The key document for identifying and delineating the administrative responsibilities of Dublin's two cathedrals is the ‘Composicio Pacis’. This ordinance, which was promulgated in 1300 by Archbishop Richard of Ferings (1299-1306) to quell the disputes that had raged between the rival chapters following St Patrick's acquisition of cathedral status, remained in force and regulated relations between the two bodies down to the sixteenth century and beyond.

In general, the ‘Composicio’ conceded the principle that, in matters of prestige and dignity, Christ Church as the ‘older’ and ‘mother’ church would take precedence. Thus all new archbishops were to be consecrated within the cathedral priory, provincial synods were to open and close there, while the ceremonial consecration of the sacred oils on Holy Thursday was to be performed by its clergy. In addition, the prior and convent were to retain custody of the archiepiscopal cross, mitre and ring during episcopal vacancies. They were also to be the first to cast their vote in meetings, such as provincial councils, in which both cathedrals were participating; and they were to take precedence in legal instruments, including documents recording the ratification of episcopal acta, in which the two churches appeared as parties.

Yet, despite the proliferation of detail in the document, the ‘Composicio’ is noticeably silent on the more substantial matters of diocesan administration. There is one simple reason for this. By the time it was drafted, Christ Church had already conceded that these matters would be the preserves of its rival, St Patrick's.