Radically new techniques are opening up exciting possibilities for those working in health care - for psychiatrists, doctors, surgeons; the option to clone human beings, to give just one example. Who should determine what is allowed and what prohibited? And what sort of consent should doctors have to have from patients before treatment. Is the trend towards consent forms helpful? Or should we trust doctors to make good decisions for us. For many years now, philosopher Onora O'neill, formerly principal of Newnham College, Cambridge, has been thinking about the issue of 'trust': trust is vital in most areas of human interaction - but nowhere more so than in health and medicine.