First Council of Nicaea

== Promulgation of canon law ==
{{canon law}}
{{Main|Canon law|Collections of ancient canons|Promulgation (Catholic canon law)}}
The Council promulgated twenty new church laws, called ''[[Canon (canon law)|canons]]'' (though the exact number is subject to debate), that is, rules of discipline. The twenty as listed in the works of [[Nicene and Post-Nicene Fathers]] are as follows:<ref>{{harvnb|Canons}}</ref>

# prohibition of self-[[castration]] for clergy
# establishment of a minimum term for [[catechumen]]s (persons studying for baptism)
# prohibition of a man and a woman who have both taken [[Religious vows|vows of chastity]] to live together in a chaste and non-legalized partnership (the so called ''virgines subintroductae'', who practiced [[syneisaktism]])
# ordination of a bishop in the presence of at least three provincial bishops<ref name=EB1911/> and confirmation by the [[metropolitan bishop]]
# provision for two provincial [[synod]]s to be held annually
# confirmation of ancient customs giving jurisdiction over large regions to the bishops of Alexandria, Rome, and Antioch
# recognition of the honorary rights of the see of [[Jerusalem in Christianity|Jerusalem]]
# provision for agreement with the [[Novatianism|Novatianists]], an early sect
# elders who had been ordained without sufficient examination were not to be recognized
# elders who had lapsed but had not been found out were to be deposed
# mercy was enjoined toward those who had lapsed without compulsion, even though it was recognized that they did not deserve it
# those who had left the military but later sought out to be restored to their military position were to be excommunicated; depending on the sincerity of their repentance, they could be readmitted to communion earlier
# those who were fulfilling [[penance]] could receive communion if they were dying, but if they got well again, they were to finish their penance
# catechumens who lapsed were to have three years as hearers before being allowed to become catechumens again
# bishops, presbyters, and deacons were not to wander into neighboring cities to officiate
# clergy who refused to return to their home church were to be excommunicated, and the ordinations of those who were ordained by these wandering clergy were to be considered null and void
# prohibition of [[usury]] among the clergy
# precedence of bishops and presbyters before deacons in receiving the [[Eucharist]] (Holy Communion)
# declaration of the invalidity of [[baptism]] by [[Paul of Samosata|Paulian heretics]]
# prohibition of kneeling on Sundays and during the [[Pentecost]] (the fifty days commencing on Easter). Standing was the normative posture for prayer at this time, as it still is among the Eastern Christians. Kneeling was considered most appropriate to penitential prayer, as distinct from the festive nature of Eastertide and its remembrance every Sunday. The canon was designed only to ensure uniformity of practice at the designated times.