I'm not exactly sure where this thread is going, but it appears that the original intent was, or at least the first question was asked, regarding the practice of the Byzantine Catholic Churches.
However, it is unfortunate that certain remarks were made regarding the what some have termed "quizzing the communicant" in the Orthodox Churches. Let us set the record straight.
In the Orthodox faith, regardless of what someone may have "observed" or "heard" or even "seen", eucharistic communion is reserved only for those who have joined themselves to the Orthodox faith through baptism and/or chrismatiobn, who attend an Orthodox Church, and who actively practice the Orthodox faith. There is no playing with words here. By Orthodox, I do not mean those who say that they are of "one mind" with the Orthodox faith or "accept" the Orthdoox faith, yet chose to be united to other Churches who are not Orthodox. I am speaking of what we all know to be the Orthodox Church.
Knowing that - there is a eucharistic discipline within the Orthodox faith. Communion is not an "open" affair. And even "membership" within the Church is not the only criteria for receiving communion (however, its the most essential creiterion). There are Orthodox Christians who may be under a ban, or have wrongly removed themselves from eucharistic communion, or have not received confession after being absent from communion for an extended period, or may have committed a grave sin. All of these situations imply that eucharistic communion is not permitted for those particular people.
Additionally, (obviously) those who are not of the Orthodox faith (see above), no matter how pious or Christian or well-intentioned they may be, are not permitted to receive the eucharist in an Orthodox Church. I do know that it happens, but it certainly is not a wide-spread occurrence. In fact, it is quite rare. There may also be certain (very few) geographical areas in the world where both Orthodox and Eastern-Rite Catholics reside and the Eastern-Rite Catholics seem to recieve in an Orthodox Church with much more freedom, however, this is clearly not the norm, and nothing should be implied regarding the normal practice of the Orthodox Church in noting these exceptions.
That being said, as a parish priest in America, where the congregatations are relatively small (in comparison to say, Russia, where 3,000 people at a liturgy is commonplace, and the overwhleming majority of people are Orthodox) I will tell you that, due to the plethora of heterodox religious experessions, the large number of seekers and inaquirers to Orthodoxy, as well as a few people who are not Orthodox but feel it is their "right" to receive in an Orthodox Church, the great majority, not all, but the great majority of Orthodox priests in America WILL ask you who you are and if you are Orthodox, if they do not recognize you. If they don't, then they don't.
Priests are given a charge when they are ordained. They are given the Lamb and told to "guard it." Here's what the bishop said to me when I was ordained and he handed me the Lamb: "Receive this pledge, and preserve it whole and unharmed until your last breath, becuase you will be held to an accounting therefore at the second and awesome coming of our great Lord, God, and Savior, Jesus Christ."
The idea of asking someone if they are Orthodox at the chalice may sound to someone to be rude or crude or unloving or intolerant or whatever... but I assure you that sometimes, it is necessary. I do ask, if I do not recognize someone, (and they have not had the wherewithall to announce their presence beforehand and make their intention to receive known, beucase this, in fact, is the norm). It doesn't mean that I'm mean or nasty or unwelcoming. I'm actually a very nice person.

However, I am also reminded of the Lord's saying about giving holy things to those who are not able to receive them (Mt 7:6) and of my own pledge to my bishop before God Himself to be held accountable for that same Lamb.
Since it is my new policy to quote some article or source which will confirm or support what I've said (in otherwise dubious circumstances) using some well-known authoritative source or writer, here's an article by Fr. Thomas Hopko, former dean of St. Vladimir's Seminary, professor of dogmatic theology, and author of numerous books on Orthodoxy regarding Eucharistic Discipline:
http://www.svots.edu/Events/Orthodox-Education-Day/Articles/2000-Fr-Thomas-Hopko.html Eucharistic Discipline in the Orthodox Church
People of whatever convictions -- theistic or atheistic, Christian or non-Christian -- who behave in an orderly and respectful manner may attend liturgical services in an Orthodox church, and participate, as possible, in the prayers and rituals (such as singing psalms and hymns, and venerating icons and relics). But only members of the Orthodox Church who practice a specific spiritual discipline may participate in the Church�s sacraments and receive holy communion at the Orthodox divine liturgy. The essential elements of eucharistic discipline in the Orthodox Church may be simply stated in five points.
