Systematic review
A new (27 March 2025) report by RAND Europe presents the findings from a systematic literature review on the impact of drug-related law enforcement activity on serious violence and homicide. The report was prepared for the Home Office to inform work undertook to implement the Drugs Strategy.
The review (written by Elle Wadsworth, Mafalda Pardal, Lucy Strang, Laura Atuesta, Fin Oades, Emily Hutton, Eric Sevigny & Emily Lawson) examined five sub-questions within this theme:
- Are certain types of drug-related law enforcement activity effective in reducing serious violence and homicide?
- What aspects of drug-related law enforcement activity make them more/less likely to be effective in reducing serious violence and homicide?
- Do certain types of drug-related law enforcement activity have unintended consequences, such as worsening adverse serious violence and homicide outcomes?
- When drug-related law enforcement activity generates adverse serious violence and homicide outcomes, what are the factors that lead to these unintended consequences?
- How do serious violence and homicide outcomes relating to drug-related law enforcement activity differ by country and local areas, and why?
Range of enforcement activities
The report reviews the evidence on 8 types of drug-related law enforcement activities:
- selective enforcement for a specific area or group
- leadership removal
- attack or removal of a drug trafficking organisation member
- arrests or charges
- illegal crop eradication
- drug seizures
- military interventions
- multi-jurisdictional anti-drug coordination and resourcing
It also explores possible barriers to effectiveness and contributing factors that may help such activities reduce violence. The report then analyses differences between and within countries regarding these interventions and their outcomes.
Findings
Overall, the findings are not encouraging. The authors find that the available evidence suggests that drug-related law enforcement activities are of limited effectiveness in reducing violence. Indeed, more studies demonstrated an association between drug-related law enforcement activities and increased violence than decreased violence. Specifically:
- most studies found an association between leadership-removal interventions and increased violence,
- four studies found an association between attacking or removing a DTO or drug gang member and increased violence,
- three out of 4 studies examining the relationship between drug arrests/charges and violence found an association between drug arrests and increased violence and
- the evidence suggests a strong association between illegal crop eradication and increased violence.
In contrast, selective enforcement tactics appeared the most promising in their capacity to reduce violence, although the evidence base covered in this review is limited.
Passive drug-related law enforcement activities, such as increasing police presence in known drug market areas, appear promising in reducing violence. However, less evidence is available on the effectiveness of these interventions than on active law enforcement activities.
The causal mechanisms of violence reduction are under-explored in the literature. However, several studies discussed supply disruptions, focused deterrence and positive relationships between police and communities as potential success factors.
Barriers to the effectiveness of violence-reduction efforts included the resilience of drug markets, the cultural significance of violence in some drug trafficking organisations, and law enforcement’s limited resources.
The authors note that this review did not identify any UK-based evidence – most research came from the Americas. While most law enforcement activities in this review also occur in the UK, they caution that the results are not directly replicable in a UK setting.
Evidence on the relationship between drug-related law enforcement and serious violence and homicide over the last decade is lacking. What was previously effective (or ineffective) in reducing violence may yield different results now.
Conclusions
The research team conclude that more evidence is needed on the effectiveness of drug-related law enforcement activities in retail-level markets or prison settings in reducing violence.
They recommend that agencies planning and implementing drug-related law enforcement activity should consider the risk of increased violence, particularly for interventions for which available evidence suggests a strong association (for example, leadership removal and seizures).
The authors suggest that future UK research on drug-related law enforcement and violence could focus on interventions that may reduce violence, such as selective enforcement, and whether the findings presented can be validated.