A diriment matrimonial impediment consisting in a relationship, which arises from a valid betrothal, or from a marriage approved by the Church but not consummated. Marriage between the persons affected by this impediment, as described below, is null; were it possible for them to marry they might be exposed to incontinency, owing particularly to their intimacy and familiar intercourse.
Traces of this impediment are found under another name in Roman law, since according to Modestinus (D. XXIII, ii, 42, De ritu nuptiarum) not only what is lawful, but likewise what is eminently fitting, is to be observed in entering into wedlock. Hence in Roman law affinity arising from a valid marriage, whether consummated or not, constituted a diriment impediment between the affined in all degrees throughout the direct line, and to the second degree (civil method of computing) in the indirect or oblique line. Moreover, there was a quasi-affinity, which, for the safeguarding of public morals, rendered matrimony null and void: (1) between a man and his stepdaughter or between a woman and her stepson; (2) between a woman and the son or father of her betrothed, and conversely between a man and the daughter or mother of his affianced (D. XXIII, ii, 12 and 14); (3) lastly, between persons affined through concubinage (bc. cit., 14 and D. XXXVIII, x, 7).
The Church, imitating this legislation, admits an impediment, which, in her estimation, is required by public decency or good morals. In canon law carnal intercourse, licit or otherwise, is the principle of affinity ; in Roman law, it is valid marriage, whether consummated or not. Public honesty then coincides at times with the affinity of the Romans, at times with their quasi-affinity. The institution of this impediment is sometimes attributed, but wrongly, to Boniface VIII . It doubtless owes its existence not to a positive law, but to custom and probably dates back to the twelfth century ( Berardi, III, diss. II, cap. iii). Canons xi, xiv, xv (Caus. II, Q. ii) in Gratian's Decretum, indicating an earlier existence of this impediment, are apocryphal (Gasparri, "Dc Matrimonio", n. 801).
According to our present legislation (Trent, Sess. XXIV, cap. iii, De Ref. Matr.) the impediment of public honesty arises from a valid betrothal between the male party to the contract and the blood relatives of the woman in the first degree (mother, daughter, sister), and conversely between the woman and the blood relatives of the man in the same degree (father, son, brother). Once existing, the impediment always remains, even though the betrothal is lawfully broken (see BETROTHAL). It is to be noted that betrothal, to be valid, must now ("Ne temere" of Pius X ) be in writing, signed by the contracting parties and by the ordinary, or a parish priest within his own territory, or two witnesses. If one or the other of the contracting parties is unable to write, an additional witness is required. If the betrothal is conditional, the impediment does not arise till the condition is verified.
Second, this impediment, for a stronger reason, is begotten by a marriage contract, not perfected by carnal relations -- and this, too, though the marriage be invalid, unless the invalidity be due to lack of lawful consent. By carnal intercourse public decency gives way to affinity, and, though some deny this, all admit that in a petition for a dispensation it is sufficient to express the impediment of affinity, while public decency, if it still exist, is understood.
A civil marriage does not give rise to this impediment (S.C.C., 17 March, 1879), nor does public decency beget a second impediment prejudicial to a former betrothal ; namely, a betrothal or marriage (unless consummated) with the mother, sister, or daughter of an affianced person does not prohibit the keeping of one's troth to the said person. Since the impediment of public decency is of ecclesiastical origin it follows that the Church may dispense from it, and that it does not affect unbaptized persons, even though later they become Christians. A dispensation from "Disparity of Worship" includes one in public decency, where the baptized party requires such. Finally it is apparent that this impediment may be multiplied in the same person, as, for instance, if one were to enter into betrothal with several women related by blood in the first degree.
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