This week we read Parashas Shekalim, which begins the order of special Shabbos Parshios leading up to Pesach. Aside from the spiritual elevation, for many of us this time of year also involves a number of material aspects, several of which include the dreaded s-word: shopping.

Yes, pre-Pesach is a renowned time for shopping. Many stores offer sale prices on men’s, women’s and children’s clothing, on electrical appliances, tableware, silverware, and plenty besides – not to mention food. In advance of the upcoming shopping expeditions we will be embarking on, we will discuss some shopping laws.

In the present article, we will discuss some aspects of mekach ta’us – cases in which a person receives something other than what he expected. The field of mistaken purchases, which corresponds to the concept of mistake in modern contract law, is a broad and extensive field, and cannot be encompassed in the scope of one article. We will therefore limit the discussion to the most frequent cases, which come up often in Beis Din.

How is the prohibition of selling a defective item defined? How is a blemish defined for voiding a sale? How does the intention of the buyer figure in the equation? To which degree is the buyer responsible for checking his purchases before completing a sale?

These questions, and others, are discussed below.

The Prohibition of Fraud

It is forbidden to sell an item—whether moveable items or real estate—if the item is defective. If this is done without informing the buyer of the defect before he completes the purchase, the seller is perpetrating a fraud (Choshen Mishpat 228:6).

If a person sells a defective item for the standard price and the defective item is worth less than the sale price, he will be violate the ona’ah law (for a relatively small deviation in price, see Choshen Mishpat 227:6).

But even when the price accurately reflects the defect (meaning, the item is sold for less than the market price), it remains prohibited to sell a defective item as though it were flawless—though for a different reason. In this case, the prohibition is not a function of difference in price (since he is selling the item for the correct price), but of the seller’s misleading of the buyer.

The Sema (228:7) explains that the essence of the prohibition is geneivas daas: the buyer is misled (intentionally or unintentionally) by the seller. According to this reasoning, it follows that the prohibition, unlike that of ona’ah (Shulchan Aruch, Choshen Mishpat 228:26), applies even to dealings with non-Jews (though there might remain differences between them). Chazal teach that that Geneivas Daas of a Gentile is prohibited just as that of a fellow Jew (Chulin 94a; see Tur and Shulchan Aruch, Choshen Mishpat 348:1).

For further details on mekach ta’us in transactions with non-Jews, see Mishpat Shalom (Kuntress Acharon 232).

Voiding a Sale

From the buyer’s perspective, the important question is not the prohibition, but rather his rights after discovering the blemish in his purchase.

The primary rule is that somebody who buys an item has a legitimate expectation that it should be without any blemish or defect. On account of this expectation, it follows that when the item supplied is blemished (in a significant way), the buyer has the right to void the sale (Rambam, Mechira 15:6; Shulchan Aruch, Choshen Mishpat 232:7).

The primary source for this matter is the Gemara in Kesubos, which deals with blemishes related to a marriage. If a couple is wed, and then one spouse discovers a blemish in the other (the Gemara discusses primarily blemishes that the husband finds in his newlywed wife), that is grounds for voiding the kesubo.

These blemishes include physical or mental flaws, or other matters that are generally considered defects. The Gemara, for instance, discusses a man who discovered after his wedding that his wife had made vows, forbidding her from certain activities that relate to her marital life (such as vows that involve suffering).

Even if no stipulation excluding a woman who had made vows was made prior to the wedding, the husband has the right to void the kesubo, since this expectation is considered inherent to the marriage (Kesubos 72b; see Rosh, Siman 10).

Defining a Blemish

Many cases of mekach ta’us are clear-cut. If food purchased from a store turns out to be rotten, the sale is of course void and the buyer gets his money back. Nobody would buy rotten food, and this was clearly not the intention of the buyer. If, on the other hand, a cheap wrist watch has a small scratch on its back, this will not be a mekach ta’us, because this is not something that people are in general particular about. Many cases, however, are less obvious.

The way in which cases of mekach ta’us are decided is by reference to local custom. Where a particular flaw is considered a significant blemish (so that people are careful not to purchase items possessing that flaw), discovery of the flaw will suffice to annul the transaction. However, in other places, the same flaw might not constitute a blemish for purposes of mekach ta’us.

This idea is ruled by the Rambam (16:5) and Shulchan Aruch (232:6). The Biur HaGra comments that the ruling emerges from the case of a man who marries a woman, only to find that she has taken vows upon herself. The only vows that have the power to void the kesubo (if the husband wishes to do so) are vows that people are particular for. If the woman has made vows that generally don’t disturb people, there are no grounds for voiding the kesubo.

For instance, the Shulchan Aruch (232:19) mentions that although the Tur rules that a buyer can void the sale of eggs after finding that they are muzoros (they are fertilized), “today (perhaps today this is no longer the custom) it is not customary to be particular for this,” so that “the custom trumps the halachah.”

It is important to note that a blemish for which a buyer may claim his money back does not refer to a physical blemish alone. The same applies to any problem that the buyer unexpectedly encounters with his purchase. For instance, if a piece of land is bought, the buyer may rightfully expect the land to have no legal attachment to a third party. Even if the buyer does not stand to lose money on the purchase, if the purchase places him in legally complicated positions, he is within his right to void the transaction (Shulchan Aruch 226:6; see especially Biur HaGra).

