The Torah in Parashat Behar (25:14) introduces the prohibition of ona’a – charging or paying an unfair price for merchandise. The Gemara in Masekhet Bava Metzia (50b) establishes that if a person overcharges, for example, and the price differential amounts to one-sixth of the fair market price, then the seller must return the difference to the buyer. If the differential exceeds one-sixth of the fair market price, then the buyer may annul the sale and return the merchandise in exchange for the money he paid. If the merchandise was overpriced by a margin of less than one-sixth, then we presume the buyer accepted the price despite its exceeding the market value, and thus the transaction is valid and binding, and the buyer has no subsequent legal recourse.
The Rosh (Bava Metzia 4:20) raises a question regarding the nature of this final halakha, the case where the price exceeded the market value by a margin of less than one-sixth. In such a case, the Rosh asks, has the seller violated the ona’a prohibition, but after the fact he bears no legal accountability, or, is the entire prohibition of ona’a applicable only when the price discrepancy amounts to one-sixth or more of the market value? One might argue that the world of commerce allows a range of acceptable prices, as buyers benefit from the availability of goods even when some stores overcharge, and sellers benefit from the interest of buyers even if they are occasionally forced to lower their profit margins. The Rosh raises the possibility that this flexibility in the marketplace is reflected by the halakha validating transactions when the difference between the actual price and the market price was less than one-sixth. Perhaps, he writes, Halakha not only absolves the seller or buyer of accountability after the fact, but fully authorizes charging or paying such a price as part of normal commercial conduct. The Rosh leaves this question unanswered, and, interestingly enough, the Shulchan Arukh, too, writes that this issue is subject to uncertainty (C.M. 227:6).
The Chafetz Chayim (Hilkhot Rekhilut, 9, Be’er Mayim Chayim 27) addresses the question of how this uncertainty might affect the laws of lashon ha-ra (negative speech about others). Clearly, Halakha permits and even requires warning one’s fellow who is considering entering into a potentially dangerous commercial relationship, even if this entails disclosing negative information about the other party. This would include warning a consumer of a proprietor who grossly overcharges for his merchandise. (This is assuming, of course, that the information is true and verified.) The Chafetz Chayim raises the question of whether this would apply also to a proprietor who overcharges by a margin of less than one-sixth. On the one hand, one might argue that since this situation is subject to halakhic uncertainty, and, as this involves a Torah prohibition, one is required to act stringently and avoid overcharging even this small amount, the seller acts improperly, and so alerting potential customers is warranted. On the other hand, one might argue that since it is unclear whether the proprietor commits a halakhic violation, as the validity of his pricing hinges on this question raised by the Rosh, it is forbidden to speak negatively about him to potential consumers.
Rav Michael Yechiel Elias, in his Minchat Mordekhai (Parashat Behar), questions the Chafetz Chayim’s line of reasoning. He notes that even if the storekeeper does not violate Halakha by charging the higher price, it should still, seemingly, be permissible to alert potential customers of the fact that this shopkeeper’s prices exceed the market value. After all, lashon ha-ra is permitted when conveying the information would save the person from a financial loss (assuming the information shared is both relevant and verified). Seemingly, then, the question of whether the storekeeper is in violation of ona’a by overcharging by a small margin seems immaterial, as regardless, warning consumers of a seller’s high prices is perfectly acceptable. It is thus difficult to understand why the Chafetz Chayim hinged this question on the issue of whether ona’a is violated in such a case.