A strategy that aims to reduce crime through aggressive law enforcement.
Focus of the intervention
Aggressive order maintenance, which is popularly known as zero-tolerance policing, is one of two strategies that is often used to address the disorderly conditions – or broken windows – that are thought to lead to more serious crime.
Aggressive order maintenance involves the police trying to re-establish order by both:
- strictly enforcing the law
- showing zero tolerance towards low level criminality and individual disorderly behaviours, such as graffiti and loitering.
Aggressive order maintenance, referred to in this summary as zero-tolerance policing, stands in contrast to community-based policing. This is the second strategy often used to address disorder.
Community-based policing takes a problem-oriented approach, with police working collaboratively with the local communities to identify and address the underlying causes of recurring problems.
This narrative is based on one meta-analytic review covering 28 studies on disorder policing strategies and including 30 individual tests. Although the review included both aggressive order maintenance and community-based strategies, this narrative summary focuses specifically on the effect of zero-tolerance policing.
Nine studies investigated zero-tolerance policing activities, accounting for 10 individual tests. One of the nine studies was conducted in the UK, with all others conducted in the USA. Among the outcome measures were officially recorded levels of crime including crime incident reports, emergency calls for service and arrest data.
Effect – how effective is it?
Overall, zero-tolerance policing strategies have not had a statistically significant effect on crime.
Of the 10 individual tests on zero-tolerance policing strategies, eight showed no statistically significant difference in crime between areas receiving zero-tolerance policing compared with those receiving traditional policing responses (business as usual). One showed a significant reduction in crime, and one showed a significant increase.
Although this summary focuses specifically on zero-tolerance policing strategies, it is worth noting that the review also found that community-based policing approaches show a significant decrease in crime compared to areas employing traditional policing responses.
How strong is the evidence?
The review was sufficiently systematic that most forms of bias that could influence the study conclusions can be ruled out.
The evidence is taken from a systematic review covering 28 studies on disorder policing strategies that demonstrated a high-quality design. The review has a well-designed search strategy. This includes unpublished literature and involved multiple coders to ensure the reliability of information collected. The review accounted for potential publication bias and used appropriate statistical methods in the analysis of effect size. Finally, the review considered unintended consequences of the intervention such as diffusion and displacement.
The review authors identified a risk of bias in the primary studies where studies did not include any measures of self-report victimisation. All measures relied on official records, therefore police decision-making processes may have caused bias in the review’s findings.
Mechanism – how does it work?
The review authors suggest that based on Wilson and Kelling’s (1982) broken windows theory, social incivility (for example, loitering, public drinking, prostitution) and physical incivility (for example, abandoned/empty buildings, litter/rubbish) generate fear among people living in the neighbourhood.
This fear is suggested to result in people moving out of the neighbourhood and the remaining residents isolating themselves, which leads to a subsequent decrease in informal social control.
This lack of control coupled with increasing disorder is thought to attract offenders to the neighbourhood, resulting in criminal invasion and increases in serious criminal behaviour.
Disorder policing strategies are assumed to modify crime opportunities by addressing these social and physical incivilities/disorder.
The review authors explicitly state that they did not aim to test the mechanisms of disorder policing.
Moderators – in which contexts does it work best?
The review examined the influence of one specific moderator – whether disorder policing strategies in general were more or less effective for different offence types.
However, because the review combined findings from both disorder policing approaches – community-based and zero tolerance – when reporting on the effect on different offence types, these findings haven't been included within the summary.
Implementation – what can be said about implementing this initiative?
The review gave no account of how the intervention was implemented, nor of any implementation challenges encountered by the primary studies.
Economic considerations – how much might it cost?
The review did not mention the costs or benefits of disorder policing strategies, and no formal economic analysis was provided.
- The majority of the evidence is based in the USA, so caution should be taken when applying to other geographical contexts.
- The review organises disorder policing strategies into two main categories – zero-tolerance and community-based policing. Categories may be blurred due to the shared tactics and variation within each strategy in targeting a disorder problem. Therefore, categories must be further refined and distinguished in future research.
- The moderator analysis examines the effect of disorder policing strategies in general on different offence types, so includes community-based approaches as well as zero-tolerance strategies.
Zero-tolerance policing strategies do not have a significantly significant effect on crime.
Although not the focus of this summary, the review did find that the implementation of community-based, problem-orientated policing disorder strategies did lead to statistically significant crime reductions. Strategies are theorised to work by addressing social and physical incivilities in specific areas, therefore modifying crime opportunity structures.
In terms of implementation, the review recommends that a community co-production model should be used. This involves enhancing relationships with the public and partner agencies, rather than adopting a zero-tolerance policing approach. Additional evidence is required to examine the economic costs and benefits of disorder policing.
Wilson J and Kelling G. 1982. Broken windows: The police and neighborhood safety. Atlantic Monthly. March 1982, pp.29-38.
Summary prepared by
This narrative was prepared by the College of Policing and was co-funded by the College of Policing and the Economic and Social Research Council (ESRC). ESRC grant title: 'University Consortium for Evidence-Based Crime Reduction'. Grant reference: ES/L007223/1.