Excerpted from the June 2000 issue of U.S. Catholic.

A few years ago, my wife and I invited her parents to join us for Mass at our new parish. We had been happy to find that the parish we had recently moved into was an extraordinarily vibrant community that was widely known both for its diversity and its rich liturgies.

Shortly after we had settled into our pew, my Lutheran father-in-law poked me and pointed to the inside cover of the missalette he had started to read. "Well, that's a fine how-do-you-do," he grumbled as he showed me the boldfaced "Guidelines for Receiving Communion," which spelled out the letter of the (canon) law: "It is a consequence of the sad divisions in Christianity that we cannot extend to [non-Catholic Christians] a general invitation to receive Communion. . . . Reception of the Eucharist by Christians not fully united with us would imply a oneness which does not yet exist, and for which we must all pray."

The Catholic Church's strict rules against non-Catholics receiving the Eucharist in Catholic liturgies--and its even stricter rules against Catholics receiving Communion in non-Catholic liturgies--have been a source of great irritation, frustration, offense, and pain both for the many Catholics with family members in other Christian churches, and in Catholics' ecumenical relations with these churches.

The printed guidelines in the missalette are just the least of it. Consider the following real-life examples:

Over the past couple of years, several heads of state--including President Bill Clinton and Britain's prime minister, Tony Blair--made headlines for various entanglements with Catholic Communion regulations. When the Irish President Mary McAleese, a devout Catholic, received Communion in the Anglican Cathedral in Dublin two years ago, Irish bishops blasted her publicly. The archbishop of Dublin said it was a "sham" for Catholics to take Protestant Communion, implying that all Protestant Communion services were a sham.

Not a few Catholic priests during Mass on the high feasts of Christmas and Easter make a special point of reminding non-Catholic family members and visitors that they are not welcome at the Lord's table. Some presiders are so concerned about potentially "illicit" communers that even during funeral services and wedding celebrations, they issue stern warnings from the pulpit whenever they know that family members from other Christian denominations are present.

When it was time for Communion during the installation Mass for a Catholic bishop in Massachusetts, ushers were posted to guard the front pews to make sure the Episcopalian, Lutheran, Baptist, and other Protestant "honored guests" stayed in their places.

Few Catholics know that in the various post-Vatican II ecumenical dialogues between Catholics and Protestants a significant consensus has been reached on the theology of the Eucharist. The "sticking point" in the Catholic denial of eucharistic sharing is not, as many mistakenly assume, any substantial disagreement regarding the Real Presence but the official Catholic view that Protestant ministers have a "defect" in their ordination because of a Reformation-era break in the apostolic succession. The ecumenical dialogue with Protestant churches is currently stalled because of an unwillingness by the Catholic Church to act on some of the proposed ways to make a mutual recognition of ordination possible.

The Catholic Church's general prohibition of eucharistic sharing with Protestants is, of course, most acutely felt within the many mixed marriages today. According to a recent survey, close to 40% of all post-Vatican II Catholics are married to non-Catholics.

It is true that in recent years, the Catholic Church has made some cautious, limited steps toward opening up eucharistic sharing in the context of mixed marriages. A 1993 directory of the Pontifical Council for Promoting Christian Unity specifically recognized marriages between baptized Catholics and non-Catholics as instances of the "grave and pressing need" required by canon law for exceptional admission to Communion. And guidelines issued since then by the archbishop of Brisbane, Australia; the German bishops; and the South African Bishops' Conference have made pastoral provisions that under certain conditions allow non-Catholic spouses to receive Catholic Communion on a regular basis.

However, in most parts of the Catholic world, including the United States, many priests and bishops continue to deny any and all requests of mixed-marriage couples to receive Catholic Communion together. Furthermore, Catholics officially are still categorically forbidden from going to Communion in Protestant churches.

The main argument of the defenders of the restrictive Catholic practice is that a more open Communion would be dishonest, since it would imply a church unity that is not yet realized. Common worship and eucharistic sharing, the Second Vatican Council's Decree on Ecumenism said, "should signify the unity of the church," which is why it is ruled out when done "generally and indiscriminately." But the ecumenism decree also says that eucharistic sharing advances unity and that "the gaining of a needed grace sometimes commends" such sharing. Pope John Paul II, in his 1995 encyclical on ecumenism, Ut Unum Sint, notes as "a source of joy . . . that Catholic ministers are able, in certain particular cases, to administer the sacrament of the Eucharist . . . to Christians who are not in full communion with the Catholic Church."