New genetic technologies promise to generate valuable insights into the aetiology of several psychiatric conditions, as well as a wider range of human and animal behaviours. Advances in the neurosciences and the application of new brain imaging techniques offer a way of integrating DNA analysis with studies that are looking at other biological markers of behaviour. While candidate ‘genes for’ certain conditions, including schizophrenia and bipolar disorders, are said to be ‘un-discovered’ at a faster rate than they are discovered, many studies are being conducted on personality traits such as aggressiveness and anti-social traits. The clinical applicability and implications of these studies are often discussed within the scientific community. However, little attention has so far been paid to their possible policy implications in relation to criminality management and to Criminal Law itself. Similarly, the related ethical issues arising in the field of crime control, and the tensions between enhancing security for society and protecting civil liberties, are currently under-explored. This paper investigates these ethical issues by focusing on the views of those professionals – including judges, lawyers, probation officers and social workers – who work with individuals ‘deemed at risk’ of violent and aggressive behaviours. It also discusses and problematizes mainstream rhetoric and arguments around the notion of ‘risky individuals’.