Yehudah purchased a new laptop from Cahane’s Computers. From the beginning, the computer flickered on and off. Yehudah brought it back to the store. The technician found that the power supply was defective, and replaced it.

A few weeks later, the screen began to malfunction. Upon examination, there proved to be a problem with the screen. That was also replaced.

Yehudah used the computer for a while, but problems continued to plague the computer. Yehudah brought it back to the store, once again. The technician examined the computer thoroughly and determined that there was a problem with the motherboard.

Mr. Cahane called Yehudah. “The motherboard is still under warranty, so we’ll replace it,” he said. “With that, the problems should be solved. All the other components were checked and are intact.”

“Three strikes and you’re out!” replied Yehudah. “I’m not interested in having the motherboard replaced. I want a brand new computer or my money refunded.”

“That’s not our policy,” said Mr. Cahane. “Each component comes with its warranty period. If we replace the defective part, the computer should be good as new.”

“I don’t care,” said Yehudah. “This computer was defective. I bought a new computer, and expect it to work like a new one, not like a refurbished one.”

“We provided you with excellent service,” said Mr. Cahane, “but no one has ever asked to return a computer half-a-year later.”

“No one has had so many problems, either,” replied Yehudah.

The two decided to bring the issue before Rabbi Dayan: Can Yehudah demand a refund rather than a repair?

“The halachic concept of mekach ta’us or mum b’mekach (defective merchandise) relates to a defect present at the time of the sale,” replied Rabbi Dayan. “The sale is then void; the customer can return the item and demand a refund. The seller cannot insist on upholding the sale and repairing the item” (C.M. 232:3).

“On the other hand, the warranty nowadays has a dual purpose,” continued Rabbi Dayan. “It guarantees the merchandise against original defects and also provides coverage for failures that arise during the warranty period. The terms of the warranty, though, often allow the manufacturer the option of repairing the item.”

“Is there any notion in Halachah of repairing a defective item?” asked Mr. Cahane.

“Halachah distinguishes between a mum oveir (temporary defect) and a permanent one,” answered Rabbi Dayan. “Someone sold a house in another city, but — before the sale was completed — vandals removed some windows and doors and dirtied the walls. The Rosh (Responsa 96:6) ruled that the sale remains intact, since the defect is proportionally minor and transitory. The house retains its status, so the seller can uphold the sale and refund the amount necessary to restore the house to its former state.”

“However, if one of the walls was defective, the Rama writes that the customer can void the sale,” continued Rabbi Dayan. “The seller cannot insist on rebuilding the wall, since this would be panim chadashos (a new entity), i.e., it is not the same house that was sold. Similarly, if an integral part of the computer was defective and has to be replaced, it would be considered a mekach ta’us” (see C.M. 232:5; Nesivos, Chiddushim 232:7; Pischei Choshen, Ona’ah 13:3–7[6,7]).

“But our warranty policy specifies replacing the defective part,” argued Mr. Cahane.

“The overriding principle in commerce is: hakol k’minhag hamedinah, everything in accordance with the local practice,” replied Rabbi Dayan. “While Halachah provides default rules, people generally conduct business with the understanding of the common commercial practice. Thus, when buying a computer from a store that operates with a standard warranty policy, that policy is binding” (Maharsham 3:28).