He was the Labor member for Victoria in the South Australian House of Assembly from 1945 until his defeat in 1947, and again from 1953 until 1956, when he transferred to the nearby seat of Millicent.
Born on 1 October 1885 at Mount Gambier in the colony of South Australia, the first-born son of Thomas Corcoran and Margaret (née Fitzgerald) of Tantanoola, James Corcoran attended Burrungule Public School and Mount Gambier Grammar School.
His father was employed by South Australian Railways (SAR) when he married Margaret at Georgetown in the mid-north of the colony, where her parents were farming.
After he left school James was a pastoral worker on Coola Station near Mount Gambier before half-a-dozen years working for SAR himself.
Corcoran embarked with the 11th reinforcement draft for the largely South Australia-raised 27th Battalion on 25 March 1916, and after further training in England and substantive promotion to corporal and promotion to the acting rank of lance sergeant, he joined the 27th Battalion on the Western Front in France and Belgium on 13 May 1917, at which time he reverted to his substantive rank of corporal.
During this period he was also president of the Tantanoola Show Society and the Children's Home Project Club, and a member of the local school committee.