Even with this added criterion, however, the definition of 'punishment arrived at would include more than that form of punishment that is the subject of penology. We must add that the offence for which it is inflicted must be a criminal offence, and that the rules and institutions of criterion 5 are the criminal law and the penal system. The punishment with which penology is concerned, then, is punishment for crime, pronounced by the judiciary and administered by penal institutions such as prisons and the probation service. Other types of 'punishment' - for example, of pupils by teachers, or of criminals by vigilantes and lynch mobs - are excluded.