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Crime prevention approaches, theory and mechanisms

Crime prevention refers to the range of strategies that are implemented by individuals, communities, businesses, non-government organisations and all levels of government to target the various social and environmental factors that increase the risk of crime, disorder and victimisation (AIC 2003; ECOSOC 2002; IPC 2008; Van Dijk & de Waard 1991). There are a variety of different approaches to crime prevention that differ in terms of the focus of the intervention, the types of activities that are delivered, the theory behind how those activities are designed to bring about the desired results and the mechanisms that are applied.

Various models have been developed to categorise the broad range of activity that falls within the definition of crime prevention (Brantingham & Faust 1976; Crawford 1998; ECOSOC 2002; Sutton, Cherney & White 2008; Tonry & Farrington 1995). Understanding the different approaches to crime prevention is important, as there are implications for determining the appropriate institutional and management arrangements necessary to support specific crime prevention interventions (Weatherburn 2004). An understanding of the different approaches available and their underlying rationale and theory is also crucial to developing effective crime prevention programs and projects (Eck 2005; Homel 2009a).

The environmental approach, which includes situational crime prevention techniques and broader urban planning initiatives, aims to modify the physical environment to reduce the opportunities for crime to occur (Crawford 1998; Hughes 2007; Sutton, Cherney & White 2008). The social approach focuses on the underlying social and economic causes of crime in the community (eg lack of social cohesion, limited access to housing, employment, education and health services) and on limiting the supply of motivated offenders, and includes developmental prevention and community development models (Crawford 1998; ECOSOC 2002; Hope 1995; Hughes 2007; Sutton, Cherney & White 2008; Weatherburn 2004). The criminal justice approach refers to various programs delivered by police, the courts and corrections that aim to prevent recidivism among those people who have already engaged in offending behaviour and who have come into contact with the criminal justice system (ECOSOC 2002; UNODC 2010).

In this section of the report, a brief outline is provided of the theory underlying environmental and social approaches to crime prevention (as these fall within the scope of the current research project), the principles underpinning effective strategies and a brief summary of the evidence in support of the different approaches. This information was used to assess whether there was a sound theoretical basis underpinning the interventions that had been evaluated. The concept of mechanisms and the CCO, which was an important component of the AIC’s classification framework for this review, are then explained. While an understanding of theory was important in the selection of strategies for inclusion in this review, the CCO provides a useful framework to understand how the interventions delivered a reduction in the targeted crimes (if at all) and to assist the transfer of these interventions to other contexts.

Environmental crime prevention

The environmental approach seeks to change the specific characteristics of the environment that may cause criminal events to occur. This includes both situational approaches to crime prevention and broader planning initiatives, and aims to reduce crime by designing and/or modifying the physical environment to reduce the opportunities for crime to occur (Sutton, Cherney & White 2008).

Situational crime prevention

Situational crime prevention is based upon the premise that crime is often opportunistic and aims to modify contextual factors to limit the opportunities for offenders to engage in criminal behaviour (Tonry & Farrington 1995). Situational prevention comprises a range of measures that highlight the importance of targeting very specific forms of crime in certain circumstances (Clarke 1997). This involves identifying, manipulating and controlling the situational or environmental factors associated with certain types of crime (Cornish & Clarke 2003). It is also based upon assumptions regarding the nature of offending and of offenders (Cornish & Clarke 2003). Underlying the situational approach are four key elements, including:

  • three key opportunity theories—routine activity, crime pattern and rational choice theory;
  • an action research methodology that involves analysing of specific crime problems and contributing factors, identifying possible responses, selecting and implementing of the most appropriate or promising response and evaluating and disseminating the results;
  • a classification of 25 situational prevention techniques; and
  • a growing body of evaluated projects and examples of different types of strategies (such as those available on the Problem-Oriented Policing Center website: www.popcenter.org), which helps to inform the selection and design of specific interventions (Clarke 2005).

The focus of the three key opportunity theories is actually quite different. Under routine activity theory, three critical elements must occur simultaneously for a criminal event to take place—a motivated offender, a suitable target and the absence of a capable guardian (Clarke 1997). The theory seeks to explain how societal changes can impact upon opportunities for crime (Sutton, Cherney & White 2008). Crime pattern theory seeks to explain the influence of communities and neighbourhoods, and focuses on how offenders may come across opportunities for crime in the course of their everyday lives (Clarke 2005). Rational choice theory has a more individualistic focus and explores the decision-making processes that lead to an offender choosing to become involved in crime or specific criminal events, including weighing up the relative risks and rewards associated with offending (Clarke 2005; 1997).

