AFFINITY, in Law, as distinguished from consanguinity, is applied to the relation which each party to a marriage, the husband and the wife, bears to the kindred of the other. The marriage having made them one person, the blood relations of each are held as related by affinity in the same degree to the one spouse as by consanguinity to the other. But the relation is only with the married parties themselves, and does not bring those in affinity with them in affinity with each other; so a wife’s sister has no affinity to her husband’s brother. The subject is chiefly important from the matrimonial prohibitions by which the canon law has restricted relations by affinity. Taking the table of degrees within which marriage is prohibited on account of consanguinity, the rule has been thus extended to affinity, so that wherever relationship to a man himself would be a bar to marriage, relationship to his deceased wife will be the same bar, and vice versa on the husband’s decease. This rule has been founded chiefly on interpretations of the eighteenth chapter of Leviticus. Formerly by law in England, marriages within the degrees of affinity were not absolutely null, but they were liable to be annulled by ecclesiastical process during the lives of both parties; in other words, the incapacity was only a canonical, not a civil, disability. By an Act passed in 1835 (5 and 6 Will. IV. c. 54), all marriages of this kind not disputed before the passing of the Act are declared absolutely valid, while all subsequent to it are declared null· This renders null in England, and not merely voidable, a marriage with a deceased wife’s sister or niece. The Act does not extend to Scotland; but it was made quite clear by a leading decision in 1861 (Fenton v. Livingston) that, as “the ...

There are several degrees of affinity, wherein marriage was prohibited by the law of Moses: thus the son could not marry his mother, nor his father’s wife, Lev. xviii, 7, &c. The brother could not marry his sister, whether she were so by the father only, or only by the mother, and much less if she were his sister both by the same father and mother. The grandfather could not marry his granddaughter, either by his son or daughter. No one could marry the daughter of his father’s wife; nor the sister of his father or mother; nor the uncle, his niece; nor the aunt, her nephew; nor the nephew, the wife of his uncle by the father’s side. The father-in-law could not marry his daughter-in-law; nor the brother the wife of his brother, while living; nor even after the death of his brother, if he left children. If he left no children, the surviving brother was to raise up children to his deceased brother by marrying his widow. It was forbidden to marry the mother and the daughter at one time, or the daughter of the mother’s son, or the daughter of her daughter, or two sisters, together. It is true the patriarchs, before the law, married their sisters, as Abraham married Sarah, who was his father’s daughter by another mother; and two sisters together, as Jacob married Rachel and Leah; and their own sisters, both by father and mother, as Seth and Cain. But these cases are not to be proposed as examples; because in some they were authorized by necessity; in others, by custom; and the law as yet was not in being. If some other examples may be found, either before or since the law, the Scripture expressly disapproves of them; as Reuben’s incest with Balah, his father’s concubine; and the action of Amnon with his sister Tamar; and that of Herod Antipas, who married ...