Kevin Lewis

March 27, 2020

Impact of defelonizing drug possession on recidivism
Mia Bird, Viet Nguyen & Ryken Grattet
Criminology & Public Policy, forthcoming


California's Proposition 47 (Prop 47), passed in November 2014, sought to scale back punishment for selected drug and property offenses, making them misdemeanors rather than felonies. Although others have examined the impacts of Proposition 47 on crime rates, here we examine the impacts on a range of recidivism outcomes specifically for individuals convicted for drug possession offenses. We focus on the defelonization of drug possession because nationally evidence suggests that public and policy maker sympathy for reducing incarceration use is greatest for nonviolent drug offenders. Thus, the greatest relevance of Proposition 47 to the nation lies in its strategy of defelonizing drug possession. We draw on an ongoing data collection effort on criminal justice populations in 12 California counties and link these data to rearrest and reconviction data from county and state‐level sources. We find people who received drug possession convictions after Prop 47 had lower overall rearrest and reconviction rates than people with comparable convictions and criminal histories released prior to the proposition. Overall reductions in recidivism rates for Prop 47 drug offenders were driven by reductions in rearrest and reconviction for drug possession offenses. These findings are robust to a variety of specifications and sensitivity analyses. When we complicate the narrative of declines in nonviolent recidivism, however, we find evidence of a 2.8‐percentage‐point increase in rearrest for crimes against persons, mainly assaults and domestic violence. Reconviction rates for crimes against persons for drug possession offenders also increased by 1.1 percentage points.

Does Race Matter for Police Use of Force? Evidence from 911 Calls
Mark Hoekstra & CarlyWill Sloan
NBER Working Paper, February 2020


While there is much concern about the role of race in police use of force, identifying causal effects is difficult. This is in part because of selection, and in part because researchers often observe only interactions that end in use of force, necessitating nontrivial benchmarking assumptions. This paper addresses these problems by using data on officers dispatched to over 2 million 911 calls in two cities, neither of which allows for discretion in the dispatch process. Using a location-by-time fixed effects approach that isolates the random variation in officer race, we show white officers use force 60 percent more than black officers, and use gun force twice as often. To examine how civilian race affects use of force, we compare how white officers increase use of force as they are dispatched to more minority neighborhoods, compared to minority officers. Perhaps most strikingly, we show that while white and black officers use gun force at similar rates in white and racially mixed neighborhoods, white officers are five times as likely to use gun force in predominantly black neighborhoods. Similarly, white officers increase use of any force much more than minority officers when dispatched to more minority neighborhoods. Consequently, difference-in-differences estimates from individual officer fixed effect models indicate black (Hispanic) civilians are 30 - 60 (75 - 120) percent more likely to experience any use of force, and five times as likely to experience gun use of force, compared to if white officers scaled up force similarly to minority officers. These findings highlight race as an important determinant of police use of force, including and especially lethal force.

Network Position and Police Who Shoot
Linda Zhao & Andrew Papachristos
ANNALS of the American Academy of Political and Social Science, January 2020, Pages 89-112


This study applies the growing field of network science to explore whether police violence is associated with characteristics of an officer’s social networks and his or her placement within those networks. To do this, we re-create the network of police misconduct for the Chicago Police Department using more than 38,442 complaints filed against police officers between 2000 and 2003. Our statistical models reveal that officers who shoot at civilians are often “brokers” within the social networks of policing, occupying important positions between other actors in the network and often connecting otherwise disconnected parts of the social structure between other officers within larger networks of misconduct. This finding holds, even net measures of officer activity, career movement, and sociodemographic background. Our finding suggest that policies and interventions aimed at curbing police shootings should include not only individual assessments of risk but also an understanding of officers’ positions within larger social networks.

Spillover Effects in Police Use of Force
Justin Holz, Roman Rivera & Bocar Ba
University of Pennsylvania Working Paper, December 2019


We study the link between officer injuries-on-duty and the force-use of their peers using a network of officers who, through a random lottery, began the police academy together. We find that peer injuries-on-duty increase the probability of using force by 7%. The effect is concentrated in a narrow time window near the event and is not associated with significantly lower injury risk to the officer. Complaints of improper searches and failure to provide service also increase after peer injuries, suggesting that the increase in force might be driven by heightened risk aversion.

Intersectional Encounters, Representative Bureaucracy, and the Routine Traffic Stop
Frank Baumgartner et al.
Policy Studies Journal, forthcoming

We evaluate the factors associated with an officer’s decision to search a driver or vehicle after a routine traffic stop, and we compare the accuracy of these searches by looking at the share leading to arrest. Racial disparities in search rates by race and gender of driver are similar for all types of officers; all tend to search Black male drivers at higher rates than any other demographic. White male officers have higher search rates for all types of drivers. Further, they conduct the greatest share of “fruitless searches” (those not leading to arrest), and these searches are particularly targeted on those drivers with the greatest number of cumulative disadvantages.

