From the 2002 General Instruction of the Roman Missal (GIRM) approved for the USA, which can be accessed from
romanrite.com/girm.html :
“42. The gestures and posture of the priest, the deacon, and the ministers, as well as those of the people, ought to contribute to making the entire celebration resplendent with beauty and noble simplicity, so that the true and full meaning of the different parts of the celebration is evident and that the participation of all is fostered.52 Therefore, attention should be paid to what is determined by this General Instruction and the traditional practice of the Roman Rite and to what serves the common spiritual good of the People of God, rather than private inclination or arbitrary choice.
A common posture, to be observed by all participants, is a sign of the unity of the members of the Christian community gathered for the Sacred Liturgy: it both expresses and fosters the intention and spiritual attitude of the participants.”
“43. … With a view to a uniformity in gestures and postures during one and the same celebration, the faithful should follow the directions which the deacon, lay minister, or priest gives according to whatever is indicated in the Missal.”
From the 2004 Instruction Redemptionis Sacramentum:
"[90.] “The faithful should receive Communion kneeling or standing, as the Conference of Bishops will have determined”, with its acts having received the recognitio of the Apostolic See. “However, if they receive Communion standing, it is recommended that they give due reverence before the reception of the Sacrament, as set forth in the same norms”.[176]
[91.] In distributing Holy Communion it is to be remembered that “sacred ministers may not deny the sacraments to those who seek them in a reasonable manner, are rightly disposed, and are not prohibited by law from receiving them”.[177] Hence any baptized Catholic who is not prevented by law must be admitted to Holy Communion. Therefore, it is not licit to deny Holy Communion to any of Christ’s faithful solely on the grounds, for example, that the person wishes to receive the Eucharist kneeling or standing.
[92.] Although each of the faithful always has the right to receive Holy Communion on the tongue, at his choice,[178] if any communicant should wish to receive the Sacrament in the hand, in areas where the Bishops’ Conference with the recognitio of the Apostolic See has given permission, the sacred host is to be administered to him or her. However, special care should be taken to ensure that the host is consumed by the communicant in the presence of the minister, so that no one goes away carrying the Eucharistic species in his hand. If there is a risk of profanation, then Holy Communion should not be given in the hand to the faithful. [179]"
Here the instructions get confusing. No. 90 above seems to say clearly that Conference of Bishops can decide that people are to receive Communion standing (for example). Along with the encouragement for uniformity in posture in the GIRM this would seem to mean that everyone would then receive communion standing. So what is it trying to say in no. 91: “Therefore, it is not licit to deny Holy Communion to any of Christ’s faithful solely on the grounds, for example, that the person wishes to receive the Eucharist kneeling or standing.”
Here is my attempt to unravel what is being said. If a person is in a wheelchair they are not expected to stand. It goes without saying that they will receive communion while sitting.
What if a person has a mental disorder, a phobia about receiving Communion standing? For this reason should they be denied communion for the rest of their life? Perhaps no. 91 is saying this would be like denying communion to someone in a wheelchair.
So what might be the solution? Uniformity of posture is important. Accepting the authority of the Conference of Bishops is, as well. One person at a normal Mass receiving Communion kneeling would be disruptive, perhaps a dangerous tripping hazard. It would create confusion for others about what is the proper posture to receive communion.
So perhaps special arrangements could be made for the person with the phobia about receiving communion standing. A mass with only a priest, altar server and the person with the phobia. A communion service, like communion to the sick, so that the person with the phobia can receive communion.
