Can. 764 Without prejudice to the prescript of can. 765, presbyters (priests) 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 (bishop of the local diocese) has restricted or taken away the faculty or particular law requires express permission.
Code of Canon Law of the Latin Church (proper term for Roman Catholic Church)
Are the lay allowed to preach in the Latin Church?
If necessity requires it in certain circumstances or it seems useful in particular cases, the diocesan bishop can admit lay faithful to preach, to offer spiritual conferences or give instructions in churches, oratories or other sacred places within his diocese, when he judges it to be to the spiritual advantage of the faithful.
In order to assist the diocesan bishop in making an appropriate pastoral decision (Interdicasterial Instruction, Ecclesiae de Mysterio, Article 2 §3), the following circumstances and cases are illustrative: the absence or shortage of clergy, particular language requirements, or the demonstrated expertise or experience of the lay faithful concerned.
The lay faithful who are to be admitted to preach in a church or oratory must be orthodox in faith, and well-qualified, both by the witness of their lives as Christians and by a preparation for preaching appropriate to the circumstances.
The diocesan bishop will determine the appropriate situations in accord with canon 772§1. In providing for preaching by the lay faithful the diocesan bishop may never dispense from the norm which reserves the homily to the sacred ministers (c. 767§1; cfr. Pontifical Commission for the Authentic Interpretation of the Code of Canon Law, 26 May 1987, in AAS 79 , 1249). Preaching by the lay faithful may not take place within the Celebration of the Eucharist at the moment reserved for the homily.
As President of the United States Conference of Catholic Bishops, I hereby decree that the effective date of this decree for all the dioceses of the Latin Church in the United States will be January 15, 2002.
Given at the offices of the United States Conference of Catholic Bishops in Washington, DC, on December 13, 2001.
Most Reverend Wilton D. Gregory
Bishop of Belleville
Reverend Monsignor William P. Fay