Born in Hawthorn, Melbourne, Victoria to Lebbeus Hordern, estate agent, and his wife Louisa Dewson (née Smith), Doris Hordern became involved in women's rights and peace issues from a young age and served as the campaign secretary of Vida Goldstein, the first woman to stand for election to federal parliament in Australia.

She married Maurice Blackburn, a fellow firebrand socialist, in Melbourne on 10 December 1914[1] and spent their honeymoon organising anti-war and anti-conscription campaigns.

Her husband continued to sit in parliament as an independent but lost his seat at the 1943 federal election to the official Labor candidate, and died the following year.

[3] In parliament Blackburn, who shared the cross benches with fellow former Labor member Jack Lang,[4] championed similar issues to those of her late husband, gaining nationwide notoriety in 1947 as the only MP to vote against the Atomic Energy Bill.

[6] Blackburn subsequently remained active in social issues, serving as president of the Women's International League for Peace and Freedom.