ne of the most tragic cases to come before the English Court of Appeal in recent years is the case of the conjoined Siamese twins "Jodie" and "Mary". Few people following the reports of the case in the media could have come away unaffected by the plight of the parents, and that of Jodie and Mary themselves.

The question before the Court of Appeal was, quite starkly, whether it should order the surgical separation of the twins in order to give Jodie a chance at survival, with the knowledge that such an operation would mean the certain death of Mary. The medical evidence before the Court was that the alternative would be the almost certain death of both of the twins - but the medical evidence on when this might happen was conflicting. Perhaps "three to six months", perhaps "even a few years", but it was agreed that there was no prospect of the twins surviving in their conjoined state into adolescence, much less adulthood.

And if the operation were to have any chance of success, it had to be carried out within the first 3 or 4 months of their short lives. This was so, because Mary was growing at the expense of Jodie: Mary's heart and lungs were not functional, so she depended on Jodie entirely for oxygen and blood circulation. Jodie was conscious and appeared to have the responses and reflexes of a normal baby. But Mary had such severe physical handicaps that, in the words of the Court of Appeal, had she been born as a single child and not as a conjoined twin, "she would not have been viable and resuscitation attempts would have been abandoned".

The parents did not want the operation. They felt that they did not have the right to condemn Mary to death in order to save Jodie. The doctors caring for the twins thought otherwise, and applied to the court for permission to have the operation carried out. The courts heard many arguments of principle from parties in favour of and opposed to the operation. In the end, the Court of Appeal held that the operation should go ahead. Eventually the parents and the Official Solicitor appointed to act for Mary also decided not to take the Court of Appeal's decision on further appeal to the House of Lords.

On 7 November 2000, the separation operation was carried out. Mary died. Jodie survived and is now recovering.

What emerges very clearly from the draft report of the case is that the court was faced with a situation in which it had to decide between two sets of equally compelling arguments.

Yet the difficulty of the court was that it could give only one answer. In giving that one answer, would it be in effect be rejecting all the arguments of principle for the contrary position? If so, how can it be that moral arguments of unquestionable pedigree conflict with one another, or be overruled in favour of others? If the court decided in favour of a given moral principle, would that mean that in the eyes of the law, the competing moral principle was of lesser authority?

The decision of Jodie and Mary illustrates well the nature of many of the ethical choices facing us both as individuals, and as a society today presented with so many advances in medical technology since the Second World War.

As medical technology advances, more such choices are likely. Nor is it just a matter of medical technology any more; technological advances in medicine and medical treatment have been merged in recent years into the newer and broader front of biotechnology. Advances in biotechnology have already presented us with some very difficult questions. Should, for example, couples be allowed to screen embryos fertilised in vitro for specific genetic properties before implantation?

There is the case of Adam Nash, who was implanted as a fertilised embryo in his mother's womb only after being screened from among other fertilised embryos to ensure that he would be a compatible donor of stem cells for his ailing 6-year-old sister Molly. Then there is the case of Alan and Louise Masterton of England, who lost their 3-year-old daughter in an accident. They have four boys, and wanted a new baby girl, but were denied permission by the regulatory authorities the choice.

There are cases of people with a family history of incurable, crippling or deadly inherited conditions, or susceptibility to such. Should such people go for tests, knowing that they will have to disclose the results to prospective insurers? Should insurers be entitled to such information at all?

A common thread that runs through all these cases is that the advent of new biotechnology brings with it difficult choices, the solution of which mere good intentions are insufficient.

For some, the ability to screen life even before they are implanted in the womb may bring with it hope of a healthy child for parents who carry in them the genes for potentially fatal congenital conditions. For others, that same ability raises the spectre of "designer babies".

If that is the case, what, it may be argued, is the use of bioethics if it is of no help at all in the very cases where moral guidance is needed? Do cases like that of Jodie and Mary then demonstrate the central poverty and impotency of modernbioethics in its inability to help us decide clearly and comfortably?

The answer could be that it may not be the function of bioethics at all to help us decide surely and confidently in such cases. On the contrary. To me, the agony expressed by the law lords in their decision on Jodie and Mary demonstrates the central purpose of the true function of the study of ethics.

To borrow from and paraphrase American philosopher John Rawls, bioethics is about reflective discourse, in which we try to arrive at what we consider to be the best humanly achievable decision in the circumstances, after taking into account what we want and should want for ourselves as human individuals, and as a civilised society.

I think that it is wrong for people who disagree with the court's decision in Jodie and Mary's case to castigate it as being wrong and immoral: rather, one should simply say that the decision in that case does not accord with one's private judgements. So one of the most important goals of bioethics is to encourage individuals in a society to seek and focus on commonalities rather than differences in positions, and to recognise that private judgements ought not be confused with public responses.

In the end, the verdict matters less for us as a society rather than the process by which it has been arrived at. Secular bioethics must start from the assumption that there are no humanly discoverable ultimate deductive truths.

Applied to the case of Jodie and Mary, this means in effect that in a society based on a secular system of law and ethics, the question is not whether the court had arrived at the correct decision (for that assumes that there was one to be discovered in the first place), but whether the court has achieved the best humanly achievable result in light of the moral values that we hold as a society.

And from my own private perspective, I believe they have.

Assoc Prof Terry Kaan can be reached at: lawterry@nus.edu.sg