He was
called to the bar at
Gray's Inn in 1925 and worked as a legal advisor to the
Foreign Service in 1929. He was seconded to the
Ministry of Economic Warfare as a legal advisor from 1939 to 1943, where he was tasked developing an
Allied legal network to restrict Germany's seaborne trade. Fitzmaurice was the UK Counsel to the
International Court of Justice at
The Hague between 1948 and 1954. He served as the
Senior Legal Advisor to the Foreign Office between 1953 and 1960. In 1954 he was advanced to a
Knight Commander of the Order of St Michael and St George. Fitzmaurice was a member of the
International Law Commission of the
UN between 1955 and 1960 and contributed to the four
Geneva Convention of the Law of the Sea adopted in 1958. He was the
Special Rapporteur on the law of treaties. He
took silk in 1957. From 1956 to 1960, he served president of the
Grotius Society.
Judicial career Fitzmaurice was a member of the
Permanent Court of Arbitration between 1954 and 1980. In 1960, he left his position as Senior Legal Advisor to accept an appointment as judge at the
International Court of Justice, completing
Sir Hersch Lauterpacht's term who had died mid-term, and was re-elected for a full term in 1963; he served in the court until 1973. He was made a Knight Grand Cross of Order of St Michael and St George in 1960, and in 1961 was elected a
Bencher of Gray's Inn. In 1974, he was elected as Judge of the
European Court of Human Rights at
Strasbourg, a position he served in until 1980. During his long career in the law he received honorary degrees of
Doctor of Law from the
University of Edinburgh in 1970 and the University of Cambridge in 1972. ==Personal life==