DETERRENCE, CRIMINAL OPPORTUNITIES, AND POLICE

• DOI: http://doi.org/10.1111/1745-9125.12057
• Published date: 01 February 2015
• Date: 01 February 2015

DETERRENCE, CRIMINAL OPPORTUNITIES,

AND POLICE∗

DANIEL S. NAGIN,1ROBERT M. SOLOW,2and CYNTHIA LUM3

1Heinz College, Carnegie Mellon University

2Department of Economics, Massachusetts Institute of Technology

3Department of Criminology, Law and Society, George Mason University

KEYWORDS: deterrence, criminal opportunities, police

In this article, we join three distinct literatures on crime control—the deterrence lit-

erature, the policing literature as it relates to crime control, and the environmental and

opportunity perspectives literature. Based on empirical findings and theory from these

literatures, we pose a mathematical model of the distribution of criminal opportunities

and offender decision making on which of those opportunities to victimize. Criminal

opportunities are characterized in terms of the risk of apprehension that attends their

victimization. In developing this model, our primary focus is on how police might af-

fect the distribution of criminal opportunities that are attractive to would-be offenders.

The theoretical model we pose, however, is generalizable to explain how changes in

other relevant target characteristics, such as potential gain, could affect target attrac-

tiveness. We demonstrate that the model has important implications for the efficiency

and effectiveness of police deployment strategies such as hot spots policing, random

patrol, and problem-oriented policing. The theoretical structure also makes clear why

the clearance rate is a fundamentally flawed metric of police performance. Future re-

search directions suggested by the theoretical model are discussed.

We develop a theoretical model that joins elements of three distinct literatures on crime

control—the deterrence literature, the policing literature as it relates to crime control,

and the environmental and opportunity perspectives literature. Each of these literatures

frames crime control differently. The deterrence literature mainly frames crime preven-

tion in terms of two theoretical concepts—the certainty and severity of punishment. The

focus of the environmental and opportunity perspectives literature is the identification of

situational characteristics of the physical and social environment that influence the vul-

nerability of potential criminal targets, whether human or physical, to victimization. The

policing literature as it relates to crime control is largely evaluative—by how much, if at

all, do police numbers and deployment strategies affect crime rates? The mechanism by

which any effect is achieved is left in the background. Our objective is to offer a theoreti-

cal framework that links these literatures for the purpose of characterizing and systemat-

ically analyzing how police numbers and deployment strategies could deter crime.

∗The authors wish to thank Anthony Braga, Phil Cook, John Eck, Christopher Koper, Lorraine

Mazerolle, Peter Neyroud, Richard Rosenfeld, David Weisburd, and Charles Wellford for their

comments and Heather Vovak and Stephen Happeny for editorial support. Direct correspondence

to Daniel S. Nagin, Heinz College, Carnegie Mellon University, 5000 Forbes Avenue, Hamburg

Hall, Pittsburgh, PA 15213 (e-mail: dn03@andrew.cmu.edu).

C2015 American Society of Criminology doi: 10.1111/1745-9125.12057

CRIMINOLOGY Volume 53 Number 1 74–100 2015 74

DETERRENCE, CRIMINAL OPPORTUNITIES, AND POLICE 75

We do this by posing a deterrence-based model in which the effect on crime of changes

in police numbers or deployment strategies is mediated by its effectiveness in altering

the availability of attractive criminal opportunities. Potential criminal opportunities are

characterized in terms of the risk of apprehension were that opportunity victimized. This

process in turn allows us to formalize the concept of the distribution of criminal oppor-

tunities in terms of a mathematical function f(pa), where padenotes the probability of

apprehension. We specify a model of criminal behavior in which ceteris paribus an of-

fender’s decision to victimize a target depends on the target’s attendant pa. This model

provides a theoretical structure for analyzing the crime prevention effectiveness of dif-

ferent strategies for using police resources in terms of their impact on f(pa). The model,

for example, helps to explain why hot spots policing is more effective in preventing crime

than random patrol. It also provides insight into why actual apprehension is not synony-

mous with crime prevention by deterrence.

Although it is not the central focus of this article, the framework we propose provides

the basis for analyzing the potential crime prevention effects of formal legal sanctions, in-

formal sanctions, and many of the subjects of environmental criminology and opportunity

perspectives such as target hardening, problem solving using crime prevention through

environmental design, and various forms of guardianship.

DETERRENCE, CRIMINAL OPPORTUNITIES, AND POLICING

The origins of most modern theories of deterrence can be traced to the work of the

Enlightenment-era legal philosophers (Beccaria, 1986 [1764]; Bentham, 1988 [1789]).

Beccaria and Bentham argued that three key ingredients to the deterrence process are

the severity, certainty, and celerity of punishment. These concepts, particularly the cer-

tainty and severity of punishment, form the foundation of nearly all contemporary theo-

ries of deterrence. The enduring impact of their thinking is remarkable testimony to their

innovation.

Recent reviews of the deterrence literature by Nagin and colleagues (Apel and Nagin,

2010; Durlauf and Nagin, 2011; Nagin, 2013a, 2013b) have concluded that evidence of the

deterrent effectiveness of these three ingredients is strongest for the certainty of punish-

ment but with one important qualification. The certainty of punishment is the product of a

series of conditional probabilities—the probability of apprehension given commission of a

crime, the probability of being charged given apprehension, the probability of conviction

given charge, and the probability of various formal sanctions given conviction. Support

for the deterrent effect of certainty of punishment, however, pertains almost exclusively

to the certainty of apprehension. Thus, as Nagin (2013a: 199) stated: “[T]he more precise

statement [about deterrence] is that the certainty of apprehension, not the severity of the

ensuing consequences, is the more effective deterrent.”

Discussions of the measurement of the probability of apprehension in the deterrence

literature, whether by an official statistic such as the percentage of crimes cleared by ar-

rest or offender perceptions of the risk of apprehension, commonly neglect a fundamental

feature of pathat is widely recognized in the environmental criminology literature—it is

closely connected to the characteristics of the criminal opportunity, even in microplaces.

Consider the example of a street block in an urban city lined with row homes on both

sides and flanked at the beginning and end by intersections that lead to other streets. Be-

hind the rows of homes are alleys that face the backs of other rows of homes to paralleling