Conventional histories of psychiatry depict the medieval and early modern period as dominated by demonological ideas about mental illness and treatment of the insane as cruel and inhumane. English legal records from the thirteenth to the seventeenth century, generated by the Crown's jurisdiction over the mentally disabled, produce a radically different picture. When royal officials examined allegedly disturbed persons before local juries, they measured mental status with common sense criteria based on psychological and physiological notions of etiology. For established cases of disability, the Crown appointed supervised guardians. In the course of these centuries, the responsibility of guardians for the care and protection of the disabled underwent increasing expansion. The records of this jurisdiction exist largely in manuscript form, a documentary source which psychiatric historians have been slow to appreciate. These records cast doubt on the accuracy of traditional accounts of psychiatric history based on printed sources and on the validity of restricting historical research to published materials.