The Qur'anic verse which prohibits foods states at the end that one forced my eat them. From this verse the following two legal maxims were derived: "Necessities overrule prohibitions" and "Choosing the lesser of two evils, if both cannot be avoided." These maxims provide the foundation for the permissibility organ donation in Islam. Saving human life is a "necessity" which outweighs the prohibition of damaging a human body (whether living or dead). Injury to the donor's body is also a lesser evil than letting the patient die. On the basis of these principles it is also permissible for someone starving to death to eat the body of someone already dead.

The sale of organs would be prohibited in Islam as it currently is internationally. Where public health facilities are not available and organ transplant operations are performed in private medical institutions, only the rich will benefit from such operations. Such a situation also promotes the trade in human organs as there are many in the Third World willing to sell organs for some quick money.

The transplanting of sex organs like testes capable of producing and discharging sperm or ovaries capable of ovulating into another person would be unlawful. It would lead to confusion of genealogy and the conception of babies by gametes not united by marriage, since the sperm and ovum will always belong to the donor and not the recipient.