Criminal activity appears to be reduced in Norway during opiate maintenance treatment. Younger age and prior history of criminal activity are important risk factors for continued criminal activity during treatment.

There is an elevated risk of death from drug overdose among individuals released from Norwegian prisons, peaking in the first week. The risk has reduced since 2000-04, but is greatest for those serving 3-12 months compared with shorter or longer periods.

The Norwegian prison inmates are burdened by problems before they enter prison. Few studies have managed to assess this burden and relate it to what occurs for the inmates once they leave the prison. The Norwegian Offender Mental Health and Addiction (NorMA) study is a large-scale longitudinal cohort study that combines national survey and registry data in order to understand mental health, substance use, and criminal activity before, during, and after custody among prisoners in Norway. The main goal of the study is to describe the criminal and health-related trajectories based on both survey and registry linkage information. Data were collected from 1,499 inmates in Norwegian prison facilities during 2013–2014. Of these, 741 inmates provided a valid personal identification number and constitute a cohort that will be examined retrospectively and prospectively, along with data from nationwide Norwegian registries. This study describes the design, procedures, and implementation of the ongoing NorMA study and provides an outline of the initial data.