Duncan is a Lecturer in the Department of Public Law since 2017. He teaches constitutional theory/law, human rights, criminal procedure and is an expert in constitutional change and transformations in Africa. He is a members of the International Society of Public Law (ICON-S); the British Institute of Eastern Africa; the Law Society of Kenya; and the International Association of Constitutional Law. Every year (since 2017) Duncan also presents a seminar for LLM Comparative Constitutional Law, at the University of Nairobi as a guest lecturer. Previously he has taught at Kabarak University where he was also the founding director of the Center for Jurisprudence & Constitutional Studies. Duncan has prior to that taught law at Catholic University of Eastern Africa and was a teaching assistant at Venda University in South Africa. Duncan has attended several conferences and seminars in Europe and Australia and his works have been published in India, the UK and the USA. Professionally, he is an an Advocate of the High Court and has prosecuted and defended several cases in the High Court, Court of Appeal and Supreme Court involving judicial/constitutional review of the powers of public bodies. He has also been a trial advocate for most of the high profiled criminal cases in Kenya and is currently working on a monograph on constitutional criminal justice in Kenya.