The legal concept of competence to stand trial has ancient roots. The history of this legal construct in Anglo-Saxon law will be reviewed. A competent defendant is a requirement of the criminal justice system because it reflects interests related to the dignity of the process, the accuracy of adjudication, and respect for the autonomy of defendants. In the United States, legal decisions have established the contours of the requirements related to competent participation in adjudication. Forensic psychiatrists have operationalized the requirements for assessment purposes. Recent decisions in the United States have expanded earlier notions of competence to include decision-making during adjudication. These decisions will be reviewed. The process of clinical evaluation, the use of collateral information, and other aspects of expert opinion formation will be reviewed. In addition, the special problems posed by amnesia, pro se defendants, competence to plead insanity, and unrestorable defendants.
