Process of developing interventions.
Developing interventions to reduce knife crime
The range of risk factors and motivations indicate that knife crime and weapon carrying cannot be solved by criminal justice measures alone. Strong conclusions about what works to reduce knife crime are difficult to draw due to the lack of robust evaluations of programmes and interventions (Silvestri, 2009).
However, the best available evidence suggests the most effective approaches tend to be multi-faceted and involve prevention at the earliest opportunity and multi-agency collaborative working. In recent years, there has been a growing recognition of the value of public health approaches to addressing violence (Bellis and others, 2012), for example in Scotland.
Public health approaches require collaboration from different fields and multi-agency involvement in ‘diagnosing the problem, analysing underlying causes, examining what works and developing solutions’.
In Scotland, the development of an approach involving the police, social services, youth and community services, offending and probation teams, the NHS and local voluntary organisations, seems to be achieving results – with violent crime reaching a 41-year low in 2017 (Linden, 2018).
The Scottish Violence Reduction Unit has developed a range of interventions focusing on preventing the onset and progression of violence, rehabilitating offenders, developing criminal justice approaches to reduce offending, and changing attitudes and behaviours on a societal, community and personal level.
General violence or weapon-related interventions with greatest potential to reduce crime
Well-implemented problem-solving and focused deterrence strategies such as the US-based ‘pulling levers’ approach can have a positive impact on reducing violence (Braga and others, 2018; Braga and Weisburd, 2012; Braga and others, 2001).
These strategies target prolific or repeat offenders, combining improved access to support with strict enforcement (sometimes called a ‘carrot and stick’ approach).
There is evidence from the US through Operation Ceasefire, and encouraging evidence from Scotland through the Violence Reduction Unit, of a positive effect of these types of approaches on violence and homicide (US) and knife carrying (Scotland) (Williams and others, 2014).
Successful implementation of these approaches involves:
- multi-agency working involving a range of partners, including law enforcement, social services and community-based practitioners
- analytical work to identify key offenders, groups and behaviour patterns
- developing a response to offenders that uses a variety of interventions, both access to services and support and criminal justice processes
- directly and repeatedly communicating with offenders to make them understand why they are receiving this special attention
A similar focused deterrence approach has been piloted in three London boroughs. No effect was found on violent offending, but there were implementation weaknesses which highlighted the need to have mutual understanding, cooperation and support from all agencies (Davies and others, 2016).
Early intervention and prevention programmes
Programmes aimed at changing norms and values towards violence at a young age have shown some promising effects (Ross and others, 2011). In the UK, these programmes are typically aimed at children aged 13 and over. However, there are calls for programmes to work with children as young as eight (Kinsella, 2010) due to the increasing number of children carrying knives (Youth Justice Board and Ministry of Justice, 2018).
Early intervention programmes that have shown promising effects include:
- child skills training – teaching social and emotional skills, problem solving and anger management
- behavioural parent training – supporting parents to reinforce good behaviour
- mentoring – with an emphasis on emotional support and role modelling
- after school recreational activities – teaching skills in a structured and supervised environment
Restorative justice conferences – meetings between victims, offenders and sometimes family or community members – can reduce reoffending.
Evidence suggests these approaches have a particularly significant effect on violent crimes, and that victims are significantly less likely to seek revenge against the offender (Strang and others, 2012; Livingstone and others, 2013).
Specific knife crime interventions with limited crime reduction evidence
Little research has accompanied the often large-scale knife amnesties across the UK. Police data shows their impact is often limited or short term (Metropolitan Police Service, 2006). This indicates that removing a proportion of knives from the streets does not address issues of availability or the motivations underlying an individual’s decision to carry knives (Eades, 2007).
Schemes such as Bin a Blade and Word 4 Weapons provide knife amnesty or surrender bins while helping to raise awareness of the dangers of knife carrying. However, little is understood about who surrenders knives and their motivations for doing so, meaning our knowledge around the effectiveness of amnesties is currently limited.
