But the power, not the will, to resist, failed Ithacius; for the heretics had won over by bribes Voluentius, the proconsul, and thus consolidated their own power. Moreover, Ithacius was put on his trial, by these men as being a disturber of the churches, and he having been ordered as the result of a fierce prosecution, to be carried off as a prisoner, fled in terror into Gaul, where he betook himself to Gregory the prefect. He, after he learned what had taken place, orders the authors of these tumults to be brought before himself, and makes a report on all that had occurred to the emperor, in order that he might close against the heretics every means of flattery or bribery.
But that was done in vain; because, through the licentiousness and power of a few, all things were there to be purchased. Accordingly, the heretics by their artifices, having presented Macedonius with a large sum of money, secure that, by the imperial authority, the hearing of the trial was taken from the prefect, and transferred to the lieutenant in Spain. By that time, the Spaniards had ceased to have a proconsul as ruler, and officials were sent by the Master to bring back to Spain Ithacius who was then living at Treves.
He, however, craftily escaped them, and being subsequently defended by the bishop Pritannius, he set them at defiance. Then, too, a faint rumor had spread that Maximus had assumed imperial power in Britain, and would, in a short time, make an incursion into Gaul. Accordingly, Ithacius then resolved, although his affairs were in a ticklish state, to wait the arrival of the new emperor; and that, in the meantime, no step should on his part be taken. When therefore Maximus, as victor, entered the town of the Treveri, he poured forth entreaties full of ill-will and accusations against Priscillian and his confederates.
The emperor influenced by these statements sent letters to the prefect of Gaul and to the lieutenant in Spain, ordering that all whom that disgraceful heresy had affected should be brought to a Synod at Bordeaux. Accordingly, Instantius and Priscillian were escorted there and, of these, Instantius was enjoined to plead his cause; and after he was found unable to clear himself, he was pronounced unworthy of the office of a bishop. But Priscillian, in order that he might avoid being heard by the bishops, appealed to the emperor.
And that was permitted to be done through the want of resolution on the part of our friends, who ought either to have passed a sentence even against one who resisted it, or, if they were regarded as themselves suspicious persons, should have reserved the hearing for other bishops, and should not have transferred to the emperor a cause involving such manifest offenses.
Source: Sacred History (New Advent)