Last week Ronald Dorkin died aged 81. He was widely respected as the most original and powerful philosopher of law in the English-speaking world. In Oxford he was the successor of the famous H. L. A. Hart whose analytic and positivistic philosophy of law he attacked all his life. He insisted on a rights-based theory of law which he expounded in his first and most influential book, Taking Rights Seriously (1977). An unapologetic liberal Democrat, Dworkin was always aware that law and in particular adjudication were, as he once put it, "a branch of morality" and that moral responsibility is a risk we must take. "If we are to be morally and ethically responsible," he wrote, "there can be no turning back once we find, as we have found, that some of the most basic presuppositions of these values are mistaken. Playing God is indeed playing with fire. But that is what we mortals have done since Prometheus, the patron saint of dangerous discoveries. We play with fire and take the consequences, because the alternative is cowardice in the face of the unknown."