Q: I knocked someone’s sefer off the table, ruining the binding completely. What do I owe him for the damage?

A: A person who damages an item is responsible to repair it, if the repair is typical, or to pay the value of the damage, if the repair is not typical. Thus, if the book can be sent to a professional binder who will repair it fully, you owe the cost of the repair (C.M. 387:1; Shach 387:1).

If the item is a total loss — not repairable and ruined completely — you owe the value of the item at the time of the damage, taking into account the age of the item and its condition. You are not liable, however, for the full cost of a brand-new item (see Mishpetei HaTorah I:24).

If the item is not repairable but still usable — even for parts — you owe the difference between the item’s value before and after the damage. You are not required to take the broken item and replace it with an intact one (403:1). [Some people prefer to do this in any case as a gesture of good will, even though there is no halachic need.]