Community and educational interventions
There are several programmes across the country aiming to tackle knife crime. These are not necessarily early interventions, because they can be applied at various ages or stages of entry to the criminal justice system.
Primarily centred on changing attitudes and behaviours towards knives (Silvestri and others, 2009), they provide people with:
- conflict resolution and emotional communication skills
- diversionary activities such as sport
- other educational support (Barry and others, 2018)
Many projects that aim to divert young people away from knife crime and violence are often run by small charities at a local level and are rarely evaluated.
Enforcement interventions where evidence suggests careful use
Stop and search
Stop and search is a police power that has the potential to reduce crime through either of the following.
- Immediate detection or confiscation of a weapon.
- Deterrence by raising the perceived risk of detection.
Previous research has estimated that over 80 per cent of all arrests for offensive weapons in the Metropolitan Police Service resulted from a stop and search (Fitzgerald, 1999).
Such offences often only come to light as a result of officers searching people they suspect to be in possession of weapons. While the number of searches has declined nationally in recent years, the proportion that result in an arrest has increased to its highest ever level (17%) (Home Office, 2018b). In 2017/18, of all those searches that led to an arrest, 14% were for offensive weapons.
In terms of deterrence, there is consistent evidence to suggest that an everyday level of police activity – including stop and search – reduces crime (Boydstun, 1975; Bradford, 2011). Beyond this level, there is limited evidence to show increases in activity reduce crime.
Analysis over a ten-year period suggests stop and search has a marginal deterrent effect on violent crime rates overall (Tiratelli and others, 2018). An evaluation of a stop and search initiative aimed specifically at knife crime found no statistically significant crime reduction effects (McCandless and others, 2016), although the authors were not able to consider local targeting. Focused police patrol activity, including stops and stop and search, has been found to reduce crime in targeted violence hotspots in the US (Ratcliffe and others, 2011; Weisburd and others, 2015; MacDonald and others, 2016)
While intelligence helps the targeting of stop and search, people’s willingness to provide information is likely to be affected by how fair they perceive the police to be in their use of this power (Bradford, 2015). Young people, the economically disadvantaged, and people from some minority ethnic groups are significantly more likely to be stopped, and to be dissatisfied with police treatment during a stop (Bradford, 2017).
If contact with officers is felt to be unfair, analysis also suggests it can undermine young people’s perception that the police are ‘on their side’. This reduces their willingness to comply with the law and is associated with increased risk that they consider violence to be an option in achieving certain goals (Jackson and others, 2012).
Despite recent changes to sentencing guidelines for knife offences aimed at deterring would-be offenders through increasing the severity of sentences, 72% of those convicted for knife and offensive weapons offences in the year ending March 2018 were first-time knife and weapons offenders (Ministry of Justice, 2018b).
It is very difficult to measure what levels of punishment produce what levels of general deterrence (Halliday and others, 2001). The impact of custodial sentences on knife crime will need longer term evaluation.
For juveniles (10–18 years), prison alone has been found to significantly increase reoffending, compared to non-custodial sanctions such as community supervision with victim reparation, and community surveillance and aftercare (Marsh and others, 2009).
Evidence also shows that educational attainment is lower for children with knife possession offences, which has been shown to be a risk marker for serious violence later in life (Ministry of Justice, 2018a).
- Knife crime perpetrators and victims are most likely to be males in late adolescence.
- Risk factors for serious violence and weapon carrying include adverse childhood experiences and poor educational attainment. Ethnicity has been found to have no significant effect on weapon carrying in the UK.
- The most successful approaches to reducing violence include well-implemented problem-solving and focused deterrence strategies, such as the US-based ‘pulling levers’, which aim to address the root causes of violence.
- Public health approaches involving multiple agencies to develop a range of interventions – including prevention work for at-risk groups as well as law enforcement activity directed at offenders – have been shown to have a positive impact.