BackgroundDrugs and crime are linked and diversion from the criminal justice system into drug treatment is a well-established policy response. The point of arrest is a pivotal moment to initiate a drug-specific intervention. This paper assesses the impact of the introduction of drug testing on arrest (DToA) into a low crime area in England. Our mixed methods study analysed performance data collected by the National Drug Treatment Monitoring/Drug Test Recorder datasets and feedback from a series of semi-structured interviews with both clients and professionals.ResultsIn total, 2210 people were tested 2861 times of which 42.0% (n = 928) tested positive. Of those, 3% subsequently engaged with effective treatment. However, throughout the criminal justice system, treatment engagements increased year on year from 20% (n = 77) to 26% (n = 131). Clients (n = 19) and professionals (n = 14) reported that DToA was an acceptable/tolerable addition to the treatment pathway. Interviews suggested that the point of arrest may help primary desistance from further offending.ConclusionsThe staggered introduction of the DToA made direct measure of impact difficult and there appears to have been a ‘displacement’ effect in response to the extra investment. However, DToA appears to have contributed towards an overall uplift in criminal justice drug treatment system performance activities (identification, assessment, referral etc.) and may have served to help strengthen care pathways. Barriers were noted about engagement with DToA by entrenched opiate users, suggesting that the effectiveness of DToA was limited within that group. This study is the first to investigate the impact of the introduction of DToA into a low crime area.