The process-based model of police legitimacy suggests, when police are perceived to make fair decisions and treat people with respect, they will be viewed as legitimate authorities. A randomized controlled trial was used to test the impact of a procedural justice policing intervention, relative to routine police behavior, during traffic stops for excessive speeding in Adana, Turkey.
Drivers stopped by traffic officers for speeding violations were randomly assigned to treatment and control groups. Subjects in the treatment group received the procedural justice policing intervention during traffic stops, while subjects in the control group experienced business-as-usual traffic stops. Treatment officer behavior was guided by a script that helped to ensure that key components of a procedurally-just encounter were delivered. After completion of the traffic stop, drivers were interviewed on the encounter and general perceptions of traffic police.
The experimental analyses show that the infusion of procedural justice principles into police traffic stops does improve citizens’ perceptions of the specific encounter relative to routine police traffic stops. However, the procedural justice treatment did not generate a robust improvement in citizens’ general perceptions of traffic officers.
These results indicate it might be overly optimistic to suggest a single positive encounter can exert a strong influence on durable citizen perceptions of confidence and trust in the police. In addition to ensuring procedurally-just encounters, police executives and police makers should also pay attention to other relevant performance dimensions such as crime control effectiveness, distributive fairness, and lawfulness to change global perceptions of the police.
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A recently-completed systematic review of randomized experiments in policing identified 63 such studies competed between 1970 and 2011 (Braga et al. 2014). All 63 policing randomized experiments were completed in the United States (47, 74.6 %), United Kingdom (11, 17.5 %), Australia (4, 6.3 %) and Canada (1, 1.6 %). The Evidence-Based Policing Matrix (Lum et al. 2011) maintained by George Mason University’s Center for Evidence-Based Crime Policy also does not identify any other randomized field experiments completed in non-Western countries between 2012 and 2014. We are also unaware of any new policing randomized experiments completed in any non-Western countries since the completion of the Braga et al. (2014) systematic review.
Schuck and Rosenbaum (2011) present the preliminary results of a randomized experiment testing the impacts of a Chicago Police Department recruit training program aimed at improving the quality of interpersonal encounters between officers and residents. Preliminary results suggest that recruits who received training displayed more positive procedural-justice attitudes, greater conflict-resolutions skills, and more empathy than did non-trained recruits. Their report did not mention any measurement of changes in citizen perceptions of encounters with treatment and control recruits, however.
While not randomized experiments, the basic propositions of the process-based model of police legitimacy have been tested in non-Western countries such as China (Hu et al. 2015), Israel (Jonathan-Zamir and Weisburd 2013), Jamaica (Reisig and Lloyd 2009), Slovenia (Reisig et al. 2014), and Trinidad and Tobago (Kochel et al. 2013).
The treatment and control traffic officers did not differ significantly in terms of age (Mean = 40.9), years on the job (Mean = 17.8), education (all but one control officer had more than a high school education), and place of birth (roughly one-third of each group were born in Adana with the remainder coming from other areas of Turkey). The control group did have two female officers while the treatment group was comprised completely of male officers. Researchers did not note any substantive differences in the way male and female control officers interacted with stopped motorists.
The final interview instrument did not contain an item that directly measured citizen compliance. The QCET compliance measures were tested for possible inclusion in the Adana RCT during a pilot speed control operation. Unfortunately, respondents provided nearly uniform responses during the pilot. The Adana RCT research team suspected that subjects may have been fearful of encountering legal consequences if reporting non-compliance immediately after the traffic stop. Therefore, a compliance measure was not included in the final instrument used during the actual RCT.
This randomization protocol bears some resemblance to the method used in the Minneapolis Domestic Violence Experiment that was well known to be subverted by some of the participating officers (Sherman and Berk 1984). In this randomized experiment, however, the presence of researchers during all speed control operations, coupled with the follow-up review by commanding officers, seemed to provide adequate safeguards against subversion of the randomization procedure. No violations of randomization protocols were noted during the implementation of the experiment.
Please see Sahin (2014) for statistical comparisons of individuals who refused to participate relative to those who did participate as well as comparisons of RCT participants to the resident populations of Adana. In both sets of comparisons, no substantive differences were noted.
