(Note: Aotearoa is the Māori name for the country more commonly known as New Zealand. Both terms are increasingly used interchangeably.)

Australia and Aotearoa / New Zealand have shared histories. While there are important differences in the specific histories, both countries were home to indigenous people and both countries were colonised/invaded by the British. I don’t know much about how the British colonists/invaders treated the Māori people, but it’s clear that the British colonists/invaders were not kind to Aboriginal Australians - it’s important to recognise that many Aboriginal Australians are suffering from ongoing harm due to the legacy of this violent colonisation project.

Today, Australia and New Zealand are widely recognised as legitimate and independent countries. The two countries have many cultural ties - they are both primarily English-speaking countries with similar national cultures and models of government. There are shared historical events and days of commemoration, such as ANZAC Day. The two countries also cooperate directly in many areas of policy - this can be seen in defense agreements such as ANZUS and shared sets of standards such as the Australia New Zealand Food Standards Code. The soccer team Wellington Phoenix competes in Australia’s domestic league, the A-League.

Here’s the interesting bit that most Australians aren’t aware of.

The Australian Constitution was established by the Commonwealth of Australia Constitution Act. Section 6 of that Act reads as follows:

The States shall mean such of the colonies of New South Wales, New Zealand, Queensland, Tasmania, Victoria, Western Australia, and South Australia, including the northern territory of South Australia […] .

New Zealand is listed as an Australian state!

In the 1890s, when the Australian colonies were holding conventions to discuss Federation (which led to the creation of Australia as a single country on 1 January 1901), there were also delegates from New Zealand. So, the Constitution was drafted in a way that would allow New Zealand to take part and eventually become an Australian state. By 1895, the New Zealanders had decided not to be a part of Australian Federation (source). You can hardly blame them!

All the same, it’s interesting that Australia and New Zealand nevertheless collaborate so closely in many areas of policy and government. It is often said that the European Union has many federal characteristics - it is a supranational organisation, not a sovereign state, but since EU member states delegate some areas of policy authority to the EU, the organisation can be seen as a less intense version of a federation. In contrast, the United States is an example of a full-fledged federation. So, you could arrange these examples along a spectrum: the Australia-New Zealand relationship is a loose collaboration, the EU is a supranational organisation with some federal characteristics, and the United States (and Australia itself) is a full federation.

(An aside: the entity currently known as the Northern Territory is listed here as the “northern territory of South Australia”. Historically, the Northern Territory was in fact governed by South Australia. This is no longer the case, but it’s interesting that few young South Australians are aware of this shared history of South Australia and the Northern Territory.)