I borrowed my friend’s stroller and someone stole one of the wheels. I told my friend that, as a borrower, I was responsible and would replace the wheel.

However, a few months passed before I got around to calling the manufacturer; by the time I contacted them, they informed me that the model and its replacement parts had been discontinued.

Q: Now that I cannot obtain a wheel and the stroller is no longer usable, what is my responsibility?

A: If it had not been possible to obtain a replacement wheel immediately after the wheel was stolen, you would have been liable for the entire value of the stroller since the theft caused it to be unusable. However, if a replacement wheel was available, the damage is assessed in terms of the cost of a replacement wheel and that was, in fact, your liability at time of the theft.

The question is the extent of your liability now, since at the time of the theft you could have obtained a replacement wheel, but because of your procrastination, it is no longer possible. Are you now liable for the entire value of the stroller?

When a borrowed object is damaged, the owner takes the broken pieces, the value of those pieces is deducted from the total value of the object, and the damager pays the difference between them. In the event that the broken pieces lost value between the time damage occurred and the time the damager paid for the damage, that loss is suffered by the owner (C.M. 344:2). The rationale behind this ruling is the fact that the damager never acquired the broken pieces and they remained in the possession of the owner. Therefore, any change in their value is the domain of the owner.

Applying this principle to your case means that whatever value the stroller retained while it was possible to be repaired with a new wheel remained the owner’s. Your level of responsibility did not change because of your negligence to contact the manufacturer before the model was discontinued.

Furthermore, although you promised that you would take care of obtaining a new wheel, that commitment was a favor you offered your friend but not part of your responsibility as a borrower. Additionally, since your commitment was never enforceable, the owner should not have relied upon you to obtain the new wheel. Even had you made a binding commitment, the damage that resulted from your negligence was indirect — grama. This is especially true since there was no reason for you to anticipate that the model would be discontinued; therefore, you are considered a shogeg, one who inadvertently causes someone a loss. As such, you are not obligated to pay any more than the value of the wheel at the time it was stolen.