27 February 2017

Does more stop and search mean less crime?

Stop and search powers are better seen as an investigative tool rather than a crime deterrent, a new study concludes.

Ten years of data from The Metropolitan Police was examined to see if stop and search had a deterrent effect on crime in London.

The study, which was a collaborative piece of work between University of Manchester and University of Oxford, found that higher rates of stop and search were occasionally followed by slightly lower rates of crime.

However, the associations found were inconsistent and small in size, which provided limited evidence of stop and search having acted as a deterrent at a borough level.

Dr Paul Quinton, Evidence and Evaluation Advisor at the College of Policing, said: "As we know very little about the effectiveness of stop and search powers, which are often the subject of intense public scrutiny, we wanted to take the opportunity of adding to the evidence base by examining data that were readily available from the Metropolitan Police.

"Ours is the first UK study to find any sort of relationship between stop and search and crime. We found some, but fairly limited evidence of it having had a deterrent effect on crime at a borough level.

"Extremely large increases in stop and search - of a scale likely to be unacceptable to some communities - would only deliver modest reductions in crime.
"However, it does not follow that stop and search is ineffective against crime and there are suggestions that the power probably has more of an impact locally."

Dr Quinton added the situation is improving as the arrest rate from stop and search is increasing.

"The arrest rate is now at its highest level since records began and this suggests that the police are taking a more targeted approach to stop and search," he said.

As stop and search is an investigative power, it may be better to see crime reduction as a useful by-product rather than its main aim. In this respect, arrest rates from stop and search have improved in recent years, rising nationally to 16 per cent in 2015/16.
The Met arrest rate was 19 per cent for stop searches in 2015/16.

Last year the College of Policing, as the professional body for the police, published new training and guidance for officers on the use of stop and search.

Q&A
 
         What did the research look at?

    • We looked at whether higher rates of stop and search in Metropolitan Police boroughs were generally followed by lower than expected crime rates the next week or month.

       

      What did you find?
    • Ours is the first UK study to find any sort of relationship between stop and search and crime.
    • We found that, in some cases, there was an association between higher rates of stop and search and lower rates of crime.
    • For example, we estimated that if total stop and search was 10% higher on a borough, total crime would be 0.1% lower the following week and 0.3% lower the following month.
    • However, the associations we found were inconsistent and small in size, which did not suggest to us that stop and search acted as a deterrent at a borough level.


          Why was the research carried out?

    • There is only a small amount of research on the impact of stop and search powers on crime, especially from the UK.
    • As we know very little about the effectiveness of these powers, which are often the subject of intense public scrutiny, we wanted to take the opportunity of adding to the evidence base by examining data that were readily available from the Metropolitan Police.

       

      What does previous research tell about the effectiveness of stop and search?
  • The previous research presents a mixed picture. No previous UK study has pointed to stop and search having any impact on crime. Some US studies have suggested there may be a link between stop, question and frisk and crime, but the size of these effects tends to be fairly small.

     

    Doesn't stop and search help take knives and other prohibited items off the streets?
  • Yes, stop and search can and does result in the police finding things like knives, drugs and stolen property. It also makes an important contribution to overall arrests for some offences, like knife possession.
  • The situation is also improving. In 2015/16, 16 per cent of searches resulted in an arrest – up two percentage points on the previous year.
  • The arrest rate is now at its highest level since records began. This suggests that the police are taking a more targeted approach to stop and search.
  • An arrest is not the only possible criminal justice outcome. In 2015/16, the first year in which provisional data were available, the Home Office estimated that 24 per cent of searches resulted in some sort of positive outcome, for example  an arrest, cannabis/khat warning, summons, penalty notices, cautions or community resolutions.

     

    Why was the effect of stop and search examined at a borough level rather more locally?
  • We would like to have looked at the effect of stop and search on crime more locally, but data were only available at the borough level.
  • The fact we found that more stop and search was followed by slightly lower levels of crime – for some crime types – at the borough level, suggests to us that stop and search might have more of an effect on crime if we were able to look at what happens in a street or neighbourhood level.
  • Our borough level analysis is still important because it tells us about the effect of widespread changes in stop and search.

     

    Has a reduction in stop and search in London led to increased knife crime?
  • We were unable to look at this issue directly. When we looked at the weekly and monthly borough-level data, there were too few knife crime incidents for the type of analysis carried out. 
  • We did, however, look at the whether there was an association between stop and search and violent crime. We didn't find a consistent pattern and the one association we did find was very small. We estimated that if searches were 10 per cent higher, violent crime would be 0.01 per cent lower than predicted the following week.
  • In addition, we did not find that higher rates of stop and search and were followed by fewer ambulance calls related to stabbings and shootings.

 

          Shouldn't the police increase stop and search to reduce crime?

  • Our research doesn't support that conclusion. The strength of the association between searches and crime would suggest that even very large increases in stop and search would only lead to slightly lower rates of crime.
  • Increases of this scale are unlikely to be acceptable to communities and are likely to come at a cost in terms of additional police time and damage to public trust.
  • Most powers of stop and search can only be used when officers have the grounds to do so.
    It would not legally be possible to instruct officers to do 'more' stop and search – as a tactic – even if you could show it had more of an effect on crime.

     

    Shouldn't we get rid of stop and search if it doesn't lead to lower crime?
  • Legally, most stop and search powers allow the police to investigate crime – to find out whether someone they reasonably suspect to be in their possession of a prohibited item does so or not.
  • In most cases, officers cannot search someone in order to prevent crime or deter it. The fact the police can stop and search members of the public when they have reasonable grounds may, nonetheless, act as a deterrent to some people who might otherwise commit a crime.
  • Our analysis explores whether stop and search has such a deterrent effect at a borough level.
    Even though we found that higher levels of stop and search being followed by slightly lower rates of crime in some cases, there was limited evidence of a stop and search being much of a deterrent at the borough level.
  • As a result, we think that crime reduction should be seen as a 'useful by-product' of stop and search rather than its main aim, which should be as an investigative tool.

     

    Was there a large cost for the research?
  • No, the Metropolitan Police provided the data freely and the academics from Oxford and Manchester who carried out the analysis did so free-of-charge. We spent a small amount of money on preparing the Metropolitan Police's data for analysis.

     

    Is further research planned?
  • We have no immediate plans for further research on the impact of stop and search, but continue to look for opportunities to work with forces and academics to develop the evidence base in this important area of policing.

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