The Church has further used her right of control over liturgical observance to protect the purity of divine worship against abuse from dangerous and imprudent innovations introduced by private individuals and particular churches. Thus it came about – during the 16th century, when usages and customs of this sort had become increasingly prevalent and exaggerated, and when private initiative in matters liturgical threatened to compromise the integrity of faith and devotion, to the great advantage of heretics and further spread of their errors – that in the year 1588, Our predecessor Sixtus V of immortal memory established the Sacred Congregation of Rites, charged with the defence of the legitimate rites of the Church and with the prohibition of any spurious innovation. This body fulfils even today the official function of supervision and legislation with regard to all matters touching the sacred liturgy.
58. It follows from this that the Sovereign Pontiff alone enjoys the right to recognize and establish any practice touching the worship of God, to introduce and approve new rites, as also to modify those he judges to require modification. Bishops, for their part, have the right and duty carefully to watch over the exact observance of the prescriptions of the sacred canons respecting divine worship. Private individuals, therefore, even though they be clerics, may not be left to decide for themselves in these holy and venerable matters, involving as they do the religious life of Christian society along with the exercise of the priesthood of Jesus Christ and worship of God; concerned as they are with the honour due to the Blessed Trinity, the Word Incarnate and His august mother and the other saints, and with the salvation of souls as well. For the same reason no private person has any authority to regulate external practices of this kind, which are intimately bound up with Church discipline and with the order, unity and concord of the Mystical Body and frequently even with the integrity of Catholic faith itself.
-Pope Pius XII
Mediator Dei, 58