Last week, Derrick Sanderlin was one of hundreds of protesters outside the city hall in San Jose, California. The 27-year-old community organizer and charity worker, who is Black, held a sign that read, We R Worthy of Life.

As he stood in the crowd, Sanderlin saw police shooting protesters with rubber bullets. He walked over to the line of officers and pleaded with them to stop.

In footage of the incident local news outlet ABC7 captured, Sanderlin stands roughly 20 feet away from police. He makes no sudden movements and doesnt reach for anything in his pockets. Without warning, the police start shooting, hitting Sanderlin in the groin. He had emergency surgery, but is not sure if he will be able to have children.

On its face, Sanderlins story is not unremarkable. He is one of dozens of protesters police have harmed as demonstrations against police violence and systemic racism spread across the country in the last two weeks. The twist is Sanderlins profession: He is an implicit bias trainer who has been working with the San Jose Police Department for three years.

The way they treated people out there over the weekend has been really heartbreaking, Sanderlin later told ABC7. San Jose Police Chief Eddie Garcia, who Sanderlin knows personally, issued a statement saying, Derrick has been a real leader in our communities efforts to reduce bias and discrimination through dialogue.

The officer who shot Sanderlin was transferred to desk duty. But still, the incident underscores an important question: If a police department can spend three years undergoing bias training and still shoot a peaceful, unarmed Black protester, what has the training really achieved?

Over the last decade, implicit bias training has become one of the primary methods for law enforcement agencies and policymakers to demonstrate that they take concerns over racist policing seriously. According to a CBS survey of 155 police departments last year, 69% said they were using implicit bias training. Half said they had initiated the programs after the controversial 2014 killing of Michael Brown, a Black teenager, by a white police officer in Ferguson, Missouri.

In the wake of the May 25 police killing of George Floyd in Minneapolis, calls have intensified to expand these programs. The mayors of Los Angeles, Milwaukee and Tampa, Florida , have signaled their intention to install or expand them. Texas and Michigan have passed bills requiring police officers to receive such training. In a Medium post , former President Barack Obama pointed readers to a toolkit urging ongoing and scenario-based anti-bias training for all police officers.

Despite its near-universal support among policymakers, however, research has failed to show that implicit bias training has any lasting effect on racial discrimination or the behavior of police officers.

We dont have any evidence that anti-bias trainings work (in general,) and we know even less about whether they work for police officers, said Joshua Correll, a University of Colorado professor who has been studying implicit bias for more than 20 years.

A 2016 study of nine different methods for reducing bias found that none had any lasting effect after a few days. Few researchers have followed up specifically with law enforcement agencies to see if the training had any effect on the practices of officers.

People have jumped on the idea that we should be providing this training without clear documentation that it makes any difference whatsoever, Correll said.