Lallah was made a Deputy to the Electoral Commissioner during the period leading up to independence of Mauritius in 1968. He was responsible for registering electors, drafting electoral regulations and administering the pre-independence general elections. Between 1970 and 1975 Lallah was a Special Adviser at the
Commonwealth Secretariat and provided legal advice to Commonwealth Governments on resource development, taxation, negotiation with multinational companies, independence negotiations and establishing constitutions. Lallah became a Queen's Counsel in 1976 and was Assistant Solicitor General in Mauritius from 1976 to 1978. He was Parliamentary Counsel from 1978 to 1980. He was Pro Chancellor and Chairman of the Council of the
University of Mauritius from 1977 to 1980. In 1980 Lallah was appointed a Judge of the
Supreme Court of Mauritius. He was Chairman of the Commission of Enquiry into the 1982 General Elections. In 1983 he was chairman of the commission that reviewed legal studies in Mauritius, causing a law school to be established at the University of Mauritius and the Council of Legal Education to be set up. From 1988 to 1994 he was Chairman of the Council of Legal Education of Mauritius. He assisted with work on a post-apartheid Constitution for South Africa in 1991. Lallah retired from the Supreme Court as Chief Justice in 1995. That year he was appointed a member of the
London Court of International Arbitration. ==International human rights work==