Skip to main content
Log in

Do Police Body-Worn Cameras Reduce Citizen Fatalities? Results of a Country-Wide Natural Experiment

  • Original Paper
  • Published:
Journal of Quantitative Criminology Aims and scope Submit manuscript

Abstract

Objectives

This study assesses the effects of body-worn cameras (BWCs) on rates of fatalities arising from police-citizen encounters. While existing experimental research has not examined this outcome because it is so rare, the staggered roll-out of BWCs across the nation’s law enforcement agencies provides an opportunity for quasi-experimental analysis.

Methods

Difference-in-difference (DID) analyses using Poisson models compare changes in U.S. law enforcement agencies’ fatality counts with changes in BWC acquisition. Using a federal law enforcement survey focused on body worn cameras (LEMAS-BWCS) and media-sourced data on fatal encounters from fatalencounters.org (FE), the research examines agencies acquiring BWCs between 2013/14 and 2015/16 and those that did not acquire them up to 2016 and had no plans to do so. It includes a fixed effects annual panel data analysis with data from 2005/06 to 2018/19 and two two-group analyses focusing on a pre-treatment period (2010/11 to 2012/13) and a post-treatment period (2016/17 to 2018/19). The latter includes a propensity score matched comparison.

Results

Two out of three DID analyses showed statistically significant negative effects of BWCs on citizen fatalities. The propensity score matched two-group analysis returned a non-significant negative effect.

Conclusions

The research finds some evidence for BWC effects on citizen fatalities. However, there are important validity threats to this conclusion. These include the possibility that BWC acquisition serves as a marker for other policy changes focused on BWC-acquiring agencies in the 2013/14 to 2015/16 period and beyond.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4

Similar content being viewed by others

Notes

  1. It is notable that the racial disparities in deaths from use of force echo larger disparities in homicides generally, with black homicide rates 7.31 times greater than white homicide rates in 2016 age-adjusted comparisons (Centers for Disease Control and Prevention, n.d.).

  2. Randomly drawing 50 encounters between May 2005 and April 2019 from the fatalencounters.org database (excluding vehicle-related, deaths, deaths involving multiple law enforcement agencies, or deaths associated with federal or corrections agencies), we found that all 50 cases involved some officer use of force. Officers shot at the suspect in 43 out of 50 cases, tasered them in 4 cases, used a stun gun in one case, used flashbang grenades and teargas in one case, and engaged in a physical struggle in two cases. In 21 cases, the victim had a gun, and in 12 further cases they had some other kind of weapon (in 9 cases a bladed weapon). In two cases, the victim shot themselves. Six encounters involved suspects barricading themselves in a building (five times with hostages). One case involved an off-duty officer killing a suspect.

  3. For the 1,346 agencies in the core sample that had acquired BWCs between 2013/14 and 2015/16, at the time of the 2016 survey: 50.3% of reported “Full deployment to all intended personnel”, 10.1% reported “Complete deployment for some assignments / partial deployment in others”, 11.5% reported “Partial deployment”, 25.6% described “Exploratory/pilot deployment”, 2.3% were unsure, and 3 cases (< 1%) had missing responses.

  4. In a small number of cases, BJS had imputed answers to this question, based on answers to downstream questions that indicated clearly that they had acquired BWCs.

  5. In a panel analysis of the full sample, agencies were assumed to have acquired BWCs in 2016/17 if they indicated doing so in the early weeks of this time period prior to survey fieldwork completion, or if they said they were likely/very likely to acquire them in the next year, and (in a subsequent question) indicated they would do so in the next 12 months. Those who said they were likely/very likely to acquire them in the next year, but could not provide an anticipated date, or specifically indicated it would be beyond 12 months, were accorded a BWC acquisition year of 2017/18. This method is far from perfect but had the value of allowing us to include two years of data post-survey.

