Reuven Lev drove carpool twice on Sundays. In the morning, he drove his older daughter and her friends to a chesed program, and in the afternoon, he picked up the boys from yeshiva.

One afternoon, his son’s friend, Avi, had trouble finding the clasp to buckle his seatbelt. As Avi dug between the seats to find the clasp, he found a $50 bill that had fallen in between the back seats.

“Wow! Look what I found!” he shouted. “A $50 bill.”

“You know, Avi,” said Mr. Lev, “you have a chance to do the mitzvah of hashavas aveidah (returning lost objects).”

“How can I know who owns this money?” asked Avi.

“When you find something, you are supposed to announce it to the people who might have lost it,” said Mr. Lev. “Next week, I can ask the girls who were in this morning’s carpool.”

The following week, Mr. Lev asked the girls, “Did anybody lose money in the car last week?”

“It could have been me,” Rivka said. “After the program, I went shopping and realized that I had lost money along the way.”

“How much did you lose?” asked Mr. Lev.

“At least $20, but I’m not exactly sure,” said Rivka. “I sat in the back middle seat; if it fell from me, it would probably be there.”

“It was found there,” said Mr. Lev. “But can you give me a more accurate amount?”

“I never counted the bills,” Rivka answered, “but I estimate between $20 and $100.”

“This is an interesting question,” said Mr. Lev. “I don’t know whether this serves as sufficient identification (siman).”

When Mr. Lev picked up the boys from yeshiva that afternoon, he told Avi, “One of the girls who sat in your seat lost money, but couldn’t identify the amount properly.”

“Can I keep the money then?” asked Avi.

“I’m not sure,” said Mr. Lev. “Maybe I should keep it, since it was found in my car. I expect to see Rabbi Tzedek tonight at a wedding, though; I’ll speak with him.”

After the chupah, Mr. Lev found Rabbi Tzedek. “Mazal Tov!” he said. “A fascinating monetary case came up last week.” Mr. Lev related what had happened.

Rabbi Tzedek replied, “Rivka does not have sufficient identification to claim the money. Therefore, you can keep the money found in your car. However, if it seems reasonably clear that the money is Rivka’s, it is meritorious to return it to her.”

Rabbi Tzedek then explained, “Identifying the denomination of a bill is not sufficient identification, since anyone could have lost a bill of that denomination. Even a particular mark on a bill is questionable, since money constantly changes hands. Only if Rivka had folded the bill in a special way, or if a number of bills were rolled or clipped together, would it be a siman (C.M. 262:11-13).”

“What about the fact that Rivka sat in that seat?” asked Mr. Lev.

“Location serves as an identifying siman when the person knows that he left or dropped his item there,” explained Rabbi Tzedek. “However, if the person was unaware that he lost the item, location is generally not a valid siman, since the owner is not aware of where along the way he lost it. Perhaps Rivka lost her money elsewhere, and someone else’s money fell in between the seats another day (262:3,9).”

“Even if Rivka cannot claim the money, why should I be entitled to it?” asked Mr. Lev. “Shouldn’t it belong to Avi, who found it?”

“If a lost item falls into a person’s property (chatzer), the property acquires it on behalf of the person if the property is secure or if the owner is adjacent,” said Rabbi Tzedek. “Therefore, since the money does not have an identifiable siman, you acquired it when it was lost in your car. However, a chatzer does not acquire a lost item that is not likely to be found. Therefore, if the lost money was buried deeply between the seats and you don’t think that it was yours, Avi could still acquire it when he found it (268:3; see Shach 268:2 and Pischei Choshen, Aveidah 2:ftnt. 12).

“Nonetheless, it is meritorious to return even an item that was found after the owner abandoned hope of reclaiming it (yei’ush),” concluded Rabbi Tzedek. “The same is true if the owner does not have a valid siman, but circumstances clearly indicate that it belongs to that person, especially if there are multiple indications (259:5; S.A. Harav, Metzia #18; see Beis Shmuel E.H. 17:73).”