Herbert Hart was a philosopher who rescued one of the most important branches of his discipline from neglect and stagnation – the philosophy of law. Philosophy of law is the enquiry into the nature and basis of law and legal institutions. It examines especially their justification and their relation to morality and society. Hart, who had both legal and philosophical training, saw that jurisprudence was in need of a revolution, and he gave it one. He did it by applying the sharp and searching techniques of analytic philosophy, using ideas he had developed under the influence of Wittgenstein and J L Austin.