[IDEM libro tertio responsorum. ] §16.2.18.prIn rem suam procurator datus post litis contestationem, si uice mutua conueniatur, aequitate compensationis utetur.
[THE SAME, Responsa, Book III.] A person who, after the joinder of issue, has been appointed an agent in his own interest, if he is sued in turn, shall enjoy the equity of set-off.
§16.2.18.1Creditor compensare non cogitur quod alii quam debitori suo debet, quamuis creditor eius pro eo, qui conuenitur ob debitum proprium, uelit compensare.
A creditor is not compelled to set off what he owes to another than his own debtor, even though that person's creditor wishes to make a set-off on behalf of the one who is sued for his own debt.