In this paper the psychiatrist's position in Dutch penal law in the periods 1890-1910 is discussed with the help of historical literature. On basis of developments in penal thinking about mentally ill offenders the psychiatrist's view on his tasks are sketched, especially those relating to advice and treatment.

Furthermore there is spoken about the psychiatrist's problems in regard of diagnosing. The guiding principle in his paragraph are the several views psychiatrists may have on, being a doctor, functioning in the penal system. This discussion is illustrated with some prominent psychiatrist's opinions on the diagnosis of `moral insanity'.