Professor Ronald Dworkin: Legal philosopher acclaimed as the finest of his generation

Ronald Dworkin was the primary legal philosopher of his generation. His key belief was that the law should be grounded in moral integrity, understood as the moral idea that the state should act on principle so each member of the community is treated as an equal. He was behind some of the most influential theories of law and morality in modern jurisprudence and overwhelmed his opponents with his ferocious debating skills. He was a committed Democrat and believed strongly in liberalism, equality and human rights. He was Professor of Law at New York University and Professor Emeritus at University College London, and wrote some 15 books and a plethora of academic papers.

Dworkin was born in Worcester, Massachusetts in 1931, one of three children. Following his parents' divorce he was brought up by his mother. "My father was, I think, born in Lithuania and came to America as a young child," he recalled.

Following a scholarship to Harvard College, from which he graduated in 1953, he went on to read Law at Oxford, gained a Masters at Yale in 1956 and an LLB from Harvard a year later. This dual training in American and British law would define his life's path – he was equally at ease in both cultures.

HLA Hart, the legal philosopher whose theories Dworkin would later go on to oppose, noted that he showed himself to be a remarkable, even intellectually intimidating, student at Oxford. He became the Clerk to Judge Billings Learned Hand, one of the most influential judges in the US, and then went to work for the commercial law firm of Sullivan and Cromwell.

In 1962 he returned to academia, joining the Law School at Yale. Seven years later he found his way back to Oxford, where he succeeded Hart as Chair of Jurisprudence at Oxford, a position he held until 1998. John Gardner, the current holder of the Chair, said: "There are several contenders for the title of greatest philosopher of law of the late 20th century. But nobody rivals Ronald Dworkin for the titles of most innovative and most provocative. Agree or disagree, Dworkin's work was impossible to ignore. He always made the most startling challenges to received wisdom and permanently changed the way we look at many ancient problems."

From the late 1960s onwards Dworkin straddled the Atlantic, physically and intellectually. "People often say which is home?" he remarked. "I don't have an answer. I would miss not being in New York for part of the year, and I would miss not being in London."

The thesis of legal positivism is that law is socially constructed, depending on social facts, rather than on intrinsic merits. Dworkin's landmark work Taking Rights Seriously (1977), tackled Hart's belief in legal positivism and asserted boldly that an individual's rights exist outside of written law. According to this thesis, for almost all cases one side has the legal right to win. A review in Time magazine commented that the book "launches a frontal attack on the two concepts, utilitarianism and legal positivism, that have dominated Anglo-American jurisprudence in the 20th century." The review observed that "Dworkin's theories have created shockwaves among jurisprudential scholars."

Also central to his beliefs was the idea that the law will always give an answer when properly interpreted. In Law's Empire (1986) he creates a fictional judge, Hercules, who in his omniscience understands all the moral principles on which law is based. According to Dworkin, the mere human judge must seek out those principles and apply them to the case in hand.

His book Freedom's Law (1999) is subtitled "The Moral Reading of the American Constitution" and argues that rights granted in abstract terms cannot be applied directly to real-world concrete issues, such as capital punishment or abortion. He contends that the US Bill of Rights defines moral principles which must then be interpreted by citizens and lawyers. But would a "moral" reading of the Constitution then be considered undemocratic? He insists that it would not. Publisher's Weekly summarised the book as "Complex and compelling, learned and readable, it goes to the heart of what it means to live in a democracy and, through concrete details, illuminates a very real, very admirable principle."

In September 2007, Dworkin received the Holberg International Memorial Prize. The citation of the award committee recognised that he had "elaborated a liberal egalitarian theory" and emphasised his work on developing "an original and highly influential legal theory grounding law in morality, characterised by a unique ability to tie together abstract philosophical ideas and arguments with concrete everyday concerns in law, morals, and politics". He was further recognised last year by the award of the Balzan Prize, for his contributions to the theory and philosophy of law.

Dworkin's most recently published work, Justice for Hedgehogs (2011), consists of wide-ranging reflections on life, morality and justice, containing the observation: "The truth about living well and being good and what is wonderful is not only coherent and mutually supporting: what we think about any one of these things must stand up, eventually, to any argument we find compelling about the rest."

The critic Simon Blackburn wrote of the book, and of Dworkin's wider body of work: "Dworkin is a very impressive writer, with what his early prey, HLA Hart, is said to have described as a 'fluent and somewhat elusive analytical style'. He has a keen lawyerly eye for the way to present a case, and is indefatigable in doing so. He knows a great deal, and deploys what he knows with admirable skill. His works are proper objects of wonder."

In the epilogue to that book Dworkin writes about the importance of a life well-lived, hints at his own eventual demise and observes that "Without dignity our lives are only blinks of duration. If we manage to lead a good life well, we create something more. We write a subscript to our mortality. We make our lives tiny diamonds in the cosmic sands." Dworkin's first wife, Betsy, died of cancer, and he later married Irene Brendel, the former wife of the pianist Alfred Brendel. Dworkin died of leukaemia.

Ronald Myles Dworkin, philosopher of law: born Worcester, Massachusetts 11 December 1931; married 1958 Betsy Ross (died 2000; one son, one daughter), secondly Irene Brendel; died London 14 February 2013.