In Re A (Children) (Conjoined Twins: Surgical Separation) [2000] 4 All E.R. 961 the Court of Appeal faced the impossible dilemma of having to decide whether to authorise a complex operation to separate Jodie and Mary, ischiopagus conjoined twins (joined at the pelvis). The condition of the babies was extremely rare, it being estimated that only about once in 100,000 births will monozygotic twins fail to separate completely. Even then, ischiopagus twins account for only about six per cent. of the total instances of conjoined twins. Another very rare peculiarity of the case was the certainty that the operation, if sanctioned, would quickly and inevitably bring about the death of the weaker twin, Mary. This was because the twins shared a common aorta. Mary’s own heart and lungs were severely deficient and incapable of oxygenating and pumping blood through her body. Her life was thus sustained only by the common artery and separation would necessarily involve clamping and severing this. It was equally clear that the effect of failing to attempt the separation would be the inevitable death of both twins within three to six months. The cause of death would be heart failure since Jodie’s heart would sooner or later fail. The parents, devout Roman Catholics, opposed the operation, believing that in God’s eyes the twins were equal and that one could not morally be sacrificed to save the other. The hospital took a different view. It believed that a successful operation could be performed which could give the stronger twin, Jodie, a reasonable prospect of a worthwhile life.