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A constitutional convention is an informal and uncodified tradition that is followed by the institutions of a state. In some states, notably those Commonwealth of Nations states that follow the Westminster system and whose political systems derive from British constitutional law, most government functions are guided by constitutional convention rather than by a formal written constitution. In these states, actual distribution of power may be markedly different from those the formal constitutional documents describe. In particular, the formal constitution often confers wide discretionary powers on the head of state that, in practice, are used only on the advice of the head of government, and in some cases not at all.

Some constitutional conventions operate separately from or alongside written constitutions, such as in Canada since the country was formed with the enactment of the Constitution Act, 1867. In others, notably the United Kingdom, which lack a single overarching constitutional document, unwritten conventions are still of vital importance in understanding how the state functions. In most states, however, many old conventions have been replaced or superseded by laws (called codification).

Historical entities often had strong emphasis on constitutional convention. For example the constitution of the Roman Republic was codified comparatively late in its development and relied for its functioning on traditions and a shared moral code called mos maiorum. In the Holy Roman Empire such important issues as who could elect the emperor were entirely uncodified before the Golden Bull of 1356 and remained subject to a certain degree of interpretation well afterwards.


The term was first used by British legal scholar A. V. Dicey in his 1883 book, Introduction to the Study of the Law of the Constitution. Dicey wrote that in Britain, the actions of political actors and institutions are governed by two parallel and complementary sets of rules:

The one set of rules are in the strictest sense "laws", since they are rules which (whether written or unwritten, whether enacted by statute or derived from the mass of custom, tradition, or judge-made maxims know [sic?] as the common law) are enforced by the courts. ... The other set of rules consist of conventions, understandings, habits, or practices that—though they may regulate the conduct of the several members of the sovereign power, the Ministry, or other officials—are not really laws, since they are not enforced by the courts. This portion of constitutional law may, for the sake of distinction, be termed the "conventions of the constitution", or constitutional morality.[1]

A century later, Canadian scholar Peter Hogg wrote:

Conventions are rules of the constitution which are not enforced by the law courts. Because they are not enforced by the law courts they are best regarded as non-legal rules, but because they do in fact regulate the working of the constitution they are an important concern of the constitutional lawyer. What conventions do is to prescribe the way in which legal powers shall be exercised. Some conventions have the effect of transferring effective power from the legal holder to another official or institution. Other conventions limit an apparently broad power, or even prescribe that a legal power shall not be exercised at all.[2]


Constitutional conventions arise when the exercise of a certain type of power, which is not prohibited by law, arouses such opposition that it becomes impossible, on future occasions, to engage in further exercises of this power. For example, the constitutional convention that the Prime Minister of the United Kingdom cannot remain in office without the support of a majority of members of the House of Commons is derived from an unsuccessful attempt by the ministry of Robert Peel to govern without the support of a majority in the House, in 1834–1835.

Enforceability in the courts

Constitutional conventions are not, and cannot be, enforced by courts of law. The primary reason for this, according to the Supreme Court of Canada in its 1981 Patriation Reference, is that, "They are generally in conflict with the legal rules which they postulate and the courts may be bound to enforce the legal rules."[3] More precisely, the conventions make certain acts, which would be permissible under a straightforward reading of the law, impermissible in practice. The court ruled that this conflict between convention and law means that no convention, no matter how well-established or universally accepted, can "crystallize" into law, unless the relevant parliament or legislature enacts a law or constitutional amendment codifying that convention.[4] This principle is regarded as authoritative in a number of other jurisdictions, including the UK.

Some conventions evolve or change over time. For example, before 1918 the British Cabinet requested a parliamentary dissolution from the monarch, with the Prime Minister conveying the request. Between 1918 and 2011,[5] Prime Ministers requested dissolutions on their own initiative, and were not required to consult members of the Cabinet (although, at the very least, it would have been unusual for the Cabinet not to be aware of the Prime Minister's intention). In 2024 Prime Minister Rishi Sunak reportedly announced his intention to hold an early election in July 2024 without even informing most of his cabinet prior to the anouncement.[6][7]

However, conventions are rarely ever broken. Unless there is general agreement on the breach, the person who breaches a convention is often heavily criticised, on occasions leading to a loss of respect or popular support.



No convention is absolute; all but one (the second) of the above conventions were disregarded in the leadup to or during the constitutional crisis of 1975.

Ignoring constitutional conventions does not always result in a crisis. After the 2010 Tasmanian state election, the Governor of Tasmania rejected the advice of his Premier to appoint the leader of the opposition as Premier because he felt the advice was tendered in bad faith. The Premier went on to form a new government.

Bosnia and Herzegovina


Commonwealth Realms






New Zealand

There is a convention that the Prime Minister of New Zealand should not ask for an early election unless they are unable to maintain confidence and supply.[clarification needed] By the 1950s, it had also become a convention that elections should be held on the last Saturday of November, or the closest date to this range as possible. There are several times when these conventions have been broken and an election has been held several months earlier:


Because of the 1814 written constitution's pivotal role in providing independence and establishing democracy in the 19th century, the Norwegian parliament has been very reluctant to change it. Few of the developments in the political system that have been taking place since then have been codified as amendments. This reluctance has been labelled constitutional conservatism. The two most important examples of constitutional conventions in the Norwegian political system are parliamentarism and the declining power of the King.


