Though formal life sentences have been abolished in Norway, forvaring (post-conviction indefinite preventive detention) – a type of informal life sentence – can be imposed on individuals convicted of certain offenses who are considered to be at high risk of future offending. While great attention has been paid to Norway as an “exceptional” penal outlier globally, there is a notable lack of comprehensive knowledge about its indefinite penal sanction. Drawing on extensive historical research and legal and policy documentary analysis as well as leveraging a unique national dataset on the total forvaring population, this article provides the first international in-depth assessment of the evolution and implementation of Norway’s ultimate penalty. In so doing, it highlights significant disparities between policy ambitions and current practice and questions the extent to which the sanction of forvaring can be considered an “exceptional” approach to life imprisonment. It is argued that the development and growth of this type of informal life sentence can be seen as the epicenter of the impact of a more punitive ideology in Norway, emphasizing the need to move away from the concept of penal exceptionalism to better understand the full spectrum and practice of Norwegian and Nordic penality.