Statute of Westminster Adoption Act 1947
The Statute of Westminster Adoption Act 1947 was a constitutional act of the New Zealand Parliament that formally accepted the full external autonomy offered by the British Parliament. By passing the Act, New Zealand adopted the Statute of Westminster 1931, an act of the British Parliament that granted full sovereign status and Commonwealth membership to the Dominions ratifying the statute.
Source: Wikipedia — Statute of Westminster Adoption Act 1947 (CC BY-SA 4.0)