Whether Mortal Enemies may be Admitted as Witnesses.
But if it is asked whether the Judge can admit the mortal enemies of the prisoner to give evidence against him in such a case, we answer that he cannot; for the same chapter of the Canon says: You must not understand that in this kind of charge a mortal personal enemy may be admitted to give evidence. Henry of Segusio also makes this quite clear. But it is mortal enemies that are spoken of; and it is to be noted that a witness is not necessarily to be disqualified because of every sort of enmity. And a mortal enmity is constituted by the following circumstances: when there is a death feud or vendetta between the parties, or when there has been an attempted homicide, or some serious wound or injury which manifestly shows that there is mortal hatred on the part of the witness against the prisoner, And in such a case it is presumed that, just as the witness has tried to inflict temporal death on the prisoner by wounding him, so he will also be willing to effect his object by accusing him of heresy; and just as he wished to take away his life, so he would be willing to take away his good name. Therefore the evidence of such mortal enemies is justly disqualified.
But there are other serious degrees of enmity (for women are easily provoked to hatred), which need not totally disqualify a witness, although they render his evidence very doubtful, so that full credence cannot be placed in his words unless they are substantiated by independent proofs, and other witnesses supply an indubitable proof of them. For the Judge must ask the prisoner whether he thinks that he has any enemy who would dare to accuse him of that crime out of hatred, so that he might compass his death; and if he says that he has, he shall ask who that person is; and then the Judge shall take note whether the person named as being likely to give evidence from motives of malice has actually done so. And if it is found that this is the case, and the Judge has learned from trustworthy men the cause of that enmity, and if the evidence in question is not substantiated by other proofs and the words of other witnesses, then he may safely reject such evidence. But if the prisoner says that he hopes he has no such enemy, but admits that he has had quarrels with women; or if he says that he has an enemy, but names someone who, perhaps, has not given evidence, in that case, even if other witnesses say that such a person has given evidence from motives of enmity, the Judge must not reject his evidence, but admit it together with the other proofs.
There are many who are not sufficiently careful and circumspect, and consider that the depositions of such quarrelsome women should be altogether rejected, saying that no faith can be placed in them, since they are nearly always actuated by motives of hatred. Such men are ignorant of the subtlety and precautions of magistrates, and speak and judge like men who are colour-blind. But these precautions are dealt with in Questions XI and XII.