What is the ruling when both the substance and the monetary value of a usurped item diminish?
General Chapter
Al-Mughni
Book of Usurpation
Primary text
If both the substance and the value of the item diminish, such as with oil that is boiled down, compensation is due for both the physical loss and the value loss, as each loss is independently compensable. For instance, if a pound of oil valued at one dirham is boiled, and one-third of the substance is lost, resulting in the remainder being valued at half a dirham, the guarantor owes one-third of a pound of oil and one-sixth of a dirham.
Supporting text
If the remaining substance still holds two-thirds of the original value, the guarantor is only liable for the loss of substance (one-third of a pound), as the value of the remaining part has not decreased. Furthermore, if a slave is gelded and his value decreases, the liability is limited to compensating for the removed testicles, analogous to the loss of the slave's eyes.