Wow, I really wish folks would read the sticky notes at the top of these forums - there’s one that specifically addresses this issue. The communion line is for communion, not for blessings. Here’s an excerpt from the sticky (my bold emphasis added):
First Mary, thank you for sharing this and bringing it to our attention. However, there are some things I think that likewise need to be emphasized in this context:
This Congregation for Divine Worship and the Disciple of the Sacraments acknowledges receipt of your kind letter of 13 August, 2008 and would like to thank you for your interest and suggestions.
This matter is presently under the attentive study of the Congregation.
For the present, therefore, this Dicastery wishes to limit itself to the following observations:
The liturgical blessing of the Holy Mass is properly given to each and to all at the conclusion of the Mass, just a few moments subsequent to the distribution of Holy Communion.
Lay people, within the context of Holy Mass, are unable to confer blessings. These blessings, rather, are the competence of the priest (cf. Ecclesia de Mysterio, Notitiae 34 (15 Aug. 1997), art. 6, § 2; can. 1169, § 2; and Roman Ritual De Benedictionibus (1985), n. 18).
Furthermore,** the laying on of a hand or hands** – which
has its own sacramental significance, inappropriate here – by those distributing Holy Communion, in substitution for its reception,
is to be explicitly discouraged.
The Apostolic Exhortation Familiaris Consortio, n. 84, “forbids any pastor, for whatever reason to pretext even of a pastoral nature,
to perform ceremonies of any kind for divorced people who remarry.” To be
feared is that any form of blessing in substitution for communion would give the impression that the divorced and remarried have been returned, in some sense, to the status of Catholics in good standing.
In a similar way,** for others who are not to be admitted to Holy Communion in accord with the norm of law**, the Church’s discipline has already made clear that they should not approach Holy Communion nor receive a blessing. This would include
non-Catholics and those envisaged in
can. 915 (i.e.,
those under the penalty of excommunication or interdict, and
others who obstinately persist in manifest grave sin).
So the issue is under investigation (“under attentive study”) and these norms were given by the CDF. What they are obviously worried about is giving the wrong message and confusing sacramental signs, especially the laying on of hands. Moreover, they make it plain that in the liturgical context blessings should only be performed by
priests.
The other stipulations are all of them quite grave: we are talking about the excommunicated here. The concern is that those who are not fully incorporated into the body of Christ would be perceived as being so incorporated. This is not the same as the person who was unable or simply failed to fast, in accordance with the Church’s discipline, for instance, before Mass. I doubt that necessarily counts as those “who obstinately persist in manifest grave sin”.
In other words, if I were Nancy Pelosi, I would be worried this might apply. If I were someone who was in the pew at Mass and suddenly became conscious of a sin, possibly grave - or even while waiting in line to receive Holy Communion - then I would not be so worried.