If a person suffers kidney failure, Heaven forbid, and requires a kidney transplant to save his life, are family members required to donate a kidney for this purpose?

A fundamental principle in Halacha states that one is not obligated to place himself in a situation of "Safeik Sakana," potential danger, to save another person's life. Even if a person will certainly die without somebody else's intervention, one is not required to risk his life to save that individual. In fact, Halacha would forbid putting oneself in a situation of potential risk to save his fellow. (The Radbaz in Helek 3, siman 625, referred to a person who does so as a "Chasid Shoteh" – a "foolishly pious" individual.) The question thus arises as to whether undergoing the surgery of kidney removal and then living with only one kidney poses a risk to one's life that would render it forbidden to donate a kidney, even if the patient is sure to die if he does not receive a transplant.

Rabbi Eliezer Waldenberg Z"L (contemporary Halachic authority in Jerusalem), in his work Tzitz Eliezer, in Helek 9 Siman 45,, writes that the physicians with whom he consulted indicated that the process of donating a kidney indeed presents a considerable risk to life. He therefore rules that it would be forbidden to donate a kidney to save a patient's life unless a consensus of doctors who are experts, analyze and conclude that there is no danger, then maybe it is permissible.

However, Chacham Ovadia Yosef, in the ninth volume of his work Yabi'a Omer, Choshen Mishpat siman 12, writes that the experts with whom he spoke reported a 95% success rate of kidney donations and a high rate of survival among people living with only one kidney. Accordingly, Chacham Ovadia ruled that it would be obligatory for a person capable of donating a kidney to do so if he could thereby save a patient's life. Failing to do so, he writes, transgresses the prohibition of "Lo Ta'amod Al Dam Rei'echa" (Vayikra 19:16), which forbids standing by idly when one is in a position to save a fellow Jew. Given the high rate of success of kidney donations, this situation does not fall under the category of "Safeik Sakana," and therefore a healthy family member of a patient suffering kidney failure would be obligated to donate a kidney to save that patient's life.

Of course, given the gravity of this issue, which involves Piku'ach Nefesh (potential risk to one's life), a person faced with such a situation must consult with a competent Halachic authority, and not rely on the information presented here for practical guidance.