Much of Spain's political framework is codified in the Spanish Constitution of 1978, which formalizes the relationship between an independent constitutional monarchy, the government, and the legislature. However, the constitution invests the monarch as the "arbitrator and moderator of the institutions" of government.


The following constitutional conventions are part of the political culture of Switzerland. They hold true at the federal level and mostly so at the cantonal and communal level. Mostly, they aim to reconcile the democratic principle of majority rule with the need to achieve consensus in a nation that is much more heterogeneous in many respects than other nation-states.

United Kingdom

Main article: Constitutional conventions of the United Kingdom

While the United Kingdom does not have a written constitution that is a single document, the collection of legal instruments that have developed into a body of law known as constitutional law has existed for hundreds of years.

As part of this uncodified British constitution, constitutional conventions play a key role. They are rules that are observed by the various constituted parts though they are not written in any document having legal authority; there are often underlying enforcing principles that are themselves not formal and codified. Nonetheless it is very unlikely that there would be a departure of such conventions without good reason, even if an underlying enforcing principle has been overtaken by history, as these conventions also acquire the force of custom. Examples include:

United States

See also


  1. ^ AV Dicey, Introduction to the Study of the Law of the Constitution, 10th edition, pp. 23-24.
  2. ^ Peter Hogg, Constitutional Law of Canada, p. 7.
  3. ^ Supreme Court of Canada, Attorney General of Manitoba et al. v. Attorney General of Canada et al. (September 28, 1981)
  4. ^ "Manuel v Attorney General [1982] EWCA Civ 4 (30 July 1982)". Retrieved 2022-09-07.
  5. ^ The prerogative power of the Crown to dissolve Parliament was abolished with the Fixed-term Parliaments Act 2011.
  6. ^
  7. ^
  8. ^ McGregor, Janyce (11 June 2012). "Feeling confident about the budget vote?". CBC News. Archived from the original on April 17, 2013. Retrieved 12 May 2013. In 1968, Lester Pearson was prime minister, presiding over a minority Liberal government. Pearson governed largely with the support of the NDP, but in February the Liberals unexpectedly lost a final Commons vote over an amendment to the Income Tax Act. A strict reading of parliamentary convention would have suggested that vote was enough to trigger an election, because the change constituted a "money bill." But the Liberals were in the process of selecting a new leader, and Pearson gambled that no one really wanted an election right away. Pearson went on television and told Canadians that his government would put a second vote before the House of Commons specifically asking whether or not his government continued to command the confidence of the House of Commons, rather than the merits or demerits of a tax change. His gamble worked: his party won the second, more specific vote and carried on governing.
  9. ^ "Constitution Act, 1867". The Solon Law Archive. V.58. 29 March 1867. Retrieved 15 January 2009.
  10. ^ "Klage der beiden Bundestagsabgeordneten gegen Bundestagsauflösung erfolglos" [Action by two Members of Parliament against dissolution of the Bundestag unsuccessful] (in German). German Federal Constitutional Court.
  11. ^ Starck, Christian (2005). "BVerfG, 25. 8. 2005 – 2 BvE 4/05 und 7/05. Die Auflösung des Bundestages" [Federal Constitutional Court, 25 August 2005 – 2 BcE 4/05 and 7/05. Dissolution of the Bundestag]. JuristenZeitung. 60 (21): 1049–1056. JSTOR 20827991.
  12. ^ " Der Bundespräsident / Reden / Auflösung des 15. Deutschen Bundestages - Fernseh- ansprache von Bundespräsident Horst Köhler".
  13. ^ Hinck, Gunnar (26 December 2017). "Steinmeier und seine SPD-Mitgliedschaft: In himmlischer Ruh". Die Tageszeitung: Taz.
  14. ^ Rudzio, Wolfgang (3 April 2008). "Informelles Regieren – Koalitionsmanagement der Regierung Merkel" [Informal governance: coalition management of the Merkel government]. Aus Politik und Zeitgeschichte (in German).
  15. ^ "Fragen an Stefan Marx zu seiner Edition über den Kreßbronner Kreis" [Questions for Stefan Marx on his edition about the Kressbronn Circle]. Parlamentarismus (in German). 23 March 2014. Archived from the original on 19 October 2021. Retrieved 28 October 2021.
  16. ^ "Österreichs Proporz - Modell für Bonn?" [Austria's proportional representation – a model for Bonn?]. Der Spiegel (in German). 11 April 1961.
  17. ^ Parliamentary briefing – the Privy Council Archived 2010-06-15 at the Wayback Machine, accessed 20 June 2012
  18. ^ "Election 2005 – Election Map". BBC News.