(Beraisa - R. Yochanan ben Nuri): See how we will conduct about this Halachah in Yisrael! If we will fulfill Beis Shamai's words [and let Tzaras Ervah do Yibum], the child is a Mamzer according to Beis Hillel!

If we will fulfill Beis Hillel's words [and exempt her from Chalitzah or Yibum], the child is a Mamzer according to Beis Shamai (according to R. Akiva, who holds that there is a Mamzer from Chayavei Lavim)!

Let us enact that the Tzaros do Chalitzah, and not Yibum!

(Beraisa): They were unable to enact before the opportunity was lost [and the Halachah was fixed in all matters like Beis Hillel. CHASDEI DAVID, on Tosefta 1:2 - Shamayim caused this, in order that the Tzaros will marry without Chalitzah, like Beis Hillel!]

R. Shimon ben Gamliel (to R. Yochanan ben Nuri): If so, what will we do for the first Tzaros who married [without Chalitzah? If we enact to require Chalitzah, people will consider their children Pasul!]