Redemptionis Sacramentum is the title of an instruction on the proper way to celebrated Mass in the Roman Rite and, with the necessary adjustments, in other Latin liturgical rites. It was issued by the Congregation for Divine Worship and the Discipline of the Sacraments on 25 March 2004. The text of the instruction is available on theHoly See's website.
As its reason for issuing the document, the Congregation stated: "It is not possible to be silent about the abuses, even quite grave ones, against the nature of the Liturgy and the Sacraments as well as the tradition and the authority of the Church, which in our day not infrequently plague liturgical celebrations in one ecclesial environment or another. In some places the perpetration of liturgical abuses has become almost habitual, a fact which obviously cannot be allowed and must cease."
The Congregation declared: "The Mystery of the Eucharist 'is too great for anyone to permit himself to treat it according to his own whim, so that its sacredness and its universal ordering would be obscured'. On the contrary, anyone who acts thus by giving free rein to his own inclinations, even if he is a Priest, injures the substantial unity of the Roman Rite, which ought to be vigorously preserved, and becomes responsible for actions that are in no way consistent with the hunger and thirst for the living God that is experienced by the people today. Nor do such actions serve authentic pastoral care or proper liturgical renewal; instead, they deprive Christ's faithful of their patrimony and their heritage. For arbitrary actions are not conducive to true renewal, but are detrimental to the right of Christ's faithful to a liturgical celebration that is an expression of the Church’s life in accordance with her tradition and discipline. In the end, they introduce elements of distortion and disharmony into the very celebration of the Eucharist, which is oriented in its own lofty way and by its very nature to signifying and wondrously bringing about the communion of divine life and the unity of the People of God."