  6. The validation exercise involved obtaining BWC information on random selections from two-groups of agencies from the LEMAS-BWCS survey: (1) those who reported not having BWCs in the original survey prior to May 2016, and (2) those that reported acquiring them between May 2006 and April 2016. For a total of 21 agencies in each of these groups (i.e., a total of 42 agencies) we successfully obtained at least some relevant BWC information by email/phone to an agency representative and/or (in a couple of cases) found relevant information using media sources. For a further 13 cases (three BWC-acquirers and nine non-acquirers) we conducted outreach but were unsuccessful in obtaining information.

  7. Ranges of fulltime officers in “agency size” were defined as fewer than 5, 5–9, 10–24, 25–49, 50–99, 100–499, 500–1000, 1,000–1,999, 2,000–4,999, 5,000–9999, 10,000 or more.

  8. Population served and county poverty rates were not applied to state agencies because these measures do not have an equivalent meaning at the state law enforcement level.

  9. County poverty rates are based on the primary agency county indicated in the BJS crosswalk file. These represent proxy measures: in most cases, county geographies areas will be larger than the areas served by individual agencies, and in a minority of cases agencies span more than one county (notably, we estimate the latter applies to about 4% of local municipal agencies).

  10. The full sample event study produced pre-treatment coefficients that were consistently above zero and formed a downward sloping line in the pre-treatment period. While, overall, these pre-intervention coefficients were not collectively significant in a joint null test (p = .138), confidence intervals for a majority of the pre-intervention points did not include zero.

  11. For the core annual panel model presented, variance in the dependent variable (.96) was over five times larger than the mean (.18), a clear indication of overdispersion.

  12. When separately examined, the single state dummy dropped in modeling (accounting for 4.6% of matched/weighted agencies) had a bias of 13.7%, a little larger than ideal, while the dropped agency type/size dummy showed 3.5% bias. Balance statistics for main effects and interactions together were reasonable, averaging 2.4%, with the largest individual imbalance at 8.4%. Variance ratios were less balanced for continuous interaction terms, however, ranging from 0.66 to 2.64. The last of these numbers (corresponding with the only interaction term outside the 0.5 to 2.0 range) is larger than ideal (Stuart and Rubin 2008).

  13. The reduced match involved 503 control and 655 treatment cases. Balance statistics were acceptable, but not as strong as the main match (mean bias for main effects was 3.7%; three main effects variables had imbalances higher than 10% with a maximum of 13.1%; the most extreme variance ratio was 1.64). Trend analysis shows no statistically significant violations of common trends for this reduced match in the pre-BWC period.

References

  • Abrams DS (2012) Estimating the deterrent effect of incarceration using sentencing enhancements. Am Econ J Appl Econ 4(4):32–56

    Article  Google Scholar 

  • Alpert GP, MacDonald JM (2001) Police use of force: An analysis of organizational characteristics. Justice Q 18(2):393–409

    Article  Google Scholar 

  • Ariel B, Farrar WA, Sutherland A (2015) The effect of police body-worn cameras on use of force and citizens’ complaints against the police: A randomized controlled trial. J Quant Criminol 31(3):509–535

    Article  Google Scholar 

  • Ariel B, Sutherland A, Henstock D, Young J, Drover P, Sykes J, Megicks S, Henderson R (2016) Report: Increases in police use of force in the presence of body-worn cameras are driven by officer discretion: A protocol-based subgroup analysis of ten randomized experiments. J Exp Criminol 12(3):453–463

    Article  Google Scholar 

  • Ariel B, Sutherland A, Henstock D, Young J, Sosinski G (2017a) The deterrence spectrum: Explaining why police body-worn cameras ‘work’ or ‘backfire’ in aggressive police–public encounters. Polic J Polic Pract 12(1):6–26

    Article  Google Scholar 

  • Ariel B, Sutherland A, Henstock D, Young J, Drover P, Sykes J, Megicks S, Henderson R (2017b) “Contagious accountability” a global multisite randomized controlled trial on the effect of police body-worn cameras on citizens’ complaints against the police. Crim Justice Behav 44(2):293–316

