Rav Kornfeld, what is the underlying principle that allows monetary tenaim that are contrary to torah? Is it the power of a person to waive debts owed to them? Some mechanism of hefker beit din hefker?
Thank you!
The first concept you mentioned is correct. A person can be Mochel monetary rights and this is therefore not opposed to the Torah(Chidushei Rebbi Shimon Shkop, Kesubos 49a). This is borne out by the Sugya there where the Gemara says that a person can waive monetary rights even if they are of Torah origin, such as a woman's rights to clothing and food in marriage.
As for other mechanisms, I don't think Hefker Beis Din would come into play as this is necessary to transfer money from one to another but not to relinquish one's rights. Another possible mechanism could be Siluk, which is also a way of relinquishing rights, as explained in Kesuvos 83a and Gitin 77a.
Yoel Domb