AFFINITÀ. – This word, derived from the Latin affinitas (signifying, according to Modestinus [fr. 4, § 10, D. 38, 10], as it were, the bringing of one generation ad fines alterius), designates the juridical bond linking one of the spouses to the blood relatives of the other.
The rules established in this regard by Roman law (of which the principal ones were: affinitas non parit affinitatem; gradus affinitatis nulli sunt) were adopted without substantial modifications both by civil legislation (v. , for example, article 78 of the Italian Civil Code) and by ecclesiastical legislation; the latter nevertheless retained, until the promulgation of the Codex, the special characteristic of grounding affinity not only in marriage but also in any illicit union between a man and a woman.
Under the currently prevailing Latin canon law (can. 97), affinity derives from a valid marriage, whether merely ratum or ratum and consummated. Whether it also derives from the marriage of two infidels and from that of a believer with an unbaptized person—that is, to use a more comprehensive term, from a legitimate marriage (v. MATRIMONIO)—is disputed in doctrine. Although affinity has no lines or degrees of its own, it is calculated in such a way that, in the line and degree in which a person is related by blood to one of the spouses, that person is related by affinity to the other spouse (for the definitions of the direct and collateral lines, as well as for the computation of degrees, V. CONSANGUINITÀ).
Besides constituting, within certain limits, a matrimonial impediment (which will be discussed in § sg.), affinity produces numerous juridical effects. Among these we may recall: incompatibility with the office of administrator of ecclesiastical property for anyone related by affinity in the first or second degree to the ordinarius loci (can. 1520, § 2); the prohibition against selling or leasing, without the special licence of the ordinary, the immovable property of a church to anyone related by affinity in the first or second degree to the administrators of that church (can. 1540); the obligation imposed upon the judge, the promoter of justice, and the defender of the bond to abstain from participating in those cases in which an affine of theirs has an interest (can. 1613, §§ 1–2); the incapacity to testify in court of persons related by affinity to one of the parties (can. 1757, § 3, n. 3), unless the matter concerns matrimonial questions (can. 1974) or causes of beatification (can. 2027, § 1). Civil law, moreover, establishes the reciprocal obligation of alimenti (v.) between affines in the first degree of the direct line (Cod. Civ. It., art. 433, nn. 4 and 5).
1. AFFINITY AS A MATRIMONIAL IMPEDIMENT
Its origin goes back to Mosaic legislation (Lev. 18, 8.14–18; 20, 11–12.14. 19–21; Deut. 27, 20.33), which strictly prohibited marriage with one’s stepmother, stepdaughter, the daughter of the latter or of one’s stepson, mother-in-law, daughter-in-law, the widow of one’s uncle, and sister-in-law, except in the case of levirate marriage (v. LEVIRATO, LEGGE DEL). Roman law recognized the impeditive force of affinity only within the first degree of the direct line; and at first the Church conformed to this provision, only later extending the scope of the impediment to the seventh degree of the collateral line and establishing, for the case of second and third marriages, a second and a third genus of affinity (v. TRIGENIA), subsequently suppressed by Innocent III at the Fourth Lateran Council (1215).Today, in Latin canon law, the impedimentum affinitatis is governed by can. 1077 of the CIC, according to which affinity in the direct line invalidates marriage in every degree, whereas in the collateral line it renders marriage invalid up to and including the second degree. This is an impediment of purely ecclesiastical origin, whose moral foundation must be sought both in those particular relations of familiarity and respect that ordinarily arise among persons united by bonds of affinity, and in the desirability of extending as far as possible, through marriages between unrelated persons, the reciprocal relations of charity and friendship among human families, and finally in the opportunity to remove the occasion and danger of gravely sinful loves. By its nature it is perpetual and multiplies: a) through the multiplication of the blood relationship from which it derives; b) through the subsequent contracting of a new marriage with a blood relative of the deceased spouse. The Holy See does not ordinarily grant dispensations from affinity in the direct line. It is easy, however, to obtain a dispensation when the affinity is in the collateral line, and especially in the second degree, which is a minor impediment.
Affinity also constitutes a matrimonial impediment under civil legislation. According to article 87 of the Italian Code, persons related by affinity in the direct line and persons related by affinity in the collateral line in the second degree (corresponding to the first degree under canonical computation) may not marry one another.
2. EASTERN CANON LAW
In Eastern canon law, affinity exists between each of those who have had sexual relations with one another and the relatives of the other, whether this occurred within marriage (affinitas ex copula licita) or outside it (affinitas ex copula illicita); affinity does not exist, however, in the case of an unconsummated marriage.The matrimonial impediment of affinity exists in the direct line in every degree; in the collateral line ex copula licita, up to and including the eighth, seventh, or sixth degree, according to the rite; in the collateral line ex copula illicita, up to and including the fourth degree.
It should be noted, however, that non-Catholic Eastern Christians generally do not recognize affinity ex copula illicita; and, with regard to affinity ex copula licita, they recognize the matrimonial impediment at most up to the fourth degree.
Among Eastern Christians (with the exception of the Melchites), degrees are calculated according to civil computation (v. CONSANGUINITÀ).
For affinity of the second and third kinds, in force among the Greeks only with regard to the matrimonial impediment, V. TRIGENIA.