A strategy that aims to reduce crime through strict law enforcement.
This summary is part of the Crime Reduction Toolkit, which presents the best available research evidence on what works to reduce crime.
Focus of the intervention
Aggressive order maintenance, popularly known as zero-tolerance policing, is one of two strategies that are often used to address the disorderly conditions – or ‘broken windows’ – that are hypothesised to lead to more serious crime.
Aggressive order maintenance involves the police trying to re-establish order by:
- 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, which is the second strategy often used to address disorder. Community-based policing takes a problem-oriented approach, with police working collaboratively with local communities to identify and address the underlying causes of recurring problems.
This summary is based on one systematic review of disorder policing, and focuses exclusively on the studies it included related to zero-tolerance policing. The review as a whole included 56 studies and a total of 59 independent tests of either zero-tolerance or community-based strategies. 20 of the 59 tests (including the test for mean effect) were for zero-tolerance policing. Of these, one was conducted in Sweden, one in the UK, with the remainder conducted in the USA.
Other summaries relevant to this topic include problem-orientated policing and hot spots policing.
Effect – how effective is it?
In general, the evidence suggests that zero-tolerance policing has not had a statistically significant effect on crime. Most studies found no significant impact on crime rates, with a few showing mixed results.
A meta-analysis of 19 tests showed that zero-tolerance policing had no statistically significant effect on recorded crime. Specifically:
- 16 tests found no evidence of effect compared to areas with no intervention.
- Two found a statistically significant increase in crime.
- One test found a statistically significant reduction in crime.
These findings indicate that zero-tolerance policing did not consistently reduce crime and may even have led to increases in some contexts.
Outcome measures included officially recorded levels of crime, such as crime incident reports, emergency calls for service and arrest data.
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 56 studies, which demonstrated a high-quality design in terms of having a transparent and well-designed search strategy, featuring valid statistical analysis, and sufficiently assessing the risks associated with publication bias. The review also conducted analyses of possible displacement and diffusion of benefits following the intervention. However, the review did not sufficiently consider the influence of statistical outliers.
Mechanism – how does it work?
The review describes zero-tolerance policing as having a specific focus on ‘increasing misdemeanour arrests, summonses, and pedestrian stops’ to curtail persistent disorderly behaviour in public areas. The policing strategy was informed by Wilson and Kelling’s (1982) ‘broken windows theory’.
The theory suggests that 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, leading 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. Zero-tolerance 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?
As hot spots policing has been shown to result in significant reductions in crime, the review looked at whether zero-tolerance policing was more effective at reducing crime in hot spots than larger areas. The review found no evidence to support the idea that zero-tolerance policing would have more of an effect if it was targeted in hot spots of crime. Zero-tolerance policing had no statistically significant effect on crime reduction in either hot spots or larger areas.
The review also explored whether a crime reduction effect was observed across different types of crime: violent, property, and disorder/drug. However, the authors reported these findings for disorder policing overall. It was decided not appropriate to report these findings in this summary because the findings for zero tolerance policing could not be separated out from those for community-based problem-solving.
Implementation – what can be said about implementing this initiative?
The authors of the review did not provide any detail on how to implement a zero-tolerance programme.
The authors did, however, report the risks of zero-tolerance policing identified by the National Academies (2018) such as racial disparities in police contacts with citizens, excessive punishment of young people of colour, and unlawful and abusive police-citizen encounters.
Economic considerations – how much might it cost?
The review did not mention the costs or benefits of zero tolerance policing strategies, and no formal economic analysis was provided.
General considerations
- The majority of the evidence originated from the USA so caution should be taken when applying to other geographical contexts.
- The review organised 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.
Summary
Zero-tolerance policing has not result in statistically significant reductions in crime overall.
Most studies found no significant impact on crime rates, with a few showing mixed results. These strategies are theorised to work by addressing social and physical incivilities in specific areas, thereby modifying opportunities for crime. However, zero-tolerance policing can have negative consequences, such as racial disparities in police contacts and excessive punishment of young people of colour.
The review suggested a community co-production model that enhances relationships with the public and partner agencies may be more effective than zero-tolerance policing. Further research is needed to explore the economic costs and benefits of disorder policing strategies.
Reviews
Review one
Reference
Braga AA, Schnell C and Welsh BC. 2024. 'Disorder policing to reduce crime: An updated systematic review and meta-analysis'. Criminology & Public Policy, 23(3), pp 745–775.
Additional resources
National Academies of Sciences, Engineering, and Medicine. 2018. ‘Proactive policing: Effects on crime and communities’. The National Academies Press.
Wilson J and Kelling G. 1982. Broken windows: The police and neighborhood safety. Atlantic Monthly. March 1982, pp.29-38.