Behind the yellow sticker: paradoxical effects of a visual warning of body-worn cameras on the use of police force

ObjectivesResearch on police body-worn cameras (BWCs) draws attention to the need for suspects to be aware of the devices for them to exert a deterrent, "civilising effect", which can manifest as a reduction in the use of force in police-public interactions. This awareness can be manipulated audibly, visually, or both, yet no trials exist to test a visual stimulus that increases awareness of BWCs relative to BWCs without this function. In this field experiment, we test the effect of a visual warning of BWCs on use-of-force incidence.MethodsA six-month cluster-randomised controlled trial involving spatiotemporal police units was conducted in Miami Beach, USA. The units were randomly assigned to the experimental group, which included officers who wore BWCs featuring multiple yellow stickers and "VIDEO & AUDIO" logo (used as a visual warning). Officers in the control group were equipped with BWCs without yellow stickers. Neither group was required to announce the presence of the BWCs, thus isolating the visual warning from the audial warning. Poisson regression models estimate the treatment effect, with confirmatory subgroup analyses based on the proactive versus reactive interactions.ResultsStatistically significant differences in the use of force by officers, but in the contrary direction: higher rate of use of force due to equipping officers with BWCs with yellow stickers relative to BWCs without the yellow stickers. Relative change analysis indicates that yellow stickers cause an increase in the rate of use of force in incidents involving proactive policing, with a less pronounced increase in reactive policing.ConclusionWithout contextualising their use to citizens, raising awareness of the presence of BWCs can aggravate police-public encounters.