The Supreme Tribunal of the Apostolic Signatura, housed in Rome's Palazzo della Cancelleria, is the highest judicial authority in the Catholic Church beside the Pope himself.
The proper law of the Apostolic Signatura, to which a few minor lexical changes have been made, was promulgated by Pope Benedict XVI in June 2008.
The changes concern the replacement of the word “clerics” with “presbyters” in Art. 1 of the Proper Law; the replacement of the word “Dicastery” with the word “Tribunal” in Art. 3 and with the word “Apostolic Signatura” in Art. 32; the replacement of the expression “issued by the Dicasteries of the Roman Curia” with the expression “issued by the Curial Institutions” in Art. 34; the replacement of the expression “to promote and approve the establishment of interdiocesan tribunals” with the expression “to approve the erection of tribunals of all kinds established by the bishops of several dioceses” in Article 35; the replacement of the word “Dicastery” with “Curial Institutions” in Articles 79, 80, 81, 92 and 105.
"In exercising its function as the Supreme Tribunal of the Church," the Pope writes in the preface to his motu proprio, "the Apostolic Signatura places itself at the service of the supreme pastoral office of the Roman Pontiff and his universal mission in the world."
"In this way, by settling disputes that have arisen over an act of ecclesiastical administrative power, the Supreme Tribunal provides a judgement of legitimacy on decisions issued by curial institutions in their service to the Successor of Peter and to the universal Church.”