Born in Bridge of Weir, Renfrewshire, Scotland in 1956, and educated at Queen's University, Canada, and at Nuffield College, Oxford, he completed his dissertation—which culminated in a book, The Authority of the State—under professors Charles Taylor and later Joseph Raz.
Like Raz, he has been an expositor and defender of the tradition of legal positivism and wrote the introduction and new supplementary materials for the third edition of H.L.A.
In 2006, Green was elected to the Professorship of Philosophy of Law at Oxford University, which includes a Fellowship at Balliol College.
Prior to this, Green taught for most of his career at Osgoode Hall Law School of York University, in Toronto.
Green and 30 other academics signed a public letter in the Sunday Times published on June 16, 2019 entitled “Stonewall is stifling academia”.