In re A was decided by the English courts in 2000. Twin girls, named Jodie and Mary for purposes of the decision, were born joined together at their lower extremities. Jodie's heart and lungs were more or less healthy. But Mary's were insufficiently developed and could not provide her with the flow of blood and oxygen needed to survive. However, the girls shared a single circulatory system so that Jodie's heart pumped blood that flowed through both their bodies. In this manner, Jodie's heart and lungs kept Mary alive. According to the doctors, this situation could continue for a period of three to six months, or a bit longer, at the most. As the girls grew, Jodie would be unable to provide sufficient blood and oxygen to support both Mary and herself. Both would die. The doctors recommended surgical separation of the two girls. Mary would necessarily die “within minutes,” being cut off from her source of sustenance. Jodie would have a good chance of surviving. The legal issue presented was whether the doctors may perform the surgery that would cause Mary's death. At issue were questions concerning the scope of self-defense and necessity. In the course of the Court's opinions, brief reference was made to Jewish law. This article considers the Jewish law sources that bear on these issues.