The exemption of clerics from secular jurisdiction presented powerful men and women of the laity with a challenge right through the Middle Ages. Really, could nothing be done if your local priest was making a nuisance of himself? Did you just have to grin and bear it?
Of course not. Here’s a case from Francia showing that actually there was always scope for influential laymen to exert pressure on local priests, not so much in spite of canon law as through it. We don’t know the name of the 9th-century priest in question, but we do know the name of his enemy: a powerful man named Anselm. This is what seems to have happened.
For some reason now unknown, Anselm had a grudge against a local priest: perhaps he had supported a rival candidate to the church, perhaps the priest had criticised him or blocked him in some way. Sometimes 9th-century priests were physically attacked and even maimed in these circumstances, but Anselm chose a different, subtler tactic. He reported the priest to his bishop, who happened to be Archbishop Hincmar of Rheims, for having slept with a woman. This was a clever move, for Archbishop Hincmar was a stickler for clerical celibacy, and the priest duly appeared before a clerical court.
Now, the normal procedure in these circumstances in 9th-c. Francia was for the priest either to confess, or to clear his name with an oath – and, crucially, with the support of a large number of oath-helpers (at least seven), who would all swear that he was telling the truth. Anselm seems to have predicted this would happen. That’s why he sent a few men to intimidate the most likely oath-helpers, the other priests of the vicinity, in advance of the court meeting. (This kind of intimidation was a fairly typical use of aristocratic retinues, about whom I’ve written here). The aim was evidently to make it difficult for the priest to find enough oath-helpers to clear his name, in which case he would be facing deposition.
Unfortunately for Anselm, Archbishop Hincmar seems to have smelled a rat. The wily archbishop arbitrarily decided that on *this* occasion it wasn’t necessary for the priest to have many (plures) oath-helpers – just a few would do. Afterwards, Hincmar sent a stiff letter to Anselm, urging him (in modern parlance) to let go of his anger against the priest; and warning him that if he didn’t, he’d be in trouble. By happy coincidence, the oath by which the priest had cleared his name survives, and so too does the oath of those oath-helpers the priest managed to find (these texts are all provided below in English).
On this occasion, then, a layman’s attempt to manipulate canon law didn’t work out, and justice was preserved. With his exacting standards, Archbishop Hincmar might not have been the easiest of bishops to work under, but in this case, thanks to a little judicious flexibility, he came up trumps. Always assuming, that is, that the priest was telling the truth. After all, 9th-century rural priests were not above collective conspiracies to support each other in court…
A letter of Archbishop Hincmar of Rheims 
“Hincmar, to the illustrious man Anselm about a certain priest, whom Anselm had accused before him [Hincmar], but had not come to the arranged court meeting. Hincmar explained that this priest had canonically purified himself there from the accusation in front of Anselm’s legates, in the sight of many people, both clerical and laymen, but had not sent many priests as his witnesses to the oath, because he did not have to.
And he [Hincmar] encouraged and exhorted that he [Anselm] should expel from his heart all the rancour which had had against the priest from his heart, showing how bad it was to retain hatred in his heart. And he forbade by the authority of God and His saints that he [Anselm] should carry out any prejudice or machination against the priest; for if he did this, he [Hincmar] would carry out his office (ministerium). And he also requested that he [Anselm] should do justice to God and to him about his men, who had dared to inflict injuries upon the priests and witnesses of the already mentioned priest. For if he [Anselm] did not do this, he [Hincmar] would carry out his office (ministerium) about them too.”
The Priest’s oath 
“I, priest N of St Mary in the village of N, declare concerning the woman N about whom I was accused by the illustrious man Anselm before my bishop H., prelate of the church of Reims: that I did not perpetrate a corporeal sin through the mingling of the flesh, for which I ought to be removed from the sacerdotal office. Thus may God help me through these holy relics.”
The oath-helpers’ oath
“As this Priest N has sworn here to clear himself of infamy, so I truly believe. Thus may God help me through these holy relics.”
 Calendered by Flodoard in his History of the Church of Reims (10th century). The letter is undated, so could have been written any time between 845 and 882, when Hincmar was archbishop. The Latin text is here.
 Preserved in a 17th-century edition: trans. from Schmitz, De Presbiteris Criminosis, p. 30.