    Article  Google Scholar 

  • Ariel B, Sutherland A, Sherman LW (2019) Preventing treatment spillover contamination in criminological field experiments: the case of body-worn police cameras. J Exp Criminol 15(4):569–591

    Article  Google Scholar 

  • Austin PC (2009) Balance diagnostics for comparing the distribution of baseline covariates between treatment groups in propensity-score matched samples. Stat Med 28(25):3083–3107. https://doi.org/10.1002/sim.3697

    Article  Google Scholar 

  • Austin PC (2010) Statistical criteria for selecting the optimal number of untreated subjects matched to each treated subject when using many-to-one matching on the propensity score. Am J Epidemiol 172(9):1092–1097

    Article  Google Scholar 

  • Baćak V, Mausolf JG, Schwarz C (2019) How comprehensive are media-based data on police officer-involved shootings? J Interpers Violence. https://doi.org/10.1177/0886260519860897

    Article  Google Scholar 

  • Banks D, Planty M, Couzens L, Lee P, Brooks C, Scott KM, Whyde A (2019) Arrest-related Deaths Program: Pilot Study of Redesigned Survey Methodology. US Department of Justice, Office of Justice Programs, Bureau of Justice Statistics

    Google Scholar 

  • Bayley DH (1986) The tactical choices of police patrol officers. J Crim Just 14(4):329–348

    Article  Google Scholar 

  • Belsley DA, Kuh E, Welsch RE (2005) Regression diagnostics: Identifying influential data and sources of collinearity, vol 571. John Wiley & Sons, New York

    Google Scholar 

  • Berk R, MacDonald JM (2008) Overdispersion and Poisson regression. J Quant Criminol 24(3):269–284

    Article  Google Scholar 

  • Binder A, Scharf P (1980) The violent police-citizen encounter. Ann Am Acad Pol Soc Sci 452(1):111–121

    Article  Google Scholar 

  • Body-Worn Camera Training and Technical Assistance (BWCTTA) (n.d.). Retrieved from https://www.bwctta.com/.

  • Braga AA, Sousa WH, Coldren JR, Rodriguez D (2018) The effects of body-worn cameras on police activity and police-citizen encounters. J Crim Law Criminol 108(3):511–538

    Google Scholar 

  • Burghart, D.B. (2019). Fatal Encounters. Retrieved from https://fatalencounters.org/.

  • Bureau of Justice Assistance (n.d.). Getting Started Body-Worn Camera Toolkit. Retrieved from https://bja.ojp.gov/program/bwc/getting-started.

  • Centers for Disease Control and Prevention (n.d.). National Center for Health Statistics: Health, united states, 2017 – data finder. Retrieved from https://www.cdc.gov/nchs/hus/contents2017.htm#029.

  • Clarey, D. (2017). Some states training police to use words, not guns. American Public Media. Retrieved from https://www.apmreports.org/story/2017/12/20/more-states-training-police-to-use-words-not-guns.

  • Davis E, Whyde A, Langton L (2018) Contacts between police and the public, 2015. Bureau of Justice Statistics, US Department of Justice

    Google Scholar 

  • Duval S, Wicklund RA (1972) A theory of objective self awareness. Academic Press, London

    Google Scholar 

  • Edwards F, Lee H, Esposito M (2019) Risk of being killed by police use of force in the United States by age, race–ethnicity, and sex. Proc Natl Acad Sci 116(34):16793–16798

    Article  Google Scholar 

  • Finch BK, Beck A, Burghart DB, Johnson R, Klinger D, Thomas K (2019) Using crowd-sourced data to explore police-related-deaths in the United States (2000–2017): The Case of Fatal Encounters. Open Health Data 6:1

    Article  Google Scholar 

  • Farman L (2016) Validation of volunteered geographic information quality components for incidents of law enforcement use of force. Thesis in Geographic Information Science and Technology University of Southern California, M.A

    Google Scholar 

  • Fyfe JJ (1978) Shots fired: An examination of New York City police firearms discharges (No. 78–14335 UMI). State University of New York at Albany.

