I am from the generation where we were to kneel until the tabernacle door was shut. I remember it quite vividly because of being an altar boy in ancient of days.
The rule has changed. The norm now says the posture is to stand. Paragraph 43 of the GIRM, with the special provision for the United States, reads:
43. The faithful should stand from the beginning of the Entrance Chant, or while the Priest approaches the altar, until the end of the Collect; for the Alleluia Chant before the Gospel; while the Gospel itself is proclaimed; during the Profession of Faith and the Universal Prayer; and from the invitation, Orate, fratres (Pray, brethren), before the Prayer over the Offerings until the end of Mass, except at the places indicated here below.
The faithful should sit, on the other hand, during the readings before the Gospel and the Responsorial Psalm and for the Homily and during the Preparation of the Gifts at the Offertory;
and, if appropriate, they may sit or kneel during the period of sacred silence after Communion.
In the Dioceses of the United States of America, they should kneel beginning after the singing or recitation of the Sanctus (Holy, Holy, Holy) until after the Amen of the Eucharistic Prayer, except when prevented on occasion by ill health, or for reasons of lack of space, of the large number of people present, or for another reasonable cause. However, those who do not kneel ought to make a profound bow when the Priest genuflects after the Consecration. The faithful kneel after the Agnus Dei (Lamb of God) unless the Diocesan Bishop determines otherwise.[53]
For the sake of uniformity in gestures and bodily postures during one and the same celebration, the faithful should follow the instructions which the Deacon, a lay minister, or the Priest gives, according to what is laid down in the Missal.
A problem arose because the “period of sacred silence” is mentioned in the GIRM as related to the moment when the priest presiding returned to the presider’s chair and thus interpreted what was prior to that (the Communion procession) as requiring everyone to be standing. In other words, the gesture of those returning from receiving Communion was only to be standing. As a result, certain geographical areas began enforcing this posture with an unbridled zeal because “the rule” was being broken.
This exchange may help to clarify:
*The July 2003 Newsletter of the Bishops Committee on the Liturgy (BCL) [this is the United States] noted the "controversy … over the proper posture of the faithful at Mass after receiving Holy Communion.
“In several dioceses people have been instructed that they must stand until the last person has received Communion, despite the long-standing custom that people knelt during the distribution of Communion”.
“Numerous inquiries” received by the BCL led Cardinal Francis George, chairman of the BCL, to submit a
dubium* (doubt, question) to the Holy See’s Congregation for Divine Worship and the Discipline of the Sacraments (CDW) on May 26, 2003:
Dubium: In many places, the faithful are accustomed to kneeling or sitting in personal prayer upon returning to their places after having individually received Holy Communion during Mass. Is it the intention of the
Missale Romanum, editio typica tertia, to forbid this practice?
Cardinal Francis Arinze, Prefect of the CDW, responded to the question on June 5, 2003 (Prot. N. 855/03/L):
Responsum: Negative, et ad mensum [No, for this reason]. The mens [reasoning] is that the prescription of the
Institutio Generalis Missalis Romani, no. 43, is intended, on the one hand, to ensure within broad limits a certain uniformity of posture within the congregation for the various parts of the celebration of Holy Mass, and on the other, to not regulate posture rigidly in such a way that those who wish to kneel or sit would no longer be free.
The BCL Newsletter continues: “In the implementation of the General Instruction of the Roman Missal, therefore, posture should not be regulated so rigidly as to forbid individual communicants from kneeling or sitting when returning from having received Holy Communion”
From:
adoremus.org/0703Kneel.html
Personally, I think it is sad that this required the submission of a
dubium to the Congregation. As His Eminence, the Cardinal Prefect, says, this rule was never meant to be used as a blunt instrument to beat people with. There is a rule…a normative posture. If one chooses a different posture – presumably since we are talking about adults, they are doing so for some good reason – they should not be punished. That way of looking at enforcing a rule is rather disturbing, frankly.