From: Rabbi Moshe Sofer
To: Rabbi Itzak
The Chasam Sofer resolves difficulties in Tosfos and the Ramban regarding the source for ed echad ne'eman be'issurin, explaining that the woman's impurity is established independently of her testimony and that a single witness can resolve a safeik created by competing chazakos. He further clarifies the Ramban's mitoch principle as rooted in the inseparability of testimony about her body from its implications for her husband, and rules that while a woman is exempt as karka olam from direct Torah liability in arayos, she nonetheless violates lifnei iver by facilitating the man's transgression.
Source: Shu"t Chasam Sofer YD §147