Opas was the son of Joseph Henry Opas and Sarah Rebecca Goodman, the oldest of five children and the only one to go to a private school, Melbourne Church of England Grammar School. Family financial problems led him to take a position as a junior clerk in a solicitor's office at the age of fifteen. He gained a law degree from the University of Melbourne in 1939 while working fulltime, and later a Master of Laws from Monash University and a Ph.D. from Pacific Western University in 1985. Married in 1939, Opas enlisted in the Royal Australian Air Force (RAAF) on 1 July 1940. In March 1942, while on leave from New Guinea, he was admitted to practice as a barrister and solicitor of the Supreme Court of Victoria. He was demobilised in January 1946. Opas became a senior Queen's Counsel (granted silk in 1958). His most famous case was the defence of Ronald Ryan 1966-1967, the last man to be judicially executed in Australia. As a consequence of this case Opas left the bar to become group legal officer of Conzinc Riotinto Limited. He was a judge-advocate in the RAAF for eleven years, and Chief Chairman of the Planning Appeals Board of Victoria for six years. In retirement Opal wrote The Great Ring-In (1982), a study of corruption in the Victorian racing industry; Our Father Which Art : Joseph Henry Opas 1883-1957 (1988); and Here's to the Next Man That Dies (1997), a war history.
(Source: Philip Opas Throw Away My Wig : a long journey with few signposts (1997))