 He was District Registrar of the High Court of Australia from 1966 to 1971 and before that was District Registrar from 1961 to 1966; and was Master of the Supreme Court of South Australia from 1966 to 1971 and Deputy Master from 1961 to 1966.A member of the Standing Committee Senate at the Adelaide University from 1967 to 1971,Forster was lecturer of Law and Procedure at the same time and lecturer of Criminal Law from 1957 to 1958.He was appointed Senior Judge of the Supreme Court of the Northern Territory on 28 June 1971 and replaced Justice Blackburn who had taken up appointment with the Supreme Court of the Australian Capital Territory.