Regarding this topic, please refer to my previous postings (http://d.hatena.ne.jp/itunalily2/20180422)(http://d.hatena.ne.jp/itunalily2/20180423)(http://d.hatena.ne.jp/itunalily2/20180426)(http://d.hatena.ne.jp/itunalily2/20180427)(http://d.hatena.ne.jp/itunalily2/20180428). (Lily)
（http://www.jewishvirtuallibrary.org/marriage-prohibited）
A marriage is prohibited whenever there is a legal impediment to a kiddushin (see *Marriage) between the particular parties. In some cases the prohibition has the effect of rendering the marriage, if it is celebrated nevertheless, null and void ab initio; in other cases it does not invalidate the marriage, but provides a ground for having it terminated by divorce.
Prohibited and Void
This category includes (1) marriages which are גִּלּוּי עֲרָיוֹת (gillui arayot) according to pentateuchal law, i.e., punishable by *karet or death, namely: (a) marriages between parties related to one another within the prohibited degrees of kinship: i.e., the marriage between a man and his mother, daughter, sister, and certain other relatives (Lev. 18:6ff.; Kid. 67b and codes); the marriage between a man and the sister of his wife is also void during the latter's lifetime (i.e., even after divorce), as is marriage with his brother's widow (except in the case of the levirate widow) or divorced wife: such marriages are punishable by karet (Yad, Issurei Bi'ah, 2:1, 9; Sh. Ar., EH 15:22, 26; 44:6; see also *Levirate Marriage); and (b) marriage between a man and a married woman, such *adultery being punishable by death (see also *Bigamy); (2) A marriage with a non-Jewish partner (Sh. Ar., EH 44:8; see also Mixed *Marriage); (3) Other cases enumerated in Shulḥan Arukh, Even ha-Ezer 15.
Prohibited but Valid
In this category are included marriages which, although prohibited, do not constitute gillui arayot according to pentateuchal law and therefore are valid and not terminable unless by the death of either party or by divorce (Sh. Ar., EH 15:1; 18; 44:7). Since these marriages are nevertheless prohibited and remain tainted with the prohibition during their subsistence, their dissolution by divorce is generally compelled, whether or not either or both of the parties consented to, or had prior knowledge of, the true situation. Marriage prohibitions of this kind derive either from the pentateuchal law imposed and punishable as a plain prohibition only (Yad, Ishut 1:7) or from the rules laid down by the scribes, i.e., marriage prohibited, as "incest of a secondary [minor] degree," not by the Torah but only by rabbinical enactment (ibid., 1:6; Sh. Ar., loc. cit.). The following are examples of such prohibitions:
(1) A married woman who has sexual relations with anyone but her husband becomes prohibited to the latter as well, and also to her lover even after her divorce from her husband (Sotah 27b; Sh. Ar., EH 11:1; 178:17). If she has had sexual relations of her own free will, she is prohibited to her husband forever, i.e., he must never remarry her after divorce from him even if in the meantime she has not married anyone else (Sh. Ar., EH 13). If she has been raped (see *Rape), she is prohibited to her husband only if he is a priest, but, if he is an ordinary Israelite, she is permitted to him. He need not divorce her and, if he has done so, he may remarry her provided she has not married someone else in the meantime (Sh. Ar., EH 6:10, 11). Similarly, the adulteress is also prohibited for all time from marrying her lover, i.e., even after divorce from her husband or his death (Yev. 24b and Rashi ad loc.; Sh. Ar., EH 11:1). This is because her lover has destroyed her family life, inasmuch as, owing to the adultery, he has rendered her prohibited to her husband. By the same token, and, because the wife of an ordinary Israelite does not become prohibited to her husband when someone else has sexual relations with her against her own free will, some scholars are of the opinion that, although beforehand she is prohibited to such a lover in order to penalize him, if they have nevertheless married each other, he will not be compelled to divorce her (Sh. Ar., EH 11; Ba'er Heitev n. 5 and Beit Shemu'el n. 2; but cf. Rema, EH 159:3, and Ba'er Heitev n. 6; Oẓar ha-Posekim, EH 11:1, n.44).
(2) A divorcee who has remarried and her second marriage has also been terminated (by divorce or death) is therefore prohibited to her former husband, in terms of an express prohibition in pentateuchal law (Deut. 24:4).
(3) A priest is prohibited by an express prohibition in the pentateuchal law from marrying a divorcee, a zonah, or a *ḥalalah (see Lev. 21:7; Sh. Ar., EH 6:1). This prohibition is still in force (Rema, EH 3:6; PDR 5, 219, 221) despite the lack of certainty that all those known as priests are in fact the descendants of Aaron, for all of them are merely presumed to be priests (Yad, Issurei Bi'ah, 20:1). A divorced woman remains prohibited to a priest even if after her divorce she has remarried and become a widow (Ḥokhmat Shelomo, EH 6:1; Sh. Ar., EH 66:11, Isserles, Ḥelkat Meḥokek, 66, n. 41). A priest is forbidden to remarry even his own former wife (Resp. Ribash no. 348; see also *Divorce). For the purposes of the above prohibition, the term zonah is not to be interpreted in its ordinary sense – i.e., a woman who has sexual relations other than within matrimony (Yev. 61b). Here it refers to a woman who is not a Jewess by birth, such as a proselyte, and also to a woman who has cohabited with a man to whom she must not be married by virtue of a general prohibition (i.e., not one relating to the priesthood as such) e.g., if she has cohabited with a non-Jew or a *mamzer (Yev. 61a and Rashi; Sh. Ar., EH 6:8).
(4) A Jewish man or woman must not marry a mamzer (et). For details see *Mamzer.
(5) A married man is prohibited, according to the decree of Rabbenu *Gershom, to marry another woman while his marriage still subsists. If contracted, the second marriage is valid but the parties will be compelled to divorce (see *Bigamy).
(6) Marriage with a divorcee or widow is prohibited before the lapse of 90 days from the date of her acquiring her new status; in order to avoid doubt concerning the descent of her offspring; similarly, for the good of her child, it is forbidden to marry a pregnant woman or nursing mother until the child has reached the age of 24 months (Sh. Ar., EH 13:1, 11–14; for further instances of prohibited, but valid marriages see Sh. Ar., EH 15).
(End)