In criminology, experimental research involving the administration of surveys to subjects generally shows response rates ranging from 60 to 70 % (Antrobus et al. 2013 drawing on randomized experiments in Lum et al. 2011). The QCET experiment reported a much lower 13.1 % overall response rate (2746 valid responses out of 20,985 surveys distributed to drivers; Mazerolle et al. 2013). In ScotCET, the overall response rate was only 6.6 % (816 responses returned out of 12,431 surveys distributed to drivers; MacQueen and Bradford 2015). However, subsequent analyses using Cochrane and Elffers methods to explore non-response bias found that the QCET results were robust to any biases associated with low response rates across the treatment and control groups (Antrobus et al. 2013). For a two-tailed α = 0.05 test, the statistical power of the Adana randomized experiment to detect a small effect size (ES = 0.20) was 0.682 and, for both medium and large effect sizes, statistical power exceeded 0.999 (Lipsey 1990).
Although the full model results are not shown, in both the robust and median regression models, gender was not significantly correlated with encounter perceptions. This contradicts the result reported in Table 2.
In the first step, a probit regression model was estimated using regressors which had the least amount of missing data, several of which were obtained from driving records. The resulting model was estimated using 686 of the original 702 drivers invited to participate in the study. The regressors included the treatment assignment dummy (b = 0.70; s.e. = 0.11), the raw number of demerits (b = –0.02; s.e. = 0.01) and its square (b × 100 = 0.06; s.e. × 100 = 0.03), a dummy for male (b = 0.23; s.e. = 0.22), a dummy for excessive speeding (b = 0.17; s.e. = 0.13), a dummy for having been born in Adana (b = 0.49; s.e. = 0.32), order of study entry (b = 0.06; s.e. = 0.03), and the interaction between the dummies for gender and birthplace (b = –0.56; s.e. = 0.34). It should be noted that the coefficients corresponding to the inverse Mills ratio are positive but not statistically significant in either of the substantive equations. Therefore, while there is evidence of positive selection (i.e., the unobservables that make a person more likely to participate in the survey also give him or her more favorable procedural justice perceptions), it is not substantial and does not appear to badly bias the reported results.
Adaman F, Carkoglu A, Senatalar B (2005) Toplumun Kamu Yönetimine ve Kamu Hizmetlerine ve Reforma Bakışı. TESEV Yayinlari, Istanbul
Adaman F, Carkoglu A, Senatalar B (2009) Hanehalki Gozunden Kamu Hizmetleri ve Yolsuzluk, vol 43. TESEV, Ankara
Andersen R (2008) Modern methods for robust regression. Sage, Thousand Oaks
Antrobus E, Elffers H, White G, Mazerolle L (2013) Non-response bias in randomized control experiments: putting the Queensland community engagement trial under a microscope. Eval Rev 37:197–212
Aytac O (2005) Halkın Polise Bakışı: Güveniyorum ama Rüşvetçi ve Kaba. Retrieved October 5, 2013, from http://www.memurlar.net/haber/20671
Beetham D (1991) The legitimation of power. Humanities Press International, Atlantic Highlands
Bland N, Miller J, Quinton P (2000) Upping the PACE? An evaluation of the recommendations of the Stephen Lawrence inquiry on stops and searches, police research series (paper 128). Home Office, London
Bottoms A, Tankebe J (2012) Beyond procedural justice: a dialogic approach to legitimacy in criminal justice. J Crim Law Criminol 102:119–170
Bradford B, Jackson J, Stanko E (2009) Contact and confidence: revisiting the impact of public encounters with the police. Polic Soc 19:20–46
Braga AA (2008) Problem-oriented policing and crime prevention, 2nd edn. Lynne Rienner Publishers, Boulder
Braga AA, Welsh B, Papachristos A, Schnell C, Grossman L (2014) The growth of randomized experiments in policing: the vital few and the salience of mentoring. J Exp Criminol 10:1–28
Brandl S, Frank J, Worden R, Bynum T (1994) Global and specific attitudes toward the police: disentangling the relationship. Justice Q 11:119–134
