I’ve been lecturing lately on constitutional conventions, one of my favourite topics in the constitutional law course. A couple of weeks ago I sketched what I think is a new argument for why conventions aren’t laws. I’m reasonably confident of the argument, but far from certain, so I thought I’d share it more widely. If you spot any flaws, please let me know!

Dicey’s Argument

Dicey distinguished laws and conventions based on enforcement. Laws, he said, ‘are enforced by the Courts’. Meanwhile, ‘conventions, understandings, habits, or practices’ aren’t ‘laws at all since they are not enforced by the Courts’.

Taken literally, this is silly. Some laws are never litigated. Section 467 of the No One Cares Act  will never make it to court, so it won’t be enforced. Let’s be charitable and take Dicey to mean that a norm is a law only if courts would enforce it were an appropriate case to arise it. Also, as Colin Munro noted, ‘enforce’ doesn’t capture how courts engage with many laws. It’s awkward to say that a court ‘enforces’ a permission or the conferral of a power, for example. ‘Apply’ or ‘act on’ are better, more encompassing terms. So, again, let’s be charitable. Let’s take Dicey to distinguish between laws and conventions based on their applicability or courts’ willingness to act on them.

Putting these two points together, here’s the argument:

1. A norm is a law only if courts would apply it, in an appropriate case.
2. Courts don’t apply conventions, even in appropriate cases.
3. So, conventions aren’t laws.

I’ll call this “Dicey’s argument”. There are two ways to attack the argument: attack premise 1 or attack premise 2. I think that premise 2 is true in the United Kingdom. That leaves premise 1.

A good objection

 The usual way to attack premise 1 is via counterexample. There seem to be laws which courts won’t apply. As a result, courts’ unwillingness to apply conventions doesn’t distinguish them from laws. This objection originated with Sir Ivor Jennings, who identified a couple of counterexamples. Scholars since have added others. Drawing them together, we have the following list of laws which courts are unwilling to apply:

• Laws protected by an ouster clause. Suppose there is a statutory duty imposed on an official. Suppose there is also a very clear “ouster clause” – a statutory provision instructing courts not to consider or question whether the official fulfilled the duty. Courts are bound by the ouster clause, so they wouldn’t apply the statutory duty. Nonetheless, the statutory duty is a legal duty. Until recently, this was theory. Since R (Privacy International) v Investigatory Powers Tribunal, it is practice.
• The law and custom of Parliament. Parliament has a wide range of norms governing its own affairs and procedures. These norms are known as the ‘law and custom of Parliament’. Even though many of the norms are laws, they are not enforceable by courts.
• Directive principles. Directive principles impose a legal obligation on a legislature or government to pursue a social value (e.g., housing, healthcare, equality) or an equally broad aim. Even though they’re legal norms, directive principles aren’t enforceable by courts. Many constitutions have directive principles, including those of India, Ireland, and South Africa, as well as the United Kingdom.

To these three traditional examples, I’ll add a fourth:

• Disapplied statutes. The Merchant Shipping Act 1988 (MSA) was ‘disapplied’ under the European Communities Act 1972 (ECA). As things stand, the MSA is not applicable by courts. Indeed, the MSA has never been applicable by courts, because it has never been consistent with EU law. And yet the MSA was validly enacted, and it has never been repealed. The norms it generates are valid legal norms, even though they are not applied by courts. This is not a rare case: there are many disapplied statutes.

Perhaps someone would suggest that the MSA is not a valid statute. They would argue that the MSA was invalidated by the ECA, just as if it had been repealed. That would be a mistake though. Suppose the ECA itself were repealed (and no relevant transitional arrangements were enacted). What would happen to the MSA? If the MSA had been invalidated or repealed, it would not come into force upon the ECA’s repeal. A repealed statute does not “revive” upon the repeal of the repealing statute. But the MSA would come into force upon the ECA’s repeal. The legal norms it creates would then be applicable. That’s one of the differences between disapplication and repeal: repeal of a disapplying statute “revives” the disapplied statute, whereas repeal of a repealing statute doesn’t revive the repealed statute. Because the ECA’s repeal would revive the MSA, we can infer that the MSA is a valid statute.

A revised argument

If even one of these examples holds good, then Dicey’s argument fails. We need to try again to distinguish conventions from laws. Here’s my best effort.

Look again at the examples in the last section. There’s a common feature, beyond unenforceability. It’s that there are two laws, structured like this:

Law A: imposes a duty on so-and-so to do such-and-such.

Law B: directs courts not to apply Law A.

We see this structure in each case:

	Law A	Law B
Ouster	Statutory duty (e.g. in the Regulation of Investigatory Powers Act 2000)	Norm ousting the courts from reviewing whether that duty is fulfilled
Law & Custom	Law and custom of Parliament	Norms of parliamentary privilege, telling courts not to ‘question’ what happens in Parliament (e.g. Article IX of the Bill of Rights 1689)
Directive Principles	Principle imposing a duty to pursue a broad aim	Norm telling courts not to enforce or act on the principle (Lael Weis has a good explanation here)
Disapplied Statutes	Statutory duties (e.g. duties in MSA)	Section 2(4) of the European Communities Act 1972

Constitutional conventions are different. Courts don’t enforce or apply conventions. But that’s not because of a legal norm which prohibits courts from enforcing convention. There isn’t any such norm. How do I know that? Well, Parliament hasn’t laid down a rule that courts shouldn’t enforce conventions. No statute says that. Courts have expressed their unwillingness to enforce conventions, but they don’t present this as a legal finding. Customary law obviously doesn’t contain such a norm either. And, as a final check, we can ask ourselves: would we say that courts act “unlawfully” by enforcing a convention? The answer is clearly “no”.

So here’s my proposal. For a norm to be a law a court would have to be willing to apply that norm, were the court presented with an appropriate case, and were it legally permitted to apply that norm. (This is a slight simplification. There are complicated questions about the legal status of rules of recognition, which aren’t relevant here.) Were a court presented with a case involving a statute, without an ouster clause, it would apply the rules it finds there. Were a court presented with a ‘law’ of Parliament, and were parliamentary privilege no bar, I take it the court would apply the law. Were a court to be presented with a case involving a directive principle, and were it permitted to enforce the principle, it would enforce it. Were the ECA no bar, the courts would apply the MSA. My counterfactuals are speculative, of course. But think about it pragmatically: why would we need Article IX, or an ouster clause, or a statement warning courts away from directive principles, or s 2(4) of the ECA unless courts might otherwise act on these norms?

If this is right, then conventions aren’t laws because courts aren’t willing to enforce them even though there’s no legal bar to them doing so. The revised argument would go like this:

1. A norm is a law only if courts would apply it, in an appropriate case, were they permitted to apply it.
2. Courts don’t apply conventions, even in appropriate cases, and even though they’re permitted to do so.
3. So, convention aren’t laws.

Further questions

I said there were two ways to attack Dicey’s argument. The other way would be to try to show that courts do apply or enforce conventions. I think that line of attack would fail in the UK, as things stand now. But of course things could change. Courts in the UK might suddenly start enforcing conventions. Would that make conventions laws?  Courts elsewhere already enforce conventions. Are conventions in those places already laws?

Not necessarily. Courts sometimes enforce or apply norms which aren’t part of their  legal system. Examples include norms of logic or maths, contractual norms, foreign laws, and so on. All of these norms are acted on by courts. None are laws of their system. Something distinguishes laws from norms which courts are willing to act on; but what? It’s a core question in legal philosophy. But it’s a question that legal philosophers have neglected, a bit to my surprise. A topic for another blog post!