Leslie C. Green was born in London, England in 1920. He earned an LLB degree from the University of London in 1941 and was awarded the Joseph Hume Scholarship in Jurisprudence and the Cecil Peace Prize.

Green served in the British Army in 1941-1946 as a Japanese translator and a Deputy Military Prosecutor. After retiring from the military in 1946 with the rank of Major, Green taught law at several different universities. He was a law lecturer at the University of London (1946-1960), Professor of International Law at the University of Singapore (1960-1965), Dean of the Faculty of Law at the University of Singapore, Professor of Political Science at the University of Alberta (1965-1991). In 1992, he retired from the University of Alberta and earned the title of professor emeritus.

Green participated in the creation of several international law manuals and protocols. In 1974-1975, he was the Academic in Residence at the Legal Department of the Canadian Department of External Affairs. In 1975-1977, he helped produce the 1977 Protocols as the legal advisor to the Canadian delegation at the Diplomatic Conference on Humanitarian Law in Geneva. In 1979-1980, he worked on the first draft of the Canadian Manual of War Law as the Academic in Residence at the Department of the Judge Advocate General. In 1989-95, he helped produce the San Remo Manual as a member of the Committee of Experts on Naval Warfare.

Other positions held by Green included Visiting Professor at Kyung Hee University in Seoul, Korea, Visiting Professor at the University of Denver College Of Law, and Stockton Professor of International Law at the US Naval War College.

In addition to his LLD degree, Green was awarded an honorary LLB from the University of London in 1974. He was also awarded an LLB by the University of Alberta. Green was a Member of the Order of Canada and a Fellow of the Royal Society of Canada. The Judge Advocate General Award was renamed the Leslie C. Green Award in his honour in 2012.
The Leslie C. Green Veteran’s Scholarship from the Canadian Council on International Law was also named in his honour.