A large-scale study of over 62,000 drug-related incidents across 13 English police forces over four years found that police drug diversion schemes—programs that steer people away from prosecution and toward health services instead—are associated with lower rates of reoffending. But the research also identified a critical condition: the schemes only work if police actually carry them out properly and consistently.

The study was published by researchers working alongside police, health professionals, and service providers. This partnership matters because it shaped how they asked their questions. Rather than simply asking "does it work?" they instead asked "what works, for whom, under what conditions, and why?" That distinction is important, because "drug diversion" is not a single thing. It ranges from informal warnings for cannabis possession to referrals into structured treatment programs and educational courses. Earlier studies often lumped these together, which meant important differences got lost.

What the Evidence Shows

The main finding—reduced reoffending—aligns with earlier research from UCL and analysis published through the White Rose repository, which found that police-based diversion schemes showed promise for health, wellbeing, and social outcomes, as well as lower reoffending rates. That earlier work also found something crucial: schemes that stuck to their intended design worked better. The new 13-force study confirms this at much larger scale.

When independent research teams using different methods all reach the same conclusion, that matters. It suggests the reoffending reduction is not a quirk of one study or region, but holds up across different police areas, different delivery models, and different ways of measuring success.

The fidelity question—whether a scheme is actually delivered as designed—turns out to be far more than a minor administrative detail. In diversion research, poor implementation is documented as a primary reason why promising ideas fail in practice. Officers might apply schemes inconsistently, fail to complete referrals properly, or use diversion tools as an informal way to reduce charges rather than as genuine pathways into health services. The 13-force study's size gives real weight to this finding in a way smaller pilots could not.

The Stop and Search Problem

There is a structural issue that sits alongside these positive findings. In 2021, His Majesty's Inspectorate of Constabulary and Fire & Rescue Services found that nearly one in five police stop-and-search operations for drugs were conducted without reasonable grounds—meaning they had no legal justification.

This matters directly to diversion because the legality of the initial encounter shapes whether what comes after is procedurally sound. If an officer stops and searches someone without proper grounds, any subsequent diversion decision is built on a flawed foundation. This does not just raise human rights concerns; it undermines the program's credibility with the communities it is meant to serve—often the same communities most exposed to police stops in the first place.

The broader context here is that this tension between police discretion and fairness is not new in British drug enforcement. What the current research does is sharpen the stakes: if diversion is expanding as an alternative to prosecution, the quality of the initial police encounter—the stop, the search, the reasons recorded—becomes more consequential, not less. A diversion that follows an unlawful stop is a diversion built on unstable ground.

Young People and the Risk of Escalation

Research from Kent found an association between previous criminal charges and higher reoffending rates among young people. This finding strengthens the argument for diversion schemes that operate before formal charges are laid.

When young people are formally charged and convicted, they carry a criminal record that creates long-term obstacles: barriers to employment, housing, and social support—the very factors that protect against reoffending in the first place. Diversion that keeps a young person out of the formal criminal justice system, before a record is created, has ripple effects that extend well beyond the immediate police encounter.

The logic is straightforward: earlier formal contact with the criminal justice system predicts worse outcomes later. Diversion interrupts that trajectory before it hardens. But the Kent research also points to a practical requirement: diversion schemes only achieve this benefit if they are properly resourced. A genuine, warm handover to a working treatment or support service produces different results than handing someone a leaflet and a caution. The difference between those two scenarios is the difference between diversion working or merely feeling like it does.

What Remains Unknown

The 13-force study's design—bringing in police, health professionals, and service providers from the start—itself says something important about how this kind of research should be done. It allows researchers to look not just at whether something works, but at how and why, which is what people actually implementing these schemes need to know.

The outstanding questions are practical ones. Which specific elements of a diversion scheme drive the reduction in reoffending: the decision to divert itself, the quality of the referral, or the quality of the service someone is referred to? Do these benefits work equally for all groups, or does the documented racial disparity in stop-and-search operations mean some communities have better access to diversion than others? And at what point does poor implementation of a scheme make it so watered-down that it becomes merely a caution with more paperwork attached?

These are answerable questions with the data that now exists. The next step depends on whether police forces and crime commissioners will invest in finding those answers.