"According to the “Diagnostic and Statistical Manual of Mental Disorders”, Fourth Edition, Text Revision (DSM-IV-TR) (American Psychiatric Association, 2000), a personality disorder is “An enduring pattern of inner experience and behavior that deviates markedly from the expectations of the individual’s culture” (p. 686). To be diagnosed with a personality disorder, an individual must manifest the disorder in two or more of the following areas: cognitions (ways of perceiving the world), affectivity (emotional response), interpersonal functioning, and impulse control. The enduring pattern must also be inflexible and pervasive across a range of circumstances and situations, lead to clinically significant impairment or distress, and be stable, having originated in adolescence or early adulthood. The pattern also cannot be the product of another mental disorder, substance abuse, or a medical condition. Of the personality disorders defined in the “DSM-IV-TR:, the ‘Axis II’, “Cluster B” disorders are most relevant to the study of criminal behavior. These disorders include “Antisocial Personality Disorder”, “Borderline Personality Disorder”, “Histrionic Personality Disorder”, and Narcissistic Personality Disorder”. These four disorders share behavioral features such as impulsive acting out, unpredictable behavior, and dramatic presentation, as well as a common intrapsychic structure centered on a lower-level defensive organization that uses primitive defenses. Wulach (1988) suggests that features of each of these disorders comprise the “criminal personality” and there is evidence to suggest that each may represent distinct behavioral expressions of psychopathy. Much of the psychological research on criminal behavior has focused on “antisocial personality disorder” and “psychopathy”. In fact,the concepts of criminality, insanity, antisocial personality, and psychopathy have been so intertwined over the past two centuries that much of the research, particularly in the discipline of psychology, has failed to clearly differentiate between meal ntdisorder (an internal condition) and crime (a behavioral symptom and social construct). Researchers have spent the last 20 years trying to sort out the conceptual differences and in recent years there have been rapid advancement in our understanding of the relationship between antisocial personality disorder, psychopathy, and crime. According to the “DSM-IV-TR”, the essential feature of APD is “a pervasive pattern of disregard for, and violation of, the rights of others that begins in childhood or early adolescence and continues into adulthood” (p.701)."