In a federal state the federal legislature and the legislatures of the regions within the federation each have their own particular roles and competence which is defined in the federal constitution.

In a unitary state there is only one legislature or, at least, there is a single legislature which is supreme and the roles and competences of any other legislatures can be changed or abolished by the supreme legislature. So if there is a supreme legislature what is the point of a constitution?

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    I’m voting to close this question because the why aways is because the lawmakers said so.
    – Trish
    Oct 19, 2021 at 22:28
  • @Trish Not always. Sometimes it's because the men with guns say so.
    – nick012000
    Oct 20, 2021 at 2:40
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    @nick012000 when they decide to use those guns for controlling what other people can do, men with guns are lawmakers.
    – Jim Cullen
    Oct 20, 2021 at 4:07
  • Kelsen would agree - but he is not without his critics.
    – Nemo
    Oct 20, 2021 at 9:57
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    That a right is established by the constitution of a state has no direct relationship with the structure of the government of that state, except inasmuch as the state must have a constitution in the first place. The question seems to suppose that the sole import of a right being established by a national constitution is to ensure that it is not denied by contrary regional laws, but there is at least one even more significant impact: protecting the right against contrary national law. How much protection is afforded depends on other factors. Oct 20, 2021 at 12:16

7 Answers 7


They don’t, or not necessarily

The primary purpose of a constitution is to define the structure, operation and limits on government. It contains the laws that the government cannot change except by any procedure included in the constitution.

It isn’t necessarily to spell out the rights of citizens. Some do, some don’t.

The median age of constitutions is 19 years - half of them are older than this, half of them are younger. Coincidentally, or perhaps not, this is close to the 20 years that Thomas Jefferson thought a constitution should last since “the earth belongs to the living, and not to the dead.” The US Constitution is the oldest (and shortest) still in modern use - it’s influential but it’s a poor example of what modern constitution’s are like.

For some particular examples:

  • the United Kingdom (a unitary state) does not have a written constitution. It’s unwritten one has only one clause - Parliament is sovereign. UK citizens have a bill of rights but that is under an Act of Parliament, they are not constitutional rights.
  • New Zealand (a unitary state) has a constitution but that constitution is an act, or more precisely acts, of Parliament and their bill of rights is also an act of Parliament.
  • Australia (a federal state) has a constitution which is an act of the UK Parliament with a single right (freedom of religion) and no bill of rights. Australians have an implied right of political discourse because the High Court has determined that that is necessary for the democracy described in the constitution to work. Their other rights are those that exist at common law. People in the state of Victoria have a bill of rights (made by Parliament) but no other state or territory has adopted one.
  • the French (unitary) constitution creates the position of “Defender of Rights” but what those rights are and the procedures for defending them are delegated to parliament to decide.
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    The UK has a written Constitution, it's just not written in one place!
    – deep64blue
    Oct 19, 2021 at 23:34
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    @Blackhole It's not an amendment, but the 1789 Declaration as well as the 1958 Constitution, the Preamble of the 1946 Constitution, and the 2004 Environment Charter are all part of the Constitutional Bloc of the Fifth Republic and have all equal constitutional value. Oct 20, 2021 at 7:04
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    To be nitpicky, the UK's unwritten constitution is definitely a lot more complex than "Parliament is sovereign" - but this is the primary/overriding principle that negates all others if they come into conflict.
    – Muzer
    Oct 20, 2021 at 9:53
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    I like the premise of this answer, but the UK and NZ examples seem a bit dubious. As far as I can make out, both use roughly the same concept of an uncodified constitution comprising a series of principles and key laws. It's therefore quite hard to define whether any particular law is or is not part of either constitution. The Australian example is better, although the fact that it was passed as law by the British Parliament is somewhat irrelevant, as it can and has been amended within Australia since.
    – IMSoP
    Oct 20, 2021 at 17:41
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    The défenseur des droits is not the most relevant feature of the French constitution. It also created a constitutional court, which was initially quite weak but gradually grew in importance. Case law also turned interrnational treaties into a kind of quasi-bill of rights that the other two supreme courts (Cour de cassation and Conseil d'État) routinely use to set laws aside so it's not the best example of a state without “constitutional” rights where parliament has unfettered power.
    – Relaxed
    Oct 21, 2021 at 10:51

As you say, anything not specifically forbidden is presumed to be allowed. But the legislature can (relatively) easily pass laws to forbid things. Most constitutions make it significantly harder to amend themselves. So enumerating specific rights in the constitution ensures that they will not be taken away without a real struggle.

