“The homily…’should ordinarily be given by the Priest celebrant himself. He may entrust it to a concelebrating Priest or occasionally, according to circumstances, to a Deacon, but never to a layperson.” (no. 64).
“The prohibition of the admission of laypersons to preach within the Mass applies also to seminarians, students of theological disciplines, and those who have assumed the function of those known as ‘pastoral assistants’;*** nor is there to be any exception for any other kind of layperson, or group, or community, or association***” (no. 66)
“If the need arises for the gathered faithful to be given instruction or testimony by a layperson in a Church concerning the Christian life, it is altogether preferable that this be done outside Mass. Nevertheless,*** for serious reasons*** it is permissible that this type of instruction or testimony be given after the Priest has proclaimed the Prayer after Communion. This should not become a regular practice, however. Furthermore,*** these instructions and testimony should not be of such a nature that they could be confused with the homily, nor is it permissible to dispense with the homily on their account.***” (no. 74).
“the homily on account of its importance and its nature is reserved to the Priest or Deacon during Mass.” (no. 161)
“As regards*** other forms of preaching***,*** if necessity demands it*** in particular circumstances, or*** if usefulness suggests it*** in special cases, lay members of Christ’s faithful may be allowed to preach in a church or in an oratory outside Mass in accordance with the norm of law.” (no. 161)