Q. 1. Other than a priest, can anyone else preach a homily at Mass?
A. 1. According to the Code of Canon Law # 767, only an ordained minister, meaning a bishop, priest or deacon, may preach the homily at Mass.
The following Codes apply to this matter:
# 762 Sacred ministers, among whose principal duties is the proclamation of the gospel of God to all, are to hold the function of preaching in esteem since the people of God are first brought together by the word of the living God, which it is certainly right to require from the mouth of priests.
# 763 Bishops have the right to preach the word of God everywhere, including in churches and oratories of religious institutes of pontifical right, unless the local bishop has expressly forbidden it in particular cases.
# 764 Without prejudice to the prescript of can. 765, presbyters and deacons possess the faculty of preaching everywhere; this faculty is to be exercised with at least the presumed consent of the rector of the church, unless the competent ordinary has restricted or taken away the faculty or particular law requires express permission.
# 765 Preaching to religious in their churches or oratories requires the permission of the superior competent according to the norm of the constitutions.
# 766 Lay persons can be permitted to preach in a church or oratory, if necessity requires it in certain circumstances or it seems advantageous in particular cases, according to the prescripts of the conference of bishops and without prejudice to can. 767, §1.
# 767 §1. Among the forms of preaching, the homily, which is part of the liturgy itself and is reserved to a priest or deacon, is preeminent; in the homily the mysteries of faith and the norms of Christian life are to be explained from the sacred text during the course of the liturgical year.
# 767 §2. A homily must be given at all Masses on Sundays and holy days of obligation which are celebrated with a congregation, and it cannot be omitted except for a grave cause.
# 767 §3. It is strongly recommended that if there is a sufficient congregation, a homily is to be given even at Masses celebrated during the week, especially during the time of Advent and Lent or on the occasion of some feast day or a sorrowful event.
# 767 §4. It is for the pastor or rector of a church to take care that these prescripts are observed conscientiously.