Do Body-worn Cameras Change Police Behavior in Brazil?

Do Body-worn Cameras Change Police Behavior in Brazil?

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Researchers in Brazil evaluated the impact of body-worn cameras on policing behavior, which led to the saving of 104 lives within the initial fourteen months of implementation. 

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In Brazil, 39,561 people were victims of homicide in 2019, making it one of the most violent countries in the world.1 While overall homicides declined since a peak in 2017, there has been an upward trend in police homicides nationwide. In 2013, police officers killed 2,212 people; in 2019, police officers killed 6,357 people, accounting for 16 percent of the total homicides.2 Each state has a military police responsible for responding to emergency calls and preventing crime. São Paulo State has the lowest rate of homicides in the country with 9 homicides per 100 thousand people, and its military police (PMESP) is one of the best trained in the country. However, the PMESP faces public scrutiny due to acts of police brutality, particularly in low-income areas, that were captured on bystanders’ videos and posted on social media. 

To increase accountability and improve policing behavior, state military police have begun to issue body-worn cameras for officers on patrol. Evidence suggests that these cameras have reduced excessive use of force by police officers in high-income areas of the country with lower rates of violence.3 However, limited evidence exists on the effectiveness of body-worn cameras on policing in large, diverse, and high-violence cities like São Paulo.

Researchers conducted an impact assessment in São Paulo in partnership with the Secretary of Public Security and Military police of São Paulo to evaluate the impact of body-worn cameras on policing behavior. The Military Police of São Paulo State deployed body-worn cameras to all officers in 48 police precincts, encompassing neighborhoods of varied income levels. Specifically, researchers measured how body-worn cameras impacted police officers’ use of force, perceptions of their activity, and interactions with citizens.

Results indicate that the body-worn cameras reduced the number of deaths from police intervention in the precincts by 57 percent relative to the average level before the rollout. This equates to 104 avoided deaths in the first fourteen months the cameras were issued in the São Paulo metropolitan region. The probability of observing one death was reduced by 51 percent, and the probability of bodily harm by police was reduced by 61 percent. There is also an increase in records kept by police, notably in domestic violence cases and lower-risk encounters, suggesting that cameras caused a change in notification behavior.

The outcome will inform the feasibility of a large-scale randomized evaluation in São Paulo as the military police deploys body-worn cameras to more officers in the city.

To learn more, read the KODLA policy paper here and a publication by UNICEF & Fórum Brasileiro de Segurança Pública here.


1, 2. FBSP, “Anuário Brasileiro de Segurança Pública,” Brazilian Forum of Public Security, 2020,
3. Barbosa, Daniel, Thiemo Fetzer, Pedro CL Souza, and Caterina Vieira. "De-escalation technology: the impact of body-worn cameras on citizen-police interactions." (2021).

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Implementing Partner

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Military Police of Sao Paulo State
Military Police of São Paulo State