Terminal illness is defined as illness from which recovery is not expected. The manner in which death is defined affects the ruling, hukm, about life support.

The following are various definitions of death: (a) traditional: cardio-respiratory arrest (b) brain death. If death is defined in the traditional way, life support cannot be withdrawn at any stage. If the definition of cerebral death is accepted, life support will be removed from persons who still have many life functions (like respiration, circulation, sensation). The question of quality of life is also raised in the definition of life. The assumption is that there must be some quality to human life for it to be worth living. The exact definition of quality is still elusive. There is consensus among most jurists that brain stem death is legal death.

Palliative care

The aim of palliative care is good death which includes: pain control, psychological support, emotional support, and spiritual support. Death can be made a pleasant experience. Palliative care was traditionally in the family but it has recently moved to institutions. Lessons about palliative care can be learned from the terminal illness of the prophet and his companions. The Quran has taught the etiquette of caring for old parents.

Principle of certainty

Since the definition of death and the exact time of its occurrence are still matters of dispute, a major irreversible decision like withdrawing life support cannot be taken with no certainty. Islamic law strictly forbids action based on uncertainty.

The purposes of life and wealth

The purpose of preserving life may contradict the purpose of preserving wealth. Life comes before wealth in order of priorities. This however applies to expenditure on ordinary medical procedures and not heroic ones of doubtful value because that would be waste of wealth that has been condemned.

Legal rulings on initiating and withdrawing life support

The patient's choices about food and medical treatment may contradict the purpose of preserving life. Where life is under immediate threat, the patient's desires may be overridden.

The terminally ill patient, who takes a major risk, should make the final informed decisions after clarification of the medical, legal, and ethical issues by physicians and fuqaha. If the patient is incompetent then resort is made to proxy decision makers.

Self-interest may motivate some members of the family and others with personal interest to hasten the legal death of the terminally ill patient. According to Islamic law, any inheritor who plays any role direct or indirect in the death of an inheritee cannot be an inheritor.