After the Emperor Constantine began the process of tolerating then adopting Christianity, councils flourished. The Council of Nicaea is the first Ecumenical (universal) council. The first four ecumenical councils, were given a special place in the traditions of the church.
Tanner Texts and Translations
Decrees of the Ecumenical Councils, 1: Nicaea I-Lateran V, 2: Trent-Vatican II, ed. Norman P. Tanner. 2 Volumes. London-Washington, D.C.: Sheed & Ward and Georgetown University Press, 1990 (Greek-Latin texts with facing English translation)
Council of Arles 314 Called by Constantine --- Letter and canons sent to Pope Silvester
Council of Cologne 346 Trial of
Eufrata, who had denied Christ was God (Eufrata
Christum Deum negat)