Orientalium Ecclesiarum, subtitled the Decree on the Eastern Catholic Churches is one of the Second Vatican Council's 16 magisterial documents.
The decree recognizes the right of Eastern Catholics to keep their own distinct liturgical practices while remaining in full communion with the Holy See.
The decree exhorts Eastern Catholics to "take steps to return to their ancestral traditions."
In particular, the Patriarch (or where applicable, major archbishop) and synod have the power to establish eparchies, to nominate bishops within their patriarchate, to legislate the rights and obligations of the minor orders (including subdiaconate), and to determine the date for celebrating Easter within their rite.
The Preamble affirms the Church's respect for Eastern Catholics (§1): The Catholic Church holds in high esteem the institutions, liturgical rites, ecclesiastical traditions and the established standards of the Christian life of the Eastern Churches, for in them, distinguished as they are for their venerable antiquity, there remains conspicuous the tradition that has been handed down from the Apostles through the Fathers and that forms part of the divinely revealed and undivided heritage of the universal Church.The Individual Churches or Rites - “Each individual Church or Rite should retain its traditions whole and entire” but “should adapt its way of life to the different needs of time and place” (§2) - The individual Churches, whether Eastern or Western, are of equal dignity (§3) - Every Catholic must retain his own rite, cherish and protect it (§4) Preservation of the Spiritual Heritage of the Eastern Churches - “The Churches of the East, as much as those of the West, have a full right and are in duty bound to rule themselves, each in accordance with its own established disciplines” (§5) - All Eastern Churches may preserve their liturgical traditions and way of life, and if history has imposed changes on them, “they should take steps to return to their ancestral traditions” (§6) Eastern Rite Patriarchs - “The patriarchate, as an institution, has existed in the Church from the earliest times” (§7) - All patriarchs are of equal dignity (§8) - The rights and privileges of patriarchs “should be re-established in accordance with the ancient tradition of each of the Churches and the decrees of the ecumenical councils” (§9) - “The patriarchs with their synods are the highest authority for all business of the patriarchate”, subject to the Pope's right to intervene in individual cases (§9) - New patriarchates should be established where there is a need (§11) The discipline of the Sacraments (§12-18) is concerned with the regulation of the sacraments.