The right of adults with sound mind to consent to treatment or risk their own health for the benefit of the community in a clinical trial is unequivocally recognised by the law. But what about those vulnerable by virtue of their age, nature or position in society? Experts from the fields of medicine, philosophy, theology and law, explore the ethical and legal principles which seek to reconcile the individual's right to autonomy with the need to protect vulnerable groups. Discussions refer both to specific groups (premature babies, children, people with mental handicaps) and specific issues (cases of abuse by sterilization of women, suicide, the right to information).