The impact of response officers wearing body worn video in the Metropolitan Police

Randomised Control Trial Status


Trial Hypothesis

​Criminal Justice
• Officers likely to capture more and better evidence at the scene
• Officers likely to follow force policy and process
• Victims and witnesses likely to participate in process because of availability of independent evidence
• Offenders likely to admit guilt because of availability of independent evidence
• Officers and public likely to be confident that a conviction will be secured

• Members of the public and officers likely to improve behaviour during contact
• Members of public likely to not make unsubstantiated complaints because of availability of independent evidence

Stop and Search
• Officers likely to carry out fewer, less speculative searches
• Stop and search based on solid grounds more likely to have a positive outcome

Officer attitudes and self-reported behaviour
• Officers likely to feel more supported, less vulnerable to complaints, more confident.
• Officers more likely to report better interactions with the public and follow expected process

Geographical area

10 boroughs have been selected to participate in the trial, nine with no / few existing cameras: Ealing, Croydon, Bexley, Lewisham, Hillingdon, Bromley, Camden, Havering and Barnet. One with cameras re-allocated: Brent.

Research Institution / Organisation

College of Policing

In Collaboration With

Metropolitan Police Service and the Mayor's Office for Policing and Crime

Contact Name

Catherine Owens

Project Start Date

April 2014

Participants - inclusion criteria

Criteria for officers: officers on active duty on response teams
Criteria for boroughs: prior experience of camera use; team size; rate of complaints, stop and search, and crime; plus contextual factors (e.g. public confidence).

Target Sample Size

500 officers have been allocated to the treatment group. The trial is required to run for 12 months to detect a difference in complaints and stop and search.

Study Design

​A cluster randomised design:

• Ten boroughs are selected using a series of criteria to take part in the study, each with five teams;
• Two teams per borough (about 20 teams or around 500 officers in total) are randomly assigned to the treatment group; and
• Three teams per borough (about 30 teams or around 750 officers in total) are randomly assigned to the control group.
• Comparisons are to be made using recorded police data and supported by qualitative research.


​The evaluation will involve a random allocation of teams of officers to:
a) Treatment group - who wear a camera when they are on duty; or
b) Control group – who do not wear a camera.

Officers in the treatment group will be required to use their BWV camera during: domestic abuse incidents; stop and searches encounters; and incidents involving any use of force. Camera use in all other incidents is discretionary.

The booking in and out of the cameras for the treatment group will also be monitored to ensure compliance.

Summary of Findings

Police, Camera, Evidence: London’s cluster randomised controlled trial of Body Worn Video - Full report

Body Worn Video trial infographic

Video: Nerys Thomas, Knowledge, Research and Practice Lead at the College of Policing, speaks about the trial

College of Policing's online news release

Date last updated

Monday 25 June 2018
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