Ibn Rushd said: “The underlying purport of retaliation is that killing was legislated only to eradicate killing, as the Quran itself makes clear. If a group were not executed for murdering one person, people would exploit that loophole and purposefully commit a murder collectively; and neither solace for the victim’s family nor deterrence would be achieved except by executing the whole group.”

For a group to be put to death for killing one person, it is required that the act of each individual would have been sufficient to cause death had he acted alone—that is, all must have directly participated in the killing, and the deed of each one, taken by itself, must be lethal.

If the act of each would not independently cause death, yet they conspired and agreed to kill the victim, retaliation is still taken from all of them, because the non-direct participant becomes an accessory to the direct killer.

Whoever coerces another person to kill someone, and the coerced individual carries it out, retaliation becomes obligatory upon both the coerced killer and the coercer, provided the conditions are met; for the killer sought to save his own life by taking another’s, while the coercer set in motion a cause that customarily results in killing.

If someone orders a minor or a mentally incompetent person to kill another, and the victim is indeed killed, retaliation falls solely upon the one who gave the order. The commanded party is merely an instrument in the hand of the commander, and retaliation cannot be imposed upon him; therefore it is imposed on the instigator.