The Importance of Intention

Sometimes, the intention of a buyer can be paramount for a mekach ta’us. A classic example of a defective purchase is given by the Mishnah (Bava Basra 92a). If one sells seeds for the purpose of planting, and the seeds do not sprout, the seller is held responsible.

The Shulchan Aruch (Choshen Mishpat 232:20) explains that unless we know of another reason the seeds failed to grow, such as a hailstorm or similar natural occurrence, we assume that the seeds were defective, and the transaction is therefore void. This, however, is only true insofar as the seeds were initially purchased for the purpose of planting them. If the seeds were purchased for consumption, a failed attempt to plant them will not give the buyer the right to void the sale. Since the seeds were bought for consumption, and they were indeed consumable, their capacity for planting is irrelevant to the transaction (Choshen Mishpat 232:21).

The Gemara describes a case of an ox, which, to the buyer’s dismay, is found to possess a tendency to gore (nagchan). This renders the ox quite unsuitable to work the land, aside from the obligation of putting him down as a dangerous animal (see Sema). Like the case of seeds, the halacha depends on the intention of the buyer. If the ox was bought for plowing, the buyer can void the transaction, since the ox is unsuitable for this purpose. If, however, the ox was bought to slaughter (for its meat), the ox’s aggressive tendencies do not constitute a blemish. Even if the buyer now wishes to use the ox for plowing and finds it useless – he cannot void the transaction (232:23).

In our day and age, questions of seeds and oxen are infrequent, but the underlying principle remains highly relevant. If a person orders matzos before Pesach and he is supplied with matzos that are chametz (for simplicity’s sake, we can discuss matzos that were delivered in his absence), he can claim mekach ta’us under the assumption that his obvious intention was for non-chametz matzos. This will not be true if he orders matzos before Sukkos.

Prior Knowledge

When a buyer is aware of a particular blemish or deficiency, and nevertheless makes the purchase, he cannot return to the seller and claim that the acquisition was mistaken. The Shulchan Aruch clearly states that the only case for a claim of mekach ta’us is when the  buyer was unaware of the problem (Choshen Mishpat 232:3).

The Sema (245:16) rules further that when the blemish is clearly visible, we assume that the buyer saw it before the purchase, and he thus loses the right to claim mekach ta’us. This, too, is based on the issue of a woman who is found to have a blemish: Where the husband saw the woman in advance, or where he is assumed to have seen it or become aware of it (because the blemish is visible to the public), he cannot claim mekach ta’us to void the marriage.

Even when the blemish was not fully visible, there are cases in which the responsibility for detecting the flaws is on the buyer. The Rashba (Vol. 1, no. 127) discusses a common case in which someone bought a house, planning to build an extension on its roof. After completing the purchase, the buyer realized that he would not be able to build the extension, due to a neighbor’s window that the extension faced.

The Rashba ruled that the buyer cannot void the transaction, because he already knew about the presence of the neighbor’s window, and accepted the purchase as it was. Although the buyer surely claims that he didn’t realize the significance of the window, the Rashba deferred his claim, because it was the buyer’s responsibility to check the details of his purchase.

This principle is ruled explicitly by the Sema (Choshen Mishpat 232:10), as based on the Maggid Mishnah (Mechirah 16:3): if the buyer could have easily (without significant effort) ascertained the blemishes in the item at the time of purchase, it is considered as though he knew about them. Although there are those who dispute the ruling, many authorities concur with the Sema (see Nesivos HaMishpat 232:1; Shvus Yaakov, Vol. 3, no. 169; Mishpat Shalom 232:4-6).

In many instances, the claim of mekach ta’us will therefore be restricted to a transaction in which the item was delivered in the absence of the buyer. In this case, the buyer cannot be blamed for not having noticed the nature of the purchased items before receiving them. The exception of course is for hidden blemishes.

Buying Used Cars

In the case of hidden blemishes, the golden rule is the reasonable behavior of the buyer. Where the buyer checked the product in a way that is considered reasonable, yet failed to detect the defect, he retains the right to void the sale. However, if he failed to act reasonably and therefore did not detect the blemish, the sale stands, and he loses his right to void the sale on account of the blemish.

The classic case that brings this point home is the sale of used cars. It is common custom in many places for a (prudent) buyer to take a car to a vehicle test center before buying the car. When a buyer chooses not to do so, he accepts the risk of finding a hidden (mechanical) flaw upon himself. Upon finding the flaw, he therefore cannot void the sale.

Naturally, this will depend on the common custom in each place and time.

Note that onus placed upon the buyer to check for blemishes only comes into effect at the time of payment. If he received the item before payment, and failed to check for blemishes, he does not lose his right to claim mekach ta’us. The reason for this is that we only expect a buyer to check for blemishes when he comes to pay for the purchase (see Mishpat Shalom 232:5).


In conclusion, to avoid mekach ta’us issues it is of great importance to ensure that all terms and condition for the sale are clarified in advance, so that buyer and seller know exactly what they are getting into. Check your purchases before taking possession of them, and make sure you are very clear about what you expect.

In cases of disappointment, seek to resolve the issue with the seller. Note that in many places there are consumer laws that require a seller to accept the purchased item back and to return the payment. If nothing simple works out, consult a competent halachic authority to know your rights.

Wishing all readers a happy shopping season!

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