Some time ago I read a leaflet, which explained that Pope Benedict started to distribute Holy Communion on the tongue and kneeling only. He has done this to promote greater reverence toward the Eucharist, and to help the communicants to express with the external posture the internal attitude that ought to be present in the believer. Sometimes I go to the Traditional Mass, where Communion is only given in this way, and also I used to attend the Novus Ordo with a community where it was the custom too, so it was nothing new to me, but it was phrased with such simplicity and such beauty that it really struck me. If I really believe that the Creator of the universe and the Savior of mankind is coming to me, what other posture can I assume? It got me thinking not only about kneeling for Communion, but my whole attitude during mass. Isn't the Blessed Trinity, Father, Son and Holy Spirit the most important thing in my life? If yes, then isn't mass the best thing I can offer to God?
Unfortunately it is very rare to see real reverence and love for Christ in the Eucharist. To receive Christ in hand and standing has become the norm. Do we not contradict ourselves in saying "Lord, I am not worthy that you should enter under my roof" and then going up to communicate without making any outward sign of acknowledgment of the Son in the Eucharist? Crossing ourselves? Genuflecting? Bowing? I decided that I would kneel down to receive Communion from then on.
I did not have to wait for long to be corrected.
Once when I went up to receive the Lord and knelt down the priest refused to give me Communion. He instructed me to stand up, which I did for peace's sake, but it would be hard to describe the way I felt. The worst thing was that after mass the priest came to me and started to correct me as if there was a problem with me. Was he not aware of what the Church officially prescribes regarding this matter?
The General Instruction of the Roman Missal deals with the posture for Holy Communion in no.160. The English translation has already been adapted to the specific countries, and the norm of the United States is to receive Communion standing, "unless an individual member of the faithful wishes to receive Communion while kneeling" (GIRM 160). The original Latin text says that the faithful will receive Communion standing or kneeling, as it has been established by the Episcopal Conference.
Little known is the fact that the Episcopal Conference can only establish the preferred way. If the bishops of a country want standing to be established as the preferred way, they need to refer the matter to the Holy See, which needs to approve the request. This is only done on the condition that the faithful remain free to kneel for Communion if they wish to.
I have done a little research, and I came across some clarification given by Cardinal Arinze. He deals with this question with great clarity and, as the Prefect of the Congregation for Divine Worship and the Discipline of Sacraments, with authority also.