The Gemara explains Rebbi Yochanan's reasoning. Rebbi Yochanan reasons that
it does not make sense that one brother (the one who did Chalitzah) should be
Asur only with a Lav, while the other brothers have an Isur Kares, since they
were all equally entitled to do Chalitzah. Rather, it must be that the
brother who did Yibum did it as the Shali'ach of all the other brothers, and
the woman who did Chalitzah did it as the Shali'ach of all the Tzaros.
We see that Rebbi Yochanan maintains that the Isur Kares of "Eshes Ach" falls
away completely in a situation of Yibum, when one brother dies and his wives
fall to Yibum (or Chalitzah) to the other brothers. According to Rebbi
Yochanan, at what point is the Isur Kares of "Eshes Ach" of all the wives
removed? Is it removed as soon as the brother dies, or only when a surviving
brother does Chalitzah? There seem to be conflicting implications from the
words of the Gemara.
The first part of the description of Rebbi Yochanan's reasoning, which says
that the Isur should be removed since *initially* any of the brothers could
do Chalitzah (or Yibum), implies that even before anyone does Chalitzah, the
Isur Kares is removed (since they *could* perform Chalitzah or Yibum). On the
other hand, from the end of the description of his reasoning, which says that
the Yavam and Yevamah who do Chalitzah (or Yibum) are acting as Shelichim for
the others, it seems that the act of Chalitzah is what removes the Isur
Kares, and until that act is done, the Isur is still in force!
(a) From the words of TOSFOS (10b, DH Ihu), it seems that the Isur of "Eshes
Ach" remains in force until the Chalitzah is performed, and the Chalitzah
then removes the Isur. When Rebbi Yochanan says that when the wife falls to
Yibum, any brother may do Chalitzah, it does not mean to imply that there is
no Isur of "Eshes Ach," but merely that it is *logical* that the Torah did
not give a Mitzvah to the brothers from which they could excuse themselves
and pass on to another brother. Rather, the brothers never actually remove
themselves from the obligation. Whichever brother does Chalitzah (or Yibum),
does it on behalf of all of the others as well.
This also appears to be the opinion of RASHI (52a, DH Nasan), who calls the
Yevamah an "Eshes Ach" even during the period of Zikah.
Further support for this can be adduced from the opinion of Aba Shaul (39b),
who argues with the Rabanan and says that it is better to do Chalitzah than
Yibum because if one does Yibum with impure intentions, "it is as if he lives
with an Ervah and the child can almost be called a Mamzer." If the Isur of
"Eshes Ach" is removed at the time that the woman falls to Yibum, before
Yibum is done, then there is no Isur of Ervah whatsoever and no reason to say
that the child is "close to being a Mamzer." (See also Insights to 7:1:b)
(b) However, the RASHBA (41a, end of DH Shomeres Yavam) writes that Rebbi
Yochanan's statement, "If this [brother] wants to do Chalitzah, then he may
do it, and if this one wants to do Chalitzah, then he may do it," implies
that the Isur of "Eshes Ach" actually falls off as soon as it is permitted
for the brothers to do Yibum. According to the Rashba, why does Rebbi
Yochanan have to add that the brother is doing the Shelichus of all the other
brothers? Even if he is not doing Chalitzah or Yibum on their behalf, the
Isur of "Eshes Ach" was already removed from them!
Furthermore, how does the Rashba understand the opinion of Reish Lakish who
says that all of the other brothers have an Isur Kares with the woman when
one brother does Yibum with her? The Rashba could not have learned that the
Isur Kares is removed and then returns to the other brothers when one brother
does Yibum, because the Rashba himself (ibid.) asserts that once the Isur of
"Eshes Ach" is removed, it cannot return.
The Acharonim offer two approaches to these questions. The simple approach is
that the reason Rebbi Yochanan says that one brother is acting as Shaliach
for the others is not to explain that the Isur of "Eshes Ach" is removed (for
it is not removed at that point, but earlier, at the time she falls to
Yibum). Rather, the fact that one brother acts as Shaliach for the others
explains why the other brothers acquire the prohibition of "Lo Yivneh." Even
though the verse implies only that the one who did Chalitzah may not marry
her and attempt to "rebuild" his brother's house, Rebbi Yochanan says that
all of the brothers and Tzaros have an Isur of "Lo Yivneh" because of the
The implication of the words of the Rashba is that Reish Lakish indeed argues
and holds that even though the Isur of "Eshes Ach" is removed at the time
that the wives fall to Yibum, nevertheless the Isur *could* return even if it
was once removed. Therefore, when one brother does Chalitzah or Yibum, the
Isur returns to the other brothers. (This also appears to be the intention of
the Rashba on 44a, DH v'Nachlotz, which appears in the Mosad Rav Kook edition
of the Rashba).
A second approach is suggested by RAV ELCHANAN WASSERMAN in KOVETZ HE'OROS
(4:9, 1:7). From the Yerushalmi it seems that when one brother does Yibum or
Chalitzah, that determines retroactively that the other brothers were not
involved with the Zikah at all. Perhaps that is the intention of Reish
Lakish, who is saying that the other brothers have an Isur Kares, because
once one brother has done Yibum, it turns out that he was the only one who
had the Heter. We only know which brother has the Heter after it is actually
utilized by one of them.
Rebbi Yochanan also agrees that in theory, the Zikah would be retroactively
removed from any brothers and Tzaros not involved in the Chalitzah. However,
he holds that because of the Shelichus, they are all considered to be
involved in the Zikah even retroactively, and thus the Isur of "Eshes Ach" is
removed from all of them. (According to this approach, that Rebbi Yochanan
agrees that Zikah can be removed retroactively, it is not clear what he is
trying to prove from the words "If this [brother] wants to do Chalitzah, then
he may do it...;" how can he prove from there that the Zikah applies
*retroactively* to all of them?)
How will the Rashba understand Aba Shaul's statement (that it is better to do
Chalitzah than to do Yibum)? The Kovetz he'Oros (ibid.) says that either the
Rashba is discussing only the opinion of the Rabanan, or, more likely, he
understood that Aba Shaul's ruling is only d'Rabanan.
In conclusion, we find that there is a basic difference in understanding
between RASHI and TOSFOS and the RASHBA regarding whether the Isur of "Eshes
Ach" is removed right away at the time the woman falls to Yibum, or whether
it is removed only at the time of Chalitzah (or Yibum).
There might be important Halachic implications of this Machlokes as well. For
example, if -- before performing Yibum -- the Yavam has relations with his
brother's wife without being aware of what he is doing (such as while he is
sleeping), in which case the Gemara (54a) says that he is not Koneh her.
According to Rashi and Tosfos, she should become Pasul to eat Terumah, since
she has had a forbidden relationship with an Ervah , while according to the
Rashba, the act was not Asur at all, and thus she should remain Mutar to
Terumah and Kehunah.