Conventions and Law Distinguished
Chapter Nineteen
Syllabus topic 2, "Conventions in Constitutional Law."
Pages 84 to 87 of 676
In one line
Law is made by a recognised legal source and enforced by a court; a convention is made by accepted practice and enforced by politics.
In the wording a student can write in an exam: a rule of law derives from a source the legal system recognises, has determinate content ascertainable by a court, and carries a remedy for its breach; a convention derives from practice accepted as obligatory, has content that may be contested at the margin, and carries no judicial remedy, although a court may recognise its existence.
The four differences
Source. A law comes from an enactment, a constitutional provision, or a judicial decision. A convention comes from a practice which those bound by it accept as obligatory.
Enforcement. A law is enforced by a court, which will grant a remedy. A convention is not: Reference re Resolution to Amend the Constitution, [1981] 1 SCR 753, decided on 28 September 1981, is a court finding a convention, declaring it broken and refusing to enforce it.
Certainty. A law's content is determined by a court if disputed. A convention's content may be genuinely uncertain, and the Supreme Court of Canada refused to say what measure of provincial consent was substantial.
Change. A law changes by the prescribed procedure. A convention changes when a new practice is accepted, which can happen quickly and without any formal act.
Where the line moves: two situations
First, a convention that a statute records. Section 28(8) of the Scotland Act 1998 provides that it is recognised that the Parliament of the United Kingdom will not normally legislate with regard to devolved matters without the consent of the Scottish Parliament. That is a convention written into an Act. In R (Miller) v. Secretary of State for Exiting the European Union, [2017] UKSC 5, [2018] AC 61, the Supreme Court held it remained a political convention which the courts would not enforce: the language recognised a practice rather than imposing a legal obligation.
The lesson for an answer is that the test is not where the words are printed. It is whether the words were intended to create a legal obligation.
Second, a court that recognises without enforcing. A court may take a convention into account when deciding what the law is, without treating the convention as itself a source of obligation. In R (Miller) v. The Prime Minister, [2019] UKSC 41, the Supreme Court did not enforce any convention about prorogation. It derived a legal limit from two principles it identified as fundamental, parliamentary sovereignty and the accountability of the executive to Parliament, which are the principles the conventions exist to protect.
A worked example
The head of State is presented with a Bill and does not act on it.
Conventions and Law Distinguished
If the rule is legal, a court can determine the content, fix the time and order compliance.
If the rule is conventional, a court cannot, and the Indian Supreme Court said so in In re Assent, Withholding or Reservation of Bills by the Governor and the President, decided on 20 November 2025: no timelines may be judicially prescribed under articles 200 and 201, no deemed assent may be granted under article 142, and the article 200 function is not justiciable on its merits. What survives is a limited mandamus against prolonged, unexplained and indefinite inaction, which is a legal remedy for a legal wrong, the failure to exercise a power at all, and not enforcement of the convention.
That case is the best modern statement of exactly where the line runs.
The cases
Facts. R (Miller) v. Secretary of State for Exiting the European Union, [2017] UKSC 5, concerned whether the United Kingdom government could trigger article 50 by prerogative, and separately whether the Sewel convention required the consent of the devolved legislatures.
Held. By eight to three, an Act of Parliament was required, because withdrawal would remove rights the European Communities Act 1972 had made part of domestic law and the prerogative cannot alter domestic law. On the Sewel question, unanimously, the convention was a political convention which the courts would not enforce, though recorded in section 28(8) of the Scotland Act 1998.
Why it matters here. It is the clearest authority that recording a convention in a statute does not convert it into law, and it is the case to cite for the second column of the table below.
Facts. In re Assent, Withholding or Reservation of Bills by the Governor and the President was a Presidential Reference under article 143, arising from Governors declining to act on Bills passed by State legislatures.
Held, decided on 20 November 2025. No judicially prescribed timelines under articles 200 and 201; no deemed assent under article 142; the article 200 function is not justiciable on the merits; a limited mandamus lies against prolonged, unexplained and indefinite inaction.
Why it matters here. It draws the line in Indian law: the manner of exercising the power is conventional and outside the courts, the total failure to exercise it is a legal wrong with a limited remedy.
