Understanding the causes of knife crime

Motivations for and factors associated with an individual’s involvement in knife crime.

First published
Written by Abigail McNeill and Levin Wheller
Knife crime evidence briefing

Motivations for carrying weapons

Evidence suggests there are three broad explanations as to why people carry knives (Brennan, 2017). These are:

  • self protection and fear (‘defensive weapon carrying’) – particularly for individuals who have previously been a victim of crime (Lemos, 2004)
  • self-presentation – particularly for individuals who want ‘street credibility’ and ‘respect’ (Silvestri and others, 2009)
  • utility (offensive weapon carrying) – particularly for individuals who use weapons to facilitate other behaviours (Brennan, 2017) such as theft, sexual assault, injury and serious harm

Evidence also suggests that a lack of trust in the police can potentially lead victims to becoming perpetrators, as they may use violence to seek revenge instead of relying on police procedures (Silvestri and others, 2009; Bradford, 2015; Brennan, 2018).

Risk factors associated with knife crime

There is some evidence that the following factors may be associated with increased risk of violence and/or weapon carrying.

  • Gender – males are more likely to commit serious violence and carry weapons (Home Office, 2018a; Brennan, 2018).
  • Age – self-reported weapon carrying peaks around the age of 15 (Home Office, 2018a; Brennan, 2018).
  • Adverse childhood experiences – including abuse, neglect, parental criminality and/or substance abuse, being taken into care (Dobash and others, 2007; Hales and others, 2006; Home Office, 2018a).
  • Educational attainment – school exclusion and low attainment (Hales and others, 2006; Home Office, 2018a; Ministry of Justice, 2018a).

Ethnicity – recent analysis of data collected in the UK indicates that there is no statistically significant relationship between ethnicity and weapon carrying (Brennan, 2018).

Is there a link between gangs and knife crime?

Evidence suggests that gang-related knife crime, although more likely to result in injury or fatality, makes up only a small proportion of total knife crime with injury (only five percent in 2016) (MOPAC, 2017).

Some subtle differences have been identified between individuals who carry a knife and those who become involved in gang crime (McVie, 2010). Analysis suggests a stronger link in London between gangs and knife crime since 2016 (Kirchmaier and Villa Llera, 2018).

Understanding patterns of knife crime

Data including homicide statistics and the Metropolitan Police Service’s Public Attitudes Survey were analysed. The analysis found that murder locations were positively correlated with the percentage of the previous years’ young Black respondents (aged 24-35) who believed knife crime was a major concern in that area (Kirchmaier and Villa Llera, 2018).

Effective engagement with young Black respondents may provide intelligence to help reduce knife-related murders.

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