A statistically significant uptick in crime rates

More emerging evidence supporting the hypothesized Ferguson Effect, i.e. reduction in police activities lead to increased criminal activity. A hypothesis that would seem reasonable on the face of it but which is hotly contested, mostly along ideological lines.

From De-Policing by Stephen Rushin and Griffin Sims Edwards. The abstract:

Critics have long claimed that when the law regulates police behavior it inadvertently reduces officer aggressiveness, thereby increasing crime. This hypothesis has taken on new significance in recent years as prominent politicians and law enforcement leaders have argued that increased oversight of police officers in the wake of the events in Ferguson, Missouri has led to an increase in national crime rates. Using a panel of American law enforcement agencies and difference-in-difference regression analyses, this Article tests whether the introduction of public scrutiny or external regulation is associated with changes in crime rates. To do this, this Article relies on an original dataset of all police departments that have been subject to federally mandated reform under 42 U.S.C. § 14141 — the most invasive form of modern American police regulation. This Article finds that the introduction of § 14141 regulation was associated with a statistically significant uptick in crime rates in affected jurisdictions. This uptick in crime was concentrated in the years immediately after federal intervention and diminished over time. This finding suggests that police departments may experience growing pains when faced with external regulation.