He joined the Norwegian Labour Party in 1911, and was elected vice chairman from 1918.

[2][3] After the death of Kyrre Grepp he was acting leader of the Norwegian Labour Party, from 1922 to 1923.

He participated in the formation of the Communist Party of Norway in 1923, where he became a member of the Central Committee.

[2] During the legal purge in Norway after World War II, Stang was one of the minority of judges to vote to execute his cousin, Axel Heiberg Stang, for treason, after he was convicted of collaborationism.

He was married to Fredrikke Elise Nicoline Bøckman Otto from 1907 to 1920, and to Sigrid Friis from 1925.