Situational crime prevention interventions include activities such as improved security through strengthening locks and improving surveillance. Cornish and Clarke (2003) have classified 25 situational crime prevention techniques into five broad categories that are based on the mechanisms underlying the different methods:

  • increasing the effort involved in offending;
  • increasing the risk associated with offending;
  • reducing the rewards that come from committing a crime;
  • reducing situational factors that influence the propensity of an individual to offend; and
  • removing excuses for offending behaviour.

This relative simple classification scheme provides a useful framework for describing the range and variety of situational techniques on offer to those working in crime prevention (Cornish & Clarke 2003).

Important lessons for the implementation of situational crime prevention projects (taken from the UK experience where situational approaches have been common), include that it:

  • works most effectively when it is targeted at a specific crime problem in a specific context;
  • involves a thorough and systematic analysis of current and emerging crime problems and their causes and risk factors that is based on accurate and wide-ranging sources of information and has analysts with the capacity to interpret the data;
  • requires appropriate consultation mechanisms to seek input from stakeholders and the community into the development of strategies that are likely to require their action, involvement or cooperation; and
  • requires strong project management skills, a comprehensive implementation plan that describes the key stages in project delivery and the interrelationships between different but complementary interventions, and a committee made up of representatives from key stakeholder groups to oversee project development, implementation and review (Marshall, Smith & Tilley 2004)

There is considerable evidence of the effectiveness of situational crime prevention in reducing crime, both in Australia and overseas. Despite there being limitations in the evaluation literature, a review of the evidence by Eck (2006a) showed that opportunity reduction measures can reduce crime in many circumstances with little evidence of displacement. An evaluation of the UK Reducing Residential Burglary Initiative found that areas where more money had been invested in situational prevention rather than offender-focused prevention and those that were flexible in their delivery, were generally more successful in reducing residential burglary (Hope et al. 2004). While there is insufficient evidence to determine the most cost-effective approach in modifying environmental conditions to prevent crime, there is sufficient evidence that situational crime prevention is an economically efficient strategy in reducing crime (Welsh & Farrington 2001).

There are some notable exceptions. A recent systemic review concluded that CCTV has a modest but significant positive effect on crime, but that it is most effective in reducing crime in car parks and when targeted at vehicle crimes (Welsh & Farrington 2008). Further, the cost of establishing, maintaining and monitoring a CCTV system can be prohibitively expensive, and potentially exceed any financial savings that might result from a reduction in property crime (Clancey 2010). Taken together, these results lend support for the continued use of CCTV to prevent crime in public space, but suggest that it needs to be more narrowly targeted than its present use would indicate (Welsh & Farrington 2008).

Urban design and planning

Broader planning initiatives include CPTED and urban renewal projects, and seek to reduce the opportunities for crime through the design and management of the built and landscaped environment (Crowe 1991; Schneider & Kitchen 2007). Crime prevention is being recognised as an increasingly important consideration in urban regeneration programs (Schneider & Kitchen 2007). This includes strategies that involve modifying the built environment to create safer places that are less crime prone or can make people feel safer (such as by designing public spaces that encourage large numbers of users and provide greater natural surveillance, or by designing pedestrian thoroughfares that are well lit and do not create places for potential offenders to hide). CPTED has a major influence on crime prevention policy and practice in Australia and in other parts of the world, and a number of state, territory and local governments now have specific planning policies that incorporate CPTED principles or guidelines (Bodson et al. 2008).

Experience has shown that CPTED:

  • needs to be integrated as part of a broader crime prevention strategy targeting other risk factors and neighbourhood problems, which requires community involvement, partnerships and the coordination of activities;
  • is underpinned by a number of important principles such as natural surveillance, territoriality, sustainability and vulnerability of public spaces, and these principles should drive design decisions;
  • should be focused at both the macro (overall design of the built environment) and micro level (finer details);
  • should be applied to both public initiatives and private developments, and involves careful management of the relationship between public and private space;
  • requires a balance between competing interests, such as between privacy and security; and
  • requires the involvement of different design-related professional disciplines (Queensland Government 2007; NZ Ministry of Justice 2003).

The evidence in support of CPTED is growing, although unlike other approaches to crime prevention, CPTED has not been systematically evaluated (Shaftoe & Read 2005). A recent review suggests that there is some evidence that CPTED is a promising approach, although this evidence is not definitive and has attracted criticism (Cozens, Saville & Hillier 2005). Research has demonstrated that there is a strong relationship between certain characteristics of the built environment and crime levels, although the research into certain relationships (such as the relationship between through-movement and connectivity and crime) has been inconsistent (Armitage 2011a). While further research into the impact of CPTED is warranted, there is sufficient evidence to support the application of CPTED principles, as well as environmental safety assessments more broadly, as a key consideration in the development of the built environment, including new development proposals and urban regeneration initiatives.

