H.L.A. (Herbert) Hart (1907-1992),was the son of a Jewish tailor of Polish and German descent. He was educated at Bradford Grammar School and New College Oxford, where he obtained a brilliant first class in Classical Greats. He practised at the Chancery Bar from 1932 to 1940 along with Richard (later Lord) Wilberforce. During the war, being unfit for active service, he worked in MI5. During this time his interests returned to philosophy and in 1945 he was appointed philosophy tutor at New College. He was strongly influenced by the linguistic philosophy then current in Oxford, but employed its techniques more constructively than did most members of the movement. In 1952, given his chancery background, he was persuaded by J.L. Austin to be a candidate for the Oxford chair of Jurisprudence when Professor Arthur Goodhart resigned. He was elected and held the chair until 1969.

From 1952 on he delivered the undergraduate lectures that turned into The Concept of Law (1961, posthumous second edition 1994). He also lectured on right and duties, but these lectures were never published. He held seminars with Tony Honoré on causation, leading to their joint work Causation in the Law (1959, second edition 1985). His visit to Harvard in 1956-7 led to his Holmes lecture on 'Positivism and the Separation of Law and Morals' (1958) and a famous controversy with Lon Fuller. Returning to the UK he engaged in an equally famous debate with Patrick (later Lord) Devlin on the limits within which the criminal law should try to enforce morality. Hart published two books on the subject, Law, Liberty and Morality (1963) and The Morality of the Criminal Law (1965). A wider interest in criminal law, stimulated by Rupert (later Professor Sir Rupert) Cross was signalled by his 'Prolegomenon to the Principles of Punishment' (1959). Nine of his essays on the criminal law were collected in Punishment and Responsibility (1968). In 1968 he was asked by Oxford University to chair a commission on relations with junior members, then at a low ebb, and produced a notably perceptive and constructive report.

Feeling that his powers were waning Hart resigned his chair in 1969, to be succeeded by Ronald Dworkin, a severe critic of his legal philosophy. He now devoted himself mainly to the study of Bentham, whom, along with Kelsen, he regarded as the most important legal philosopher of modern times. Ten of his essays were collected in Essays on Bentham (1982). From 1973 to 1978 he was Principal of Brasenose College. In his last years he was much concerned to find a convincing reply to Dworkin's criticisms of his version of legal positivism. A sketch of Hart's reply is to be found in the postscript to the second edition of The Concept of Law.

Hart's main aim as a lecturer and writer was to tell the truth and be clear. He was the most widely read British legal philosopher of the twentieth century and his work will continue to be a focus of discussion.