Superb analysis from City Journal’s incomparable Heather MacDonald.

An excerpt.

A group of criminologists has purported to answer the question: “Was there a Ferguson effect on crime rates in large U.S. cities?” The “Ferguson effect” refers to the phenomenon of police officers backing off from proactive policing in response to the anti-cop Black Lives Matter movement, with a resulting rise in violent crime. The criminologists answer their own question with a minutely qualified “No.” In fact, their analysis resoundingly confirms the existence of the Ferguson effect.

Anyone not well-versed in “discontinuous growth models,” “empirical Bayes predictions,” the “Bonferroni correction,” and “Nakagawa’s hypotheticals” will have to take on faith a great deal of the recent paper published in the Journal of Criminal Justice. The authors, four professors led by sociologist David Pyrooz of the University of Colorado Boulder, created a complex econometric model that analyzed monthly rates of change in crime rates in 81 U.S. cities with populations of 200,000 or more. The other 24 cities in that size cohort were not included in the study due to lack of crime data.

The researchers found that in the 12 months before Michael Brown was shot in Ferguson, Missouri—the event that catalyzed the Black Lives Matter movement—major felony crime, averaged across all 81 cities, was going down. In the 12 months after Brown was shot, that aggregate drop in crime slowed down considerably. But that deceleration of the crime drop was not large enough to be deemed statistically significant, say the criminologists. Therefore, they conclude, “there is no systematic evidence of a Ferguson Effect on aggregate crime rates throughout the large U.S. cities . . . in this study.”

But the existence of a Ferguson effect does not depend on its operating uniformly across the country in cities with very different demographics. When the researchers disaggregated crime trends by city, they found that the variance among those individual city trends had tripled after Ferguson. That is, before the Brown shooting, individual cities’ crime rates tended to move downward together; after Ferguson, their crime rates were all over the map. Some cities had sharp increases in aggregate crime, while others continued their downward trajectory. The variance in homicide trends was even greater—nearly six times as large after Ferguson. And what cities had the largest post-Ferguson homicide surges? Precisely those that the Ferguson effect would predict: cities with high black populations, low white populations, and high preexisting rates of violent crime.

A virulent anti-cop protest movement dedicated to the proposition that murderous, racist cops are the biggest threat facing young black men today will have its biggest impact on policing in black neighborhoods. It is in these neighborhoods that cops will face the most hostility from residents steeped in the Black Lives Matter ideology and where cops will most worry that, if an encounter with a civilian goes awry, they will become the latest racist officer-of-the-week on CNN. It is in black neighborhoods, in other words, where proactive policing—making pedestrian stops, enforcing quality-of-life public order laws—will be most inhibited. And given the already high rates of violent crime in black neighborhoods, any drop-off in policing is going to unleash even more crime, since it is in these high-crime neighborhoods where informal social controls have most disintegrated and where cops alone stand between law-abiding residents and anarchy. Even if the Black Lives Matter movement inhibited proactive policing uniformly in cities across the country, a place like Scottsdale, Arizona, say, will suffer less of an impact if cops back off, because the police are not as essential there to maintaining order as they are in Baltimore and St. Louis.

The researchers are unwilling, however, to accept the implication of their findings. They grudgingly admit that “the data offer preliminary support for a Ferguson Effect on homicide rates in a few select cities in the United States”—those cities, according to their model, are Baltimore, St. Louis, New Orleans, Washington, D.C., Newark, Milwaukee, Rochester, Detroit, Oakland, Richmond, Cincinnati, Fort Wayne, and Baton Rouge—but then they backpedal furiously. (Cities that barely missed making the “statistically significant” cut include Kansas City, Indianapolis, Oklahoma City, and Chicago.) What’s important about those cities, they claim, is that “they had much higher crime rates before Ferguson.” Those higher crime rates, they say, “in turn may have primed [those cities] for increases in crime.”