Q: My roommate was missing his phone. After searching for a week, he finally said, “I give up!” and bought a new one. I later found the phone deep in the back of the drawer in our desk. May I keep the phone?
A: Yei’ush in error, such as if the owner thought that the item was lost, but it was actually in a secure place, is not considered yei’ush, and the finder may not keep the item (Pri Yitzchak 2:64; Nesivos.259:1).
Only when the circumstances are appropriate for yei’ush, does yei’ush take force (Maharik #3; Rema C.M. 163:3).
Some explain that for this reason, if a person was held liable in beis din and paid, but the ruling turned out to be in clear error, or he brought new evidence to overturn the ruling, the money is returned. We do not say that he had yei’ush on the money, since the erroneous ruling is something that can be clarified even much later, so that the yei’ush was in error (Chiddushei Harim, C.M. 25:4; Sha’ar Mishpat 25:2).
