The three branches; the executive, the legislature and the judiciary of government, should be separate, unique and equal. There should be a clear separation between the people and functions of the legislature, executive and judiciary. As Montesquieu said “that each function should be exercised individually by three institutions; When the legislative and executive powers are united in the same person or in the same body of magistrates, there can be no liberty, because apprehensions may arise, lest the same monarch or senate should enact tyrannical laws to execute them in tyrannical manner. Again there is no liberty if the judiciary power be not separated from legislative and executive.”
However this does not mean that the bodies should have no power over each other, what is required is a “check and balance” system between them. If the branches were completely separate it would be unworkable, particularly as the Parliament is Supreme. There should be sufficient interplay between the branches, for example, the executive proposes legislation, Parliament debates and passes the law, and the judiciary upholds the Acts of Parliament.
In the United States there is a formal separation of powers, with a deliberate system of checks and balances. Even in a constitution built on principle of the separation of powers, the separation cannot be absolute. There is separation of personnel between the Executive and the Legislature. The legislature controls the levying of taxes and allocation of the funds and can therefore cut off funds to executive policies and project of which Congress do not approve. The Supreme Court of United States has the power to declare legislation unconstitutional. Both the Supreme Court and the President are subject to removal by impeachment in the legislature, Hubbard, Thomas and Varnham, (2010).
In New Zealand there is no formal separation of powers.
Legislature/Executive
There is no separation between the executive and legislature nor do many of the checks and balances exist. Hubbard et al. (2010).There is no separation of personnel between the Executive and the Legislature. The Governor-General is formal head of the executive branch and required to assent legislation before it becomes law. The MMP electoral system and the strong select committee system to ensure that the Executive does not dominate the legislature
There is evidence of mixing function between the Executive and the Legislature. The legislature’s ability to delegate its law making powers to executive branch, “Parent Statutes” is the specific example of delegation of powers, McDowell and Webb, (2002).
Legislature/Judiciary
There is no common membership between the two branches of government. In all circumstances Judiciary is considered to be subordinate to Parliamentary control and Parliament can exercise its supreme law making power to check judicial decision. Parliamentary supremacy is clear as it may enact any law that it pleases and courts must apply the law and cannot question it. There is no power by which Judiciary can exercise any control over legislature.
But courts can only exercise law making powers by interpreting legislation, developing legal principles through the common law and precedent and pronouncement of fundamental rights, McDowell and Webb, (2002).
Executive/judiciary
In limited circumstances, there may be an overlap in membership between them, e.g. High Court Judges may be called upon to exercise an executive function as Royal Commissioner for a commission of enquiry.
On the other hand Judges are appointed by the members of the executive ( the Chief Justice is nominated by Prime Minister and Cabinet).
Executive functions are capable of being limited by judiciary by way of administrative law and judicial review, McDowell and Webb, (2002).
Conclusion
As from all above it is clear that the New Zealand government system lack full application of theory separation of powers due to Westminster system. How ever it is not possible to adopt full separation of power but it is necessary and important to have close and coordinated interaction and must have check and balance system among the three parts of government to work effectively.
References
Hubbard, J., Thomas, C. & Varnham, S. (2010). Principles of law for New Zealand business students (4th ed.). North Shore, New Zealand: Pearson.
McDowell, M. & Webb, D. (2002). The New Zealand legal system, structures, Processes & legal theory (3rd ed.). Wellington, New Zealand: LexisNexis Butterworths.
Montesquieu, C.L. (1748) Esprit des Lois, Book XI Ch. VI.