazy," Powell said.

I was thinking about Clark when I went to Hasta Muerte Coffee, in the Fruitvale neighborhood of East Oakland, last week. In February, a barista refused service to an Oakland police officer.

The worker-owned cafe on the corner of Fruitvale Avenue and East 27th Street opened in November. It explained its policy of "asking police to leave for the physical and emotional safety of our customers and ourselves" in a Feb. 22 Instagram post. The policy applies to armed police officers in uniform — not off-duty cops.

Its reasoning has been lambasted by critics — many of them supporters of the president — who have ripped into the coffee shop for not serving police. But they clearly don't get it.

There are people who fear the police precisely because of what happened to Clark, who was fatally shot as he stood in his grandmother's yard. According to police, Clark was a suspect in nearby auto break-ins reported in the South Sacramento neighborhood.

The deadly use of force in this case doesn't fit the alleged crimes.

And this is why there's a need for safe spaces >>>