"What Does 2009 Traffic Stop Data Tell Us About Police Behavior in Champaign-Urbana?"

The sixth annual state report on Illinois Traffic Stop Statistics was recently released by the Center for Research in Law and Justice of the University of Illinois at Chicago.  The statistics provide a window into local traffic stop data that helps local communities answer a fundamental question:   “Are the number of traffic stops and searches involving motor vehicles operated by members of a racial minority disproportionate to the number of traffic stops involving motor vehicles operated by persons who are not members of a racial minority?”

What does the data tell us about traffic stop behavior of the Champaign, Urbana, and University of Illinois police departments?

To help analyze this, the state assigns an annual “ratio” to each police department.  This “ratio” is determined by dividing the percentage of minority stops by the percentage of the minority driving population in a community.   In this way, a ratio of 1.00 means local police departments stop Caucasian and minority drivers in proportion to their composition of the driving public.  As an example, the 2009 statewide ratio of 1.12 indicates that a minority driver is 12% more likely to be stopped than a Caucasian driver in Illinois.

In contrast, the 2009 ratios for the Champaign, Urbana, and U of I police departments were 1.45, 1.56, and 1.36, respectively.  All three local police departments stop minority drivers in significantly greater numbers than their percentage of the driving public.  Minority drivers accounted for 43%, 48%, and 38% of the stops in each of the three police jurisdictions respectively while composing only 30%, 31%, and 28% of the driving public.

This is not a new phenomenon.  In fact this disparity has been the case for all three police departments since traffic stop statistics were first released in 2004.  The last three years, ratios have steadily increased from 1.34, 1.43, 1.45 in Champaign and 1.47, 1.49, 1.56 in Urbana.  Urbana’s ratio of 1.56 represents a six-year high, placing it in the top 29% of 970 state law enforcement agencies with the highest ratios.  The University police’s ratio has remained fairly constant near 1.36.

A second component of the Illinois Traffic Stops Statistics Study focuses on the percentage of citations issued.  This is of particular interest because the officer has clear knowledge of the race of the driver when he is deciding to write a ticket or give a warning.  The citation percentages below are six-year averages.

Percent of Citations    

                                                            Caucasian        Minority

                        Champaign                  65%                 64%

                        Urbana                        57%                 61%

                        U of I                          18%                 25%

Champaign police appear to ticket Caucasian and minority drivers similarly (65% vs. 64%).  But a distinct disparity appears for the Urbana (57% vs. 61%) and U of I (18% vs. 25%) police departments.  In fact, in each of the last six years minority drivers were given a higher percentage of citations than their Caucasian counterparts by both departments.  It is also misleading to describe the situation in Champaign in strictly equitable terms, for although Caucasian and minority drivers are ticketed relatively equally, minority drives are still 45% more likely to be pulled over in the first place. It is interesting to note the low percentage of citations given by the U of I police.  Evidently drivers on campus are treated differently, with Caucasian drivers being ticketed only 18% of the time.

A final component of the Illinois Traffic Stops Statistics Study reports on consent searches. Although the number of consent searches is small, they are important statistics because they can reveal potential bias in the officer’s decision to request to search a car.

In 2009 Champaign, Urbana, and U of I police requested 22, 17, and 84 searches of stopped drivers respectively.  However, each police department requested minority drivers roughly twice as often as Caucasian drivers to consent to a search although the statistics show that contraband was found approximately twice as often in Caucasian vehicles.  Also, the 84 consent searches by campus police appears to be inordinately high when compared to Urbana and Champaign.

Can we now answer the question posed at the beginning of this article?  “In our community do police stop minority drivers disproportionately to their composition of the driving public?”  The bulk of traffic stop statistics suggest an affirmative answer.  The numbers do not tell us why this disparity exists only that it does.  Racial bias must be considered as a possible factor.

To comprehend the economic impact of these traffic stop disparities in our local community, it is helpful to visualize a situation where stop figures are actually equitable and proportional between minority and Caucasian drivers.  Adjusting minority driver figures to be proportional to Caucasian driver figures or adjusting Caucasian driver figures to be proportional to minority driver figures can easily do this.

Thus, if minority drivers were stopped proportionally to Caucasian drivers in our community, there would have been 18,311 fewer stops and 10,936 fewer citations of minority drivers over the past six years.  At the minimum moving violation rate of $125, that would have been a savings of $1,367,000 to minority drivers in Champaign/Urbana. Conversely, if Caucasian drivers were stopped proportionally to minority drivers, there would have been 43,211 more stops and 27,589 more citations of Caucasian drivers over the past six years, or an additional cost of $3,447,500 to Caucasian drivers in Champaign/Urbana.

The State Traffic Stops Statistics Studies show that for some reason minority and Caucasian drivers in our community are policed differently.  With this information in hand, it is now the responsibility of our communities, elected officials, and local police departments to begin answering the question of why?

For more information, the reports for the years 2004 through 2009, as well as a methodological overview of the project are available at: www.dot.il.gov/trafficstop/results09.html

Compiled by Durl Kruse


I would like to ask if location of the communities and the racial make-up is calculated into the study above? 

The Ratio Addresses That

The ratio that is assigned to each community addresses the issue of commuity racial composition.

If the law is enforced equally, then enforcement will reflect an equitable ratio.

Stats do not reflect all reality

The main problem with this study has been and always will be is its failure to observe all factors when compiling the numbers. One can not just compare simple raw traffic stop data and overlay it on population numbers and get an idea of how the police in your area are doing. There are so many other factors that go into the equation that one would have to make a real effort to come up with a real and comprehensive study to make any results valid. Variables such as time of day, location of stops, crime waves at time of study, and seriousness of stops are just a few that would need to be taken into account if these numbers would ever be taken seriously. And my guess is no one really wants to do that as it would cost a great deal of money and the results might not be what we think they would.

Here is an example of how variables can throw off the stats. If one is looking at the raw data of citations vs. warrnings it could show one result. But if you take the seriousness of the crime into the data, it might show a completely different story. For instance, if most of the warrnings in a area are for no headlights at night,a stop that is rarely ticketed, but almost always stopped by police, then there would be a majority of theses stops would be cleared in warnings. Compare that with how often one is ticketed for driving while license suspended, almost always ticketed and often arrested, then it would show more citations. Now, im not saying that more minorities drive suspended and more whites drive with no lights. What I am saying is that if you only take a rough guess of the overall numbers and then try to get a real answer, the results are anything but valid.


Furthermore, there are plenty of other variables that can throw off the numbers. For example, if a local bar in a small community starts to have a "hip hop" night or a Latin night every Friday night that draws more minorities to the area tha live there, it can throw off he numbers in a big way. Or if there is a number of crimes in an area that has only minority suspects, like the "polar bear' hunting of this last summer on the UofI compus, it will most likley throw off the stats.

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