NUNZIO APOSTOLICO. – According to the modern concept, he is a titular archbishop sent by the Supreme Pontiff as his representative, with a permanent commission and diplomatic status, to the head of a State. The functions of the nuncio are of two kinds: those of representing the Supreme Pontiff before the civil government, and those of representing the same Roman Pontiff before the Catholic communities existing in the State to which he is accredited: the first representation is absolutely essential to the status of nuncio, and it is by virtue of this that he is distinguished from the apostolic delegate; the second is common to both (can. 267). As representatives of the pope before civil governments, nuncios enjoy the rights accorded to representatives of a foreign State; they attend to relations between the Apostolic See and the governments to which they are accredited; they supervise observance of mutual agreements both by the civil authorities and by the local ecclesiastical authorities, and in all cases the respect due to the prerogatives of the Church and to the rights of Catholic communities, serving as interpreters of their just aspirations and well-founded complaints; they direct negotiations between the Holy See and the State, reporting to the former on the progress and conclusion of the discussions; they inform the same Apostolic See concerning the attitude of the political authorities, public opinion, the parties, and the press with regard to the rights of the Church, and convey to governments the desires, requests, or even representations of the Holy See, in accordance with its norms and instructions.
According to the regulations adopted at the Congress of Vienna in 1815, nuncios are accorded the same rank as ambassadors (v. AGENTE DIPLOMATICO); generally, the nuncio is also dean of the diplomatic corps.
As representatives of the Supreme Shepherd before Catholic communities, nuncios perform a function identical to that of apostolic delegates (v.), with equal powers and functions; they must supervise, in order to report to the Holy See (can. 267 § 1, n. 3), the condition of the Churches—that is, observance of ecclesiastical discipline by the clergy and faithful, the progress or decline of Catholic life in the country, the conditions that promote or hinder its development, and the means to be adopted to facilitate its growth or remove its difficulties. Nuncios, however, like apostolic delegates, neither should nor may take the place of the Ordinaries by exercising acts of jurisdiction within their dioceses (can. 269 § 1), unless they have been granted special faculties for this purpose.