  • Fyfe JJ (1980) Geographic correlates of police shooting: A microanalysis. J Res Crime Delinq 17(1):101–113

    Article  Google Scholar 

  • Fyfe JJ (1982) Blind justice: Police shootings in Memphis. J Crim L Criminol 73:707

    Article  Google Scholar 

  • Fyfe JJ (1986) The split-second syndrome and other determinants of police violence. Viol Trans 207:225

    Google Scholar 

  • Fyfe JJ (1988) Police use of deadly force: research and reform. Justice Q 5(2):165205

    Article  Google Scholar 

  • Geller WA, Scott M (1992) Deadly force: What we know: A practitioner’s desk reference on police-involved shootings. Police Executive Research Forum, Washington, DC

    Google Scholar 

  • Graham v. Connor, 490 U.S. 386 (1989)

  • Guardian (2017). Retrieved from https://www.theguardian.com/usnews/ng-interactive/2015/jun/01/the-counted-police-killings-us-database.

  • Hedberg EC, Katz CM, Choate DE (2017) Body-worn cameras and citizen interactions with police officers: estimating plausible effects given varying compliance levels. Justice Q 34(4):627–651

    Article  Google Scholar 

  • Hickman MJ, Piquero AR (2009) Organizational, administrative, and environmental correlates of complaints about police use of force does minority representation matter? Crime Delinq 55(1):3–27

    Article  Google Scholar 

  • Hirschfield PJ (2015a) Lethal policing: making sense of American exceptionalism. Sociol Forum 30(4):1109–1117

    Article  Google Scholar 

  • Hirschfield PJ (2015b) Why do American cops kill so many compared to European cops? The Conversation. Retrieved from http://theconversation.com/why-do-american-cops-kill-so-many-compared-to-europeancops49696

  • Hyland SS (2018). Body-worn cameras in law enforcement agencies, 2016. Washington, DC: U.S. Department of Justice, Office of Justice Programs, Bureau of Justice Statistics.

  • Hyland S, Langton L, Davis E (2015). Police use of nonfatal force, 2002–11. Washington DC: US Department of Justice, Office of Justice Programs, Bureau of Justice Statistics.

  • Kania RR, Mackey WC (1977) Police violence as a function of community characteristics. Criminology 15(1):27–48

    Article  Google Scholar 

  • Klinger DA (2005) Social theory and the street cop: The case of deadly force. Police Foundation, Washington

    Google Scholar 

  • Klinger DA, Rosenfeld R, Isom D, Deckard M (2016) Race, crime, and the micro-ecology of deadly force. Criminol Public Policy 15(1):193–222

    Article  Google Scholar 

  • Klinger DA, Slocum LA (2017) Critical assessment of an analysis of a journalistic compendium of citizens killed by police gunfire. Criminol Public Policy 16(1):349–362

    Article  Google Scholar 

  • Koen MC, Willis JJ, Mastrofski SD (2018) The effects of body-worn cameras on police organization and practice: a theory-based analysis. Polic Soc 1–17.

  • Lechner M (2011) The estimation of causal effects by difference-in-difference methods. Found Trends Econom 4(3):165–224

    Article  Google Scholar 

  • Leuven E, Sianesi B (2003) PSMATCH2: Stata module to perform full Mahalanobis and propensity score matching, common support graphing, and covariate imbalance testing.

