Heather MacDonald has this article in the City Journal:

Will the anti-cop Left please figure out what it wants? For more than a decade, activists have demanded the end of proactive policing, claiming that it was racist. Pedestrian stops--otherwise known as stop, question, and frisk--were attacked as a bigoted oppression of minority communities. In March 2015, for example, the ACLU of Illinois accused the Chicago Police Department of "targeting" minorities because stops are "disproportionately concentrated in the black community."

And what happens when they win that battle?

And the Left is once again denouncing the police--this time for not doing enough policing. [Black Lives Matter activist Shaun] King now accuses police in Chicago of not "doing their job," as a result of which "people are dying." Stops in Chicago are down nearly 90 percent this year through the end of March, compared with the same period in 2015; shootings were up 78 percent and homicides up 62 percent through April 10.