Politician and writer William Pember Reeves treated the seven Australasian colonies (including New Zealand) as a single site of social experiment in his State experiments in Australia and New Zealand (1902), even though he emphasised environmental differences in his marketing role as agent general in London.
There was a trans-Tasman transfer of policy and innovation. The seven colonies shared a model of state development. This had its basis in their British constitutional heritage and British law, as well as in participation in inter-colonial and imperial (later Commonwealth) conferences. The shared model was highly efficient because it saved time and resources.
One shared policy was the system of compulsory arbitration in industrial disputes, established between 1890 and 1914, and the male-breadwinner model of labour and welfare during much of the 20th century.
There was a similar pattern of policy convergence in the 1980s and 1990s, when both countries abandoned this model. In the 1990s Victoria borrowed many of its public-sector reforms from New Zealand. Convergence, however, did not mean uniformity. Each learnt from, and adapted, the other’s experiences.
New Zealand secured formal ties with Australian government structures in the late 20th century. New Zealand participated in the Council of Australian Governments (COAG) from 1992. The country functioned like a seventh state in COAG ministerial councils and committees (but not premiers’ conferences). By the early 2000s New Zealand was a member or observer on about half the COAG ministerial councils.
A joint institution to regulate food standards, Food Standards Australia New Zealand, grew out of COAG in 1996, as did the Trans-Tasman Mutual Recognition Arrangement (TTMRA) from 1998. This provided for a single trans-Tasman market for the sale of goods and registration of occupations.