An ordinary (from Latin ordinarius) is an officer of a church or civic authority who by reason of office has ordinary power to execute laws.
Such officers are found in hierarchically organised churches of Western Christianity which have an ecclesiastical legal system. For example, diocesan bishops are ordinaries in the Roman Catholic Church and the Church of England. In Eastern Christianity, a corresponding officer is called a hierarch (from Greek hierarkh?s "president of sacred rites, high-priest" which comes in turn from ? ta hiera, "the sacred rites" and ? arkh?, "I rule").
In canon law, the power to govern the church is divided into the power to make laws (legislative), enforce the laws (executive), and to judge based on the law (judicial). An official exercises power to govern either because he holds an office to which the law grants governing power or because someone with governing power has delegated it to him. Ordinary power is the former, while the latter is delegated power. The office with ordinary power could possess the governing power itself (proper ordinary power) or instead it could have the ordinary power of agency, the inherent power to exercise someone else's power (vicarious ordinary power).
The law vesting ordinary power could either be ecclesiastical law, i.e. the positive enactments that the church has established for itself, or divine law, i.e. the laws which the church believes were given to it by God. As an example of divinely instituted ordinaries, Catholics believe that when Jesus established the Church, he also established the episcopate and the primacy of Peter, endowing the offices with power to govern the Church. Thus, in the Catholic Church, the office of successor of Simon Peter and the office of diocesan bishop possess their ordinary power even in the absence of positive enactments from the Church.
Many officers possess ordinary power but, due to their lack of ordinary executive power, are not called ordinaries. The best example of this phenomenon is the office of judicial vicar, a.k.a. officialis. The judicial vicar only has authority through his office to exercise the diocesan bishop's power to judge cases. Though the vicar has vicarious ordinary judicial power, he is not an ordinary because he lacks ordinary executive power. A vicar general, however, has authority through his office to exercise the diocesan bishop's executive power. He is therefore an ordinary because of this vicarious ordinary executive power.
Also classified as local ordinaries, although they do not head a particular church or equivalent community are:
In the Orthodox Church, a hierarch (ruling bishop) holds uncontested authority within the boundaries of his own diocese; no other bishop may perform any sacerdotal functions without the ruling bishop's express invitation. The violation of this rule is called eisp?d?sis (Greek, "trespassing", literally "jumping in"), and is uncanonical. Ultimately, all bishops in the Church are equal, regardless of any title they may enjoy (Patriarch, Metropolitan, Archbishop, etc.). The role of the bishop in the Orthodox Church is both hierarchical and sacramental.
This pattern of governance dates back to the earliest centuries of Christianity, as witnessed by the writings of Ignatius of Antioch (c. 100 AD):
The bishop in each Church presides in the place of God.... Let no one do any of the things which concern the Church without the bishop.... Wherever the bishop appears, there let the people be, just as wherever Jesus Christ is, there is the Catholic Church.
The episcopate is a single whole, in which each bishop enjoys full possession. So is the Church a single whole, though it spreads far and wide into a multitude of churches and its fertility increases.
Bishop Kallistos (Ware) wrote:
There are many churches, but only One Church; many episcopi but only one episcopate."
In Orthodox Christianity, the church is not seen as a monolithic, centralized institution, but rather as existing in its fullness in each local body. The church is defined Eucharistically:
in each particular community gathered around its bishop; and at every local celebration of the Eucharist it is the whole Christ who is present, not just a part of Him. Therefore, each local community, as it celebrates the Eucharist ... is the church in its fullness."
This is not to say that the Orthodox Church has a Congregationalist polity; on the contrary, the local priest functions as the "hands" of the bishop, and must receive from the bishop an antimension and chrism before he is permitted to celebrate any of the Sacred Mysteries (sacraments) within the diocese.
An Orthodox bishop's authority comes from his election and consecration. He is, however, subject to the Sacred Canons of the Orthodox Church, and answers to the Synod of Bishops to which he belongs. In case an Orthodox bishop is overruled by his local synod, he retains the right of appeal (Greek?, Ékkl?ton) to his ecclesiastical superior (e.g. a Patriarch) and his synod.