Roebuck was a senior figure in the Hepburn government serving as Attorney-General of Ontario from 1934 to 1937 as well as Minister of Labour from 1934 until 1935. A progressive, Roebuck promoted the rights of Jews against the anti-Semitism that was still prevalent in 1930s Ontario, and defended the rights of trade unions. He broke with Hepburn over the government's handling of the 1937 United Auto Workers strike against General Motors in Oshawa, and resigned in protest with fellow minister David Croll. Roebuck remained as the Liberal Member of the Legislative Assembly for the Toronto riding of Bellwoods until 1940.