Important factors, frequently transcending all countries, associated with a high prevalence of mental disorder in prisons are: (1) The criminalization of mentally ill individuals by pressing charges instead of tolerating socially deviant behaviour; (2) Economizing on the treatment of mentally disordered individuals by reducing the services of psychiatric institutions (keyword deinstitutionalization) and complementary community-based care structures, especially for young adult chronic psychiatric patients; (3) Strict criteria for civil legal or public legal confinement, which appear to be best met by the penal system for individuals with abnormal and legally deviant behaviour who require therapy but are unwilling to comply; (4) The reluctance of general psychiatric facilities to accept mentally disordered prisoners; (5) The rejection of 'difficult' chronic psychosis patients because of doubts about their suitability for treatment; (6) A political climate that keeps the resources for mentally disordered offenders at a low level.