Participation in Holy Communion in the Orthodox Church requires first of all that a person be a baptized, chrismated member of the Orthodox Church who fully accepts the conditions and demands of his or her baptism and chrismation. Eucharistic discipline in the Orthodox Church demands that communicants in the eucharistic sacrifice understand themselves at all times and in all circumstances as having died and risen with Christ, as sealed by the Holy Spirit, and as belonging to God as His bonded-servants and free-born sons in Jesus.
Baptism and chrismation, and so, participation in holy communion, require a person to believe in the Word of God, the Gospel of Christ, and the Christian Faith summarized in the Nicene-Constantinopolitan creed, as these are proclaimed and interpreted in the Orthodox Church. Members of the Orthodox Church who question biblical or churchly doctrines may participate in holy communion if they are praying and working to come to an enlightened understanding of the Faith under the guidance of their pastors and teachers. But those who have been baptized and chrismated in the Orthodox Church who publicly express doubt and disbelief about the faith as confessed and lived in the Orthodox Church, or secretly harbor such doubt and disbelief, may not partake of holy communion at an Orthodox divine liturgy.
Confessing the Christian faith as understood and practiced in the Orthodox Church is to identify fully with Orthodox Church history and tradition, and to take full responsibility for it. It is to accept and defend the dogmas and canons of the councils accepted by the Orthodox Churches, to worship according to Orthodox liturgical rites, to venerate those who are glorified as Orthodox saints, and to struggle to practice the ethical and moral teachings of Christ and his apostles as recorded in the holy scriptures and elaborated in Orthodox Church tradition. Because participation in the holy Eucharist is not only a sacred communion with God through Christ and the Holy Spirit, but also a holy communion with Orthodox believers of all times and places, responsibility for the whole of Orthodox Church history and tradition is an absolute condition for partaking in the holy communion of Christ�s body and blood at the Church�s divine liturgy.
Identifying fully with Orthodox Christian teaching and practice requires a communicant in the Orthodox Church to strive to put the Church�s biblical, evangelical and apostolic teachings into practice in their everyday lives. No one can believe and do everything perfectly. Eucharistic discipline, however, demands that a communicant struggles to do so, admitting when he or she fails, and repenting without self-justification over one�s failures and sins. This means, concretely, that eucharistic discipline requires a communicant to study God�s Word in scripture, to pray and fast and give alms as one can, to attend church services as regularly as possible, and to live according to God�s commandments in all aspects of one�s life and work, regularly giving an account of one�s behavior to one�s pastor and spiritual guide, repenting of one�s sins, and struggling by God�s grace to change and improve. Persons rejecting such a disciplined life may not partake of Holy Communion in the Orthodox Church.
Eucharistic discipline in the Orthodox Church finally requires that a communicant be in constant repentance, realizing that he or she is never worthy of receiving holy communion, and knowing that the heartfelt confession of one�s unworthiness is an absolute condition for partaking in a worthy manner. The essential expression of one�s unworthiness to receive Christ�s body and blood in Holy Communion, with the admission of one�s sins, is the forgiveness of others. Eucharistic discipline demands that communicants of Christ�s body and blood be at peace with everyone as far as they can be, even when others are unwilling to forgive and be reconciled. At least within themselves, partakers of Holy Communion at an Orthodox Divine Liturgy must be in a union of love with all people, including their worst enemies.
Acceptance of one�s baptism and chrismation in the Church, responsibility for the Church�s faith and life, the struggle to put the faith fully into practice, accountability for one�s personal belief and behavior, constant and continual repentance, and peace with all people in the union of love commanded and given by God in Christ and the Holy Spirit -- these are the requirements for participation in holy communion in the Orthodox Church. They are, ultimately and essentially, what Holy Communion itself is all about.
Priest Thomas Soroka
St. Nicholas Orthodox Church [
stnicholas-oca.org]
McKees Rocks, PA