Police‐Monitored Cameras and Crime*

• Author: Martín A. Rossi,Ignacio Munyo
• DOI: http://doi.org/10.1111/sjoe.12375
• Published date: 01 July 2020
• Date: 01 July 2020

Scand. J. of Economics 122(3), 1027–1044, 2020

DOI: 10.1111/sjoe.12375

Police-Monitored Cameras and Crime*

Ignacio Munyo

Universidad de Montevideo, 16000 Montevideo, Uruguay

imunyo@um.edu.uy

Mart´ın A. Rossi

Universidad de San Andr´es, B1644BID Victoria, Buenos Aires, Argentina

mrossi@udesa.edu.ar

Abstract

We study the effects of police monitoring on crime. We exploit detailed information on the

location and date of installation of police-monitored surveillance cameras, coupled with data at

the street-segment level on all reported crimes in the city of Montevideo, Uruguay. Wefind that

the introduction of police-monitored surveillance cameras reduces crime by about 20 percent in

monitored areas relative toa pure c ontrol group located outside the city.Wealso explore potential

displacement effects, and we do not find evidence of such effects.

Keywords: Crime; monitoring cameras; police

JEL classification:K42

I. Introduction

A growing number of cities from all around the world are relying on

surveillance cameras as a tool for preventing crimes and supporting

investigations and prosecutions. However, not enough is known about the

effect of surveillance cameras on crime and, in particular, little is known

about whether cameras reduce crime or simply relocate criminal activity to

other areas.

In this paper, we study the effects of a large-scale introduction of police-

monitored cameras in Montevideo (the capital city of Uruguay, with 1.5

million inhabitants). In 2013, the Ministry of the Interior of Uruguay started

to install surveillance cameras in some areas of the city. These cameras are

continuously monitored by police officers located in a monitoring center that

combines video surveillance technology with the action of police patrol

*We are grateful to the General Director of the Ministry of the Interior of Uruguay and the

Police Department of Montevideo for providing the database on crime. We thank Juan Dubra,

Sebasti´an Galiani, Mar t´ın Gonzalez Rozada, and Christian Ruzzier for useful comments and

suggestions. Victoria Dotta, Natalia Otero, PatriciaPereyra, Antonia V´azquez, and Maximiliano

Lauletta provided excellentresearch assistance. Anonymous referees provided us with extremely

helpful reports.

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The editors of The Scandinavian Journal of Economics 2019.

1028 Police-monitored cameras and crime

response. In order to study the effects of this policy on crime, we take

advantage of a really unique database that includes the universe of reported

crime in the entire city of Montevideo, by street segment, for the three-year

period between January 2012 and December 2014, and the location and the

time of the installation of all police-monitored cameras in the city.

Our difference-in-differences estimates indicate that the presence of

police-monitored cameras is associated with a reduction of about 20

percent in crime in treated areas of the city. What is the rationale

behind these results? In principle, the effect that police monitoring has

on crime could potentially work through deterrence (a police presence

makes criminal activity less attractive) and incapacitation (police officers

apprehend criminals, leaving fewer of them around to commit future

crimes). Even though there is anecdotal evidence of arrests made by police

patrols alerted by officers in the monitoring center,1our results are unlikely

to reflect changes in the numbers of incarcerated criminals. Thus, we believe

that our estimates should be interpreted as a deterrent effect on crime

provided by police monitoring.2

It is well known that, potentially, the reduction in crime in areas

with police monitoring can be compensated by an increase in crime

somewhere else – a “displacement” effect.3Thus, we have explored

potential displacement effects and we have not found evidence of such

effects.

Our paper is related to the literature on the effects of police-monitored

cameras on crime.4In particular, the effect of surveillance cameras on

1As an example, in May 2015 the newspaper El Pa´ıs reported a case in which surveillance

cameras captured a robbery. Police officers in the monitoring center called a patrol in the area

and nine minutes later two police officers apprehended the offender.In court, the suspect denied

everything, without being aware that the surveillance cameras had registered the crime scene.

The video recording was used as probative material in court and the offender was sentenced to

prison.

2G´omez-Cardona et al. (2017) report no significant effects on apprehensions following the

installation of surveillance cameras in Medell´ın, Colombia. Unfortunately, we cannot formally

test the effect of surveillance cameras on apprehension rates because there is no information

available.

3The criminology literature has a long tradition of recognizing the complexity of measuring a

displacement effect. For example, Weisburd and Green (1995) analyzed the tension between

research designs for measuring direct (or partial equilibrium) effects and displacement effects.

In particular, they suggested that the usual design generates a potential bias toward the null

hypothesis of no displacement. Along these lines, Braga et al. (1999) examined the effects of

problem-oriented policing interventions on the problems caused by urban violent crime in Jersey

City (NJ, United States), and they found positivelocal effects and no evidence for displacement.

4There is also an important and related body of literature on the effects that police monitoring has

on crime; see, for example, Levitt (1997), DiTella and Schargrodsky (2004), Klick and Tabarrok

(2005), Poutvaara and Priks (2009), and Draca et al. (2011).

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The editors of The Scandinavian Journal of Economics 2019.