Council of Clermont (535)

At the Council of Clermont in 535, fifteen prelates of the kingdom of Austrasia assisted, under the presidency of Honoratus, Bishop of Bourges, at a synod in the city now called Clermont-Ferrand. Among those bishops attending was the bishop of Clermont, canonized as saint Gal.

They drew up seventeen canons, of which the first sixteen are contained in the Decretum Gratiani compiled in the twelfth century by Gratian; they have become part of the corpus of canon law of the Catholic Church, the Corpus Iuris Canonici.

The following is a summary:

The council also declared itself forcefully against the marriages of Christians with Jews, marriages between relatives, and the misconduct of the clergy.

...
Wikipedia