Medical definitions are not merely abstract categorizations. They are used in the real world, where they have social effects, and nowhere is this more true than for diagnoses of personality disorder. This article considers the relevance of personality disorder in legal contexts and questions whether meaningful analysis of how the new diagnostic structures proposed for ICD-11 and DSM-5 will play out in real, social situations has been carried out. Without such analysis, it is not possible to know whether the new criteria will be an improvement or a step backwards. Copyright © 2011 John Wiley & Sons, Ltd.