Legal philosopher;

Born: December 11, 1931; Died: February 14, 2013.

Ronald Dworkin, who has died aged 81, was the pre-eminent legal scholar of his age and a philosopher famous for emphasising the importance of putting morality at the centre of legal decisions. Revered for his sharp intellect and prolific writing, he was a professor of law at New York University and emeritus professor at University College London and one of the best known and most quoted legal scholars on American and British law.

He was born in Massachusetts and studied in the US and UK, first as a Rhodes scholar at Magdalen College, Oxford, then Harvard. From an early age, he impressed with his intellect and willingness to question orthodoxy. After university, he worked for a New York law firm before embarking on a fully academic career by becoming professor of law at Yale University.

He began to develop his theories in a number of highly influential books, the first of which was Taking Rights Seriously in 1977. This was followed, among others, by A Matter of Principle, Law's Empire, and Justice for Hedgehogs, a reference to Isaiah Berlin's theory that thinkers could be divided into foxes who have many ideas and hedgehogs, who have one big idea and pursue it their whole lives.

If he was a hedgehog, then his big idea was his theory of law as integrity which states that propositions of law are true if they follow the principles of fairness and justice; it effectively encourages judges to use moral considerations when deciding cases rather than literally applying the law free of any moral context. The theory was highly influential and Dworkin would often apply it to sensitive issues such as abortion, triggering intense debate in international philosophy and legal theory circles.

In person, he was famous for the seemingly spontaneous yet effortless way that complex arguments would flow out of him – he would usually lecture without notes, for example. He was a committed Democrat and believed strongly in liberalism.

He was Professor of Jurisprudence at Oxford and Fellow of University College and had a joint appointment at Oxford and at NYU where he was a professor both in the Law School and the Philosophy Department.

NYU Law School Dean Richard Revesz said he was not only an intellectual giant, but also a masterful teacher, admired colleague and beloved friend. He called him the most important legal philosopher of his generation.

He is survived by his wife, Irene Brendel Dworkin, his children Anthony and Jennifer Dworkin and two grandchildren.