Authoritate et iussu amplissimi ordinis Iuridicae Facultatis in celeberrima Basiliensi Academia, Conclusiones has de iureiurando voluntario

XXV.
A necessary or judicial oath is that which is deferred by a judge in doubtful cases, or in the absence of proofs.

XXVI.
I call doubtful cases those that are uncertain, according to the opinion of Duarenus original: "Duareni", referencing the French jurist François Douaren, as when equally effective proofs are brought forward by both sides, so that the judge does not know what he ought to follow.

XXVII.
Whether a judge ought to decide a case by oath in the absence of proofs, he will estimate according to his own judgment, but he is not to be compelled to do so.

XXIIX.
He shall defer the oath after the case has been examined, not to whomever he pleases, but to whomever it is just to defer it.

XXIX.
I believe this definition in canon law is to be understood in such a way that if some grave presumption favors the plaintiff, and he is of better reputation and greater honesty than the defendant, he should defer it to the plaintiff. If, however, the defendant and plaintiff are in an equal position, he should defer it to the defendant.

XXX.
But neither the defendant nor the plaintiff will be able to refuse this oath for any reason, unless the judge defers one that cannot be taken while preserving piety.

XXXI.
This oath can be retracted later if new documents are found, and this is done either by the law itself or by appeal.

XXXII.
An action in fact original: "actio in factum", a specific legal remedy is given based on the oath, similar to a matter judged.

XXXIII.
That must not be omitted: no oath that is deferred from party to party, or by a judge to a party in a lawsuit, is valid unless it is taken in the presence of the judge.