The Mishna (Sota 7) writes that when a husband brought his wife to Yerushalayim to drink the sotah waters, he was accompanied by two talmidei chachamim who could give him hasra’ah should he be tempted to have relations with his wife. What purpose this hasra’ah served seems to be a debate between Rashi and Tosfos. Rashi on the Mishna writes that the husband would be warned that the sotah waters would be ineffective if he has relations with his suspect wife. Tosfos (Yevamos 11b – see R’ Akiva Eiger in the gilyon as well) explains that husband is given hasra’ah for the punishment of malkos. Even though there is no explicit lav in the Torah for relations with a sotah, since the Torah teaches us with respect to sotah to treat safeik k’vaday, i.e. there is a presumption of guilt even though the facts remains uncertain, the lav of having relations with a vaday adulteress applies.
The point of debate between Rashi and Tosfos seems to parallel the debate between R’ Chaim Brisker and Tosfos discussed in yesterday’s post. Even though the facts of whether the sotah is guilty or not remain uncertain, the Torah declares her prohibited to her husband. Does this din mean that we assume factually that the woman did commit adultery until proven otherwise, or does it mean that although the facts of the case remain in doubt, the Torah created a categorically new prohibition that puts this case of doubt off-limits? According to Tosfos in Yevamos, the sotah is assumed factually to have committed adultery, and therefore the lav of relations with an adulteress applies equally to a sotah. According to Rashi, a sotah is a categorically new prohibition that leaves the uncertainty of the situation unresolved. The lav of relations with a proven adulteress does not apply to this indetermined situation.