Massat is a lawyer who has previously served as Bougainville's police minister.
[1] He represents the Tonu constituency on Buka Island in North Bougainville.
[1] President James Tanis appointed Massat as vice president following pressure by the Central and North Bougainville regions for more inclusion in the Bougainvillaen government.
[1] Massat was sworn in as vice president in a ceremony at the Bougainville House of Representatives on the afternoon of January 19, 2009, by senior magistrate Bruce Tasikul.
[3] On 2 October 2020 Massat was appointed Attorney General and Minister of Justice and Post-Referendum Dialogue in the cabinet of Ishmael Toroama.