The police can reduce crime by increasing the chance of being caught, reducing opportunities for crime and by winning hearts and minds.
In the absence of an extensive evidence base on what tactics work to deal with specific crime problems, it can be useful to think through whether a particular policing activity is likely to be effective in terms of how the police can reduce crime.
The police can reduce crime by:
- increasing the chance of being caught
- reducing opportunities for crime
- winning hearts and minds
For a more detailed description of these mechanisms, see Bottoms (2002).
Increasing the chance of being caught – deterrence
The very existence of a criminal justice system will act as a deterrent to the general public by showing that there are negative consequences to offending (Von Hirsch and others, 1999; Apel and Nagin, 2011; Nagin, 2013; Chalfin and McCary, 2017). The police can also specifically discourage offenders, by increasing their chances of being caught.
Pratt and others (2009) combined the results of 40 studies in a meta-analysis to examine whether the risk of being caught deters members of the general public from breaking the law.
Their analysis provided evidence in support of the idea that the certainty of being caught has a deterrent effect, regardless of the type of punishment that follows. This idea is also supported by Nagin (2013), who found that the certainty of apprehension, not the severity of the ensuing consequences, is the more effective deterrent. More recent studies have suggested however that increased severity might magnify the deterrent effect of certainty and be important in preventing repeat offending (Friesen, 2012; Mungan, 2016).
Similarly, survey research from the UK has shown that the risk of being caught and punished was associated with lower levels of reported traffic offending (like speeding), but not other minor crime (Myhill and Quinton, 2011). The pervasiveness of speed cameras and traffic wardens in some places could mean the enforcement of traffic offences effectively becomes – and feels to the public like it becomes – an inevitability, which may be harder to repeat for other offences.
Bates and others (2012) found that actual and perceived risk of detection are both important in traffic policing, by ensuring enforcement is sufficiently intensive, unpredictable and conducted as widely as possible. There is evidence of a more specific deterrent effect where prolific or repeat offenders are targeted by the police (Weisburd and others, 2010).
Increasing the risk of offenders being caught can reduce reoffending, particularly when that increased risk is effectively communicated to offenders, pathways out of crime are provided by partners and the overall approach of using carrots and sticks in combination has public support (Braga and others, 2019). There is a risk, however, that if offenders are not caught – and think they got away with it – they are more likely to reoffend in the future (Pogarsky and others, 2005; Matsueda and others, 2006; Earnhart and Friesen, 2014).
An efficient way to target repeat and prolific offenders would be to focus police activities in the places where crime is concentrated and they are most likely to offend (find out more about targeting places).
One implication of these findings is that a targeted or high level of enforcement is needed to achieve a deterrent effect on the wider general public. Research from Australia for example has shown that the deterrent effect of random breath tests on drink-driving declined when enforcement levels reduced (Homel, 1988).
Deterring people from offending in general might be a more sustainable option when it is possible for people to be caught remotely or automatically (for example with fraud) or when public awareness of the risk can be raised. The potential negative impact of high levels of enforcement on public perceptions is worth considering (read about the evidence on zero-tolerance policing).
Reducing opportunities for crime – situational crime prevention
It is also possible the police can cut crime by reducing the opportunities that exist for people to break the law. The prevention mechanism is based on the idea that crime occurs in specific situations when a likely offender and suitable target come together in the absence of a capable guardian (Cohen and Felson, 1979; Clarke and Felson, 2017; Clarke, 2018).
With this starting point and on the basis that people behave differently in different situations, there would be scope for the police to identify those situations where likely offenders and suitable targets could meet and change the situation to prevent crime from happening.
There are numerous examples of situational crime prevention where the police and others have taken action to remove the opportunities for crime. For example, manufacturers have made it much harder for vehicles to be stolen by fitting anti-theft devices to new cars, such as immobilisers (Laycock, 2004; Bässman, 2011; Farrell and others, 2011; Farrell and others, 2014).
Similarly, there is consistent evidence that burglary can be prevented by increasing natural surveillance (for example, cutting back hedges to increase the visibility of access points) and by target hardening. For example, Roe (2009) found that houses with at least a basic level of security (such as window locks and deadbolts on doors) were nearly 10 times less likely to be burgled than those without.
Particular combinations of security devices may also magnify this target hardening effect. Tseloni and others (2014) found for example that having door and window locks alongside external lights or security chains gave at least 20 times greater protection than having no security.
New homes with a range of Secured by Design features have been shown to be less than half as likely to be burgled than similar homes without those features.
Alley gates, which restrict access to the rear of terraced houses, have also been shown to be effective at target hardening (Sidebottom and others, 2015). Even simple measures, such as warning stickers and police advice to local residents, may help reduce burglary (Johnson and others, 2017; Park and others, 2017).
Winning hearts and minds – enhancing police legitimacy
Over time, the police may be able to reduce crime by encouraging people to obey the law because they think it is the right thing to do. This approach may reduce overall demand on the police.
The evidence on procedural justice suggests fair decision-making and respectful treatment by the police can enhance the legitimacy of the police in the eyes of the public. This in turn can foster greater law-abiding behaviour and co-operation with the police (Tyler, 2006; Tyler and Fagan, 2008).
Why should procedural justice have this effect? The theory suggests that the way the police interact with people – including suspects – has a bearing on whether they feel valued and part of society (Tyler and Blader, 2000; Jackson and others, 2012).
While experiences of fair decision-making and respectful treatment help build a sense of group identity and shared values, experiences of unfairness and disrespect erode feelings of public trust in the police.
They send out a clear signal to citizens that they are not valued and that the rules do not apply to them. Therefore procedural justice can encourage people to feel a sense of obligation and responsibility – making it more likely they will help the police and not break the law.
While there is a large body of research on the association between procedural justice, police legitimacy and public compliance, the evidence on what interventions are effective at reducing offending through increased police legitimacy is much more limited (Nagin and Telep, 2020).
Even then, it may only be possible to improve public perceptions of the police slowly over time, particularly in communities that feel over-policed and under-protected and have had difficult relationships with the police historically (for example, Patten Commission, 1999; Riots Communities and Victims Panel, 2012).
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 This section focuses mainly on the police role, and therefore on the likelihood of being caught as a deterrent, rather than on the type of punishment which might follow (for example a fine, community or prison sentence or other sanction), as this will tend to involve the wider criminal justice system.
 A meta-analysis – a study which combines data from across a number of high quality studies (usually identified through a systematic review) to give an overall summary of the direction of findings from existing research evidence