Sachenrecht
De Gaay Fortman attended a Gymnasium in Dordrecht from June 1923 until September 1925 and the Amsterdams Lyceum from September 1925 until July 1929 and applied at the Free University Amsterdam in July 1929 majoring in Law and obtaining an Bachelor of Laws degree in June 1930 before graduating with an Master of Laws degree in July 1933 and worked as a researcher at the Free University Amsterdam from 5 July 1933 until 12 June 1936 when he got a doctorate as an Doctor of Law on 12 June 1936. De Gaay Fortman worked as a civil servant from April 1934 until January 1947 for the department of Agricultural Emergency Management of the Ministry of Economic Affairs from April 1934 until September 1935 and for the department of Legal Affairs of the Ministry of Agriculture and Fisheries from September 1935 until February 1938 and for the department of Employment Insurances of the Ministry of Social Affairs from February 1938 until January 1947 and as Deputy Director-General of the department for Employment Insurances from April 1939 until August 1943 and as Director-General of the department for Employment Insurances from August 1943 until January 1947. On 10 May 1940 Nazi Germany invaded the Netherlands and the government fled to London to escape the German occupation. During the German occupation De Gaay Fortman continued his work for the Ministry of Social Affairs and but sympathetic with the Dutch resistance against the German occupiers and worked as an editor for the underground newspaper "Free Netherlands" from January 1943 until May 1945. De Gaay Fortman worked as professor of Labour law, Privacy law and Property law at the Free University Amsterdam from 10 January 1947 until May 1973. He also served as Rector Magnificus of the Free University Amsterdam from 1 January 1961 until 1 January 1962 and from 1 January 1965 until 1 January 1972. De Gaay Fortman was elected as a Member of the Senate after the Senate election of 1960, taking office on 20 September 1960. After the Senate election of 1971 De Gaay Fortman was selected as Parliamentary leader of Anti-Revolutionary Party in the Senate, taking office on 11 May 1971.