The season was soon after Easter; the year may be safely deduced from the fact that the first nine canons are intended to repair havoc wreaked in the church by persecution, which ceased after the overthrow of Maximinus II in 313.
[1] Only about a dozen bishops were present, nonetheless representing nearly every part of Syria and Asia Minor.
Either Vitalis, Bishop of Antioch, or Marcellus of Ancyra presided, and possibly both were present, although the Libellus Synodicus, also known as the Synodicon Vetus, assigns to the latter.
[1] The sixteenth canon brackets the Christians who have committed bestiality, or may still have been doing so, into several different groups based on the offender's age, and assigns different penances to each group; married men over 20 were sanctioned more harshly than unmarried youths, and married men over 50 received the harshest sanctions.
[1] Canon XXII: Concerning wilful murderers let them remain prostrators; but at the end of life let them be indulged with full communion.