Police Drug Diversion (PDD): A realist impact, process, and economic evaluation

While drugs policing often involves enforcement interventions that seek to tackle drug problems through criminal sanctions, in England and Wales diversion now occupies a central position in police responses to people suspected of either a drug offence or an offence related to their drug use. Police-led drug diversion (PDD) schemes have the potential to reduce the harms that are done by, and to, people who use drugs (Spyt & Kew in Bacon & Spicer, 2023).They are offered to people who are caught by the police in unlawful possession of substances that are controlled under the UK’s Misuse of Drugs Act 1971. People can be diverted away from prosecution and criminal sanctions and towards educative, therapeutic or support services. Diversion schemes are shaped by both national and force-led policy.

In this paper we present the initial findings of a large-scale Cabinet Office funded national evaluation of three contrasting PDD schemes in Durham, Thames Valley, and West Midlands. This ongoing mixed methods project led by the University of Kent adopts a realist framework to evaluate the effects of PDD on crime, health, public spending and to explore any inequalities in the use and effects of PDD schemes.

The first phase of the evaluation was producing PDD scheme manuals in order to inform a fidelity assessment. The process was collaborative and workshops were held in the three scheme areas as well as a national stakeholder’s workshop. Representation included police management, front line police officers, diversion service providers, academic partners, researchers from a lived experience organisation and people with direct experience of being policed. Prior to the workshops, descriptions of the schemes were captured through a TIDieR Framework (Template for Intervention and Replication, Cochrane), which was used to interrogate the scheme’s complexities, compare scheme specific elements of diversion and gain operational insight into how diversion operates. The workshops also tested ideas that emerged from the literature and informed the programme theory of change.

A programme theory based on a realist review of alternatives to criminalisation for the Irish government (Stevens et al., 2022) informed the initial design for this research project. The review established that depending on specific combinations of contexts, mechanisms and outcomes, alternative measures can reduce harms imposed by criminal justice processes without increasing drug use or related health and crime harms. A rapid review of more recent evidence (published since June 2018) was conducted to produce a revised programme theory of change of how diversion schemes work. This theory of change will be used to inform other phases of the project which include the collection and analysis of qualitative data (including interviews with police, diversion provision partners and those with lived experience of being diverted) and quantitative data (including data from Police National Computer and NHS databases) to answer the research questions.

The evaluation outcomes will expand a limited UK evidence base for police drug diversion and will inform the Government 2025 spending review.