Core 10: The Change Makers' Manual

Decision-Making & Analytics


The racial bias of stop and search Data shows black people are nearly three times more likely to be searched by police. So what needs to change?

and higher crime rates? We looked to answer this question by analysing data shared by West Midlands Police, one of the largest forces in the UK. The dataset covered 1,194 officers in 29 teams, 203,176 reported crimes and 36,028 stop and searches from April 2014 to September 2018. The research was funded by the West Midlands Police and Crime Commissioner and by the University of Warwick. The data provides great detail on who the officer was and the exact location a nd time of the stop and search, plus information on all the crimes, incidents, and suspects across the West Midlands. We combined this with population data from the 2011 Census to work out the ethnic composition of the areas to which officers were deployed. Using data science statistical modelling, we were able to calculate if there was an over-searching of black and Asian people by officers compared to the population and crime rates in the area, and if there was a bias in the deployment of police to certain locations. That way we could compare a police officer’s stop and searches of an ethnic group with their actual experience of crime involving this group. This can help us understand whether the racial bias is down to the officer or the fact they are being sent to areas with more black and Asian people. Replicating previous findings, we found that black and Asian people are over-searched. Across the West Midlands, Asian people make up 25.1 per cent of the searches but only 19.8 per cent of the population, which means they are over-searched by a factor of 1.26. For black people, the factor is larger, at 2.79. We see over- searching against both the ethnic composition of the population that officers patrol and against officers’

own experience of crime suspects. However, the choice of individual officers to over-search black and Asian people whom they encounter is not the sole cause of racial bias in stop and search. Deployment decisions also play a role. Police officers are, on the whole, sent to more ethnically diverse areas in the West Midlands. Even if officers are blind to the ethnicity of the people they stop, if more officers are sent to more ethnically diverse areas, stop and search will be racially biased. We found that areas with high numbers of black and Asian people are over- patrolled and so contribute to the racial bias of stop and search. The average officer patrols an area that has 1.16 times more Asian people and 1.37 times more black people than the West Midlands average. “If more officers are sent to more ethnically diverse areas, stop and search will be racially biased” How the headline search factors break down into the decisions of individual officers versus the deployment of officers to ethnically diverse regions differs for Asian and black people. For Asian people, the headline factor of 1.26 is due mostly to officer deployment, with a smaller contribution coming from the finding that some officers over-search Asian people. However, for black people, while over-patrolling plays a role in the

headline factor of 2.79, the larger component comes from almost all officers over-searching black people. Interestingly, we also discovered that the make-up of a team of police officers has an effect on stop and search biases. Teams that have more white officers stop and search fewer black and Asian people. There are virtually no black police officers, but teams with more Asian officers actually search more black people. This could be caused by ‘stereotype threat’, where teams of white officers might feel they will be stereotyped as racist if they stop and search ethnic minorities. It is clear policymakers and police chiefs must overhaul their deployment strategy and take into account the bias they currently struggle with. The ethnic composition of teams of police officers should also be considered, as this seems to have an effect on the biased nature of stop and searches. Addressing the norms and biases of police officers through training must also be considered if police forces are to reverse the racial bias of stop and searches. The 14-year-old boy from South London was so distressed by his experience that he was afraid to go out, not because of high levels of crime in the area, but because of the police. Although stop and search is just a tiny fraction of police activity, its impact is large. Substantial changes to operational procedures and deployment decisions will be needed if young people are not to grow up seeing the police as the enemy.

by Neil Stewart

black 14-year-old boy in South London has reportedly been

Wales as part of the Police and Criminal Evidence Act in 1984, officers are able to stop and search anybody if they have “reasonable cause to suspect” they are breaking the law, while, in the US, ‘stop- and-frisk’ has been around in one form or another since 1968. In England, black and Asian people make up 11 per cent of the

population, yet they account for 30 per cent of all stop and searches. There are numerous studies showing the racial bias of stop and search. So, why exactly is stop and search so racially biased? Is it down to individual officers or is it because more officers are deployed to more ethnically diverse areas that suffer socio economic depravation

stopped and searched by police 30 times over two years. It

is an illustration of racial bias in

police stop-and-search tactics. First introduced in England and

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