 He was a member of Stavanger city council from 1945 to 1955, and was represented at the Storting between 1950 and 1965, for a period leader of the Standing Committee on Finances and Customs .He was in the national board of the Labour Party between 1949 and 1953 and deputy chairman of the party group at Stortinget from 1958.Hegna was one of many "Mot Dag" members that became influential in the Labour Party after the second world war, but in a contrast to many of these, Hegna was active in the left wing of the party, among other things against Norwegian membership in the European Economic Community in 1972, but he chose to remain with the party.