From: Rabbi Moshe Sofer
To: Rabbi Berel Segal
The Chasam Sofer dismisses his student's proposed answer and offers his own resolution to the Taz's difficulty regarding why an oath applies in a case of modeh b'miktzas despite the rule that one does not swear over denial of land liens. He argues that when the debtor's only "land" status derives from his own false courtroom admission, that admission is credited only to his detriment — enabling collection — but not to his benefit as an exemption from the oath.
Source: Shu"t Chasam Sofer CM §72