As a young man in 1952 he joined a team of lawyers from various Commonwealth countries, including the British barrister Denis Nowell Pritt and other lawyers educated in England but not born there, defending Kenyans accused of Mau Mau activities by the British colonial administration, in a series of trials including that of Jomo Kenyatta.
[3] In the early 1960s he was a legal adviser at the Lancaster House conferences in London where Kenyatta and the Kenyans worked with the UK Colonial Secretary, Reginald Maudling, and his team to develop a constitution for the country.
[4] De Souza was an elected member of the Kenyan Parliament even before full independence in 1963, and Deputy Speaker of the Lower House from June 1963.
[8] These figures have been challenged by John Darwin, a fellow of Nuffield College, and lecturer on the History of the British Commonwealth at the University of Oxford.
[9] In December 2006, Commissioner for Non-Resident Indian affairs (Government of Goa) Eduardo Faleiro announced that de Souza would be one of the eight persons to be honoured during the Global Goans Convention.