Having graduated from the Ceylon University College with a BA degree from the University of London, Jansze qualified as an advocate from the Ceylon Law College and was admitted to the bar in 1934. He acted as Assistant Legal Draftsman in 1936 and Crown Counsel in 1937 and 1943 on occasions between when he was appointed a Crown Counsel in 1943; he served as Acting Deputy Commissioner, Compensation Claims (1946-1947). In 1949 he was appointed Senior Crown Counsel, having served in an acting capacity.[2] He was appointed Solicitor General of Ceylon in 1955 succeeding T. S. Fernando and served until 1957. He was appointed on 1 April 1957, succeeding Edward Fredrick Noel Gratiaen, and held the office until 1966. Abdul Caffoor Mohamad Ameer succeeded him.[3]