  • Lum C, Koper CS, Wilson DB, Stoltz M, Goodier M, Eggins E, Higginson A, Mazerolle L (2020) Body-worn cameras’ effects on police officers and citizen behavior: a systematic review. Campbell Syst Rev 16(e1112):1–40. https://doi.org/10.1002/cl2.1112

    Article  Google Scholar 

  • Lum C, Stoltz M, Koper CS, Scherer JA (2019) Research on body-worn cameras: What we know, what we need to know. Criminol Public Policy 18(1):93–118

    Article  Google Scholar 

  • Malm A (2019) Promise of police body-worn cameras. Criminol Public Policy 18(1):119–130

    Article  Google Scholar 

  • Marenin O (2016) Cheapening death: Danger, police street culture, and the use of deadly force. Police Q 19(4):461–487

    Article  Google Scholar 

  • Munger K, Harris SJ (1989) Effects of an observer on handwashing in a public restroom. Percept Mot Skills 69(3–1):733–734

    Google Scholar 

  • Newell BC, Greidanus R (2017) Officer discretion and the choice to record: Officer attitudes towards body-worn camera activation. NCL Rev 96:1525

    Google Scholar 

  • Nowacki JS (2015) Organizational-level police discretion: an application for police use of lethal force. Crime Delinq 61(5):643–668

    Article  Google Scholar 

  • Perez-Pena, R. (2016). Why First Aid Is Often Lacking in the Moments After a Police Shooting. The New York Times. Retrieved from https://www.nytimes.com/2016/09/22/us/why-first-aid-is-often lacking-in-the-moments-after-a-police-shooting.html

  • Police Executive Research Forum (2016). Guiding Principles on Use of Force. Critical Issues in Policing Series. Retrieved from http://www.policeforum.org/assets/30%20guiding%20principles.pdf.

  • Perrow C (1984) Normal Accidents: Living with High- Risk Technologies. Basic Books, New York

    Google Scholar 

  • Pischke J (2005). Empirical methods in applied economics: Lecture notes. London School of Economics.

  • President's Task Force on 21st Century Policing. (2015). Interim report of the President's Task Force on 21st Century Policing, 28. Washington, DC: Office of Community Oriented Policing Services. Retrieved from cops.usdoj.gov/pdf/taskforce/Interim_TF_Report_150228_Intro_to_Implementation.pdf.

  • Rosenbaum PR, Rubin DB (1983) The central role of the propensity score in observational studies for causal effects. Biometrika 70(1):41–55

    Article  Google Scholar 

  • Rowe M, Pearson G, Turner E (2018) Body-worn cameras and the law of unintended consequences: Some questions arising from emergent practices. Polic J Policy Pract 12(1):83–90

    Article  Google Scholar 

  • Sherman LW (2018) Reducing fatal police shootings as system crashes: Research, theory, and practice. Ann Rev Criminol 1:421–449

    Article  Google Scholar 

  • Sherman LW, Cohn EG, Gartin PR (1986) Citizens killed by big city police, 1970–84. Crime Control Institute, Washington, DC

    Google Scholar 

  • Shjarback JA, White MD (2016) Departmental professionalism and its impact on indicators of violence in police-citizen encounters. Police Q 19(1):32–62

    Article  Google Scholar 

  • Stephens, D. W. (2019). Officer involved shootings: Incident executive summary. Washington, DC: National Police Foundation & Major Cities Chiefs Association. Retrieved from https://www.policefoundation.org/publication/officer-involved-shootings-incident-executive-summary/

  • Strumpf EC, HarperS KJS (2017) Fixed effects and difference-in-differences. In: Oakes JM, Kaufman JS (eds) Methods in social epidemiology, 2nd edn. Wiley, New York, pp 341–368

    Google Scholar 

  • Stuart EA, Rubin DB (2008) Best practices in quasi-experimental designs. In J Osborne (ed) Best practices in quantitative methods, pp 155–176.

  • Subramanian R, Skrzypiec L (2017) To protect and serve: New trends in state-level policing reform, 2015–2016. Vera Institute of Justice, New York

    Google Scholar 

  • Tennenbaum AN (1994) The influence of the Garner decision on police use of deadly force. J Crim L & Criminology 85:241

    Article  Google Scholar 

  • Tennessee v. Garner, 471 US 1 (1985)

  • Three Ways to Fix Toxic Policing. (2020). Scientific American, 323(3).

