109 Wherefore We exhort you, Venerable Brethren, that each in his diocese or ecclesiastical jurisdiction supervise and regulate the manner and method in which the people take part in the liturgy, according to the rubrics of the missal and in keeping with the injunctions which the Sacred Congregation of Rites and the Code of canon law have published. Let everything be done with due order and dignity, and let no one, not even a priest, make use of the sacred edifices according to his whim to try out experiments. It is also Our wish that in each diocese an advisory committee to promote the liturgical apostolate should be established, similar to that which cares for sacred music and art, so that with your watchful guidance everything may be carefully carried out in accordance with the prescriptions of the Apostolic See.
Source: Mediator Dei (Vatican.va)