In this first Bioethical Issues column the author outlines some of the distinctions and congruities between ethics and law, and between bioethics and medical law. The evidence for connections is obvious and wide-ranging, appearing within health and medical education, the academic literature, statute and case law, professional guidelines and the activities of professional associations, the history of legal practice and philosophical inquiry, and the emergence of human rights theory and applications. The interpenetration of morals and law is examined first by briefly tracing the development of natural law and legal positivism. These links are then developed through a number of examples which are the subjects of both bioethical and legal interest: decision-making capacity, what constitutes good medical practice in the advance care planning context, sex selection, embryo experimentation and posthumous conception. These topics illustrate some of the explicit and some of the less obvious ways in which moral considerations and medical law interact, and suggest that biolaw can involve inconsistencies and even obfuscation which, while difficult to avoid in plural societies, are appropriate areas for examination. In the final section the author argues that bioethics and medical law share some important logical features, including a prescriptivist, principled structure, which is subject to the related requirements of specification and universalisability. Again, medico-legal illustrations are used to support this proposal, which also constitutes a suitable topic for critique. Future columns will provide the opportunity for those who care about the issues of bioethics and medical law to share their thoughts and those of their colleagues.