Although there is a growing interest in evidence-based medicine in clinical practice, translation of the same principles to health policy is more sporadic. This article examines the gap between reality and aspiration in the area of mental health. It specifically examines two initiatives in the wake of public concern about the link between violence and psychiatric disorder: specialist services for severe or dangerous severe personality disorders, and compulsory community treatment. Neither of these interventions has been shown to be clearly evidence based. In terms of numbers needed to treat, it would take 100 community treatment orders to prevent one readmission and 500 to prevent one arrest. This paper asks for more honesty about how, when, and if we use research evidence.