Such plenary synods are frequently called national councils.

They are of the same nature as provincial councils, with the accidental difference that several ecclesiastical provinces are represented in national or plenary synods.

Decrees of the Plenary Synod of the Bishops of Ireland (Decreta Synodi Plenariae Episcoporum Hiberniae) was published in 1851 following the synod.

The first, an orthodox plenary synod, was held in 314, and its 25 disciplinary canons constitute one of the most important documents in the early history of the administration of the Sacrament of Penance.