The elusive concept of dangerousness: The state of the art in criminal legal theory and the necessity of further research

Preventing future crime has become an increasingly dominant function of the criminal law of many liberal democracies. This “preventive turn” has led to a profound debate on the legal and ethical boundaries of the “preventive state.” However, the concept at the core of preventive justice—the dangerousness of the offender—has attracted relatively little attention in the current debate. This is remarkable, as the legal establishment of dangerousness permits intrusive preventive measures, such as preventive detention for an indeterminate period of time. In the past, various concepts of dangerousness have been developed by criminal law scholars. We discuss these concepts in a chronological order to demonstrate how the meaning of dangerousness has evolved over time, and how it has been shaped by concurrent developments in forensic psychiatry and penology. Our description of the state of the art of legal scholarship on the concept of dangerousness also shows the lack of a fully developed theory of dangerousness, and therefore the necessity of further research. We identify five “aspects” of the concept of dangerousness on which scholars have widely diverging views. These five aspects are intended to guide further research on the concept of dangerousness in preventive criminal law.