Constitutional conventions are the most unwritten part of the New Zealand constitution. They are practices of constitutional behaviour that have been followed so consistently and which are believed to have such force that they are generally considered to govern constitutional behaviour.
Canadian constitutional conventions
The Canadian Supreme Court has pointed out that constitutional conventions may be more important than some laws and summarised the situation in an equation: ‘constitutional conventions plus constitutional law equal the total constitution of the country.’1
Conventions may not be enforced by the courts. They live and die according to continued practice and belief.
Examples of constitutional conventions
Constitutional conventions provide some of the key rules of New Zealand’s constitution. They add to, or take away from, legal rules in sometimes dramatic ways. Examples include:
- the convention of individual ministerial responsibility, which gives individual ministers the responsibility to answer to the House of Representatives for the exercise of their powers, including their powers to direct the public service within their portfolio and within the law
- the convention of collective cabinet responsibility, which gives cabinet collectively the power to direct individual ministers, since all ministers have to publicly support the decisions of cabinet
- the convention of collective cabinet responsibility is also significant for the stability of a government – if the House of Representatives passes a motion of no confidence in the government then the government falls and becomes a caretaker government until a new government can be formed with the confidence of the house
- the convention of caretaker government, which provides that a government must significantly constrain its decision-making if it loses the confidence of the House of Representatives, even while having full legal powers to govern
- the convention that the sovereign only acts on the advice of ministers subordinates the queen’s legal powers (and those of her representative in New Zealand, the governor-general) to cabinet.