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Little evidence that military policing reduces crime or improves human security


Governments in low- and middle-income countries routinely deploy their armed forces for domestic policing operations. Advocates of these policies claim they reduce crime, while detractors argue they undermine human rights. Here we experimentally evaluate a military policing intervention in Cali, Colombia. The intervention involved recurring, intensive military patrols targeting crime hot spots, randomly assigned at the city block level. Using administrative crime and human rights data, surveys of more than 10,000 residents, and firsthand observations from civilian monitors, we find little to no credible evidence that military policing reduced crime or improved perceptions of safety during the intervention. If anything, we find that military policing probably exacerbated crime after the intervention was complete. We also find evidence of increased human rights abuses in our survey data (though not in the administrative data or in the firsthand observations of civilian monitors), largely committed by police officers rather than soldiers. We argue the benefits of military policing are probably small and not worth the costs.

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Fig. 1: The world’s most dangerous cities by homicide rate, 2019.
Fig. 2: Randomized military patrols had little to no effect on crime even while soldiers were physically present on the streets.
Fig. 3: Randomized military patrols did not improve perceptions of safety, except among business owners.
Fig. 4: Randomized military patrols may have exacerbated human rights abuses, especially by the police.

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Data availability

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Code availability

All code required to replicate the analyses in this study can be found on Dataverse at


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Funding for this project was provided in part by the UK Foreign, Commonwealth & Development Office, awarded through Innovation for Poverty Action’s Peace & Recovery Program (grant #MIT0019-S3). Funding for this project was also provided in part by the Open Society Foundations, awarded through Innovation for Poverty Action’s Peace & Recovery Program (grant #OSF-19-10002-S1). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. We thank staff at Innovations for Poverty Action Colombia (K. Holloway and S. Jaramillo) for coordination of the project; the Secretaría de Seguridad de Cali (M. A. Arboleda, P. Gracia, A. Sánchez, J. D. Tabares, P. Uribe and A. Villamizar) for logistical oversight; the Third Battalion of the Armed Forces of Colombia (especially O. Arciniegas) for its commitment to the evaluation; and C. Bohm, M. F. Cortés, A. Farfán, S. Flórez, C. Gúzman, S. Hernández and L. M. Mora for terrific research assistance. For helpful feedback we thank P. Aronow, G. Blair, C. Blattman, A. Coppock, E. De Bruin, L. Fergusson, D. Green, A. Moya, M. Offer-Westort, M. Ross, S. Parkinson, S. Tobón, J. Vargas, J. Zarkin and participants at workshops and conferences convened by the American Political Science Association, the American Economic Association, Brown University, Cornell University, Duke University, the Folke Bernadotte Academy, Harvard University’s Belfer Center, the Households in Conflict Network, the International Studies Association, Oxford University, Peace Research Institute Oslo, Universidad de los Andes, Universidad del Valle, University of California–Berkeley, University of Pennsylvania, Uppsala University and the Virtual Crime Economics Online Seminar.

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R.B. and M.W. contributed equally to this article.

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Correspondence to Robert A. Blair or Michael Weintraub.

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Blair, R.A., Weintraub, M. Little evidence that military policing reduces crime or improves human security. Nat Hum Behav 7, 861–873 (2023).

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