The act received Royal Assent on 9 October 1942, but the adoption of the Statute was made retroactive to 3 September 1939, when Australia entered World War II.

After the end of World War I, each of the Dominions (including Australia, Canada, New Zealand and South Africa but not Newfoundland) independently signed the Treaty of Versailles, but under the collective umbrella of the British Empire.

However, the Australian prime minister, acting in line with the principles of the Balfour Declaration permitting Dominion governments to look after their own affairs, insisted on the appointment of Isaacs.

In June 1937, the Lyons government introduced the Statute of Westminster Adoption Bill into the parliament, where it passed its second reading in the House of Representatives.

[1] In introducing the 1937 bill, Attorney-General Robert Menzies said that adopting the Statute had only "relatively minor advantages" and would alter Australia's existing constitutional arrangements "to a very trifling extent".

Prior conservative governments had asserted that British military forces would be able to protect Australia, but Curtin, along with External Affairs Minister Dr H. V. Evatt, thought that focusing on an alliance with the United States would be more valuable.

The immediate prompt for the adoption of the Statute of Westminster was the death sentence imposed on two homosexual Australian sailors for the murder of their crewmate committed on HMAS Australia in 1942.

Since 7 November 1939, the Royal Australian Navy had operated subject to British imperial law, under which the two men were sentenced to death.

Adopting the Statute of Westminster, so that Australia became able to amend applicable imperial law, avoided a potential repetition of this situation.