Social crime prevention

Rather than focusing on the physical environment, social crime prevention is most commonly directed at trying to influence the underlying social and economic causes of crime, as well as offender motivation. This approach tends to include crime prevention measures that take some time to produce the intended results. This may include action to improve housing, health and educational achievement, as well as improved community cohesion through community development measures.

Developmental crime prevention

Developmental crime prevention initiatives are becoming increasingly popular in Australia (Weatherburn 2004). There has been considerable investment in early intervention programs in Australia, many of which do not have explicit crime prevention objectives (Homel et al. 1999; Weatherburn 2004). Developmental crime prevention is based on the premise that intervening early in a young person’s development can produce significant long-term social and economic benefits. While there is evidence of the importance of intervening early in life, the focus of developmental crime prevention is on intervening early at any of a number of critical transition points in a person’s development to lead them on a pathway to prevent future offending. Transition points occur around birth, the preschool years, transition from primary to high school and from high school to further education or the workforce (Homel et al. 1999).

Early intervention aims to address risk factors and enhance protective factors that impact upon the likelihood that a young person will engage in future offending behaviour (Homel et al. 1999). Risk and protective factors can be categorised into child factors, family factors, school context, life events and community and cultural factors (Homel et al. 1999). Developmental programs aim to identify, measure and manipulate risk and protective factors that research has confirmed are important in predicting future offending (Homel 2005). In practical terms, developmental crime prevention involves providing basic services or resources to individuals, families, schools or communities to minimise the impact of risk factors on the development of offending behaviours (Homel 2005). Most often these resources and services are directed towards disadvantaged or ‘vulnerable’ families with young children.

Several factors have been identified as contributing to the successful implementation of developmental crime prevention initiatives, including:

  • the importance of timing and intervening at critical junctures, such as times of stress or when people are open to external influences (which may not mean early in life);
  • the need to target multiple risk factors due to their cumulative impact, with bias towards those factors regarded as having the greatest impact, and to target multiple offence types;
  • the need to be sensitive to the needs of the local area (including the need to be culturally sensitive), involve and empower the community (in decision making, as volunteers and as paid professionals) and identify local change agents;
  • the importance of detailed assessments of community readiness (the presence of existing partnerships and management structures, leadership stability, community engagement and support for and commitment to prevention), which is a key component of programs such as Communities that Care (Crow et al. 2004);
  • the importance of strategies to make programs accessible, keep people involved and to avoid stigmatising at-risk young people or families;
  • the value of partnerships and coordination between new and existing service providers, whether they rely on formal interagency structures or more simple arrangements; and
  • the requirement for longer term investment, as the benefits of developmental crime prevention are not immediate (Crow et al. 2004; Homel et al. 1999).

Evidence from a small (but growing) number of comprehensive evaluation studies has demonstrated the long term effectiveness of early intervention in achieving significant reductions in participant’s involvement in crime, as well as improvements in areas such as educational performance, child maltreatment, workforce participation, child and youth behaviour, income and substance abuse (Homel 2005). In addition to the obvious social benefits, these outcomes are also associated with significant financial savings, both for the community and the participant (Homel et al. 2006; Schweinhart et al. 2004). The savings produced by early intervention programs include reductions in welfare assistance, decreased need for special education, increases in income tax revenue from the higher wages of participants (due to improved educational attainment), reduced operational costs to the criminal justice system and reduced costs to victims (Homel et al. 2006).

Conversely, at least one study has demonstrated long term negative outcomes for participants and the problems of stigmatising participants as being ‘at risk’ or delinquent (Homel R 2005). Further, despite the increased popularity of early intervention as a crime prevention strategy with promising results, evidence of long term cost effectiveness has been limited to a small number of overseas studies and one notable Australian example. Nevertheless, taken as a whole, research into the impact of developmental crime prevention suggests that intervening early in a young person’s development is a promising strategy in improving the life course development of at-risk children and their families, and in reducing the long-term costs associated with delinquency and future criminal offending (Schweinhart et al. 2004; Welsh & Farrington 2001).

