Two powerful reasons make a regulated market in live organs imperative. First is the evil of the present unbridled and unregulated global market in organs in which people are sometimes kidnapped, often coerced and even murdered to obtain organs. The second equally powerful driver is the tragic, unnecessary and wasteful loss of life caused by the global shortage of donor organs.

I have not only advocated such a regulated market since 1992, but set out in detail how it might work and meet the ethical objections that continue to be voiced. Markets are not ends in themselves. I, and most others who have proposed a regulated market for live donor organs, do so not because we love commerce but because we hate the terrible waste of life and liberty that the organ shortage entails. I say life and liberty because the alternative to transplants is either death or dialysis, which is a confining and onerous procedure.

Keith Rigg, of the British Transplantation Society, fears an organ market would attract paid donors at the expense of voluntary donors. It might, but if it also removes the organ shortage, it would be a small price to pay. As Professor Sir Peter Bell notes, the savings on one or two years' dialysis would cover the financial costs, and lives would be saved.

Kenneth Boyd, of the University of Edinburgh, worries about potential donors being given incomplete details on the level of risk, but I believe the risks of not ending the shortage of organs are greater.

Anthony Warrens at the London School of Medicine and Dentistry, fears it would be "the most disadvantaged" people who would sell parts of their bodies. It might, but kidney donation has become safe and ethically justifiable. Given how altruistic, not to mention life-saving, provision of an organ is, one might more appropriately ask why only the advantaged should have the privilege of such heroic altruism?

Some fear that the rich will queue-jump, but if we remove the organ shortage, there need be no queues, and bridling the liberties of the rich in order to secure life-saving operations for all is an infringement of liberty to which there can be no rational objection.

Professor John Harris is Professor of Bioethics and Director of the Institute for Science, Ethics and Innovation at the University of Manchester