Euthanasia is the act of either painlessly causing the death or failing to prevent death from occurring from natural causes in an individual with a terminal illness or in an irreversible coma. The term is derived from the Greek words eus (good) and thanatos (death). Although advances in medical technology have made it possible to prolong the life of patients with no hope of recovery, at times the quality of life of the terminally ill individual is called into question.

The term "negative" or "passive euthanasia" is used to describe the practice of withholding or withdrawing extraordinary means of preserving life. The term "positive" or "active euthanasia" involves any direct intervention to cause death, such as injecting a lethal drug or participating in a form of assisted suicide in which another person provides the means for the patient to die. Active euthanasia is sometimes called mercy killing.

The...