Decision Making in Traffic Stop Encounters: A Multivariate Analysis of Police Behavior

• Author: Andra J. Katz-Bannister,William M. Wells,David L. Carter,Joseph A. Schafer
• Published date: 01 June 2006
• Date: 01 June 2006
• DOI: http://doi.org/10.1177/1098611104264990
• Subject Matter: Articles

ARTICLE
10.1177/1098611104264990 POLICE QUARTERL
Schafer et al. / TRAFFIC STOP ENCOUNTERS Y (Vol. 9, No. 2, June 2006)
DECISION MAKING IN TRAFFIC STOP
ENCOUNTERS: A MULTIVARIATE
ANALYSIS OF POLICE BEHAVIOR
JOSEPH A. SCHAFER
Southern Illinois University–Carbondale
DAVID L. CARTER
Michigan State University
ANDRA J. KATZ-BANNISTER
Wichita State University
WILLIAM M. WELLS
Southern Illinois University–Carbondale
In recent years, there has been a growth in public concern over police decision-
making practices during traffic enforcement. Catch phrases such as “racial
profiling,” “driving while Black,” and “driving while brown” typify the pub-
lic’s concern that race and ethnicity have undue influence on police discretion.
This study analyzes traffic stop data from a medium-sized midwestern commu-
nity to better understand this facet of police behavior. Although the authors
contend that “proving” racial profiling may be outside of current empirical
capabilities, useful insights can still be obtained by examining broader
aspects of traffic enforcement behaviors. The analysis indicated that race
was powerful in shaping police decision-making patterns, but so were gen-
der, age, and situational considerations. A number of implications for
research and policy emerging from the analysis are discussed.
Keywords:
police discretion; decision making; profiling; police behavior;
traffic enforcement
Since the inception of modern policing systems, there has been concern
about the role played by race and ethnicity in policing and police decision-
making practices. One of the most pervasive issues currently is the debate
POLICE QUARTERLY Vol. 9 No. 2, June 2006
184–209
DOI: 10.1177/1098611104264990
© 2006 Sage Publications

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over the use of “racial profiling” by the police. Although a universally
accepted definition of racial profiling has not emerged, this term generally
refers to situations in which police use their perception of a driver’s “race as a
key factor in deciding whether to make a traffic stop” (Ekstrand, 2000, p. 1).1
By extension, racial profiling may also encompass other police-initiated
behaviors in which decisions are made based on a citizen’s race/ethnicity,
rather than behavioral/legal cues (Ramirez, McDevitt, & Farrell, 2000).
“Profiling” may be used in a variety of policing contexts, both formally
(as a matter of organizational policy) and informally (based on an officer’s
personal biases and assumptions) (Harris, 2002). Such practices are not
always based on factors other than actual behavior such as race, nor are they
limited to traffic enforcement (see Ekstrand, 2000); examples are readily
apparent in federal efforts to identify “high” and “low” risk travelers in air-
port environments. The term “racial profiling” generally describes police
officers using pretext2 (often minor traffic or equipment violations) to stop
and interview minority drivers to satisfy the officer’s curiosity and/or search
for drugs and other contraband. There is general consensus among citizens,
advocates, and police that such police behavior is inappropriate, although
some contend that targeting minorities is pragmatic and rational police con-
duct (Taylor & Whitney, 1999). Police, the public, and various advocates
differ, however, in their beliefs about the extent to which racial profiling
actually occurs.
Perhaps one of the reasons that racial profiling is so controversial is
because it stirs deep-seated emotions within the United States public. Afri-
can American citizens consistently express the belief that they are subject to
differential treatment by the police and the justice system, although White
citizens may (Weitzer, 2000) or may not (Henderson, Cullen, Cao, Brown-
ing, & Kopache, 1997) agree with such beliefs. Public perceptions of the
police have been linked with more general views of the justice system
(Albrecht & Green, 1977), thus public perceptions of profiling may tarnish
broader views of the equity of the entire criminal justice system. In some
regards, racial profiling has become the latest “poster child” representing a
broader concern for injustice and disparate treatment within the criminal
justice system and society as a whole (Cole, 1999; Kennedy, 1997; Mann,
1993; Russell, 1998; Walker, Spohn, & DeLone, 2000).
The authors wish to thank the anonymous reviewers as well as Beth Huebner and Jody Sundt for their
contributions to this article. Special thanks also go to the women and men of the Central City Police De-
partment for their cooperation, candor, and efforts.

