Australia did not have a single event that marked its independence from the United Kingdom. Instead, it was a gradual process that took place over several decades. The most significant milestone in this process was the passage of the Statute of Westminster Adoption Act in 1942, which was backdated to 1939. This act formally adopted the Statute of Westminster 1931, granting Australia full legislative independence from the UK.
However, Australia’s journey to full sovereignty continued even after this act. The final step was the Australia Act 1986, which was passed by both the UK and Australian parliaments. This act severed the last remaining constitutional ties between Australia and the UK, making Australia fully independent.
In summary, while Australia became largely independent in 1942 with the adoption of the Statute of Westminster, it was not until 1986 that the country achieved complete independence from the United Kingdom.