Community development

Community development is premised on the notion that changing the physical or social organisation of communities may influence the behaviour of individuals who live there (Tonry & Farrington 1995). The risk of becoming involved in crime, or being victimised, is greater in those communities that experience high levels of social exclusion or a lack of social cohesion. Also underlying the community development approach is the belief that crime in a particular community is not primarily or solely the result of the actions of a small number of criminogenically disposed individuals, but the result of the coincidence of a series of structural determinants present within particular communities (eg differential rates of access to housing, employment, education and health services, among other factors; Bennet 1998; Welsh & Hoshi 2006). The underlying assumption is that if these crime-promoting structural stress factors can be relieved, reconfigured or removed, then crime will be reduced (Hope 1995). Community development strategies can aim to build social cohesion and address factors leading to community disorganisation, empower communities to participate in decision-making processes, increase resources, services and economic opportunities in disadvantaged communities or address low level physical or social disorder that may be a precursor to more serious problems (Bennet 1998; Lane & Henry 2004; Welsh & Hoshi 2006). Community development programs that focus on strengthening informal networks and enhancing community structures have the potential to build community capacity, which can, in turn, provide opportunities to mobilise communities to address local crime problems.

The implementation of community-wide programs has proven difficult due to the challenges of rolling out these types of programs on a broader scale, including problems associated with engaging the wider community (or even identifying who the ‘community’ is) and maintaining their involvement (Bushway & Reuter 2006). For example, cooperation and participation can be lacking in highly disorganised communities, who might benefit most from these types of programs. Community development-type programs are more likely to be effective when they:

  • identify communities at need based on evidence and community consultation, and analyse factors that may contribute to social disadvantage or exclusion;
  • take into consideration a community’s capacity to implement change and level of social disorganisation;
  • increase opportunities to participate and promote community involvement and consultation in program design and decision making, as well as in the management of activities that impact on, either directly or indirectly, those social conditions believed to sustain crime in residential settings;
  • encourage representation from diverse groups, particularly those community members most at risk of being marginalised;
  • coordinate efforts between agencies across government and non-government sectors to target multiple areas of disadvantage, supported by neighbourhood regeneration;
  • are provided with ongoing support (including human, financial and physical resources); and
  • regularly review progress to ensure that initiatives remain on track (Forrest, Myhill & Tilley 2005; Hayes, Gray & Edwards 2008; Johnson, Headey & Jensen 2005; Social Inclusion Unit 2009).

When compared with situational or developmental approaches, there is limited evidence of the effectiveness of efforts to modify community level factors to reduce crime (Tonry & Farrington 1995). Hope (1995: 22) observed that ‘…much of the effort to alter the structure of communities in order to reduce crime has not been noticeably successful or sustainable’. There is some evidence that neighbourhood level interventions to address issues related to economic and social regeneration in deprived areas in the United Kingdom (as part of the New Deal for Communities Programme) resulted in reductions in crime and fear, and increased satisfaction with the local area (Pearson et al. 2008). However, these interventions were not subject to rigorous testing.

Crime prevention mechanisms

To accurately identify and share information on the types of mechanisms used in the studies reviewed as part of this project, a consistent and comprehensive framework was required for classifying the mechanisms underpinning the various interventions that have been evaluated. Without a clear framework for their classification, it would be difficult to describe an intervention in a way that can be shared and potentially replicated in another crime prevention strategy. For this reason, the CCO was chosen as the conceptual framework for this review.The CCO framework has been developed to provide a common point of reference to facilitate the effective and efficient transfer of knowledge about the principles underpinning the full range of prevention strategies, as well as to help inform the choice of interventions by practitioners and policymakers (Ekblom 2010, 2002). The CCO framework allows for interventions to be classified in accordance with one or more identified precursors for crime and disorder events (see Table 4). These classifications take into consideration both social and environmental causes (reflecting the range of approaches to crime prevention described above). For each precursor, a corresponding principle of prevention is also identified.

However, the CCO does not explicitly identify the specific causal mechanisms that explain how an intervention aims to bring about the desired outcomes. The mechanism is the theory that explains how the intervention is intended to prevent or reduce crime through targeting specific precursors for criminal events. To overcome this limitation, the AIC has extrapolated the CCO to identify eleven common mechanisms underpinning different prevention strategies (as shown in Table 4).

