Elias moved from Manchester to Oxford in 1954, when he became the Oppenheimer Research Fellow at the
Institute of Commonwealth Studies,
Nuffield College and Queen Elizabeth House. He continued his research into Nigerian law and published Groundwork of Nigerian Law in the same year. He returned to London in 1957 and was appointed a governor of the
School of Oriental and African Studies. As the constitutional and legal adviser to the National Council of Nigeria and the Cameroons (which later became the National Convention of Nigerian Citizens), he participated in the 1958 Nigerian Constitutional Conference in London. He was one of the architects of Nigeria's independence constitution He served in this capacity through the whole of the first republic. Although later dismissed after the
coup d'état in January 1966, he was reinstated in November of that year. In addition to contributing to Nigerian and African law, Elias had long been active in the field of international law. He was a member of the
United Nations International Law Commission from 1961 to 1975, he served as General Rapporteur from 1965 to 1966 and was its chairman in 1970. In 1966, Elias was appointed professor and dean of the Faculty of Law at the
University of Lagos. Four years earlier he had received the LLD degree from the
University of London for his work on African law and British colonial law. (He would go on to receive a total of 17 honorary doctorate degrees from various universities around the world Several of his works on various legal subjects were standard reading in Africa in law schools of the former British colonies. Later in 1966, Elias was re-appointed as Nigeria's attorney-general and commissioner for justice (a position he held while remaining dean and professor at the University of Lagos), until 1972, when he became
Chief Justice of the Supreme Court of Nigeria. He was ousted from this position by a military regime that took power in Nigeria at the end of July 1975. A few months later (in October 1975), he was elected by the General Assembly and the Security Council of the United Nations to the
International Court of Justice at
The Hague. In 1979, he was elected vice-president by his colleagues on that court. In 1981, after the death of Sir
Humphrey Waldock, the president of the court, Elias took over as acting president. In 1982, the members of the court elected him president of the court. He thus became the first African jurist to hold that honour. Five years later, Elias was also appointed to the
Permanent Court of Arbitration at
The Hague. == Death ==