Brunson RK (2007) ‘Police don’t like black people’: african American young men’s accumulated police experiences. Criminol Public Policy 6:71–102
Brunson RK, Miller J (2006) Young black men and urban policing in the United States. Brit J Criminol 46:613–640
Brunson RK, Weitzer R (2009) Police relations with black and white youths in different urban neighborhoods. Urb Aff Rev 44:858–885
Bucke T (1997) Ethnicity and contacts with the police: latest findings from the British Crime Survey (study 59). Home Office, London
Campbell DT, Stanley J (1966) Experimental and quasi-experimental designs for research. Rand McNally, Chicago
Cao L, Burton V (2006) Spanning the continents: assessing the Turkish public confidence in the police. Policing 29:451–463
Carr PJ, Napolitano L, Keating J (2007) We never call the cops and here is why: a qualitative examination of legal cynicism in three Philadelphia neighborhoods. Criminology 45:445–480
Cohen J (1988) Statistical power analysis for the behavioral sciences, 2nd edn. Lawrence Erlbaum, Hillsdale
Coicaud J-M (2002) Legitimacy and politics. Cambridge University Press, Cambridge
Dai M, Frank J, Sun I (2011) Procedural justice during police–citizen encounters: the effects of process-based policing on citizen compliance and demeanor. J Crim Justice 39:159–168
Elliott I, Thomas S, Ogloff J (2011) Procedural justice in contacts with the police: testing a relational model of authority in a mixed methods study. Psychol Public Policy Law 14:592–610
Engel R (2005) Citizens’ perceptions of distributive and procedural injustice during traffic stops with police. J Res Crime Delinq 42:445–481
Fagan J (2002) Law, social science and racial profiling. Justice Res Policy 4:104–129
Farrington D (2003) Methodological quality standards for evaluation research. Annals 587:49–68
Fine M, Freudenberg N, Payne Y, Perkins T, Smith K, Wanzer K (2003) ‘Anything can happen with police around’: urban youth evaluate strategies of surveillance in public places. J Soc Issues 59:141–158
Gallagher C, Maguire E, Mastrofski S, Reisig M (2001) The public image of police. International Association of Chiefs of Police, Washington, DC
Gau J, Brunson RK (2009) Procedural justice and order maintenance policing: a study of inner-city young men’s perceptions of police legitimacy. Justice Q 27:255–279
Hawdon J (2008) Legitimacy, trust, social capital, and policing styles. Police Q 11:182–201
Heckman J (1979) Sample selection bias as a specification error. Econometrica 47:153–161
Hohl K, Bradford B, Stanko E (2010) Influencing trust and confidence in the London Metropolitan Police. Brit J Criminol 50:491–513
Hu R, Sun I, Wu Y (2015) Chinese trust in the police: the impact of political efficacy and participation. Soc Sci Q 96:1012–1026
Hurst Y, Frank J (2000) How kids view cops: the nature of juvenile attitudes toward the police. J Crim Justice 28:189–202
Hurst Y, Frank J, Browning S (2000) The attitudes of juveniles toward the police: a comparison of black and white youth. Policing 23:37–53
Jackson J, Bradford B (2009) Crime, policing and social order: on the expressive nature of public confidence in policing. Brit J Sociol 60:493–521
Jackson J, Bradford B, Hough M, Myhill A, Quinton P, Tyler T (2012) Why do people comply with the law? Legitimacy and the influence of legal institutions. Brit J Criminol 52:1051–1071
Jonathan-Zamir T, Weisburd D (2013) The effects of security threats on antecedents of police legitimacy: findings from a quasi-experiment in Israel. J Res Crime Delinq 50:3–32
Kazu I (2003) Polis-Halk İlişkileri (Elazığ Örneği). Polis Dergisi 39:169–199
Kochel T, Parks R, Mastrofski S (2013) Examining police effectiveness as a precursor to legitimacy and cooperation with police. Justice Q 30:895–925
Koenker R (2005) Quantile regression. Cambridge University Press, New York
Leiber M, Nalla M, Farnsworth M (1998) Explaining juveniles’attitudes toward the police. Justice Q 15:151–174
Lum C, Koper C, Telep C (2011) The evidence-based policing matrix. J Exp Criminol 7:3–26
