I think we should clarify the difference between denying communion and excommunication. A priest can't excommunicate anyone, only bishops can do this. He can refuse the chalice to someone.
The priest's job is to pastor his parish and take care of his flock. If, for example, he knows a person is unrepentant and willfully sinning, he should not commune them. But he's not omniscient. If anything this whole discussion is an exercise in the examining the intermittent practice of priests only communing people they know in their parish, or at least inquiring before communion. Difficult, messy during Liturgy? Perhaps.
A bishop's job on the other hand is to pastor his episcopate and take care of his (larger) flock. The bishop can and should make judgments on matters such as this. This is why the Orthodox liturgy prays for the episcopate to rightly divide the word of Christ's Truth (and then for the priesthood and diaconate separately).
St Ambrose wrote in a letter:
quote:
If it were a civil cause the right of reply would be reserved for the opposing party; it is a religious cause, and I the bishop make a claim...Certainly if anything else is decreed, we bishops cannot contentedly suffer it and take no notice; you indeed may come to the church, but will find either no priest there, or one who will resist you.
And another letter:
quote:
When have you heard, most gracious Emperor, that laymen gave judgment concerning a bishop in a matter of faith? Are we so prostrate through the flattery of some as to be unmindful of the rights of the priesthood, and do I think that I can entrust to others what God has given me? If a bishop is to be taught by a layman, what will follow? Let the layman argue, and the bishop listen, let the bishop learn of the layman. But undoubtedly, whether we go through the series of the holy Scriptures, or the times of old, who is there who can deny that, in a matter of faith,in a matter I say of faith,bishops are wont to judge of Christian emperors, not emperors of bishops.
Would that we had a St Ambrose today to judge our "emperors" or a St John Chrysostom to homily to both Empresses (like Eudoxia) and the laity alike.