Is the usurper obligated to return the skin of an unslaughtered animal if he tans it?
General Chapter
Al-Mughni
Book of Usurpation
Primary text
If the usurper tans the skin, return is required if we hold that tanning purifies it, as this resembles wine that has turned into vinegar (khamr idha takhallala). If we hold that it does not become pure, its return is not required because it is unlawful to benefit from it.
Supporting text
It is plausible that return is not required because it has become property through the usurper's action, unlike wine. Alternatively, return may be required if we hold that its use on dry things is permissible, as it then resembles a dog—an impure item whose benefit is permitted, which applies even before tanning.