More cops, fewer prisoners?

Abstract

Research Summary The results reported in a large amount of the criminology literature reveal that hiring police officers leads to reductions in crime and that investments in police are an efficient means of crime control compared with investments in prisons. One concern, however, is that because police officers make arrests in the course of their duties, police hiring, albeit efficient, is an inevitable driver of “mass incarceration.” In this article, we consider the dynamics through which police hiring affects downstream incarceration rates. Policy Implications Using state‐level panel data as well county‐level data from California, we uncover novel evidence in favor of a potentially unexpected and yet entirely intuitive result: that investments in law enforcement are unlikely to increase state prison populations markedly and may even lead to a modest decrease in the number of state prisoners. As such, investments in police may, in fact, yield a “double dividend” to society by reducing incarceration rates as well as crime rates.

The Slow Violence of Contemporary Policing

“…A trio of natural experiments leveraging a national hiring grant change finds that increases in police funding led to declines in violent and property crime (Cook et al 2017, Mello 2019, Weisburst 2019b). Another study using an instrumental variable approach, in fact, reveals that more policing in California led to less incarceration, providing further evidence of safety and financial benefits (Kaplan & Chalfin 2019). Together, these studies indicate that policing is efficacious for crime control, as hiring more officers is less costly than the crime those officers prevent.…”

Indirect simultaneity

“…I use data on prison admissions and police numbers for each state from 1974 to 2015. The take-away from Kaplan and Chalfin (2019) is that any effect police have on prison admissions is far from statistically significant. That is my result also.…”

“…Thus, it is risky to enter control variables that might be endogenous.6 Overdetermination is a potential problem when entering numerous controls, but that is unlikely with the large data sets now available in criminology. Estimates of the maximum feasible number of variables vary from 10% to 50% of the sample size(Austin & Steyerberg, 2015;Draper & Smith, 1998).7 This regression, like that ofKaplan and Chalfin (2019), was conducted in levels, weighted by population, and with-…”

Can both crime and imprisonment be reduced by investing in police?

“…Thomas Marvell (, this issue), in his policy essay, goes into greater detail on the difficulties surrounding this type of analysis, specifically because of indirect simultaneity, a threat to valid estimates less often considered. He notes several examples in the literature in which scholars do not adequately account for indirect simultaneity and indicates how Kaplan and Chalfin () address the issue. He also offers an additional test of the marginal effect of police on prison admissions using a Granger test.…”

“…Kaplan and Chalfin's () study is a valuable addition to the literature. Although more research is always warranted, especially research that is designed to estimate these margins more precisely, Kaplan and Chalfin provide key evidence for Durlauf and Nagin's () argument that one path down the mountain of mass incarceration is to shift resources from corrections to policing.…”