Table 4: Conjunction of criminal opportunity
Immediate precursors to crime or disorder event Principle for prevention Mechanism

Crime promoters

A crime promoter is someone or something that makes crime easier to occur. Interventions aim to discourage or deter promoters and awaken their conscience. This can be through naming and shaming, civil liability, tackling a criminal subculture, procedural controls or market reduction

Encourage individuals (potential targets or individuals who facilitate access to targets) to consider the implications of their actions and discourage behaviour that may create opportunities for crime to occur and/or encourage behaviour that minimises opportunities for crime to occur

Crime preventers

Sometimes the presence of people in an area may deter offenders to from committing a crime. This includes formal control (surveillance, access control), informal social control, self-protection or avoidance

Introduce or improve formal or informal surveillance to increase the perceived risk that committing an offence will result in identification or capture

Wider environment

The aim is to make the physical environment safer, or to make the environment less likely to encourage conflict through environmental design and management, including aiding surveillance, resolving conflicts and setting rules

Manipulate the physical environment (built or landscape) to improve surveillance, define ownership of spaces and minimise conflict between users

Target enclosure

A ‘target enclosure’ is the business, room or space (such as a car, home or shop) that contains the target of the crime. Interventions include perimeter access and security

Make target enclosures harder to penetrate to increase the perceived effort associated with a crime

Target person or property

Projects in this category focus on strengthening the actual target, not just its surroundings. It could include what is sometimes termed ‘target hardening’, or the removal of the target from a vulnerable area.

Increase the perceived effort or rewards associated with a crime by making targets harder to access, remove or dispose

Offender presence in situation

This is an activity that targets an offender’s presence in a situation, possibly by placing restrictions on their access to a certain area at a certain time or by providing alternative activities. It is trying to remove or deter potential offenders from situations that might result in an offence occurring

Prevent potential offenders from being able to access locations where there are potential targets (property or people) or where provocation may occur

Anticipation of risk, effort and reward

People can be influenced to commit an offence by weighing up what they will benefit from it, how much they are willing to risk to commit the offence and what would be involved in committing it. Projects can be aimed specifically at deterring and/or discouraging potential offenders by making the offence riskier, requiring more effort, or have less reward.

Increase the perceived risk of crime, the perceived effort of crime or reduce the anticipated rewards of crime to discourage potential offenders

Resources for crime

Restricting resources for crime—control of weapons, tools and information on targets and transfer of criminal knowledge

Prevent offenders from being able to access the resources they need in order to commit an offence, or that may be used as an excuse for offending behaviour

Readiness to offend

There could be some situations where a person’s current life circumstance may suddenly change. This category could be seen as targeting (often unexpected) short-term situations for potential offenders (eg money problems, relationship problems, substance use), including changing current life circumstances and conflict resolution techniques

Alleviate (or minimise the impact of) stressors (relating to the individual or environment) that may influence the behaviour of potential offenders or that might be used as an excuse for offending

Resources to avoid crime

Training potential offenders in areas such as social and work skills to target factors that can make some people at a greater risk than others to commit crimes

Build a person’s resilience to offending by providing them with the resources, skills, knowledge and ability to avoid situations in which their risk of offending might be increased

Criminality (predisposition)

Reduce known risk factors and enhance known protective factors through family, school and peer groups; also includes supplying remedial treatment for those who have been convicted

Intervene early at key developmental stages to alleviate risk factors and enhance protective factors

Address the underlying factors that contributed to an offender’s behaviour in the first place and support their transition back into the community

Source: Adapted from Ekblom 2002

Interventions and mechanisms

This review involved categorising crime prevention interventions so that conclusions could be drawn about their effectiveness in different contexts. In practice, developing typologies for crime prevention and categorising interventions is a notoriously difficult task. As illustrated above, crime prevention is a broad area that encompasses such a wide range of activity that there are inevitably going to be interventions that don’t appear to fit within neat groupings. It also frequently involves the delivery of multiple overlapping interventions delivered in combination.

There was a need to find a balance between specificity and flexibility. Specificity was important from the point of view of trying to provide clear guidance to policymakers and practitioners (in this case NSW CPD and local government). Yet flexibility was necessary to ensure that evidence can be accumulated for certain interventions and lessons learned about their application to specific contexts. The final list of intervention types developed for this project is provided in Appendix A (see Table A1). These intervention types were used to categorise activities delivered as part of the evaluated strategies examined as part of this review. It was common for crime prevention strategies reviewed for this project to involve multiple intervention types.

Once these intervention types had been identified, it was necessary to determine the range of mechanisms through which they aim to bring about the desired results. Understanding these mechanisms is an important step in understanding why a particular intervention is or is not successful, why it may have been effective in one study but not another, or why it works for one type of crime or target group and not another. As has been argued here, it is also useful in adding value to systematic reviews, as it provides clear guidance as to what needs to happen in order for an intervention to work and therefore assists practitioners and policymakers to determine how best to modify and adapt interventions to different contexts.

The range of mechanisms that can be activated by different intervention types are also described in Appendix A. Notable in Table A1 is the potential for interventions to apply different mechanisms—ultimately dependent upon the precise nature of the intervention(s) that are used and the context in which they are applied. Further, multiple interventions may be combined to activate a single mechanism and address the same problem.