This should be required reading for every parish liturgy director:
"Those therefore who after the manner of wicked heretics dare to set aside Ecclesiastical Traditions, and to invent any kind of novelty, or to reject any of those things entrusted to the Church, or who wrongfully and outrageously devise the destruction of any of those Traditions enshrined in the Catholic Church, are to be punished thus:
IF THEY ARE BISHOPS, WE ORDER THEM TO BE DEPOSED;
BUT IF THEY ARE MONKS OR LAY PERSONS, WE COMMAND
THEM TO BE EXCLUDED FROM THE COMMUNITY."
From the Second Council of Nicaea 787 A.D.