For example, the 2nd Amendment makes it impossible to pass laws forbidding gun ownership, and even makes it hard to pass laws regulating the process of acquiring guns.

There's also a philosophical aspect to this. A nation's constitution describes the fundational principles of the nation. Enshrining certain rights in the constution indicates that they are of supreme importance. These aren't just laws, they're what the nation represents.

Consider, for example, how the US 2nd Amendment empowers gun-rights advocates. Or how often people invoke the 1st Amendment's rights to freedom of speech, religion, and the press. Denying these rights is considered "un-American".

On the other hand, the Affordable Care Act (AKA "Obamacare") is just a set of laws. Many politicians and laypeople disagree with the principles that it espouses, but would not be considered un-American on this basis.

  • I think this is the best answer, the only thing I might add is to correct OP's misapprehension where they seem to believe that the point of a constitution is superseding laws of the lower governments. This isn't particular to a constitution, this is just what federal laws do
    – llama
    Oct 20, 2021 at 18:30
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    I think everyone else is misunderstanding the question. It's not asking what the point of a constitution is, just asking why the constitution needs to grant some rights.
    – Barmar
    Oct 20, 2021 at 19:06
  • In the case of a federal system, the national constitution may need to do this to prevent states from denying those rights. His question is why this is necessary when there are no states to override.
    – Barmar
    Oct 20, 2021 at 19:07

A constitutional law is harder to reverse than a simple law

For example, France absolished the death penalty though a simple law, which could have been reversed through another simple law, with 50% of the lower house.

It was added to the Constitution in 2007 (Article 66-1: "No one shall be sentenced to death"), and now requires a two-thirds majority in both houses: much, much harder to achieve.


Constitutions are more than their Bill of Rights, and in fact, the U.S. Constitution was first written without the Bill of Rights (They were added in through the amendment process shortly after the document was ratified).

Constitutions are the supreme law of a nation and will outline the nation's government structure (Who is the Commander in Chief of the military? Who writes the Laws? Who is head of government? Who is head of State? How are the courts set up? Who can override who and when can they do it and how?) as well as delegate authorities to different government branches.

Consider the First Amendment of the U.S. constitution, which begins with "Congress shall make no law...". This essentially establishes that it's beyond congress's ability to make a law that punishes speech or religious expression, thus a limit on the Federal Legislature's powers. The States were not so bound until the 14th Amendment was passed, which among other things, forced the states to adopt the Bill of Rights. Similarly when amendments to the constitution banned things, (13th which banned slavery and 18 which banned alcohol) both Amendments included language to give Congress the power to make laws to enforce those bans (since those laws were previously powers of the state). Those laws actually gave the amendments some teeth to enforce the bans. The 21st Amendment (Which banned the 18th Amendment didn't include such language as repealing Prohibition reverted the powers to regulate alcohol to the states again.). A specific amendment (10th) actually explicitly makes it so the Federal Government may not assume power which the Constitution did not delegate to it by making it a right of the state or the people.

In fact, even in Federal Nations, Constitutions still delegate soveriegn powers to the member states and each member state has their own Constitution (The California Constitution is one of the longest such documents in the world, even though the United State's is one of the shortest in the world). All U.S. States are themselves Unitary States with devolved power to non-sovereign sub-regions (counties, Parishes in Louisiana, Burroughs in Alaska) that are created by the state's constitution.

