A member of my shiur asked a very good, but apparently obvious question on Daf 18b. The Gemara says that Rav Hamnuna's statement about a Yevama being asurah le'ba'alah conforms to Rav Akiva's opinion on Chayvei Lavin.
He asked that if we are working with Rav Akiva, then the Yavam would not be koneh her afterwards, since she is asurah to him, and according to Rav Akiva, Kedushin is not tofes on chayvei lavin. If they aren't married, you lack the basic requirement of Sotah, that her husband bring her to drink the water.
I answered him that even according to Rav Akiva, the mitzvah of Yibum would be docheh the issur lahv, and so he would be koneh her despite the issur.
However, I realized that this is not a good answer. According to Rav Akiva, although the first biyah would fall under the rule of asei docheh lo sa'aseh, after the first biyah she would revert to the status of issur lahv without a mitzvah. According to Rav Akiva, the marriage should automatically be nullified on the basis of "ee lo tafsi, pak'i," as would be true according to us if a woman would, during her marriage, suddenly become a chayvei krisus, in which case the marriage would automatically be nullified.
So, once again, even according to Rav Akiva, there is no state of marriage if she was guilty, and this man cannot make her into a Sotah.
Barzilai, Chicago, IL
(1) This question is asked by the Kehilas Ya'akov (Sotah 5:2). Since the "Shomeres Yavam" - the sister-in-law waiting to do Yibum - was "Mezaneh" - unfaithful - there is no longer any "Zikah" - connection - to the Yavam according to Rebbi Akiva, because since there is now a Lav for her to do Yibum with the Yavam, Rebbi Akiva maintains that this is equivalent to a woman who is forbidden as a Chiyuv Kares that the Rabanan also agree has no longer any Zikah to her husband. Since she could never become his wife, clearly the water cannot check her.
(2) The Kehilas Ya'akov (Yevamos 7:3) cites Achiezer 1:1:10 who answers that in fact, even though the Shomeres Yavam who was Mezaneh is forbidden to her husband, nevertheless she must still do Chalitzah because the Zikah does not disappear. The Shomeres Yavam is not entirely similar to the typical Sotah who is exempt from Chalitzah and Yibum if her husband died. The very fact that she is still called a Shomeres Yavam even though she was Mezaneh, suggests that she is different from a Sotah, because otherwise there would be nothing for her to wait for if she no longer had any connection with the Yavam.
(3) The Kehilas Ya'akov in Yevamos also cites the Chazon Ish EH 130:5 who too makes this distinction between being forbidden to marry her and between a Zikah still remaining. As a result of the Znus, the Yavam could never acquire her as his wife, but even so the Zikah between them is not totally severed. It follows that even though he cannot make her drink the water by claiming she is his wife, nevertheless in his role as Yavam he can make her drink. The Chazon Ish bases himself on a principle that he proved (ibid. 130:4) that Zikah does not disappear as a result of Znus.