Do you own your own body? It may appear a ridiculous question, but after the shock of learning that pathologists kept, unbeknownst to their parents, the hearts of 170 babies who died after cardiac surgery at the Bristol Royal Infirmary, one might be forgiven for wondering just what else might disappear into the hospital archives after a death or surgery.

While few people these days want to keep a diseased kidney or a gory tumour floating in formaldehyde on their mantlepiece, the increasing knowledge about the human genome and the potential for creating cell lines which could eventually produce whole new organs is turning tissue for research into a valuable commodity.

Surprisingly, though it's easy to state ownership of your car or stereo, ownership of your 'body' is far less clear.

Legally there is no 'property' in the body: you may inhabit yours, but you do not own it. On the other hand, the tradition of medical consent relies on the principle that a patient has control over what is done to their body. And that, says Len Doyal, professor of medical ethics at the University of London, implies ownership.

However, he adds, we would hardly claim to 'own' the millions of skin cells we discard every night or the various other bodily wastes we produce, and unwanted tissue or organs - such as those removed in operations - are seen in the same light.

So, unless you specifically request any tissue excised during surgery, it is considered abandoned and can be stored and used for research without consent.

Once you're dead, things are slightly different. There's still no direct ownership of your body but the law does allow someone to have 'lawful possession' of it - usually the next of kin, who then take over the responsibility of giving consent. In the case of the Bristol heart babies, however, parents were asked to consent to a postmortem, but were not specifically told that the hearts or any other part of the body would be kept for future research.

But why do doctors need whole organs? Many major advances in healthcare have relied heavily on research into archived tissues -including tracing HIV, identifying genes for a large number of hereditary cancers, exploring viral infections and producing new drugs via cell lines. Human tissue is also vital to finding out where and how genes are expressed.

In most cases only tiny sections of tissue are needed. However, when it comes to brains and hearts, says Dr Jennian Geddes, head of the Department of Morbid Anatomy at the Royal London Hospital and an expert in brain diseases, having access to whole organs - though a highly sensitive and emotive request - is essential.

'The brain is a very complex structure. Different diseases affect different parts of it and one or two samples aren't representative of the whole structure.' Similarly whole hearts are needed to investigate structural malformations. However, Geddes is adamant that families must know when researchers want to retain an organ after death and, most importantly, why.

'What people need to ask the pathologist is what will you be keeping from the postmortem, will you use it for teaching, or for research and why is it important? Consent forms need to spell out that whole organs may be removed for teaching and research purposes and people should be able to strike that out if they want to.' The problem, adds Geddes, is that it's usually junior doctors who don't necessarily know the answers to these questions who are detailed to ask families for consent.

Use of coded tissue archived from surgical operations also carries another potential problem these days - the possibility that researchers using it might uncover something its erstwhile owner may desperately want to know - such as the discovery of a genetic condition that could be treated.

Whether researchers should be able to break the anonymity code on tissue samples and contact families in this situation is controversial.

'What someone may not think they want to know at 20, they may want to know at 30. It may save their life. We would have to reconfirm their consent decision for every study,' says Prof Roy Weller, head of pathology at Southampton General Hospital, who adds that this could be so time-consuming as to bring tissue research to a halt. Others however believe it is essential to give patients the choice of knowing.

The final conundrum is the question of commerce. If bits of your body become the raw material from which highly profitable treatments emerge, could you be in for a windfall? It all comes back to whether you 'abandon' tissue in an operation or not. So far, in Britain, there's no case law to clarify this. But in one of the few cases to come to court in the US, the Supreme Court found that a man whose diseased spleen provided a rare cell line for hairy cell leukaemia valued at around $3 billion had no property rights to the cells used because he had consented to a clinically-needed splenectomy.

The court did, however, order that the researchers should go to trial to test whether they had breached their duty to obtain informed consent since there was evidence that they knew clearly the value of the man's spleen before the operation. In the event, the patient settled out of court, leaving the question still unresolved.

Till death do us part

Bodies should become public property at death, says John Harris, Manchester professor of bioethics. If we forfeited ownership of our bodies after death, the crisis in organs for transplantation could be eased.

'Postmortems can be ordered in the public interest. If there's a public interest in finding out the cause of death - and last week's events in Bristol show not all the bits are put back - how much greater is the public interest in saving the life of a citizen at risk?' Harris, who will address a conference in Manchester this weekend, says compulsory donation could save 1,000 lives a year.

Whilst acknowledging that some people feel upset about having their bodies used in this way, he notes that no argument is countenanced when the court orders a postmortem, 'so why should we allow it when it comes to organ donation?' And to those anxious that their organs might be harvested before they're truly dead, Harris adds they're far more likely to need a donor organ and not get it than to lose one prematurely.