Responsa for Shevuot 88:6

Q. A traded his horse with B for wine, and B received the horse. Before B shipped the wine to A, a Gentile claimed that the horse had been stolen from him, and took it away from B. Now B refuses to ship the wine to A, claiming the transaction was made in error.
A. As soon as B received the horse, the wine became A's property, and B cannot retain it. If A claims that his horse was not a stolen horse and that the Gentile took it away unjustly, or that he (A) had no knowledge that it was a stolen horse, he is not responsible (since we cannot rely on the Gentiles' word). If, however, B can prove that at the time of the transaction A knew that it was a stolen horse and that the Gentile had a right to take it, B may keep his wine.
SOURCES: Cr. 186; Pr. 35; Tesh. Maim. to Kinyan, 6; Mord. B. M. 298.

Q. A lent a silver key to B's wife. She says that she has lost the key. Has A any claim upon B, or his wife, for the value of the key?
A. Most authorities agree that a person cannot collect from the husband the value of an object lent to, or deposited with, his wife, and lost by her, even in cases where she is a business woman conducting her husband's affairs with his full knowledge and consent. But a ban should be pronounced in the synagogue against those persons (including B's wife) who have the silver key in their possession and do not return it to A, and also against those persons who may receive such key in the future and will not return it to its owner. Moreover, A should receive a court decision entitling him to collect from B's wife, should she become widowed or divorced, an amount equal to the value of the key. A clause should be included in the decision providing that in case of a dispute between A and B's wife regarding the value of the key, it will be incumbent upon her to take an oath as to the value of the key.
SOURCES: L. 206.

Q. A demands that Leah return to him the money he deposited with her. Leah claims that A deposited the money with her on condition that she do not return it to him without his wife's consent. [A's wife does not consent to the return of the deposit]. Are we to believe a trustee who was appointed by the two opposing parties regarding the terms of his trusteeship, or may we require him to take an oath? Moreover, Leah is a married woman. May her husband object to her being degraded by imposing an oath on her?
A. A trustee appointed by both parties is not required to take an oath regarding the terms of his trusteeship. But, Leah was not appointed trustee by both parties. She was only appointed by the husband, and, therefore, is required to take an oath. Leah's husband cannot object to imposing an oath on her. If the law requires that a woman take an oath, the husband has no right to protest against her being degraded in court. But, since Leah, as long as she is married, has no money of her own, and were she to claim that she had already returned the deposit, no oath would be imposed on her, we now lend credence to her words and require no oath. However, the court should give A a writ stating that after Leah will be divorced or widowed she will have to return the money to A or take an oath to the effect that A deposited the money with her on condition that she return it upon his wife's consent only.
SOURCES: L. 306–7; Mord. B. K. 89. Cf. Pr. 739; Tesh. Maim. to Mishpatim, 44.