The effect of a procedural justice and deterrence-based letter on recidivism for smartphone use while driving in the Netherlands: a randomized controlled trial

This study evaluates the effectiveness of a Dutch police intervention conducted in March 2025 targeting drivers sanctioned for using a smartphone in traffic. As part of the intervention, individuals in the treatment group received a warning letter from the police incorporating elements of deterrence theory and procedural justice theory, in addition to the business as usual fine. A randomized controlled trial (RCT) design was employed to assess the intervention’s impact on specific and general recidivism. Offenders in the sample were assigned to either receiving the letter (treatment) or not (control). Specific and general recidivism were measured over a six-month follow-up period by comparing repeat offenses among offenders who received the letter with those who did not. Data were analyzed using negative binomial regression models. Results indicated no statistically significant differences between the treatment and control groups with respect to either form of recidivism.