Distinctions
| Law | Convention | |
|---|---|---|
| Source | Enactment, constitution, precedent | Accepted practice |
| Determined by | A court | The actors, and history |
| Remedy for breach | Yes | No |
| Change | Prescribed procedure | New practice accepted |
| Written | Usually | Sometimes; and being written does not make it law |
| Recognised by courts | As binding | As existing |
| Situation | Is it law? | Authority |
|---|---|---|
| Convention recited in a statute | No, if the words only recognise a practice | Miller No 1, section 28(8) |
| Convention enacted as an obligation | Yes | Article 74(1) as amended; article 75(5) |
| Court derives a legal principle from the values a convention serves | The principle is law; the convention is not | Miller No 2 |
| Total failure to exercise a power the convention governs | Reviewable, narrowly | In re Assent, 20 November 2025 |
Conventions and Law Distinguished
What beginners get wrong
"If it is in a statute it is law." Section 28(8) of the Scotland Act 1998 is in a statute and is not enforceable.
"A court can never mention a convention." Courts mention them constantly. What they do not do is grant a remedy for breach of one.
"A convention is a weaker kind of law." It is a different kind of rule, with a different source and a different sanction. Calling it weak law suggests a court might enforce it if it felt strongly enough, and no court has.
Limits and criticism
The line is a matter of degree in practice. Miller No 2 took a legal principle from constitutional values that are otherwise protected by convention, and reasonable lawyers disagreed about whether that crossed the line.
Conventions can be legislated into rigidity and back. The Fixed-term Parliaments Act 2011 converted the dissolution convention into statute; the Dissolution and Calling of Parliament Act 2022 repealed it and revived the prerogative, adding an ouster clause in section 3.
The distinction assumes an independent judiciary willing to police the legal side. Where that is absent, both categories fail together.
Quick revision
- Four differences: source, enforcement, certainty, mode of change.
- Recording a convention in a statute does not make it law: section 28(8) of the Scotland Act 1998 and Miller No 1.
- Enacting it as an obligation does: article 74(1) as amended in 1976, article 75(5).
- A court may recognise a convention without enforcing it: the Patriation Reference.
- A court may derive a legal principle from the values a convention protects: Miller No 2.
- In re Assent, Withholding or Reservation of Bills, 20 November 2025: manner of exercise conventional, total inaction reviewable.
- The test is intention to create a legal obligation, not the location of the words.
Test yourself
1. State four differences between law and convention. Source: enactment, constitution or precedent, against accepted practice. Enforcement: a court with a remedy, against political consequences only. Certainty: content determined by a court, against content that may be contested and left undetermined, as the Supreme Court of Canada left it in 1981. Change: by the prescribed procedure, against acceptance of a new practice.
2. Does putting a convention into an Act of Parliament make it enforceable? Not necessarily. Section 28(8) of the Scotland Act 1998 records the Sewel convention and the Supreme Court held in R (Miller) v. Secretary of State for Exiting the European Union, [2017] UKSC 5, that it remained a political convention. The question is whether Parliament intended a legal obligation; words that recognise an existing practice do not.
Conventions and Law Distinguished
3. Where exactly does Indian law draw the line on a Governor's inaction over a Bill? In re Assent, Withholding or Reservation of Bills by the Governor and the President, decided on 20 November 2025, holds that the manner and timing of the exercise of the article 200 power are not for the courts, that no deemed assent may be given under article 142, and that the function is not justiciable on its merits, but that a limited mandamus lies where the inaction is prolonged, unexplained and indefinite.
4. Give one example of a convention that has become law and one of a law that has become a convention again. The rule that the President of India acts on ministerial advice became law in article 74(1) as amended by the Forty Second and Forty Fourth Amendments. The rule about dissolution in the United Kingdom became law in the Fixed-term Parliaments Act 2011 and reverted to prerogative and convention when section 2 of the Dissolution and Calling of Parliament Act 2022 revived the prerogative as if the 2011 Act had never been enacted.
The rest of this subject
These notes are cut from the University's printed syllabus. Open the syllabus itself, or the past papers, for the same subject.