To stop or continue counting? Calculating reconviction leading to imprisonment after preventive detention in Norway

In Norway, the ultimate penalty is post-conviction indefinite preventive detention (forvaring), an informal life sentence that can be imposed when a determinate sentence is deemed insufficient to protect society. In this article, we examine reconviction leading to imprisonment among persons who completed their forvaring sentence between 2002 and 2022, drawing on a unique national dataset. Across a range of follow-up periods, reimprisonment rates ranged from 2% for serious offences within two years to 37% overall. Reconviction for serious crimes mostly occurred beyond the usual two- and four-year follow-up periods, with persons convicted of sexual offences showing higher rates of reconviction. We also discuss factors influencing the risk of offending, such as previous convictions, age and sentence progression, and highlight the challenges of predicting future criminal behaviour. As forvaring is intended solely to protect society from serious crimes violating the life, health or freedom of others, we argue that within a risk-management context any assessment of the success or failure of forvaring must be grounded in estimates of reconvictions for such serious crimes within limited follow-up periods.