MacQueen S, Bradford B (2015) Enhancing public trust and police legitimacy during road traffic encounters: results from a randomized controlled trial in Scotland. J Exp Criminol 11:419–443
Mastrofski S, Snipes J, Supina A (1996) Compliance on demand: the public’s response to specific police requests. J Res Crime Delinq 33:269–305
Mazerolle L, Bennett S, Davis J, Sargeant E, Manning M (2012) Legitimacy in policing: a systematic review. Camp Syst Rev 9
Mazerolle L, Antrobus E, Bennett S, Tyler T (2013) Shaping citizen perceptions of police legitimacy: a randomized field trial of procedural justice. Criminology 51:33–64
McCluskey J (2003) Police requests for compliance: coercive and procedurally just tactics. LFB Scholarly Publishing, New York
Meares T, Kahan D (1998) Law and (norms of) order in the inner city. Law Soc Rev 32:805–838
Moore M (1992) Problem-solving and community policing. In: Tonry M, Morris N (eds) Modern policing, crime and justice, vol 15. University of Chicago Press, Chicago, pp 99–158
Moore M (2002) Recognizing value in policing. Police Executive Research Forum, Washington, DC
Murphy K, Hinds L, Fleming J (2008) Encouraging public cooperation and support for police. Polic Soc 18:136–155
Ozbaran Y (2010) The relationship between Turkish traffic enforcement officers’ job satisfaction and officers’ perception of their leaders’ leadership styles. Ph.D. dissertation, University of Texas, Dallas
Parsons T (1967) Some reflections on the place of force in social process. In: Parsons T (ed) Sociological theory and modern society. The Free Press, New York, pp 192–219
Paternoster R, Brame R, Bachman R, Sherman L (1997) Do fair procedures matter? Law Soc Rev 17:457–479
Quinton P, Bland N, Miller J (2000) Police stops: decision-making and practice, police research series (paper 130). Home Office, London
Reisig M (2010) Community and problem-oriented policing. In: Tonry M (ed) Crime and Justice, vol 39. University of Chicago Press, Chicago, pp 1–53
Reisig M, Chandek M (2001) The effects of expectancy disconfirmation on outcome satisfaction in police–citizen interactions. Policing 21:88–99
Reisig M, Lloyd C (2009) Procedural justice, police legitimacy, and helping the police fight crime: results from a survey of Jamaican adolescents. Police Q 12:42–62
Reisig M, Bratton J, Gertz M (2007) The construct validity and refinement of process-based policing measures. Crim Justice Behav 34:1005–1028
Reisig M, Tankebe J, Mesko G (2014) Compliance with the law in Slovenia: the role of procedural justice and police legitimacy. Eur J Crim Pol Res 20:259–276
Rosenbaum D, Schuck A, Costello S, Hawkins D, Ring M (2005) Attitudes toward the police: the effects of direct and vicarious experience. Police Q 8:343–365
Sahin NM (2014). Legitimacy, procedural justice, and police–citizen encounters: a randomized controlled trial of the impact of procedural justice on citizen perceptions of the police during traffic stops in Turkey. Ph.D. dissertation, Rutgers University
Sarat A (1977) Studying American legal culture. Law Soc Rev 11:427–488
Schuck A, Rosenbaum D (2011) The Chicago Quality Interaction Training Program: a randomized control trial of police innovation. National Institute of Justice, Washington, DC
Sechrest L, Rosenblatt A (1987) Research methods. In: Quay H (ed) Handbook of juvenile delinquency. Wiley, New York, pp 417–450
Shadish W, Cook T, Campbell D (2002) Experimental and quasi-experimental designs for generalized causal inference. Houghton Mifflin, Boston
Sherman L, Berk R (1984) The specific deterrent effects of arrest for domestic assault. Am Sociol Rev 49:261–272
Skogan W (2006) Asymmetry in the impact of encounters with police. Polic Soc 16:99–126
Skogan W, Frydl K (eds) (2004) Fairness and effectiveness in policing: the evidence. National Academies Press, Washington, DC
Skogan W, Hartnett S (1997) Community policing, Chicago style. Oxford University Press, New York
Snyder H, Sickmund M (1996) Juvenile offenders and victims: a national report. Office of Juvenile Justice and Delinquency Prevention, Washington, DC
