Born in Narrabri, New South Wales, he was educated at St Joseph's College in Sydney and the National University of Ireland, becoming a doctor and a house surgeon in Dublin.

[1] In 1943, he transferred to federal politics, winning the House of Representatives seat of Denison by defeating sitting United Australia Party MP Arthur Beck.

[3] According to Alexander Alam, another Lebanese Australian whose parents immigrated in similar circumstances, Gaha's father was originally from the town of Zahlé.

Having earlier run an oyster bar in Quirindi, he became a successful horse-breeder and acquired extensive rural landholdings before eventually retiring to Sydney.

[6] In 1921, Gaha moved to Tasmania to work as a health officer for the Hydro-Electric Department, the government agency overseeing the state's expanding hydroelectric power scheme.

In 1923, Gaha accepted a position as an "honorary" (unpaid consultant) at Hobart General Hospital, working under Victor Ratten.

[7] Gaha resigned from the Legislative Council on 10 July 1943 in order to contest the House of Representatives seat of Denison at the 1943 federal election.