Reuven sent his son to the shoe store right before Pesach to pick up shoes, providing him with clear instructions for the size. He also instructed him to have a shoe repair shop place taps on them. When Reuven tried on the shoes, he realized that the shoe store had given his son the wrong size. The owner admits the mistake but refuses to take back shoes with taps on them.

Q: Does the owner need to accept the return for a full refund?

A: The relevant issue is whether there is liability for damaging purchased merchandise that is, in retrospect, the seller’s object, before realizing that it was defective, in our case the wrong size. Shulchan Aruch (C.M. 232:13) differentiates in such a case between two categories of damage: one resulting from ordinary use of the object, and the other resulting from an unusual use of the object. If the customer used it in an accustomed manner, not realizing that it was defective, he is exempt. If he used the object in an unusual manner, he must pay for the damage.

The Nesivos (ibid 5) hinges the matter on whether the customer should have exercised more caution. Halachah differentiates between circumstances where one should have exercised greater caution - oness k’ein aveidah - and circumstances where there was no reason to have exercised greater caution - oness k’ein geneivah. When handling a newly purchased object, one must consider that the object may be defective and therefore use it in an accustomed manner; otherwise, he will be liable for the damage.

Another rationale why the customer is liable for damages resulting from unusual usage is the ruling that the customer is retroactively an unpaid custodian for damaged merchandise that he will return to the seller. As such, he is liable for acting negligently with the object but is exempt if he used it in an ordinary manner (Divrei Mishpat, ibid).

It would appear, therefore, that Reuven is exempt from paying damages on the returned shoes, since putting taps on shoes is considered ordinary usage. Further consideration, however, indicates otherwise. It is not uncommon for one who orders merchandise to receive the wrong item (e.g. wrong color, size, etc.); therefore, one should not physically change that item until he confirms that it meets his specifications. In particular, when purchasing merchandise in the busy erev Yom Tov season, one should realize that people are prone to making mistakes when filling an order.

Accordingly, the storeowner must take back the shoes since he gave the wrong size, but the customer must reimburse him for putting taps on the shoes if it reduced the value of the shoes. If the owner would be able to sell them for a higher sum to someone who appreciates having taps already on the shoes, the original customer would receive that profit (C.M. 323:14).