When Mary therefore was come where Jesus was, seeing him, she fell down at his feet...(John 11:32a).
Is it contrary to liturgical law to receive Holy Communion at an altar rail in the renewed postconciliar Mass?
It is not. The USCCB has given norms directing the faithful in the United States to receive Holy Communion standing and on the hand in the renewed postconciliar Mass, but the documents do not prohibit receiving Holy Communion according to these norms at an altar rail. Archbishop Aymond has given permission for the use of the altar rail at Our Lady of the Holy Rosary Church in Hahnville.
At the same time, Holy Mother Church allows for the reception of Holy Communion kneeling and on the tongue, which is quite difficult and unsafe to do with a communicant kneeling on the floor without the aid of a kneeler of some sort. Since the altar rail is usually fixed (ours is not fixed but just quite long and heavy), the communicant who chooses to kneel to receive Holy Communion will not have to worry that the rail will slide, and it will also help them to return to standing should they need the assistance.
Why use an altar rail?An altar rail is an invitation to receive Our Lord from the altar, which is the Cross. Our Blessed Lord reaches across the chasm between heaven and earth and communicates Himself to us, whether we are standing or kneeling. Receiving at an altar rail has the added benefit of allowing us to receive next to each other, recalling that being in Holy Communion with God allows us to be in Holy Communion with all Catholics in sanctifying grace and praying for those receiving unworthily or who do not yet believe.
How to receive at an altar rail?
When it is time for the reception of Holy Communion, the faithful are welcome to process to the altar rail and fill in any empty space from the Epistle side to the Gospel side (right to left). As soon as the communicant has received Our Lord, they are invited to return to their pew not waiting for everyone else at the rail. As soon as there is a vacated space, the next person in line is invited to fill it.
Where can I learn more?
For an excellent article on this topic, read "The Deeper Meaning of Receiving at the Altar Rail" by Susanna Spencer in the National Catholic Register.
For a more theological and historical perspective on the theology of kneeling, read an excerpt from Pope Benedict's chapter "The Body and the Liturgy" from The Spirit of the Liturgy, which is reprinted with permission in the Adoremus publication.