There is mounting evidence for something that some criminologists have dubbed “The Ferguson Effect”—when police face hostile public scrutiny, in the wake of a highly publicized incident of police misconduct, there is impressive evidence of police retreat, sometimes referred to as “de-policing.” Recent data reviewed by Professors Richard Rosenfeld and Paul Cassell in their important papers document sharp spikes in violent crime in major cities following protests against police violence beginning in May 2020. It is a devilishly difficult business to ascertain the causes of changes in crime rates. Even granting the ineradicable uncertainties, this article argues that there is an impressive case that this crime spike reflects a Ferguson Effect. The incentives confronting police offices suggest the likely mechanism for the decline in law enforcement activity documented by Professor Cassell. Because officers internalize few, if any, of the benefits of effective policing, when they perceive a risk that they will be made to internalize its costs, over-deterrence is the likely outcome. There are, moreover, important policy implications of this conclusion. Policing reforms must be alert to the risk that they will over-deter officers, and thereby spur increases in violent crime, which will impose disproportionate costs on disadvantaged communities and people of color.

Paul Cassell maintains that de-policing was a major cause of the spike in violent crime many American cities experienced during the summer of 2020. While plausible, Professor Cassell’s argument is unconvincing because it fails to explain why de-policing did not produce a rise in property crime, and it overstates the impact of policing on crime. Nor does he present evidence of a drop in police presence and activity large enough to produce such a huge increase in violence. Professor Cassell’s criticism of the argument that diminished police legitimacy caused the violence spike is more persuasive. He and I agree that the explanation for the spike lies somewhere in the nexus between the police and the disadvantaged communities they serve more or less effectively.