Sinclair is an associate professor at DPA. He has a background in socio-legal studies and criminology, and completed his PhD at the Australian National University in 1996. His doctoral research investigated gang crime and other forms of communal conflict in PNG and was undertaken while working at the National Research Institute in Port Moresby. Sinclair also previously lectured in law at the University of Papua New Guinea. He has longstanding research interests in the areas of legal pluralism, policing and justice reform, conflict and peacebuilding, and ongoing processes of state and nation-building in the postcolonial Pacific.

Sinclair is a chief investigator on 2 ARC Discovery projects. One (with Professor Miranda Forsyth) looking at Community Rule-Making in the Pacific Islands as Regulatory Innovation. Another (with Dr Judy Putt) on Improving responses to sexual violence against children in Papua New Guinea.