I asked my friend if I could borrow his umbrella. He agreed and told me that it was next to the stairs. I took it, but unfortunately, an unusually strong wind broke the umbrella. Meanwhile, my friend realized that his umbrella was in his car. I had taken someone else’s umbrella.

Q: The owner of the umbrella claims that I must reimburse him for the umbrella. Am I obligated to pay him?

A: If this had occurred to your friend’s umbrella, you would be exempt based on the principle of meisah machmas melachah - a borrowed item that breaks in the normal course of usage (C. M. 340:1). Presumably, this exemption does not apply in your case, as you used someone else’s umbrella without permission (Ritva, B.M. 40b).

On the other hand, since you thought that the umbrella belonged to your friend, you never accepted responsibility if it would be meisah machmas melachah (see Pischei Choshen, geneivah 7:[2)], and you should not be liable for the occurred damage.

There is another dimension to your case. Since you took the umbrella without permission (shoel shelo midaas) you are liable like a thief (C.M. 292:1) who is responsible for the stolen object even on damages occurring beyond his control (oness). Although you did not intend to be a shoel shelo midaas, we nevertheless might apply the liabilities of a thief based on the principle of adam muad l’olam. This rule teaches that a person is always guilty for his actions, even when done unintentionally. Accordingly, it seems that you must reimburse the owner.

However, there are authorities who contend that this principle of adam muad l’olam applies only to a damager (mazik) but does not include cases of ganav b’shogeg (inadvertent theft). In other words, although a thief is certainly obligated to return an object he stole, if it was destroyed due to an oness, a ganav b’shogeg is not obligated to pay (Ketzos and Nesivos 25:1). Others maintain that even one who steals an object inadvertently, albeit realizing that he is taking possession of an object belonging to someone else, may carry the liabilities of a thief; if he cannot return the stolen object, he must reimburse the owner.

This happens when one purchases an object not realizing that the seller stole it, or if one borrows an object thinking that it belongs to the lender when, in fact, it does not. In both of these examples, he intended to take possession of somebody else’s object and is therefore a shoel shelo midaas - a thief. He is exempt only when he thought the object was his own and did not realize he was taking possession of another person’s object (Machaneh Efraim, gezeilah 7).

The question of your liability depends on the above dispute, and since the matter is not resolved, you are exempt.