Nicene and Post-Nicene Fathers, Ser. II, Vol. XIV:
The Canons of the Synods of Sardica, Carthage, Constantinople, and Carthage Under St. Cyprian, Which Canons Were Received by the Council in Trullo and Ratified by II. Nice.: Canon VIII

Canon VIII.

Of those who make accusation against an elder; and that no criminal is to be suffered to bring a charge against a bishop.

Numidius, the bishop of Maxula, said:  Moreover, there are very many, not of good life, who think that their elders or bishops should be the butt for accusation; ought such to be easily admitted or no?  Aurelius the bishop said:  Is it the pleasure of your charity that he who is ensnared by divers wickednesses should have no voice of accusation against these?

All the bishops said:  If he is criminous, his accusation is not to be received.

Notes.

Ancient Epitome of Canon VIII.

It has seemed good that they who are themselves defendants for crimes should not bring accusations; nor should they be allowed to lay crimes to anyone’s charge.

This is Canon vi. of Genethlius’s Synod at Carthage, a.d. 387 or 390.

Johnson.

See Canons 132 and 133 and Constantinople Canon 6.

[The “elders” mentioned in this canon are] probably the same with senes in other canons, viz., Metropolitans, as is generally believed.  The Latin here calls them Majores p. 447 natu, the Greek πατέρας.  Bishop Beveridge supposes that the word denotes bishop, though perhaps Majores natu may signify presbyters.  Justellus on the canon produces some seeming authorities for this.