The question came up recently with a deacon candidate, so I thought it would be useful to post some information on the subject.
The short answer is: no.
For a longer answer, here’s Paul Matenaer from the Diocese of Madison:
In 2008, the Congregation for Divine Worship and the Discipline of the Sacraments received a letter asking precisely this question. The congregation responded in a private reply with five observations on why this practice is not permitted.
But first, let me note that even though private replies do not have the force of universal law, they typically (and this one especially) contain an excellent analysis and resolution of the issue, giving us a unique look at the practice of the Roman Curia. In other words, this private reply is persuasive not by reason of authority but by the authority of right reason, to which every well-intentioned Catholic should submit. Here are their five observations:
The Congregation for Divine Worship points out in their first observation that the liturgical blessing of the Mass is given to everyone gathered in the church just a few moments after the distribution of Holy Communion. This occurs when the priest, making the sign of the cross, says, “May Almighty God bless you, the Father, and the Son, and the Holy Spirit.”
In other words, there is no need to bless only some members of the congregation (e.g. children and non-Catholics) during communion, when the entire congregation is blessed by the priest just moments later.
In the second observation, we are reminded that within the context of Mass, blessings are the competency of the priest, not lay persons. Article 18 of the Book of Blessings notes that even though lay persons may give some blessings, “whenever a priest or deacon is present, the office of presiding [over a blessing] should be left to him.”
A 1997 instruction, Ecclesia de Mysterio, on the collaboration of the lay faithful further indicates that the laity should never say prayers or perform actions during the Mass which are proper to the priest, as this may lead to a confusion of roles. Since the blessing of the congregation during Mass is reserved to the priest, lay persons must avoid doing so.
The third observation addresses the practice in some places where the EMHC lays hands on a member of the congregation as a sign of blessing. The private reply states that this practice “is to be explicitly discouraged” because the laying on of hands has its own “sacramental significance” which is inappropriate here. The Catechism notes that since this specific sign commonly accompanies the administration of sacraments (e.g. Confirmation) and the succession of the apostles, the laying on of hands must not be used here.
Finally, in the fourth and fifth observations, the private reply notes there are some who should neither approach Holy Communion nor receive a blessing. This would include non-Catholics and those mentioned in canon 915 of the Code of Canon Law, such as those under the penalty of excommunication and those persisting in manifest grave sin. Giving a blessing to these persons might give the impression that they are in full communion with the Church or have returned to good standing. In order to avoid the possibility of scandal, EMHCs should not give blessings.
Finally, even though the private reply does not specifically mention this, we ought to recall that “no one may on a personal initiative add to or omit or alter anything in [liturgical] books” as canon 846 of the Code of Canon Law clearly states. Nowhere in the Roman Missal or the GIRM are the extraordinary ministers of Holy Communion instructed to bless those unable to receive communion; therefore, this practice of blessing is one of these additions to the rite which is strictly prohibited.
He has more to say about the subject here.
And canon lawyer Ed Peters has addressed the topic, as well:
Lay ministers of holy Communion (by definition, extraordinary ministers thereof), in response to people approaching them without the intention to receive Communion (maybe such folks are non-Catholics or are Catholic kids prior to First Communion), currently do one of three things: they (1) speak and gesture a sign of the cross over such folks, or (2) lay hands on such persons’ heads or shoulders while voicing a blessing, or (3) waive the Eucharist over them while purporting to confer a blessing. I think all three actions are liturgical abuses.
Let’s consider them in order of gravity:
1. Blessing the faithful with the Most August Sacrament is expressly reserved to the ordained. Lay persons may not confer any blessings with the Host (Eucharistic worship outside of Mass nn. 91, 97-99, and 1983 CIC 1168). This practice should therefore be immediately halted wherever it has cropped up.
2. Touching many persons’ hair, faces, and/or garments while serving food (albeit divine Food) to the public has to be a violation of some health and safety regulation somewhere, not to mention its being poor manners. If the swine flu makes distribution from a common Cup an issue, surely touching hair and heads while serving others food from a common Plate is a problem. This particular practice should therefore be halted promptly, regardless of what one might think about lay blessings during Mass.
3. Ministers of holy Communion have, I suggest, no authority by their office to confer any sort of blessing on anyone. Neither the General Instruction on the Roman Missal nor the Book of Blessings (which later source makes provisions for laity to administer certain blessings) authorizes ministers of Communion to confer blessings during Mass. Given that lay persons serving as extraordinary ministers of holy Communion have no liturgical duties besides the administration of Communion, the introduction of a mini-blessing rite to be performed by them seems to me a plain violation of Canon 846. This practice should, I think, be halted pending a study of its liceity by qualified persons and, if appropriate, its authorization by the competent authority (1983 CIC 838,1167).
In brief, I suggest that lay ministers of holy Communion have no authority to bless anyone in Communion lines, they should refrain from touching people while distributing holy Communion, and they should immediately cease using the Blessed Sacrament for mini-Benediction rites.
UPDATE: Several years ago, Archbishop Charles Chaput offered one helpful solution to this problem. Read all about it.