text: Ecumenical councils ARE the supreme law of the Church.  It has always been.  When the first Ecumenical Council at Nicaea [325 AD] occurred---and the Second Council at Constantinople I in 381 AD. the doctrine that the assembled bishops [NO POPE was in attendance] crafted became the Nicene Creed that we recite today.  
  
  The big thing that came from Vatican I was that of Papal Infallibility on matters of faith.  Dei Filius was the only other document passed at this council [the bishops got away as fast as they could from Rome--because of the impending Italian force stood ready to defeat the Papal States which they did].
  
  "Dei Filius" discussed the nature of God, the need for revelation, the nature of faith and the relationship of faith to reason.   Not all the ecumenical councils were dogmatic; Lyons I--1245; Lyons II---1274; Vienne, 1311-12; and the ecumenical council held during the Great Western Schism in Constance---1414-18.