Psychopathy is an important forensic construct, and a personality disorder, that is, a chronic disturbance in an individual's relations with self, others and their environment resulting in distress or failure to fulfill social roles and obligations. Those with psychopathic personality disorder (PPD) are not only pathologically dominant, but they may also suffer from attachment difficulties, being detached, uncommitted and unempathic. In terms of emotional functioning they can be characterized as lacking anxiety, empathy and emotional depth, while cognitively they may be suspicious, intolerant and inflexible. Critical features of the disorder include deceptiveness, impulsivity and failure to stick to rules, which can make those with PPD hard to interview, manage and monitor. Psychopathy and cognate constructs can be assessed using a variety of procedures, including self-report, clinical criteria or, most commonly in the forensic arena, the Psychopathy Checklist Revised and Psychopathy Checklist: Screening Version.