[ ]Mapping the Familysister-in-law who is related to the surviving brother beyond her marriage
to his brother. Still, these discussions underscore the problem inher-
ent in levirate: not only is an otherwise forbidden union permitted, it is
encouraged.
There appear, then, to be two types of “brother’s wife.” One type,
married to a man with children, is forbidden to her brother-in-law, both
during her husband’s lifetime, even if he has divorced her, and after his
death. The other type, the widow of a childless man, is permitted to
marry her brother-in-law; and in fact, it is his religious duty to marry
her. This dichotomy, however, is complicated further by rabbinic dis-
cussions of eligibility for levirate marriage. The rabbis create a third
category, in which a widow is related to her brother-in-law in a way that
prohibits a sexual relationship between the brother-in-law and the wid-
ow’s co-wives. In the event that marriage does take place in such cases,
the union is considered incestuous, even if it was intended to fulfill a
perceived duty to the deceased.^54
The intersection between the levirate obligation and the prohibition
against incest arises several times in Bavli Yevamot. Levirate marriage
between a man and his brother’s widow is expressly prohibited when
she is a relative forbidden to him (beyond her status as his brother’s
w i fe).^55 Such a woman does not even require halitza; her status as his
close relative eliminates any levirate obligation, and she is treated like a
widow of a man with children. The opening mishna of the tractate goes
further, extending the prohibition against levirate and halitza beyond
t he related w idow to a ny ot her women to whom t he brot her wa s ma r r ied
at the time of his death. The mishna states:
Fifteen women exempt their co-wives and the wives of their co-
wives from halitza and levirate marriage ad infinitum. They are:
[h]is daughter, his daughter’s daughter, his son’s daughter, his
wife’s daughter, her son’s daughter, her daughter’s daughter, his
mother-in-law, the mother of his mother-in-law, the mother of his
father-in-law, his sister by the same mother, his mother’s sister, his
wife’s sister, the wife of his brother by the same mother, the wife of a
brother who died before he was born, and his daughter-in-law.^56
This list of women in Mishnah Yevamot : corresponds, in part, to
the lists in Leviticus and . The Mishnah extends the list, adding the