Formerly Professor of Psychiatry, University College of Los Angeles, USA, and Visiting Professor of Psychological Medicine, Imperial College, London, UK

Throughout his life, Richard Green, who died on 6 April 2019, though heterosexual himself, acted as an effective advocate for gay men and women. In 1972, still in his 30s, he published a paper calling for the removal of homosexuality from the American Psychiatric Association's list of mental disorders.^{Reference Green1} A year later, despite considerable opposition, this was achieved and there has been no subsequent attempt to reinstate it. Before this, in the 1960s, Green had worked with Harry Benjamin, who was seeing transgender patients. At that time surgical procedures to effect sex change could not be carried out in the USA. Green referred cases to Europe for sex reassignment.

From the 1960s he was active as an expert witness for gay men and women denied human rights on the grounds of their sexuality. In 1974, he appeared in a US television series advocating same-sex marriage. In the same year, he successfully pleaded that lesbian mothers should be allowed to have custody of their children in the event of a marriage break-up. Similarly, in 1979, he successfully supported a request from two gay Californian men that they should be allowed to co-adopt a child.

In addition to his successful legal advocacy, Green was responsible for groundbreaking research into homosexuality and transsexualism. He carried out highly significant, pioneering follow-up studies of effeminate boys and girls who were tomboys, establishing the extent to which they later developed a homosexual orientation. Among numerous publications, which include eight books and 200 papers and textbook chapters, Green co-edited the first multidisciplinary text (Transsexualism and Sex Reassignment ^{Reference Green and Money2}) on what was then commonly referred to as sex change. Green wrote about his career researching and advocating for people with homosexual orientation and transgender in his final book, Gay Rights, Trans Rights, self-published in 2018.^{Reference Green3}

In 1971, he founded and edited the Archives of Sexual Behavior, which has remained the principal journal in the field. He continued as Editor until 2001. In 1974, he founded the International Academy of Sex Research (IASR) and was its first President. This has remained the principal academic society in the field and has an annual meeting that involves a programme of sex research-related presentations. Over the past 43 years, these meetings have been held in 18 different countries around the world.

Green was born in New York to secular Jewish parents, Leo (an accountant) and Rose Ingber (a teacher, later a civil servant). It is possible that his interest in homosexuality arose from the fact that, as he had no talent for sport, his father thought he was a sissy. After graduating with a BA from Syracuse University, Green studied medicine at Johns Hopkins School of Medicine. At medical school he came under the influence of John Money, a distinguished psychologist who studied gender development. Later, during psychiatric training at Los Angeles School of Medicine, he worked with Robert Stoller, a psychoanalyst with a particular interest in sexual behaviour. Green completed his psychiatry training at the National Institute of Mental Health in Bethesda, Maryland (1964–66), and was then awarded a fellowship assignment at the Maudsley Hospital in London (1966–67). He subsequently returned to the USA to direct the Human Sexuality Program at the State University of New York at Stonybrook.

In the 1980s, Green took a degree in law, graduating from the Yale Law School in 1987. His legal training was a major asset in subsequent court appearances. In the 1990s, he moved to the UK, where he became Professor of Psychological Medicine and Research Director of the Gender Identity Clinic at Charing Cross Hospital in London, and Senior Research Fellow at the Institute of Criminology in Cambridge.

Green was an attractive, engaging man who was able to take on the establishment because, as a complete non-conformist, apart from those he loved, he had little interest in what others thought of him.

He is survived by his son, Adam Hines-Green, an artist; his previous wife, Melissa Hines; and his recent partner, Clare Loveday.