In cases of qisas for part of human body, section 55 of Iran's penal code grants the victim or victim's family to, with permission of the court, inflict an equal injury to the perpetrator's body.
If the victim lost the right hand and perpetrator does not have a right hand for qisas, then with court's permission, the victim may cut the left hand of the perpetrator.
Narrated Abdullah Ibn Abbas: A blind man had a slave-mother who used to abuse the Prophet and disparage him.
(...) So he took a dagger, placed it on her belly, pressed it, and killed her.
I have two sons like pearls from her, and she was my companion. So I took a dagger, put it on her belly and pressed it till I killed her.
Qisas principle is available against the accused, to the victim or victim's heirs, when a Muslim is murdered, suffers bodily injury or suffers property damage. the law of equality is prescribed to you in cases of murder: the free for the free, the slave for the slave, the woman for the woman.
But if any remission is made by the brother of the slain, then grant any reasonable demand, and compensate him with handsome gratitude, this is a concession and a Mercy from your Lord.
After this whoever exceeds the limits shall be in grave penalty.
Allah's Apostle said, "The blood of a Muslim who confesses that none has the right to be worshipped but Allah and that I am His Apostle, cannot be shed except in three cases: In Qisas for murder, a married person who commits illegal sexual intercourse and the one who reverts from Islam (apostate) and leaves the Muslims." Narrated Abu Juhaifa: I asked 'Ali "Do you have anything Divine literature besides what is in the Qur'an?