This is a single section from Chapter 9. Read the full chapter here.

Is a treaty being implemented?

The appropriate method of incorporating treaty obligations into New Zealand law should be used to ensure that all relevant international obligations are given full effect.

To have effect in New Zealand, international obligations must be incorporated into New Zealand law. In many cases, this will require an amendment to domestic law to give effect to a treaty obligation. In other cases, it will be necessary to pass entirely new legislation.

The language in treaties is often ambiguous. This is so that a diverse group of governments can reach agreement. Any terms or language that may be ambiguous should be identified and parliamentary counsel should be consulted to determine whether the language needs to (or can) be adjusted in the proposed legislation, and what method of incorporation is most appropriate.


The text following is intended only as a brief summary of the main methods of incorporation (further advice should be sought from legal advisers, MFAT and the Parliamentary Counsel Office as to which method is the most appropriate):

  • Wording methodThis is the most common method. The wording of the treaty is reflected in the body of the legislation, although the legislation may or may not specify the treaty that it is incorporating. The wording may be reflected verbatim or, if necessary, translated to more accurately reflect local conditions. This method is useful if it is necessary to translate the wording of a treaty to reflect local conditions or if the treaty requires additional steps to be taken in New Zealand law (for example, one purpose of the New Zealand Bill of Rights Act 1990 was to implement the International Covenant on Civil and Political Rights).
  • Formula method “force of law”The full or partial text of the treaty is set out in the legislation, usually in a schedule. The legislation will use a form of words to proclaim that the treaty has the “force of law” and will apply domestically. This method is rarely used, but it is useful if the treaty amounts to a self-contained body of law that does not require any operational structures to support it (see sections 202 – 206 of the Contract and Commercial Law Act 2017).
  • Subordination methodThe legislation contains a provision that authorises the making of regulations or rules that give effect to the treaty or particular parts of it. This method is useful if the treaty provides for, or will require, ongoing technical changes that are appropriate to delegate to the Executive, or in rare cases that require implementation under strict and compressed timetables (see section 36(1) of the Maritime Transport Act 1994).
  • Hybrid methodIn some cases, more than one method may be used. For example, legislation may use the wording method to set out the relevant treaty rights and protections, but use the subordination method to trigger the application of those provisions. Another example is where the formula method is used to give the treaty force of law in New Zealand, but the wording method is used to create the specific mechanisms necessary for the administration of the law. The Adoption (Intercountry) Act 1997 is an example of this.

If the purpose of legislation is to implement a treaty, it is best practice for the purpose clause of the legislation to explicitly state that to help interpretation.

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