  • United States. Bureau of Justice Statistics (2016). Law Enforcement Management and Administrative Statistics Body-Worn Camera Supplement (LEMAS-BWCS), 2019 (ICPSR 37302), Version Date: June 20, 2019. Retrieved from https://www.icpsr.umich.edu/icpsrweb/ICPSR/studies/37302.

  • United States. Bureau of Justice Statistics (2012). Law Enforcement Agency Identifiers Crosswalk, 2019 (ICPSR 35158.v2), Version Date: September 18, 2018. Retrieved from https://www.icpsr.umich.edu/web/NACJD/studies/35158

  • Wedekind C, Braithwaite VA (2002) The long-term benefits of human generosity in indirect reciprocity. Curr Biol 12(12):1012–1015

    Article  Google Scholar 

  • White MD (2001) Controlling police decisions to use deadly force: Reexamining the importance of administrative policy. Crime Delinq 47(1):131–151

    Article  Google Scholar 

  • White MD (2002) Identifying situational predictors of police shootings using multivariate analysis. Polic Int J Police Strat Manag 25(4):726–751

    Article  Google Scholar 

  • White MD (2014) Police officer body-worn cameras: Assessing the evidence. Office of Community Oriented Policing Services, Washington, DC

    Google Scholar 

  • White MD, Coldren J (2017) Body-worn police cameras: separating fact from fiction. PM Magazine.

  • White MD, Flippin M, Katz CM (2017) Key trends in body-worn camera policy and practice: a two-year policy analysis of US Department of Justice-funded law enforcement agencies. Center for Violence Prevention and Community Safety. Arizona State University, Tempe

    Google Scholar 

  • White MD, Malm A (2020) Cops, cameras, and crisis: The potential and the perils of police body-worn cameras. NYU Press.

  • Wicklund RA (1975) Objective self-awareness. In: Advances in experimental social psychology, Academic Press, vol 8, pp 233–275 .

  • Williams HE, Bowman SW, Jung JT (2019) The limitations of government databases for analyzing fatal officer-involved shootings in the United States. Crim Justice Policy Rev 30(2):201–222

    Article  Google Scholar 

  • Wing C, Simon K, Bello-Gomez RA (2018) Designing difference in difference studies: best practices for public health policy research. Annu Rev Public Health 39:453–469

    Article  Google Scholar 

  • Wooldridge J (2007) What’s new in econometrics? Lecture 10 difference-in-differences estimation. NBER Summer Institute, available at: www.nber.org/WNE/Slides7–3107/slides_10_diffindiffs.pdf

  • Wooldridge JM (2010) Econometric analysis of cross section and panel data. MIT Press, London

    Google Scholar 

  • Wong A, Bibring P (2017) Patterns & practices of police excessive force in Kern county. findings and recommendations. California: American Civil Liberties Union. Retrieved from https://www.aclusocal.org/sites/default/files/patterns_practices_police_excessive_force_kern_county_aclu-ca_paper.pdf.

  • Zimring FE (2017) When Police Kill. Harvard Univ. Press, Cambridge, MA

    Book  Google Scholar 

Download references

Acknowledgements

The authors would like to thank Professor John MacDonald, journal co-editor, for his guidance and support in bringing this article to fruition. We also thank Rutgers colleague Professor Robert Apel, for his helpful statistical assistance. Finally, we express our thanks to Brian Burghart for his valuable work maintaining the Fatal Encounters database.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Joel Miller.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Miller, J., Chillar, V.F. Do Police Body-Worn Cameras Reduce Citizen Fatalities? Results of a Country-Wide Natural Experiment. J Quant Criminol 38, 723–754 (2022). https://doi.org/10.1007/s10940-021-09513-w

Download citation

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10940-021-09513-w

Keywords

Navigation