Date: Purim Katan 5588
From: Rabbi Moshe Sofer
To: Unknown recipient
The Chasam Sofer composes a self-standing analytical treatise defending the Poskim (Rosh, Tur, Shulchan Aruch, Rashba) against the Noda BiYehudah's critique that applying the distinction between chakako u'levasof kav'o and kav'o u'levasof chakako to de'oraisa matters contradicts the Gemara in Bava Basra 65. Through thirteen foundational principles, he demonstrates that the distinction is operative even at the Torah level, offering multiple reconciliations with the Talmudic sugya and addressing practical applications for mikvaos and netilas yadayim.
Source: Shu"t Chasam Sofer YD §198