Mr. Gefen was buying wine for Shabbos sheva berachos. He placed the bottles, including five bottles of an expensive vintage, on the checkout counter. “How many of these do you have?” asked the cashier.
“Five,” replied Mr. Gefen. “Actually, I’ll take one more. Please ring up six, and I’ll get another bottle.” The cashier entered six bottles.
The following day, Mr. Gefen returned to the store. “I purchased six bottles of wine yesterday,” he said to the storeowner. “I had five on the checkout counter and was supposed to take a sixth, but forgot. I’d like to take the other one.”
“Can I see your receipt?” asked the owner.
“Certainly,” said Mr. Gefen, handing him the receipt.
The owner approached the cashier. “This man claims he bought six bottles yesterday, but took only five,” he said. “Do you recall that?”
“I recall ringing up six,” said the cashier, “but didn’t notice whether he took the additional bottle.”
“I would give you the benefit of the doubt on regular items,” the manager said to Mr. Gefen. “However, on expensive items I cannot afford that luxury. Do you have any proof that you took only five?”
“I have no proof,” said Mr. Gefen, “but I know I forgot to take the sixth.”
“I’m sorry, but I can’t give you another bottle when you have no proof,” said the owner.
Mr. Gefen walked home disappointed. “The store is holding a bottle I paid for,” he remarked to a friend.
“If you’re certain,” suggested the friend, “next time you’re in the store, simply take what you deserve!”
Can I really do that?” asked Mr. Gefen.
“I don’t see why not,” said the friend. “If you doubt me, you can ask Rabbi Dayan.”
Mr. Gefen approached Rabbi Dayan and related the story. “Can I take from the store what I deserve?” asked Mr. Gefen.
“This relates to the topic avid inish dina l’nafshei – taking the law into your own hands,” replied Rabbi Dayan. “Rav Yehuda maintains that one may not take the law into his own hands; Rav Nachman maintains that one may [B.K. 27b]. Most Rishonim rule like Rav Nachman. However, elsewhere Rav Huna was censured for withholding vines from his sharecropper who had stolen fruit from the vineyard. (Berachos 5b).”
“There seems some contradiction,” noted Mr. Gefen. “What is the halacha?”
“Shulchan Aruch rules that, in principle, one can take the law into his own hands,” answered Rabbi Dayan, “but with significant limitations.” (C.M. 4:1)
“What are the limitations?” asked Mr. Gefen.
Shulchan Aruch, based on the Rosh [B.K. 3:3], requires that you are able to prove in court that the item is yours,” replied Rabbi Dayan. “The Rama further cites from Maharam of Rothenberg [Mordechai B.K. 3:30] that you can take only the object the other person is withholding but you cannot take something else in lieu. Third, regarding a loan there is a specific prohibition of taking collateral from the borrower against his will (see C.M. 97:6). Thus, if you cannot prove you deserve another bottle, you cannot take from the store.”
“However,” added Rabbi Dayan, “many authorities maintain the requirement that you can prove your case applies only when you take in the presence of others.
“If you take unnoticed, though, so that you could claim you didn’t take, they allow you to take what you deserve even if you cannot prove it, since you are believed with a migo. Maharshal, though, writes that even when you have a migo you are not permitted to take l’chatchila, but if you already took, you can keep it. All this, of course, is when you are certain you forgot the additional bottle.” (Sma 4:2; Shach 4:3; Pischei Teshuvah 4:5; Misphat K’halacha, Sim Shalom 4:1, citing Rav Y.S. Elyashiv.)