Tāpiritanga 1: Ngā Whakamārama Ture Kāwanatanga mō te Tuku Whakatau

Annex 1: Constitutional Background to Decision-Making

Three branches of government

New Zealand’s government has three parts: the executive, the legislature, and the judiciary.

  • The executive is central government.  It is headed by Cabinet.  It includes Ministers and government departments.  The executive makes policy, proposes laws, and implements the law.  It is the ‘administration’ arm of government.
  • The legislature is Parliament.  It is comprised of elected members, including those who are Ministers (and so part of the executive).  Parliament makes statute law and supervises the executive through Parliamentary question-time and select committees.
  • The judiciary is the courts (made up of all judges).  The courts interpret and apply statute law, and make and apply common law.  The courts ensure that both statute law and common law is correctly applied by the executive.

Separation of powers

The three branches of government operate separately from one another.  It is important they respect each other’s different roles. 

For example, the courts cannot interfere with Parliament’s decision to pass a law – they cannot overrule a statute.1Except in the exceptional circumstance of a ‘manner and form’ challenge, where the courts may be asked to declare invalid a statute based on an alleged failure to follow a legislative requirement associated with its passage (such as passing an statute without a necessary super-majority as required by another statute). Nor do the courts interfere with parliamentary process, or with the executive’s political role in terms of its control of the legislative agenda or the policies it wishes to implement.

Equally, the executive respects the law-making functions of Parliament and the courts.  This means the executive must carefully follow the law as set in statute and in decisions of the courts.

The hierarchy of law and the importance of precedent in the common law

Statute law, made by Acts of Parliament, is the most authoritative source of law in New Zealand.  It supersedes all other law.  The Courts cannot overrule legislation and the executive must abide by it.  Secondary (and tertiary) legislation is the body of regulations, rules, orders and policies made pursuant to statutory authority by the executive.  It has the force of law and is legislation made under delegation from Parliament.  It is subject to scrutiny and oversight by the courts, especially to ensure that it has been made through proper processes and within the scope of the delegated power.

Common law is judge-made law.  It is made up of the decisions of courts on individual cases that come before it.  Parliament can overturn common law by passing legislation.

The courts operate in a hierarchy – the decisions of more superior courts take precedence.  Courts are also extremely respectful of previous decisions. This means that previous decisions will generally be followed by courts at the same level and that decisions of a higher court must, other than in exceptional circumstances, be followed in lower courts. There can also sometimes be useful guidance from the courts of similar common law jurisdictions such as Australia, the United Kingdom and Canada. Those decisions are not binding on New Zealand courts, and may not reflect the New Zealand circumstances, but can still in appropriate cases be persuasive.

The powerful role of precedent in the common law is intended to provide certainty and stability and support the rule of law – so that citizens can structure their affairs and operate with confidence that a court will rule in a particular way if presented with a decision for which there is strong precedent.