Posted by Jay Livingston
Does crime go up when cops, turtle-like, withdraw into their patrol cars, when they stop “proactive policing” and respond only when called? That’s the idea of the Ferugson effect is a variant on this idea. It adds the reason for the return to “reactive policing” – criticism from citizens and politicians, usually touched off by the police killing of an unarmed person.
The Ferguson effect is a corollary of another idea, “Broken Windows” policing. That policy is based on the idea that if police do not enforce laws on minor “quality of life” offenses, serious crimes will increase.
The Ferguson effect has been blamed for increases in homicides and shootings in Chicago, Baltimore, and perhaps other cities. In New York too the police, angry at the mayor, drastically cut back on “Broken Windows” policing starting in early December of 2014. The slowdown lasted through early January. The change in policing gave researchers Christopher M. Sullivan and Zachary P. O'Keeffe a natural experiment for looking at the effects of Broken Windows. First of all, they made sure that cops had cut back on enforcing minor offenses.
In the graphs below, the yellow shows the rate of enforcement in the previous year (July 2013 - July 2014) when New York cops were not quite so angry at the mayor. The orange line shows the next year. The cutback in enforcement is clear.
Note also that even after the big dip, enforcement levels for the rest of the year remained below those of the previous year, especially in non-White neighborhoods.
Sullivan and O’Keeffe also looked at reported crime to see if the decreased enforcement had emboldened the bad guys. The dark blue line shows rates for the year that included the police cutback; the light blue line shows the previous year.
I have the impression that many people, when they think about crime, use a sort of cops-and-robbers model: cops prevent crime and catch criminals; the more active the cops, the less active the criminals. There may be some truth in that model, but the New York data shows that the connection between policing and crime is not so immediate or direct.
Sullivan and O’Keeffe have written up their research in the Monkey Cage section of the Washington Post website (here). I have copied their graphs. I do not know if their work has been published in any peer-reviewed journal.