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    The focus on the United States seems misplaced, as neither it nor any of its member states is a unitary state.
    – bdb484
    Oct 19, 2021 at 15:47
  • @bdb484: Either way, the discussion is to show that the OP's original question which seems to assume that a nation must be a Federation to have a constitution. The point of a constitution is that it is a law which establishes what a government can and cannot do and which parts of government can do which actions. And yes, the individual U.S. States are themselves Unitary in nature (several of them were independent nations prior to becoming states).
    – hszmv
    Oct 19, 2021 at 16:28
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    It's funny how people often mention the constitution's function of outlining the government's structure as if it were secondary, when it is this function that gives the document its name.
    – phoog
    Oct 19, 2021 at 20:40
  • @hszmv In what way are you saying the states unitary? I think the generally accepted reading of McCulloch v. Maryland and the Supremacy Clause is that the opposite is true.
    – bdb484
    Oct 19, 2021 at 21:42
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    Yes, I'm familiar with basic U.S. history, but I don't see how their unitary nature 250 years ago means that they are still unitary today.
    – bdb484
    Oct 20, 2021 at 13:46

Unless something is explicitly forbidden in law it is allowed, so why do unitary states have constitutional rights? There is no level below them that could mean differently. Nothing would counteract a constitutional right if it was removed.

Any state with a constitution of any form has rights that arise from it. Any kind of law establishes rights and responsibilities, and constitutions are not an exception to that rule.

In Europe and other places with a constitutional tradition of parliamentary sovereignty largely unfettered by judicial rule, the primary mechanism by which human rights are protected that is resistant to ephemeral or bare majority parliamentary action, and which is enforced by courts, is through international human rights treaties. In Europe, these were devised and administered largely by an international organization parallel to the European Union called the Council of Europe which promulgated and secured widespread adoption of with little qualification, the European Human Rights Convention.

Most Western democracies, unlike the United States, provide that a conflict between a duly adopted treaty that remains in force, and subsequently adopted domestic legislation, is resolved by the courts in favor of the treaty. These treaties are the strongest protections of human rights in most of these countries that are enforced in their own domestic courts and regional international human rights courts which countries in such treaties take more seriously than the U.S. does.

There is circumstantial evidence from the structure of the U.S. Constitution that the drafters of the 1789 Constitution of the United States intended the same thing, but the Courts promptly settled on the opposite rule flowing from a very literalist reading of Article III of the U.S. Constitution that doesn't consider intent or context and now has the force of precedent behind it.

While it is much easier to amend constitutions in most unitary states (which are frequently amended much like U.S. state constitutions), many still do have human rights protections in their constitutions, largely as a result of a movement when constitutions were redrafted following World War II which interrupted most of Europe's national regimes at least temporarily due to Nazi occupation or rule, on the model of the United States Constitution and as a way to honor their new membership in the United Nations by incorporating much of the U.N. Declaration of Human Rights (a non-self-executing instrument) into enforceable domestic law, usually supervised by a separate constitutional court. As recent shifts away from a consensus around those rights have eroded, treaty rights have proven more important than constitutional rights (e.g. in Poland and Hungary). But inertia, and the popularity of the general idea of protecting constitutional rights even though particular aspects of those rights may be unpopular, has kept those protections on the books as a political matter even though they wouldn't be hard to repeal from a process standpoint.

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    While Germany is not a unitary state and thus not under the purview of this question, there are two things I always found interesting in our constitution. Like most constitutions, ours has a builtin way to be changed. However, it also has builtin protections for a few Articles that cannot be changed, even following the process laid out in the constitution for changing Articles. In fact, depending on your interpretation, these Articles cannot even be changed by adopting a new constitution. I.e. whatever constitution Germany has, until all eternity, must have equivalent protections to … Oct 20, 2021 at 12:04
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    … the rights laid out in those Articles. Oct 20, 2021 at 12:04
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    In particular, those are Articles 1 (The Human Dignity is Untouchable …) and Article 20 (Germany is a Democratic and Social Federation. …) as well as Human Rights. Oct 20, 2021 at 12:13

A constitution does not grant rights the citizens already have. It prevents the state from taking those rights away.

For example, when a constitution says "Every citizen has the right to mow their lawn on Sunday morning", then that says that the legislature is prohibited from passing a law which infringes on that right and that the executive is prohibited from enforcing laws if doing so would infringe on that right.


One point that hasn't been detailed in other answers is how this affects the balance between different institutions. In practice, a written constitution with a bill of rights often empowers the courts to nullify actions by other branches of the government. International human rights treaties can play the same role, even in places where court activism is traditionally frowned upon like France.

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