According to some authorities, among them Amydenus (De officio et jurisdictione datarii necnon de stylo Datariae), the office of the dataria is of very ancient origin, but that it is not appears from the fact that the business which eventually fell to it was originally transacted elsewhere. The Dataria was entrusted, chiefly, with the concession of matrimonial dispensations of external jurisdiction, and with the collation (the abstract of conferring) of benefices reserved to the Holy See. To this double faculty was added that of granting many other indults and graces, but these additions were made later. Until the time of Pope Pius IV matrimonial dispensations were granted through the Apostolic Penitentiaria; and as to the collation of reserved benefices, that authority could not have been granted in very remote times, since the establishment of those reservations is comparatively recent: although some vestige of reservations is found even prior to the twelfth century, the custom was not frequent before Innocent II, and only from the time of Pope Clement IV the reservation of benefices was adopted as a general rule [c. ii, "De pract. et dignit." (III, 4) in 6°]. It may be said that, while this office certainly existed in the fourteenth century, as an independent bureau, it is impossible to determine the precise time of its creation.
The Dataria consisted first, of a cardinal who was its chief and who, until the Sapienti consilio of Pope Pius X, was called the pro-datary, but since had the official title of datarius, often anglicized as datary. There was formerly as much discussion about the title of pro-datary as about that of vice-chancellor in the Apostolic Chancery. Some hold it is derived from the fact that this office dated the rescripts or graces of the sovereign pontiff, while others hold it to be derived from the right to grant and give (dare) the graces and indults for which petition is made to the pope. It is certain that, on account of these functions the datary enjoyed great prestige in former times, when he was called the oculus papae ("eye of the pope"). After the cardinal came the subdatary, a prelate of the Curia who assisted the datary, and took his place, upon occasion, in almost all of his functions. In the old organization of the Dataria there came after the subdatary a number of subordinate officials who, as De Luca says, bore titles that were enigmatical and sibyllic, for example the "prefect of the per obitum", the "prefect of the concessum", the "cashier of the componenda", an "officer of the missis" etc.
Pope Leo XIII had already introduced reforms into the organization of the Dataria, to make it harmonize with modern requirements. Pius X, reducing the competency of the office, gave it an entirely new organization in his apostolic constitution "Sapienti consilio", according to which the Dataria consisted of the cardinal datary, the sub-datary, the prefect and his surrogate (sostituto), a few officers, a cashier who had also the office of distributor, a reviser and two writers of Papal Bulls. The new Constitution retained the theological examiners for the competitions for parishes. Among the Datary offices that were abolished mention should be made of that of the Apostolic dispatchers, which in the new organization of the Curia had no longer a reason for being: formerly these officials were necessary, because private persons could not refer directly to the Dataria, which dealt only with persons approved by itself, but since, anyone could deal directly with the Dataria, as with any of the other pontifical departments.
To the Dataria, which was commissioned to grant many papal indults and graces, remained only the tasks to investigate the fitness of candidates for Consistorial benefices, which are reserved to the Holy See, to write and to dispatch the Apostolic Letters for the collation of those benefices, to dispense from the conditions required in regard to them, and to provide for the pensions, or for the execution of the charges imposed by the Pope when conferring those benefices.
It would be both lengthy and difficult to retrace the former modes of procedure of this office, all the more as it was mainly regulated by tradition, which was jealously guarded by the officers of the Datary, who were generally laymen, and who had in that way established a species of monopoly as detrimental to the Holy See as profitable to themselves. Thus it happened that these offices often passed from father to son, while the ecclesiastical superiors of the officials were to a great extent blindly dependent upon them. Leo XIII began the reform of this condition of things so unfavorable to good administration, and Pius X totally abolished it.