Professor Sir John Smith, who died on Valentine's Day aged 81, was one of the foremost experts on English criminal law.

His book Criminal Law (1965), written with Brian Hogan, has run to 10 editions and sold more than 170,000 copies, more than virtually any other student law book. Known by lawyers simply as "Smith and Hogan", it remains the standard academic textbook on the subject, and exercises considerable influence on decisions in courts. The same can be said for Smith's Law of Theft (1968).

From the early 1950s until this year, Smith's commentaries on cases in the monthly Criminal Law Review kept lawyers up to date with developments in the law and his analysis of them. They were regularly cited in decisions by the Court of Appeal and House of Lords.

At Nottingham University, whose Law department he transformed, Smith not only excelled as a teacher but also generously dispensed advice over the telephone to practising barristers and judges.

One evening, a barrister in a difficult case rang to ask what Smith thought. Next evening there was a telephone call from the judge in the same case: counsel had advanced a clever argument, what should he do? Without disclosing the authorship of the argument, Smith gave what help he could.

John Cyril Smith was born on January 15 1922 at Barnard Castle, Co Durham, where his father ran the family's iron and steel works. Young John was educated at St Mary's Grammar School, Darlington, whence he won a scholarship to read History at Oxford.

He never took it up. Instead, on leaving school, he worked for London and North Eastern Railway, where he helped design points and also a moveable embankment which enabled two lines to cross each other without a bridge (which, during wartime, might become a target for bombs).

In 1942 Smith volunteered for the Army, joining the Royal Artillery and training on 25-pounders. The next year he went to India. He saw action at Imphal, the largest land battle of the Far Eastern war, after being flown in by Dakota to join the 23rd Indian Division ("the Fighting Cock"), to help direct its mortar fire when its members found themselves surrounded by the Japanese.

The Japanese eventually capitulated, and Smith took the road into Burma, which was strewn with rotting Japanese corpses. He contracted typhoid and almost died. He later became involved organising courts martial, which sparked his interest in the Law.

Demobbed in the rank of captain in 1947, Smith went up to Downing College, Cambridge, to read Law. He was called to the Bar by Lincoln's Inn in 1950, and then began his career as an assistant lecturer at Nottingham University, at that time an obscure and unfashionable place for undergraduate study.

To begin with he taught a range of subjects, including contract, tort and crime. In 1952-53 he spent a year at Harvard, where he came across the American casebook method of teaching. On his return, Smith wrote, with a colleague, J A C Thomas, A Casebook on Contract, originally intended for use only at Nottingham; it was published, however, in 1957, and has so far run to 11 editions.

Within just six years of arriving at Nottingham, Smith had risen to be head of the department, and in 1957 he was appointed professor. He remained in the post until 1987, by which time Nottingham's law department was receiving 2,000 applications each year for 100 places, more than either Oxford or Cambridge.

As a teacher, Smith had the ability to make difficult things appear simple. Students would be expected to come prepared to discuss particular texts. At first this could be intimidating, since Smith would have "written the book"; but he was never hard on his charges, however inadequate their contributions. He was a modest, unassuming man, never dogmatic and with an impish sense of fun. His students were devoted to him.

Led by Smith, the Nottingham Law department attracted a highly talented group of lecturers, many of whom went on to senior posts. These included Ian Brownlie, now Professor of Public International Law at Oxford; Sir David Williams, later Vice Chancellor of Cambridge; and Smith's successor as head of department at Nottingham, Professor David Harris.

In 1970 Smith was invited to give a lecture to judges in the Lord Chief Justice's Court on the substance of criminal law. This became a regular event, three or four times a year, later formalised by the Judicial Studies Board, whose specimen judges' directions to juries Smith also helped draft.

He was a member of the Criminal Law Revision Committee, whose recommendations resulted in the two Theft Acts (1968 and 1978). In the 1980s he also produced a report for the Law Commission on the Codification of the Criminal Law (with I H Dennis and E J Griew, 1985) which brought coherence to the principles of criminal law, but has never been implemented. In 1989 Smith acted as one of the lay assessors helping Sir John May to weigh the evidence in the judicial inquiry into the wrongful conviction of the Guildford Four. In 1989-90 he was Arthur Goodhart Visiting Professor in Legal Science at Cambridge.

Smith was elected a Fellow of the British Academy in 1973. He became an honorary bencher of Lincoln's Inn in 1977, took Silk in 1979, and was appointed CBE in 1983. He was knighted in 1993.

His other publications included: Criminal Law, Cases and Materials (1975), which has run to eight editions; Justification and Excuse in the Criminal Law (Hamlyn lectures, 1989); Contract (1989); and Criminal Evidence (1995).

He married, in 1957, Shirley Ann Walters, who died in 2000. They had two sons and a daughter.