Is a killer of an adulterer ('Zani Muhsan') subject to retaliation (Qisas), blood money (Diyya), or expiation (Kaffarah)?
General Chapter
Al-Mughni
Book of Wounds
Primary text
Retaliation (Qisas), blood money (Diyya), and expiation (Kaffarah) are not obligatory upon the killer of an adulterer who has been proven guilty (Zani Muhsan). This is the clear position within the Shafi'i school of jurisprudence. The justification is that the adulterer's blood is lawful (Mubah al-Damm), and his killing is incumbent (Mutahattam). Therefore, the killer incurs no liability, similar to the status of a combatant enemy (Harbi). The killing is incumbent for the sake of Allah (Lillahi Ta'ala), resembling the ruling for an apostate (Murtadd). This principle also applies to a highway robber (Muharib) whose execution is incumbent.
Supporting text
Some jurists hold an opposing view, suggesting that retaliation (Qisas) is due upon the killer because the execution of the adulterer belongs to the Imam (ruler). Thus, anyone who executes him other than the rightful authority must face retaliation, analogous to when someone other than the rightful heir kills a person upon whom Qisas was due. This opposing view is invalidated by comparing the case to an apostate, whose killing is not incumbent upon a private individual in the same necessary manner as the highway robber.