Solis C, Portillos E, Brunson RK (2009) Latino/a youths’ experiences with and perceptions of negative police encounters. Annals 623:39–51
Stone V, Pettigrew N (2000) The views of the public on stops and searches, police research series (paper 129). Home Office, London
Sunshine J, Tyler T (2003) The role of procedural justice and legitimacy in shaping public support for policing. Law Soc Rev 37:513–548
Tankebe J (2009) Public cooperation with the police in Ghana: does procedural fairness matter? Criminology 47:1265–1293
Tankebe J (2013) Viewing things differently: the dimensions of public perceptions of police legitimacy. Criminology 51:103–135
Taylor T, Turner K, Esbensen F-A, Winfree L (2001) Coppin’ an attitude: attitudinal differences among juveniles toward the police. J Crim Justice 29:295–305
Tyler T (2003) Procedural justice, legitimacy, and the effective rule of law. In: Tonry M (ed) Crime and Justice, vol 30. University of Chicago Press, Chicago, pp 431–505
Tyler T (2004) Enhancing police legitimacy. Annals 593:84–99
Tyler T (2005) Policing in black and white: ethnic group differences in trust and confidence in the police. Police Q 8:322–342
Tyler T (2006) Why people obey the law. Princeton University Press, Princeton
Tyler T, Fagan J (2008) Legitimacy and cooperation: why do people help the police fight crime in their communities? Ohio State J Crim Law 6:231–276
Tyler T, Huo Y (2002) Trust in the law: encouraging public cooperation with the police and courts. Russell Sage Foundation, New York
Tyler T, Wakslak C (2004) Profiling and police legitimacy: procedural justice, attributions of motive, and acceptance of police authority. Criminology 42:253–281
Verardi V, Croux C (2009) Robust regression in Stata. Stata J 9:439–453
Warren P (2011) Perceptions of police disrespect during vehicle stops: a race-based analysis. Crime Delinq 57:356–376
Weitzer R, Tuch S (2005) Racially biased policing: determinants of citizen perceptions. Soc Forces 83:1009–1030
Weitzer R, Tuch S (2006) Race and policing in America: conflict and reform. Cambridge University Press, New York
Winship C, Mare R (1992) Models for sample selection bias. Annu Rev Soc 18:327–350
Yalcinkaya A (2012) Polis Halk İlişkilerini Olumlu Yönde Katalizleyecek Unsurlar ve İzlenmesi Gereken Yol. Polis Akademisi, Ankara
Appendix 1: Procedural Justice Script
Good morning/afternoon sir/madam. My name is officer_________
Do you know how we conduct our speed control operations?
Let me provide you some brief information about speed controls.
It is one of the most well-enforced traffic controls in Turkey.
The radar equipment in our patrol car accurately records the car’s speed
We give tickets to all drivers who pass the speed limit we stop for speeding regardless of their socioeconomic and occupational position.
Our aim is to reduce traffic accidents
Do you know that approximately 30 percent of traffic accidents in Turkey are related to speeding?
In Adana alone there were 55 deaths and 5371 injuries in 2011 related to traffic accidents.
Guess how difficult for us to tell a person that his/her loved one has died or has been seriously injured.
You can help us reduce these accidents by continually driving carefully and responsibly.
Do you think we should continue conducting speed controls?
Today, you have been stopped because our radar equipped patrol car detected that your speed was ___________. This speed is clearly above the stated limit of 70 km/h.
Now, may I have your documents please?
Thank you. I wish you a safe trip. Please be careful next time. Thank you for your cooperation.
See Table 5.
See Fig. 3.
See Fig. 4.
See Fig. 5.
See Table 6.
See Table 7.
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Sahin, N., Braga, A.A., Apel, R. et al. The Impact of Procedurally-Just Policing on Citizen Perceptions of Police During Traffic Stops: The Adana Randomized Controlled Trial. J Quant Criminol 33, 701–726 (2017). https://doi.org/10.1007/s10940-016-9308-7
- Procedural justice
- Traffic stops
- Randomized experiment