Part II, Article 6. Liturgical Celebration

§ 1. Liturgical actions must always clearly manifest the unity of the People of God as a structured communion.[89] Thus there exists a close link between the ordered exercise of liturgical action and the reflection in the liturgy of the Church's structured nature.

This happens when all participants, with faith and devotion, discharge those roles proper to them.

§ 2. To promote the proper identity (of various roles) in this area, those abuses which are contrary to the provisions of canon 907 are to be eradicated. In eucharistic celebrations deacons and non-ordained members of the faithful may not pronounce prayers - e.g. especially the eucharistic prayer, with its concluding doxology - or any other parts of the liturgy reserved to the celebrant priest. Neither may deacons or non-ordained members of the faithful use gestures or actions which are proper to the same priest celebrant. It is a grave abuse for any member of the non-ordained faithful to "quasi preside" at the Mass while leaving only that minimal participation to the priest which is necessary to secure validity.

In the same way, the use of sacred vestments which are reserved to priests or deacons (stoles, chasubles or dalmatics) at liturgical ceremonies by non-ordained members of the faithful is clearly unlawful.

Every effort must be made to avoid even the appearance of confusion which can spring from anomalous liturgical practices. As the sacred ministers are obliged to wear all of the prescribed liturgical vestments so too the non-ordained faithful may not assume that which is not proper to them.

To avoid any confusion between sacramental liturgical acts presided over by a priest or deacon, and other acts which the non-ordained faithful may lead, it is always necessary to use clearly distinct ceremonials, especially for the latter.