Q: Someone dropped an item while getting on the train. I picked it up immediately, but it had no simanim. May I keep it?
A: Although the item has no simanim, so that the owner will have yei’ush when he realizes the loss, you picked it up before he realized and had yei’ush.
When the item has simanim, you remain obligated in hashavas aveidah even after the owner has yei’ush, and may not take it for yourself. Many Rishonim maintain that also when there is no siman you may not take the item for yourself, because it entered your hands before yei’ush, when you did not yet have a right to take it for yourself (Rema C.M. 260:10).
However, Rambam writes that because there is no way to return the item, you may keep it. Some explain that you never became obligated in hashavas aveidah, because it is not possible to return it. Others explain that it is not yours, but because there is no way to return it, you may use it freely meanwhile, until the owner is located (C.M. and R’ Akiva Eiger 260:9).
