Ronald Dworkin, widely respected as one of the greatest philosophers of law of his age, has died of leukemia at the age of 81 in London. He was the Frank Henry Sommer Professor of Law and Philosophy at New York University and professor emeritus of jurisprudence at University College London, and frequently contributed to The New York Review of Books. He advocated his influential "moral reading" of the United States Constitution and insisted that judges interpret the law in terms of moral principles. He thought of the law as a theory of rights, which he expounded in his influential 1977 book, Taking Rights Seriously, in opposition to the positivism of the powerful scholar H. L. A. Hart and the theories of philosopher John Rawls. The liberal Dworkin also feuded with conservative legal scholars such as Robert Bork, althought strangely they taught a joint course at the Yale Law School in the '60s.