A major point of contention is whether transplantation should be allowed at all if the patient is not yet fully biologically dead, and if brain death is acceptable, whether the persons whole brain needs to have died, or if the death of a certain part of the brain is enough for legal and ethical and moral purposes. Most organ donation for organ transplantation is done in the setting of brain death. However, in Japan this is a fraught point, and prospective donors may designate either brain death or cardiac death – see organ transplantation in Japan. In some nations such as Belgium, France, Netherlands, New Zealand, Poland, Portugal, Singapore and Spain, everyone is automatically an organ donor unless they opt out of the system. Elsewhere, consent from family members or next-of-kin is required for organ donation. The non-living donor is kept on ventilator support until the organs have been surgically removed. If a brain-dead individual is not an organ donor, ventilator and drug support is discontinued and cardiac death is allowed to occur. In the United States, where since the 1980s the Uniform Determination of Death Act has defined death as the irreversible cessation of the function of either the brain or the heart and lungs, the 21st century has seen an order-of-magnitude increase of donation following cardiac death. In 1995, only one out of 100 dead donors in the nation gave their organs following the declaration of cardiac death.
Expansive legal definitions of death, such as Spain uses, also increase the pool of eligible donors by allowing physicians to declare a patient to be dead at an earlier stage, when the organs are still in good physical condition. Allowing or forbidding payment for organs affects the availability of organs. Generally, where organs cannot be bought or sold, quality and safety are high, but supply is not adequate to the demand. Where organs can be purchased, the supply increases. Iran adopted a system of paying kidney donors in 1988 and within 11 years it became the only country in the world to clear its waiting list for transplants. Healthy humans have two kidneys, a redundancy that enables living donors (inter vivos) to give a kidney to someone who needs it. The most common transplants are to close relatives, but people have given kidneys to other friends. The rarest type of donation is the undirected donation whereby a donor gives a kidney to a stranger. Less than a few hundred of such kidney donations have been performed. In recent years, searching for altruistic donors via the internet has also become a way to find life saving organs.