A diocesan chancery is the branch of administration which handles all written documents used in the official government of a Catholic or Anglican diocese.
It is in the diocesan chancery that, under the direction of the bishop or his representative, all documents which concern the diocese are drawn up, copied, forwarded, and a record kept of all official writings expedited or received.
The official charged with the execution of these duties is known as the diocesan chancellor.
Diocesan chanceries may be universal, but there is nothing in the common ecclesiastical law concerning their creation and equipment. The explanation lies in the very nature of this law, which provides only for what is general and common, and takes no account of local means of administration, which it abandons to the proper authority in each diocese, the concrete circumstances offering always great variety and calling for all possible freedom of action.
Although, as above described, the methods of diocesan administration exhibit no little variety, there exists on the other hand a certain uniformity. Each diocese, after all, is bound to observe the common law, has an identical range of freedom, and identical limits to its authority. Each diocese, therefore, is likely, a priori, to develop its administration along similar lines, but does so regularly in harmony with others, particularly neighbouring dioceses. In this way the dioceses of a given country come to have similar official administration.
In many dioceses, the chancellor exercises some of the faculties which in other dioceses are exclusively reserved to the vicar-general. This happens more frequently in smaller dioceses, administered directly by the bishop himself, and in which the vicar-general (often not resident in the episcopal city) is called on only when the bishop is absent or hindered.
In such cases the chancellor is also the confidential secretary of the bishop. A similar system obtains even in many extensive dioceses which are administered by the bishop with the aid of one or more vicars-general and the diocesan chancery. There are, however, some large dioceses in which all matters personally reserved to the bishop are executed by him with the aid of a secretary or chancellor, usually a priest or deacon, while the greater part of the diocesan administration is handed over to a body of officials under the direction of the bishop or his vicar-general.