§1. The supreme tribunal of the Apostolic Signatura adjudicates: 1/ complaints of nullity, petitions for restitutio in integrum and other recourses against rotal sentences; 2/ recourses in cases concerning the status of persons which the Roman Rota refused to admit to a new examination; 3/ exceptions of suspicion and other cases against the auditors of the Roman Rota for acts done in the exercise of their function; 4/ conflicts of competence mentioned in can. 1416.
§2. This tribunal deals with conflicts which have arisen from an act of ecclesiastical administrative power and are brought before it legitimately, with other administrative controversies which the Roman Pontiff or the dicasteries of the Roman Curia bring before it, and with a conflict of competence among these dicasteries.
§3. Furthermore it is for this supreme tribunal: 1/ to watch over the correct administration of justice and discipline advocates or procurators if necessary; 2/ to extend the competence of tribunals; 3/ to promote and approve the erection of the tribunals mentioned in cann. 1423 and 1439.
Source: Code of Canon Law (Vatican.va)