The Australia Act 1986 commences, causing Australia to become fully independent from the United Kingdom.

The Australia Act 1986 is the short title of each of a pair of separate but related pieces of legislation: one an act of the Parliament of Australia, the other an act of the Parliament of the United Kingdom. The Acts eliminated the ability for the United Kingdom to legislate with effect in Australia, for the UK to be involved in any Australian government, and for an appeal from any Australian court to a British court. This act formally severed all legal ties between Australia and the United Kingdom.

Australia, officially the Commonwealth of Australia, is a country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands. It has a total area of 7,688,287 km² (2,968,464 sq mi), making it the sixth-largest country in the world and the largest in Oceania. Australia is the world's flattest and driest inhabited continent. It is a megadiverse country, and its size gives it a wide variety of landscapes and climates including deserts in the interior and tropical rainforests along the coast.

The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland. The UK includes the island of Great Britain, the north-eastern part of the island of Ireland, and most of the smaller islands within the British Isles, covering 94,354 square miles (244,376 km²). Northern Ireland shares a land border with the Republic of Ireland; otherwise, the UK is surrounded by the Atlantic Ocean, the North Sea, the English Channel, the Celtic Sea and the Irish Sea. It maintains sovereignty over the British Overseas Territories, which are located across various oceans and seas globally. The UK had an estimated population of over 68.2 million people in 2023. The capital and largest city of both England and the UK is London. The cities of Edinburgh, Cardiff and Belfast are the national capitals of Scotland, Wales and Northern Ireland respectively.