Summary — The Codex Canonum Ecclesiarum Orientalium includes the pontifical jurisdiction common to all the Churches «sui iuris» of the Catholic East, but its legislation extends at times also to the Latin faithful. This had already been stated by the first canon of the last scheme of the Codex Iuris Canonici Orientalis, which dates back to 1948 and was put into practice in a number of canons of the sections promulgated by Pope Pius XII. The first part of the present study treats with the evolution of the text of the first canon of the scheme cico 1948 up to the definite formulation of canon 1 of cceo. According to this first canon, the Code concerns only the Catholic Oriental Churches, unless it declared explicitly, in the cases of relations with the Latin Church, of intending to bind it.The cases in which the principle of the explicit extension of the cceo is applied to the Latin Church are eight and these are dealt with in the second part of this study.This extentions of the Oriental Law to the Latin faithful can occur even in other cases in which they come in contact with Oriental Catholics, and these are the cases which refer to their canonical status or even certain inalienable rights; in the last part the author makes evident the relevance within the Latin Church of the juridical status of the Oriental faithful in the field of matrimonial law and that of religious. This third part concludes with some reflections on the duties of pastors — bishops and parish priests — toward the Oriental faithful entrusted to their care. The particular aspect of the normative term «oriental» elucidated in this study is well corroborated by the decision made by Pope John Paul II of offering the Codex to the Universal Church through its presentation at the Bishops' Synod.