[2] During his time practising law, Blackburn won cases that played a key role in establishing rights, including the 40-hour working week, wage equality for indigenous workers and women.

[3][better source needed] In late 1934 and early 1935, Blackburn acted as legal counsel to prevent the deportation of the noted Czech anti-fascist Egon Kisch.

[1] Blackburn was re-elected to the Legislative Assembly at a 1925 by-election for the seat of Fitzroy, despite an alleged attempt by John Wren and his supporters to rig the preselection ballot.

[1] Blackburn's support for international socialism, and his opposition to conscription,[6] frequently caused him to take positions opposed to Labor policy and, in October 1935, he was expelled over his membership of the Movement Against War and Fascism.

[8] Blackburn died of cerebral tumour on 31 March 1944,[1] in Prahran, Victoria, and was buried in Box Hill Cemetery, survived by his wife, two sons, a daughter, and his mother.

[1] In a eulogy, Australian Prime Minister John Curtin referred to Blackburn as "one of the great servants of the people of the Commonwealth of Australia".

[9] His widow, Doris, won Bourke as an Independent Labour candidate at the 1946 election and spent much of her time in Parliament promoting similar policies to those that Blackburn had supported.