1. The following rules are not intended to describe in detail a model system of penal institutions. They seek only, on the basis of the general consensus of contemporary thought and the essential elements of the most adequate systems of today, to set out what is generally accepted as being good principle and practice in the treatment of prisoners and the management of institutions.
2. In view of the great variety of legal, social, economic and geographical conditions of the world, it is evident that not all of the rules are capable of application in all places and at all times. They should, however, serve to stimulate a constant endeavour to overcome practical difficulties in the way of their application, in the knowledge that they represent, as a whole, the minimum conditions which are accepted as suitable by the United Nations.
3. On the other hand, the rules cover a field in which thought is constantly developing. They are not intended to preclude experiment and practices, provided these are in harmony with the principles and seek to further the purposes which derive from the text of the rules as a whole. It will always be justifiable for the central prison administration to authorize departures from the rules in this spirit.
