One of the greatest medical triumphs of the post-war years has been the development of routine, reliable transplant technology: first of kidneys, then human hearts and livers. But for a number of well-rehearsed reasons - such as safer seat-belts and better-designed cars and roads leading to fewer healthy people dying prematurely - there is a shortage of available organs, and a long waiting list of desperately sick people has developed.

One of the greatest medical triumphs of the post-war years has been the development of routine, reliable transplant technology: first of kidneys, then human hearts and livers. But for a number of well-rehearsed reasons - such as safer seat-belts and better-designed cars and roads leading to fewer healthy people dying prematurely - there is a shortage of available organs, and a long waiting list of desperately sick people has developed.

Where the supply from humans has failed to fill the gap between hope and reality, medical research has focused on other members of the animal kingdom - in particular the pig. But now it transpires that this development may not, after all, be the answer. The British transplantation regulatory body has found that there are still major barriers to such inter-species transplants.

Science does offer other avenues. In due course stem-cell technology may allow us to grow new organs in laboratory conditions; but that could be as much as a generation away. Fortunately, simpler stem-cell technologies have already enabled researchers to grow replacement skin to treat burn victims and new brain cells to treat sufferers from such debilitating ailments as Parkinson's disease.

Manufactured organs, such as heart pumps, seem to offer another hope, but, due to the highly complex nature of our organs, it is unlikely that much else can be expected from this direction. Immuno-suppressant drugs could be improved, in order to make it easier to insert alien organs; but there continues to be a worry about side-effects.

This leaves the so-called "opting out" option, under which organ donors would no longer need to carry a card saying they grant permission in the case of accident for their organs to be removed. Instead, those who did not wish their organs to be transplanted would have to register this "opt-out" in advance of their death.

Due to the role inertia plays in human decision-making, this reform could increase the supply of organs dramatically while satisying any moral qualms. And, combined with improved immuno-suppressant drugs, the instances of people suffering and dying for lack of replacement parts would decline sharply. There is understandable reluctance among some to make this change, especially in the wake of the Alder Hey scandal, but the advantages clearly outweigh the concerns. The living are, after all, more important than the dead.