Blog of the International Journal of Constitutional Law

Why Codify?

Adam Perry, Lecturer in Law, Queen Mary University of London

Britain is always tinkering with its constitution. Sometimes it talks about a more radical change: constitutional codification. Over the past few years, talk of constitutional codification has grown a little more serious. High-profile committees, centres, and scholars have spent a lot of time and energy discussing the issue. Sophisticated reports have been produced (see here and here). Articles have been written.

But I still wonder: what difference would codifying the constitution actually make?

It could make a political or a practical difference. The process of codification might, for example, lead the public to think about what it values most in a constitution. The codification itself might make it easier to identify the country’s most basic rules. It could serve as a source of national pride. These are the sorts of considerations that have been raised in Britain lately. There is valuable literature about them.

I am an academic lawyer, though. I want to know what legal difference codification would make. That issue is rarely squarely addressed. My guess is that most scholars simply assume that codifying a constitution would not in itself make any legal difference. But I suspect that’s a mistake.

I need to be precise. I shall stipulate that a codified constitution is a single legal instrument that sets out all of a legal system’s constitutional rules. (This is a demanding definition. Few if any states’ constitutions meet it. I show how to relax it below.) Now, a state could codify its constitution and, at the same time, reform its substance in all sorts of ways. Britain, for example, could codify its constitution and, at the same time, abolish the House of Lords or add a Bill of Rights. Suppose we do not want any of these optional extras. We want to leave the substance of the constitution as intact as possible, while radically altering its form. Here is my question: if we alter the form of the constitution in this way, do we thereby alter its substance? In other words, does codification in itself bring about substantive change?

My argument for answering ‘yes’ starts with an analogy to statutory interpretation. Consider the following two maxims or presumptions of interpretation:

  1. Presumption of inter-statutory consistency: two statutes are presumed to be consistent with one another.
  2. Presumption of intra-statutory consistency: two parts of one statute are strongly presumed to be consistent with one another.

Suppose that Act A and Act B are statutes in the same area. They are potentially inconsistent. Applying the first presumption, a court would try hard to reconcile A and B. Now suppose the legislature codifies the law in this area: it repeals A and B and replaces them with Act C, which reproduces the material in A and B, including the potentially inconsistent material. Applying the second presumption, a court would try very hard to reconcile the material within C. So, the codification made a legal difference. Specifically, it strengthened the presumption that the codified material is consistent.

I should mention a third presumption: that a statutory codification does not change the law in the area it codifies. Does this presumption overturn the conclusion in the last paragraph? No. That would be contrary to case law, for one thing. More importantly, the whole point of a codification is to bring together the law in some area. Surely we can presume that the legislature intends the law in that area to make sense taken together.

(Almost any book on statutory interpretation will tell you about all three of these presumptions. But in my view the best work on the topic is by JF Burrows: see ‘Inconsistent Statutes’ (1976) 3 Otago LR 601 and chapter 14 of Statute Law in New Zealand.)

The constitutional context is similar, I think. Codifying the constitution would strengthen the presumption that the parts of the constitution are consistent. That is to say, codification would make courts more inclined to interpret the constitution as a coherent whole. This is a substantive difference in the law, and potentially an important one.

What I see in practice mostly bears this claim out. For example, the various parts of the Britain’s uncodified constitution are presumed to be consistent with the other parts – but to more or less the same degree they are presumed to be consistent with ordinary law. (That claim is a little more contentious now than it was a few years ago. See here.) In Canada, by contrast, the various parts of the codified constitution are generally subject to an extraordinary strong presumption of internal coherence. (My impression is that Canada is typical in this regard, but please let me know if I am wrong.)

Could a state codify its constitution without giving rise to a presumption of constitutional coherence? Yes, if it went about it explicitly. It would need to add words like: ‘The parts of the constitution are to be interpreted as if the constitution was not codified’. So, the emergence of a presumption of constitutional coherence is not an inevitable upshot of codification. But it is not like the abolition of the House of Lords or the addition of a Bill of Rights either. It is a substantive change a state needs to take steps to avoid, rather than to take steps to introduce.

My definition of a ‘codified constitution’ says that a codification is a single instrument. That is probably too strict, though. It better reflects our usage to say that, other things being equal, a constitution is more codified the fewer the instruments involved. We could then say that as the constitution becomes more codified, more of the constitution is strongly presumed to be coherent.

Why does any of this matter?

First, and more obviously, if constitutional coherence is of value, then here we have a distinctively legal reason for codification.

Second, this may be the tip of the interpretive iceberg. Codification might trigger other familiar interpretive principles. For example, similar terms within a statute are presumed to carry the same meaning, and likewise, similar terms within a codified constitution would be presumed to carry the same meaning. Codification might also give rise to new interpretive principles.

Overall, I wonder whether the main legal difference that codification would make is interpretive.

Suggested Citation: Adam Perry, Why Codify?, Int’l J. Const. L. Blog, June 24, 2015, at:


2 responses to “Why Codify?”

  1. […] post originally appeared on the blog of the International Journal of Constitutional Law here on 24 June […]

  2. Jon Roland Avatar

    The most important justification for codification, that is, for establishing a written constitution of government, is to prevent the House of Commons, which now sits as an ongoing constitutional convention, from overturning important parts of the traditional unwritten constitution. As the old saying goes, “No man’s life, liberty, or property are safe while Parliament is in session.”

    The major impediment to adopting a written constitution in the UK is, of course, that it would force the British to confront the fact that there is really no good way to reconcile such a constitution with having a monarchy as anything but a silly symbol. That would also mean divesting the Queen of most of her property, and subjecting her to paying taxes like anyone else.

    It would also provide the average Brit a standard to which they could repair, other than vague traditions that almost none of them know much about. Last I searched, I could not find a comprehensive collection of the historic documents of the British “constitution” on a web site hosted in Britain, but only on hosted in the U.S. See

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