1 Since only general laws can be made where there exists a wide variety of nations and regions, a special "program of priestly training" is to be undertaken by each country or rite. It must be set up by the episcopal conferences, revised from time to time and approved by the Apostolic See. In this way will the universal laws be adapted to the particular circumstances of the times and localities so that the priestly training will always be in tune with the pastoral needs of those regions in which the ministry is to be exercised.
Source: Optatam Totius (Vatican.va)