Since the riots in London and England earlier this month, there has been a flurry of debate as to the effectiveness of the police response. Drawing on new research into the police response to the 2005 bombings in London, Mirko Draca finds that a 10 per cent increase in police patrols in a certain area leads to a 3 per cent drop in crime in that area. While police patrols will not solve all our crime problems, they are very effective in reducing crime in the short-term, and there may be room to improve the effectiveness of smaller scale police patrols outside of emergencies.
The recent riots that took place across England have stimulated debate on effective law and order policy. So far this debate has been unfocused – a huge mix of policy proposals have entered the discussion. Recent media coverage has dealt with issues such as increased criminal sanctions (particularly incarceration), the role of inequality, and most bizarrely proposals to shut down communication systems (i.e.: social media) in times of crisis.
So, what is the effect of increased police resources on crime? In general, research on crime and police faces an endogeneity problem – governments allocate more police resources to high crime areas. This allocation policy results in a positive correlation between the levels of crime and police resources across geographical areas. Superficially, more police is associated with more crime. In response, researchers need to use ‘natural experiments’ – situations where where police have been reallocated in unexpected ways – in order to estimate the causal impact of police on crime.
The recent paper ‘Panic on the Streets of London’ by myself, Stephen Machin and Robert Witt follows this approach by looking at the impact of the central and inner London police deployments that followed the July 2005 terrorist attacks. The policy deployments that occurred after the attacks broke the endogenous relationship between police and crime by temporarily re-allocating police resources in an unanticipated pattern that was unrelated to prior crime levels or trends.
The scale of the post-attacks police deployment in London makes it a unique case amongst similar studies in the crime-police area. There was a 34% increase in hours worked by police in central-inner London in the six weeks that followed the attacks. In turn, we find that this increase was associated with an 11% fall in crime. Together, these estimates imply an elasticity of approximately -0.3 between crime and police deployment. Taken literally this says that a 10% increase in police patrols leads to a 3% fall in crime. This is broadly consistent with previous casual estimates of the impact of police on crime.
The timing of the ‘policy on’ period is crucial to our estimates. In principle, it is plausible that the terrorist attacks could have affected crime through channels other than the increased police deployment. For example, the attacks changed commuter travel patterns across London and there was a general increase in public safety awareness in the period after the attacks. Either of these changes could also have had an impact on the pattern of crime in London. However, we find that the pattern of the deployment and the fall in crime match each other very closely – no other factor can account for the 6-week timing of the reduction in crime.
These findings in relation to the 7/7 attacks seem to be validated by recent events. The riots quickly dissipated once extensive, highly visible police patrols were put in place. Practically then, what are the implications of this research for law and order policy? In short, the main conclusion is that police patrols are one tool that policy-makers can count on. They will not solve all our crime problems but they are very effective for reducing crime in the short-term and there may be room to improve the effectiveness of smaller scale police patrols outside of emergency periods. Another issue here is that these types of patrols are resource-intensive. It will be hard to sustain patrol policies when police service budgets are being reduced by 20%, as currently proposed. Few organisations are able to sustain a 20% cut in their budget without visible impacts on ‘frontline’ service levels. Unless the government is able to squeeze some big efficiency gains out of the police service the proposed cuts will put strong upward pressure on crime rates.
The full article, “Panic on the Streets of London: Police, Crime, and the July 2005 Terror Attacks” is available from LSE Research Online, here.
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