Baltimore Ceasefire 365: Estimated Impact of a Recurring Community-Led Ceasefire on Gun Violence
Peter Phalen et al.
American Journal of Public Health, April 2020, Pages 554-559

Methods: The City of Baltimore releases detailed data on all crimes occurring in the city. We compiled daily counts of fatal and nonfatal shootings occurring between January 2012 and July 2019 and fit a Bayesian model to estimate the impact of the ceasefires on gun violence during designated weekends after accounting for yearly seasonality, day of the week, calendar days, and overall time trends. We also looked at the 3-day periods following each 3-day ceasefire weekend to test for a possible postponement effect.

Results: There was an estimated 52% (95% credible interval [CI] = 33%, 67%) reduction in gun violence during ceasefire days and no evidence of a postponement effect on either the next 3 days or the next 3-day weekend following each ceasefire weekend (incidence rate ratio = 0.88; 95% CI = 0.72, 1.06).

Assessing the Impact of Restrictive Housing on Inmate Post-Release Criminal Behavior
Kristen Zgoba, Jesenia Pizarro & Laura Salerno
American Journal of Criminal Justice, February 2020, Pages 102–125


The placement of inmates in restrictive housing (RH) units has become a staple of corrections policy in recent years. Despite its increased use, research on its continued effects is relatively rare when compared to the breadth of general correctional research. This study contributes to the literature by examining the effect placement in restrictive housing has on offender recidivism post prison release. Subjects include approximately 4000 inmates matched through Propensity Score Matching (PSM) techniques and followed 36 months post-release. The findings reveal that inmates placed in restrictive housing had elevated levels of recidivism and proportionally more new commitments for all crime types than those not placed in restrictive housing. Restrictive housing subjects also displayed shorter time to rearrest than non-RH individuals. The theoretical and policy implications of these findings are discussed.

The use and effectiveness of investigative police stops
Derek Epp & Macey Erhardt
Politics, Groups, and Identities, forthcoming


This article asks if investigative police stops (1) help officers find contraband, and (2) serve as a bulwark against violent crime. We focus on the experiences of Fayetteville, North Carolina, which in 2012 mandated that police officers obtain written permission from motorists before conducting searches absent any probable cause. The effect of these mandates was a dramatic reduction in the use of so-called “consent searches.” Using traffic stops data available from the North Carolina Department of Justice, we show that after these reforms went into effect officers made fewer overall searches, but contraband continued to be recovered at pre-reform levels, indicating a reduction in low-quality searches with minimal substantive impact. Moreover, we find that homicide rates are statistically indistinguishable between the pre- and post-reform periods. Thus, Fayetteville local government was able to implement community pleasing police reforms without jeopardizing community safety.

Who is the Key Player? A Network Analysis of Juvenile Delinquency
Lung-Fei Lee et al.
Journal of Business & Economic Statistics, forthcoming


This paper presents a methodology for empirically identifying the key player, whose removal from the network leads to the optimal change in aggregate activity level in equilibrium (Ballester et al., 2006), allowing the network links to rewire after the removal of the key player. First, we propose an IV-based estimation strategy for the social-interaction effect, which is needed to determine the equilibrium activity level of a network, taking into account the potential network endogeneity. Next, to simulate the network evolution process after the removal of the key player, we adopt the general network formation model in Mele (2017) and extend it to incorporate the unobserved individual heterogeneity in link formation decisions. We illustrate the methodology by providing the key player rankings in juvenile delinquency using unique information on friendship networks among U.S. teenagers. We find that the key player is not necessarily the most active delinquent or the delinquent who is the highest in standard (not microfounded) centrality measures. We also find that, compared to a policy that removes the most active delinquent from the network, a key-player-targeted policy leads to a much higher delinquency reduction.

