In 2012, San Francisco Mayor Ed Lee, after a discussion with New York Mayor Mike Bloomberg, proposed upping San Francisco’s stop, question and frisk activity to combat a spike of shootings in the city’s housing projects. Protests broke out immediately. Local activists called police stops the “New Jim Crow.” A petition signed by thousands claimed that stop-and-frisk would “legitimize and legalize racial discrimination.” Police Chief Greg Suhr announced “we do not racially profile in San Francisco.” After nearly two months of agitation, Mayor Lee backed down.

Reaction was even more furious to a proposal this January by Oakland Mayor Jean Quan to hire William Bratton, the original architect of New York’s policing revolution, as a crime consultant. Crime in Oakland has soared while pedestrian and car stops have plummeted under a federal policing consent decree that imposes enormous amounts of red tape on police stops and the use of force. Protesters from the Occupy Oakland movement and other left-wing groups brandished “Killer Cops” signs at City Council meetings discussing the Bratton contract. When Mayor Quan and the city council hired Mr. Bratton anyway, the crowd in City Hall shouted: “Let the war begin!”

These incidents are a harbinger of the opposition likely to be spurred in other cities if the Floyd ruling goes against the NYPD. Milwaukee Police Chief Edward Flynn has said that it will be a “tragedy” if his city is forced to curtail the pedestrian stops that have reduced crime in inner-city neighborhoods. “That’s what worries us about what’s happening in New York,” Chief Flynn told the Los Angeles Times in April. “It would just be a shame if some people decided to put us back in our cars just answering calls and ceding the streets to thugs.”