A convention, also known as a constitutional convention, is an uncodified tradition that is followed by the institutions of a state. In some states, notably those Commonwealth states that follow the Westminster system and whose political systems derive from the constitution of the United Kingdom, some 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 In most states, however, many old conventions have been replaced or superseded by laws (called codification).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.
Definitions 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:
A century later, Canadian scholar Peter Hogg wrote:
Origins
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."Supreme Court of Canada, Attorney General of Manitoba et al. v. Attorney General of Canada et al. (September 28, 1981) 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. 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,The prerogative power of the Crown to dissolve Parliament was abolished with the Fixed-term Parliaments Act 2011. 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 announcement.
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.
Examples
Australia Whoever can command a majority in the House of Representatives is entitled to be asked by the Governor-General to form a government, and take the title Prime Minister. Governors-General always act on the advice of their Prime Minister or other relevant minister in regard to particular powers they may exercise. An incumbent Prime Minister who loses an election will advise the Governor-General to appoint the leader of the larger party as Prime Minister so the Governor-General does not need to act alone. State Premiers tender advice to State Governors for Federal Senate elections, in response to the Prime Minister's advice to the Governor-General to call a Federal House of Representatives election. State Governors are given a dormant commission to administer the Commonwealth if the Governor-General is unable to. Vice-regal officers act in a politically neutral way.
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 The six members of the Constitutional Court of Bosnia and Herzegovina, that are chosen by the Parliaments of entities of Bosnia and Herzegovina, should be chosen in a way as to establish the national balance, of "constituent peoples", in the Court (two Bosniaks, two Croatians and two Serbs), although the Constitution does not have this requirement. The chairman of the Council of Ministers of Bosnia and Herzegovina should be of different nationality in every new term (establishing the "rotation"), although this is not formally regulated. The government of an entity should inform the government of Bosnia and Herzegovina of its intention to establish special parallel relationships with neighboring states, including negotiations. Also, the High Representative should be notified of any such intent, especially if there is a document that should be signed between parties, although the Constitution does not have this requirement (also for first example).
Canada The Prime Minister will request the Governor General to call an election upon the defeat of the government in a confidence or money vote. This convention was broken in 1968 when the ruling minority government of Lester B. Pearson unexpectedly lost a money vote. All the parties in Parliament, who were not prepared for a snap election, agreed to pass a resolution retroactively declaring the lost money vote was not a matter of confidence. Though it is mentioned in various constitutional documents, the precise nature of the office of the prime minister operates mostly according to understood, uncodified British conventions. The Supreme Court of Canada is, by statute (the Supreme Court Act), composed of three justices from Quebec and six from anywhere in Canada (including Quebec). This is because Quebec uses civil law rather than the common law system used elsewhere in Canada; it is necessary to have a panel of at least three judges to hear civil law cases. By convention, the remaining six positions are divided in the following manner: three from Ontario; two from the western provinces, typically one from British Columbia and one from the prairie provinces, which rotate amongst themselves (although Alberta is known to cause skips in the rotation); and one from the Atlantic provinces, almost always from Nova Scotia or New Brunswick. The appointment of the most senior puisne justice to chief justice is a convention that has recently fallen into disuse.
Chile Under the 1925 Chilean Constitution, the president was elected by an absolute majority of the popular vote; if no candidate won an absolute majority, the National Congress would hold a contingent election between the top two candidates. A constitutional convention developed that Congress would always elect the candidate with the most popular votes at a contingent election. In a television interview ahead of the 1964 Chilean presidential election, presidential candidate (and eventual winner) Eduardo Frei Montalva upheld this convention.Hurtado-Torres, Sebastian (2020). The Gathering Storm: Eduardo Frei's Revolution in Liberty and Chile's Cold War. Cornell University Press. pp. 36 However, this convention was nearly broken in 1970, where the Socialist candidate Salvador Allende, a self-proclaimed Marxist, won the most votes; thus, the contingent election became a battleground between the two major powers of the Cold War, with the United States launching a campaign to prevent Allende's election by Congress while the Soviet Union gave its support to Allende. Although Allende was eventually elected at the contingent election, he was later overthrown by the military in 1973; under the military regime of Augusto Pinochet, which succeeded Allende, a new constitution was adopted in 1980, which replaced the contingent election with a runoff by popular vote, rendering the convention obsolete.
Commonwealth realms The Governor-General is appointed on the advice of the Prime Minister of the day, is a resident of the country he or she will represent, and can be dismissed immediately on the advice of the Prime Minister (exceptions are Papua New Guinea and the Solomon Islands, where the Governor-General is elected by Parliament and then formally appointed by the Monarch, and the United Kingdom, which has no vice-regal office). However, in Canada, provincial lieutenant-governors are appointed on the advice of the federal prime minister, not the provincial premier. Neither the Monarch nor a Governor-General will participate in the political process unless there is an extreme circumstance that merits the use of reserve powers, or when the advice tendered is contrary to established convention. Neither the Monarch nor a Governor-General will make partisan speeches or state partisan opinions. This convention was broken in 1975 by Sir Colin Hannah, the governor of Queensland, who called for the defeat of the Whitlam government. The Queen, on Whitlam's advice, revoked Hannah's dormant commission to act as Administrator of the Commonwealth of Australia and the Foreign and Commonwealth Office later refused the premier of Queensland's request that they advise the Queen to appoint Hannah to a second term as Governor (in 1975, Australian State Governors were still appointed on the advice of UK ministers).
Denmark The Danish Constitution makes reference to the King in great detail. Apart from the fact that this is understood to include a Queen regnant as well, references to the King acting in a political capacity are understood to mean the Prime Minister, as the Constitution stipulates that the King exercises his powers through the Cabinet.