Crime and Inequality in Academic Achievement Across School Districts in the United States
Gerard Torrats-Espinosa
Demography, February 2020, Pages 123–145


This study investigates the effect of violent crime on school district–level achievement in English language arts (ELA) and mathematics. The research design exploits variation in achievement and violent crime across 813 school districts in the United States and seven birth cohorts of children born between 1996 and 2002. The identification strategy leverages exogenous shocks to crime rates arising from the availability of federal funds to hire police officers in the local police departments where the school districts operate. Results show that children who entered the school system when the violent crime rate in their school districts was lower score higher in ELA by the end of eighth grade, relative to children attending schools in the same district but who entered the school system when the violent crime rate was higher. A 10% decline in the violent crime rate experienced at ages 0–6 raises eighth-grade ELA achievement in the district by 0.03 standard deviations. Models that estimate effects by race and gender show larger impacts among Black children and boys. The district-wide effect on mathematics achievement is smaller and statistically nonsignificant. These findings extend our understanding of the geography of educational opportunity in the United States and reinforce the idea that understanding inequalities in academic achievement requires evidence on what happens inside as well as outside schools.

Evidence concerning the regulation of firearms design, sale, and carrying on fatal mass shootings in the United States
Daniel Webster et al.
Criminology & Public Policy, February 2020, Pages 171-212


We used data from the FBI's Supplemental Homicide Reports and other publicly available databases to calculate state‐level annual incidence of fatal mass shootings for 1984–2017. Negative binomial regression models were used to estimate the associations between changes in key gun laws and fatal mass shootings. Handgun purchaser licensing laws and bans of large‐capacity magazines (LCMs) were associated with significant reductions in the incidence of fatal mass shootings. Other laws commonly advocated as solutions to mass shootings — comprehensive background checks, assault weapons bans, and de‐regulation of civilian concealed carry of firearms — were unrelated to fatal mass shootings.

The Role of Individual Officer Characteristics in Police Shootings
Greg Ridgeway
ANNALS of the American Academy of Political and Social Science, January 2020, Pages 58-66

Assessing whether individual characteristics of police officers such as age, race, and prior performance influence police behavior has been a long-standing topic of social science research. The effect of officer characteristics on their risk of shooting people is confounded by police assignments and by the environmental factors associated with those assignments. This article provides a method to separate out the influence of individual officer characteristics from environmental factors. Using data from the New York City Police Department (NYPD) and the Major Cities’ Chiefs Association (MCCA), the analysis finds that police officers who join the NYPD later in their careers have a lower shooting risk: for each additional year of their recruitment age, the odds of being shooters declines by 10 percent. Both officer race and prior problem behavior (e.g., losing a firearm, crashing a department vehicle) predict up to three times greater odds of shooting, yet officers who made numerous misdemeanor arrests were four times less likely to shoot.

Street Light Outages, Public Safety and Crime Displacement: Evidence from Chicago
Aaron Chalfin, Jacob Kaplan & Michael LaForest
University of Pennsylvania Working Paper, January 2020


For more than one hundred years, street lighting has been one of the most enduring capital investments to maintain public safety. In this study we provide a comprehensive examination of the effect of street lights on crime, by estimating the effect of nearly 300,000 street light outages in Chicago neighborhoods on crime. We find that outdoor nighttime crimes change very little on street segments affected by street light outages, but that crime appears to spillover to nearby street segments during these outages. These findings suggest that crime may follow patterns of human activity and that the impact of localized street light outages can reverberate throughout a community.

Proximity of Gun Stores to High Schools and Student Gun Carrying
Gary Zhang, Jonathan Nakamoto & Staci Wendt
Crime & Delinquency, forthcoming


Although research has examined various correlates of weapon and gun carrying at school and among adolescents, it has yet to consider the relationship between gun stores around schools and the carrying of guns at school. This study uses data from the 2015–2016 California Healthy Kids Survey, the California Department of Education, and geocoded data on public high schools and gun stores in Orange County, California, to examine the association between proximity of gun stores to schools and the carrying of guns by high school students. Using geographic information system analysis and hierarchical logistic regression, results indicate that the proximity of gun stores to schools is significantly associated with self-reported gun carrying at school. Implications for policy and practice are discussed.

Where’s the Crime? Exploring Divergences Between Call Data and Perceptions of Local Crime
Lauren Porter et al.
British Journal of Criminology, March 2020, Pages 444–467


Scholars typically use calls to the police to study crime patterning; however, crime reporting may be systematic across space. Using spatial video and geonarrative methodology, we investigate the overlap between perceived crime hot spots among 35 neighbourhood insiders (police officers, ex-offenders and residents) and hot spots gleaned from call data. In general, perceptual hot spots diverge from call data, but in particular, a corner store emerges as a perceptual hot spot across all groups, but not in call data. We use our data to explore the microgeographic dynamics of this ‘hidden hot spot’. We find that the corner store is relatively isolated, with few occupied residences around it and participants avoiding it. In addition, our geonarratives suggest that the store lacks adequate guardianship. We argue that mixed methodological approaches such as these are useful for understanding discrepancies between measures as well as the situational and environmental dynamics of problem places.

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