Because it has a synodical system canonically, it is significantly distinguished from the hierarchically organized Catholic Church, whose doctrine is papal supremacy and whose head is the pope.

[7][8][9][10] The ecumenical patriarch of Constantinople is the direct administrative superior of dioceses and archdioceses serving millions of Greek, Ukrainian, Rusyn and Albanian believers in North and South America, Western Europe, Australia and New Zealand, South Korea, as well as parts of modern Greece which, for historical reasons, do not fall under the jurisdiction of the Church of Greece.

Athos, officially the "Autonomous Monastic State of the Holy Mountain" (Ancient Greek: Αυτόνομη Μοναστικὴ Πολιτεία Ἁγίου Ὄρους), is a self-governed polity within the Greek state subject to the Ministry of Foreign Affairs in its political aspect and to the ecumenical patriarch of Constantinople as regards to its religious aspect[14] and is home to 20 monasteries and numerous other monastic communities.

This primacy, expressed in canonical literature as presbeia ("prerogatives", literally: "seniorities"), grants to the ecumenical patriarch the right to preside at pan-Orthodox synods.

Additionally, the canonical literature of the Orthodox Church grants to the ecumenical patriarch the right to hear appeals in cases of dispute between bishops.

Such a title is acceptable if it refers to this unique role, but it sometimes leads to the mistaken belief that the office is thus the equivalent of an Orthodox pope.

[18] According to Lumen Gentium, the patriarch is a validly consecrated bishop in Roman ecclesiology, and there is merely an imperfect ecclesial communion between Constantinople and Rome, which exists nevertheless and which may be improved at some point in history.

After Constantine the Great had enlarged Byzantium to make it into a second capital city in 330, it was thought appropriate that its bishop, once a suffragan of the Exarch of Thrace and Macedonia, the Metropolitan of Heraclea, should be elevated to an archbishopric.

[20] For many decades the heads of the church of Rome opposed this ambition, due to their existing papal claims, and because they defended the 'Petrine principle' by which all Patriarchates were derived from Saint Peter and were unwilling to violate the old order of the hierarchy for political reasons.

The patriarch was designated millet-başı (ethnarch) of the Millet of Rum, which included all Orthodox Christians under Ottoman rule, regardless of their ethnicity in the modern sense.

This role was carried out by ethnic Greeks at their great peril, in the midst of enormous difficulties and traps[citation needed] and inevitably with mixed success.

Several patriarchs were summarily executed by the Ottoman authorities, most notably Gregory V, who was lynched on Easter Monday 1821 in revenge for the outbreak of the Greek Revolution.

Human rights groups have long protested against conditions placed by the secular government of Turkey on the ecumenical patriarch, a religious office.

For example, the ecumenical status accorded him traditionally within Eastern Orthodoxy, and recognized previously by the Ottoman governments, has on occasion been a source of controversy within the Republic of Turkey.

This policy results in problems in the function of the patriarchate, since clergy coming from abroad are not eligible to apply for residence and work permits.

[23][better source needed] Expropriation of Church property and the conditions of state control imposed on the Orthodox Theological School of Halki that have led to its closure by the Patriarchate, are also cited by human rights groups.