Why does Rashi say that the Chachamim were lenient in the case of a
Shevuyah? There is a general rule that "one witness is believed in matters
of prohibitions" ("Ed Echad Ne'eman b'Isurim"), even if the witness is not
valid for testimony in court (such as a woman or relative). The case of
Shevuyah involves an Isur (whether or not the woman is permitted to marry a
Kohen), and thus the normal rule of "Ed Echad Ne'aman b'Isurim" should
permit us to accept the testimony of a single witness! Why does Rashi say
that there is a special leniency in the case of Shevuyah?
(a) The TOSFOS RID in Kidushin (66a, cited by the SHEV SHEMAITSA 6:15)
proves from the Gemara there (see Shev Shemaitsa) that judging whether or
not a woman is a Shevuyah, or whether she is prohibited to marry Kohanim for
another reason (such as Gerushah or Chalutzah), is considered a "Davar
sheb'Ervah" and therefore two witnesses are required. Accordingly, it is
clear why we need a special leniency in the case of Shevuyah in order to
accept the testimony of a single witness.
The source for the requirement of two witnesses to prove a "Davar
sheb'Ervah" is from a verse discussing a woman who becomes prohibited to her
husband becuase she committed adultery (Devarim 24:1). According to the
Tosfos Rid, the verse apparently refers not only to an adulteress (who
transgressed an Isur Kares), but to any testimony that causes a woman to
become prohibited (or permitted) to certain men. According to this logic, it
would seem that two witnesses are required even in order to prove that a
person is, or is not, a Mamzer or Mamzeres. (One might, however, distinguish
between Isurim that can only take effect upon a woman -- such as Pesulei
Kehunah and Zenus, which require two witnesses -- and those that can apply
to men as well -- such as Mamzer, which is not a Davar sheb'Ervah and
requires but a single witness.)
(b) The REBBI AKIVA EIGER and the NESIVOS HA'MISHPAT (both cited in TESHUVOS
REBBI AKIVA EIGER #124, 125) posit, based on a MORDECHAI in Yevamos, that a
court case is considered to be a Davar sheb'Ervah only if it creates (or
removes) an Isur on the woman which prevents the enactment of Kidushin with
that woman (similar to the Isur of Eshes Ish).
This explanation of the Mordechai needs clarification, though, since the
Isur of an adulteress to her husband does not preclude Tefisas Kidushin; it
is simply an Isur Lav. Similarly, the Isur of Shevuyah to a Kohen is only a
Lo Ta'aseh (a normal negative commandment) which does not prevent Kidushin
from taking effect, yet it is clear from the Gemara in Kidushin (ibid.) and
from our Gemara that two witnesses are required to prohibit a Shevuyah.
The Nesivos ha'Mishpat explains that according to this Mordechai there are
two acts which are considered Davar sheb'Ervah: (1) An act which *creates*
an Isur which precludes the enactment of Kidushin, and (2) an act in which
a woman becomes prohibited to others because she *had relations with* a
person with whom she could not enact Kidushin. A Shevuyah (who is suspected
of being raped by her non-Jewish captors) and an adulteress fit into the
second category.
However, Rebbi Akiva Eiger asserts that this is not the Mordechai's
intention. Instead, he suggests that prohibiting an adulteress to her
husband is considered a "Davar 'b'Ervah" even though it does not prevent
Kidushin from being enacted with her because the Torah refers to that
particular Isur as "Tum'ah," (see Yevamos 11a) just like the Arayos.
Shevuyah is considered a "Davar sheb'Ervah" for the same reason, since the
Gemara in Yevamos (56b) tells us that the wife of a Kohen who was raped is
prohibited to her husband because of an Isur of "Tum'ah." This is only true
of a married woman who was raped, though (seeTeshuvos Rebbi Akiva Eiger
#125, and TESHUVOS V'CHIDUSHEI REBBI AKIVA EIGER, 20:3). If a single woman
is captured and raped, it would not be considered a Davar sheb'Ervah at all
according to this logic. According to Rebbi Akiva Eiger, we will have to
find another reason why any Shevuyah, even a single woman, should require
two witnesses if not for a special leniency.
This also appears to be the opinion of the RAMBAM (Hilchos Sanhedrin 16:6,
see Shev Shemaitsa ibid.), who writes that only one witness is necessary to
determine whether or not a woman is a Zonah or Gerushah and prohibited to a
Kohen. Similarly, TOSFOS in Gitin (2b, DH Midi) writes that the law that a
"Davar sheb'Ervah" requires two witnesses applies only to testimony
concerning marriage, divorce, and Zenus that prohibits a woman to her
husband.
(c) Tosfos (Gitin 2b DH Ed Echad) writes that one witness is not believed
even for a regular Isur in order to *remove* an Isur that has already been
established ("Ischazek Isura," or a "Chezkas Isur"). If so, since the
Chachamim assume that a Shevuyah was definitely defiled until proven
otherwise (see Kesuvos 13b), she is considered to have a "Chezkas Isur," and
therefore a single witness would not be believed to remove that Isur if not
for the special leniency the Chachamim instituted in the case of a Shevuyah.