Police drug diversion: A realist, impact, process and economic evaluation

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Grant details

Cabinet Office Evaluation Accelerator Fund

Project start and end dates

01/09/22 - 31/03/26

Research team members

Background and aims of the project

This research project evaluated the effectiveness and cost-effectiveness of police-led diversion (PDD) schemes for drug-involved suspects. A team of academic, policing, health and service user partners did detailed research on PDD schemes that were already operating in three areas; Durham, Thames Valley and West Midlands. Quantitative data were also collected from 10 other police forces, with a total sample of over 60,000 criminal incidents.

People on the PDD schemes were assessed, then referred to education, treatment or support (as needed) with an ‘out of court resolutions’ which did not create a criminal record.

We successfully linked data held by the police, the Ministry of Justice and the National Drug Treatment Monitoring System to assess the impacts of diversion on crime and engagement with drug treatment. We compared the outcomes for people eligible for diversion in the police force areas that had PDD schemes to the outcomes of similar people in areas which did not yet use PDD. We found that diverting people who were caught in possession of drugs led to lower rates of reoffending, both when comparing between police forces that did or did not use PDD, and between individuals who were or were not diverted.

In order to learn how PDD schemes work in practice, we also carried out interviews and focus groups with the 221 people who work with these schemes, including police officers, drug treatment providers, service users and other stakeholders. We also examined how equitable the effects of PDD are (e.g. by ethnicity and gender).

Partners in the project brought a range of skills and included the Universities of Sheffield, Kent, York and Loughborough, the Open University, Anglia Ruskin University, Bradford Institute for Health Research, the Office for Health Improvement and Disparities, the Office of the West Midlands Police and Crime Commissioner, Thames Valley Police, Durham Police and the charity Use Voice.

People with direct experience of being policed played a key role in this project. They collaborated in designing the research, especially in creating our plans for research with service users. They were equal partners in the collection and analysis of data. They are helping to share the results and our ongoing work on translating them into improvements in policy and practice.

A full list of the research outputs so far, with links. More articles and other outputs are in the way.

There is also a video about police-led drug diversion, based on the PDD project.

The full results of the PDD project will be presented at the National Symposium on Police-led Drug Diversion at the University of Sheffield on 18th June 2026

Publications so far:

Stevens, A., Hendrie, N., Bacon, M., Parrott, S., Monaghan, M., Williams, E., Lewer, D., Moore, A., Berlin, J., Cunliffe, J., & others. (2023). Evaluating police drug diversion in England: Protocol for a realist evaluation. Health & Justice, 11(1). 

Smith, R., Bacon, M., Monaghan, M., Glasspoole-Bird, H., Hendrie, N., Sutton, C., & Stevens, A. (2025). Achieving collaborative advantage in policing: Strategic and frontline partnership in police-led drug diversion schemes in England. Policing: A Journal of Policy and Practice, 19, 1–9. 

Sutton, C. E., Bacon, M., Glasspoole-Bird, H., Hendrie, N., Monaghan, M., Smith, R., & Stevens, A. (2025). Triggering motivations for change: Exploring engagement in adult police-led drug diversion programs. Drugs: Education, Prevention & Policy. DOI: 10.1080/09687637.2025.2566921.

Bacon, M., Glasspoole-Bird, H., Hendrie, N., Lewer, D., Mills, A., Monaghan, M., Pascual, G., Quinton, P., Smith, R., Sutton, C., Williams, E., & Stevens, A. (2026). Implementation fidelity matters: insights from a realist evaluation of police drug diversion schemes in England. Policing & Society. 1–24. DOI: https://doi.org/10.1080/10439463.2026.2651196.

Stevens, A., Agnew-Pauley, W., Bacon, M., Glasspoole-Bird, H., Hendrie, N., Hughes, C. E., Lloyd, C., Monaghan, M., Smith, R., Sutton, C., Williams, E., & Quinton, P. (2026). Cascading constraint and subsidiary discretion: Perspectives on police discretion from police-led drug diversion and stop and search in England. The British Journal of Criminology. 66(2): 448–466.