This case occurred in 2001. A discussion of the case arose in my discussion group as we were considered the distinction between direct and indirect abortion.
The medical situation was this: conjoined twins shared a heart, lungs, and abdomen. If they remain joined, physicians concluded they would die within six months. An operation to move the organs to one twin only, would save the one twin and result in the death of the other.
The parents opposed the operation, thinking that it would be a grave sin to choose one life over the other. The Bishop opposed the operation on the grounds that the State should allow the parents to decide the matter.
From the point of view of moral theology, this is not a very controversial case. Given that both would die without the operation, and that they share organs, there is a moral obligation to act. Taking shared organs from one, and giving them solely to the other is an act that directly saves one life. The loss of the other life is indirect, because the organs are shared. In other words, the one child is not saved by the death of the other, but instead the death of the other is a result of saving the one life.
Let’s compare this situation to direct and indirect abortion.
Direct abortion: a mother is pregnant and has severe chronic illnesses. The physicians conclude that her pregnancy will endanger her life, due to the additional stress on the body as pregnancy advances. An abortion would save her life. The abortion is direct because her life is saved by means of the abortion.
The moral object of the act is what makes any act intrinsically evil or intrinsically good. The moral object is the proximate end, i.e. the morally immediate end, toward which the act is inherently ordered.
In the above example, the immediate end is the death of the prenatal, and the chosen act is inherently ordered toward that end. There is a morally-direct or we could say morally-immediate relationship between the chosen act, with its inherent ordering, and the moral object. The life of the mother is saved only by means of the death of the prenatal, so the saving of her life is not morally immediate or direct.
Indirect abortion: a mother is pregnant and has cancer. Treating the cancer will kill the prenatal. Which end is the moral object, the treatment of the mother, or the death of the prenatal? The death of the prenatal occurs as a result of treating the cancer, so that end is not proximate. Therefore, the abortion is indirect.
Similarly, with the conjoined twins case, the one life is saved, not by the death of the other, but by moving shared organs to the one. The life of the other is lost as a result of this life-saving treatment, and so that loss of life is indirect.
On the question as to whether the State should intervene, the State has a moral obligation, from a Catholic point of view, to intervene in order to save the life of innocent persons when necessary. This principle is what allows the State to outlaw all direct abortion, even if the parents wish to choose abortion, even if the direct abortion would save a life. So it is a grave moral error to claim that the State must let the parents decide the question.
The decision of the parents (which was overruled by the courts) to allow both children to die was objectively gravely immoral. When two lives are in danger, and inaction will result in the loss of two lives, and a moral act is possible that will likely save both lives, there is a positive moral obligation to act. The situation is not unlike the common moral hypothetical, in which two persons are drowning, but you are only able to save one life. It would be gravely immoral to allow both to die, merely because you do not want to have to make the difficult decision as to which one to save.