Former Prime Minister Sir Geoffrey Palmer is promoting a written constitution for New Zealand, arguing it is necessary because the current constitution is not readily accessible to the non-specialist.
Two principal difficulties immediately come to mind. The first is the question of a written entrenched constitution (one changeable only by a special process), and the second is the (not unrelated) issue of the Treaty of Waitangi.
In the modern world New Zealand, together with the United Kingdom and Israel, are exceptional in not having a codified, usually entrenched, constitution. Unlike the United States, Canada and Australia - not coincidentally all federal systems - New Zealand cannot look to one single document embodying its constitution.
But, although the provisions of the Constitution Act 1986 are not entrenched, and major constitutional changes could legally be effected virtually overnight by a bare majority of the House of Representatives, the issue is not purely or even mainly the legal one of entrenchment.
The approach of the New Zealand constitution is one of flexibility. The written rules are underpinned by what are called conventions. These are rules of political practice which are regarded as binding by those to whom they apply.
Laws are enforceable by the courts, conventions are not. The major convention upon which the constitution is built is the constitutional principle known as the rule of law. This is based upon the practice of liberal democracies of the Western world. It means that what is done officially must be done in accordance with law.
In Europe, where an entrenched constitution is the touchstone for legitimacy of government, there might be a general grant of power to the executive, and a bill of rights to protect the individual. In the New Zealand tradition public bodies must point to a specific authority to act as they do.
Thus we rely upon numerous specific grants of authority to the various organs of government, a much more flexible approach.
New Zealand might choose to adopt an entrenched constitution, but this would mean adopting a new approach to public law. In Canada, the newly renamed Constitution Act 1982 attributed to itself a position of legal paramountcy. This has meant that the Supreme Court of Canada has had to become increasingly involved in the political arena.
This has its advantages and its disadvantages, both in principle and in practice. One consequence is for the constitutional locus of authority in the state - if the courts have the power to invalidate legislation then parliamentary sovereignty, and even democracy itself, must be understood differently.
It is a debatable whether New Zealand has lost anything by not having an entrenched constitution. It is doubtful that the relative inaccessibility of the constitution is a serious issue, since only the specialist could unravel the supposedly codified US Constitution.
Not only would an entrenched constitution require the courts to assume a greater, potentially more controversial role, but entrenched constitutions also tend to become out of date and it is difficult to amend them. There have only been 17 amendments to the US Constitution since it was introduced in 1789, whilst there have been some 11,000 proposals for amendments.
An entrenched constitution is no guarantee of better government, nor necessarily an effective limitation on excessive legislative, executive (or judicial) independence. Those countries which suffer most from military coups, revolutions, putsches and similar upheavals normally have (ostensibly) entrenched codified written constitutions.
The way in which society functions, and the emotional attachment to democratic processes, are a better safeguard than a so-called written constitution.
Because in Canada and Australia authority is shared between the federal and provincial or state parliaments, there must be some higher authority which determines who shall have what power or responsibility. As a unitary state, there is arguably no technical need for the New Zealand constitution to be entrenched, apportioning authority and placing limits on the powers of Parliament.
It is generally agreed that Parliament is a sovereign body, able to enact, repeal or amend any law, including any self-imposed limitations. Limitations on such powers are only effective in a federal state, where limitations on capacity are, by definition, part of the constitutional structure. It is questionable whether any New Zealand constitution would be held by the courts to be truly entrenched.
A more important factor to consider, and one which might point the way to the adoption of a new theory of government (one in which entrenchment, should this be necessary or desirable, is possible) is the position of the Treaty of Waitangi.
The Treaty is now politically all but entrenched. It occupies an uncertain place in the constitution. Parliament has never doubted it had full authority despite the Treaty. There have been some signs this orthodoxy may be challenged, but it is difficult how this could be done in the absence of an entrenched constitution and a Supreme Court on the American model.
As will be seen from this cursory examination of two issues, any serious revision of the constitution risks rapidly becoming an unmanageable exercise. Although the general public may not be overly concerned with esoteric concepts of constitutional theory - public involvement with the reviews of 2004 and 2013 highlighted this - any reform must first seriously consider the theoretical basis of our legal and political system. This is especially important in view of Māori claims for sovereignty.
It might be worthwhile looking at solutions within the existing structures, rather than to call for the codification and entrenchment of the constitution.
Unless they are prepared to wrestle with large issues, most contentious of which is the Treaty of Waitangi, or entrenchment, proponents of constitutional reform should tread warily.
Dr Noel Cox, a barrister in Auckland, was previously professor of law at Auckland University of Technology and more recently at Aberystwyth University in the UK.