Dr Grant Phillipson's professional involvement with the Waitangi Tribunal began in 1993 as a commissioned researcher. In 1995, he was appointed research manager and, two years later, chief historian. He held that role until his appointment to the Tribunal in 2011. Dr Phillipson has written numerous research and historical reports, commissioned by the Waitangi Tribunal, the New Zealand Māori Congress–Crown Joint Working Party, and the Crown Forestry Rental Trust. As chief historian, Dr Phillipson was responsible for supervising the Tribunal's commissioned research programme and providing research and report writing advice to numerous Tribunal panels. Dr Phillipson has published academic papers on questions relating to the church in nineteenth century New Zealand, Treaty history, the Waitangi Tribunal, and Māori land.