Mediator Dei on the Vatican web site, for your reference.
The priest is the primary “performer” of rubrics and such, but in any event, Church authority is ultimately responsible for liturgy:
44. Since, therefore, it is the priest chiefly who performs the sacred liturgy in the name of the Church, its organization, regulation and details cannot but be subject to Church authority. This conclusion, based on the nature of Christian worship itself, is further confirmed by the testimony of history.
Why? Liturgy reflects doctrine, for one reason:
45. Additional proof of this indefeasible right of the ecclesiastical hierarchy lies in the circumstances that the sacred liturgy is intimately bound up with doctrinal propositions which the Church proposes to be perfectly true and certain, and must as a consequence conform to the decrees respecting Catholic faith issued by the supreme teaching authority of the Church with a view to safeguarding the integrity of the religion revealed by God.
One problem emphasized for the bishops, namely that doctrine is not judged through the liturgy:
46. On this subject We judge it Our duty to rectify an attitude with which you are doubtless familiar, Venerable Brethren. We refer to the error and fallacious reasoning of those who have claimed that the sacred liturgy is a kind of proving ground for the truths to be held of faith, meaning by this that the Church is obliged to declare such a doctrine sound when it is found to have produced fruits of piety and sanctity through the sacred rites of the liturgy, and to reject it otherwise. Hence the epigram, “Lex orandi, lex credendi” – the law for prayer is the law for faith.
The Mass, sacraments, and Divine Office are judged, as the public witness of the Catholic faith, to have the faith as its content:
47. But this is not what the Church teaches and enjoins. The worship she offers to God, all good and great, is a continuous profession of Catholic faith and a continuous exercise of hope and charity, as Augustine puts it tersely. “God is to be worshipped,” he says, “by faith, hope and charity.”[Enchiridion, c. 3] In the sacred liturgy we profess the Catholic faith explicitly and openly, not only by the celebration of the mysteries, and by offering the holy sacrifice and administering the sacraments, but also by saying or singing the credo or Symbol of the faith – it is indeed the sign and badge, as it were, of the Christian – along with other texts, and likewise by the reading of holy scripture, written under the inspiration of the Holy Ghost. The entire liturgy, therefore, has the Catholic faith for its content, inasmuch as it bears public witness to the faith of the Church.
In the post-conciliar era, do you think this is still emphasized, recognized, or in some corners, hoped that it wouldn’t be noticed?
Catholic Sensibility 