Q. I bought an item which turned out to be stolen goods. The owner already replaced the item and chalked it up as a loss. Must I return it to him?
A: According to the letter of Halachah, this constitutes yei’ush v’shinui reshus – abandonment and change of ownership, so that you have acquired the item. Nonetheless, there is a middas chassidus to return it to the owner (at least if he will reimburse you) (C.M. 356:3; 369:5; 259:5).
However, Rema (356:6; 368:1) rules that the practice now is to return the item even after yei’ush and shinui reshus on account of dina d’malchusa, but the owner must reimburse you. Some Acharonim question the applicability of dina d’malchusa to this case between Jews, but write that if the practice is to return the item in such cases, it is binding at least on account of minhag hamedinah (Shach 356:10).
Some explain that on account of the common practice, it is similar to a case of acquiring before yei’ush (Tzemach Tzedek C.M. #46; Pis’chei Choshen, Geneivah 3:21).