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POLICE QUARTERLY (Vol. 9, No. 2, June 2006)
Despite the considerable attention racial profiling has received, under-
standing of this issue is largely perceptual and anecdotal, rather than empir-
ical. Although a number of states have initiated efforts to collect systematic
data on traffic stops (Bureau of Justice Statistics, 2001), only a handful of
studies have been released to date. A variety of methodological concerns
are likely to produce mixed confidence in the validity and reliability of this
information. In particular, many studies were internal products of the agen-
cies in question; several studies were an outgrowth of court orders for data
collection; few studies have been subject to peer review; many studies
reported on data collected during relatively short periods of time, offering
no control over possible seasonal effects on police behavior; and most stud-
ies used only descriptive statistics in their analyses. As a result of these and
other limitations, empirical knowledge of police behavior in traffic stop
encounters is limited.
This study examines police decision-making patterns in traffic stop
encounters. For reasons discussed within, establishing that racial profiling
is actually occurring is a conceptually and methodologically challenging
endeavor. As a result, research examining broader police behaviors during
traffic stop encounters with citizens is more likely to produce meaningful
knowledge. After reviewing the research literature and discussing the chal-
lenges of studying racial profiling behavior, this study seeks to achieve four
goals. First, the study considers the factors that shape an officer’s decision
to search a driver, with special attention to the demographics of drivers. Sec-
ond, the study examines the role of various legal authorities that allow offi-
cers to conduct searches during traffic stops. Third, the study seeks to
understand the factors that predict whether officers discover contraband
during a search. Fourth, the study considers the factors that shape the proba-
bility of legal sanctions being used in a traffic stop. The authors also discuss
the management and methodological implications emerging from these
research findings and other studies of traffic stop encounters between police
and the public.
THE DENOMINATOR PROBLEM
In an effort to better understand racial profiling, a variety of studies has
been undertaken to examine whether, and to what extent, this practice is
occurring. To this end, a number of police agencies have instituted proce-
dures through which officers report information on the traffic stops they
make (i.e., driver demographics, situational factors, searches made,

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187
sanctioning decisions, etc.). A consistent problem encountered by scholars
and practitioners has been finding a baseline to which data on police traffic
stops might be compared (Cox, Pease, Miller, & Tyson, 2001; Ekstrand,
2000; Ramirez et al., 2000; Zingraff et al., 2000). Walker (2001) referred to
such a comparative baseline as “the denominator.” Given a group of citizens
stopped by the police (the numerator), what could be used as a denominator
to conclusively determine whether certain drivers were stopped at a
disproportionate rate?
Identifying and measuring an appropriate denominator is difficult for
two reasons. First, “racial profiling” remains a conceptually ambiguous
term (Engel, Calnon, & Bernard, 2002; Fridell, Lunney, Diamond, & Kubu,
2001); as a result, it is difficult for researchers to make the requisite opera-
tional decisions that would facilitate measurement. What types of police
behavior does “racial profiling” encompass (disproportionate stops,
searches, sanctions, etc.)? The exact behaviors included within this term’s
definition have not been adequately defined, making it difficult for
researchers to identify what aspects of policing require further inquiry. Sec-
ond, even if racial profiling were conceptually defined, reaching a consen-
sus on the most valid and reliable methods by which to operationalize and
measure such a rate would be equally problematic.3 Because of these com-
plications, determining whether racial profiling exists (in general or in spe-
cific jurisdictions) may not be feasible at the present time (Engel et al.,
2002; Verniero & Zoubek, 1999; Walker, 2001). Rather, it may be more
beneficial for researchers to focus on understanding patterns of police
behavior after traffic stops have been initiated.
CITIZEN ATTRIBUTES AND POLICE DECISION MAKING
Because of the denominator dilemma and associated methodological
concerns, at the present time empirical studies of the practice of racial pro-
filing are arguably infeasible. It may be more fruitful to examine whether
police officers appear to engage in disparate decision-making behaviors
during traffic stop encounters. The study of the factors influencing criminal
justice decision making can be traced back to the Survey of the Administra-
tion of Criminal...