Constitutional convention (political custom) in the context of "Governor-General of the Irish Free State"

An uncodified constitution is a type of constitution where the fundamental rules often take the form of customs, usage, precedent and a variety of statutes and legal instruments. An explicit understanding of such a constitution can be developed through commentary by the judiciary, government committees or legal experts. In such a constitutional system, all these elements may be (or may not be) recognized by courts, legislators, and the bureaucracy as binding upon government and limiting its powers. Such a framework is sometimes imprecisely called an "unwritten constitution"; however, all the elements of an uncodified constitution are typically written down in a variety of official documents, though not codified in a single document. However, there may be truly "unwritten" constitutional conventions which while not usually legally enforceable may hold just as much sway as the letter of the law.

An uncodified constitution has the advantages of elasticity, adaptability, and resilience. A. V. Dicey described the uncodified constitution as "the most flexible polity in existence." A significant disadvantage, however, is that controversies may arise due to different understandings of the usages and customs that form the fundamental provisions of the constitution.

The Constitution of Canada (French: Constitution du Canada) is the supreme law in Canada. It outlines Canada's system of government and the civil and human rights of those who are citizens of Canada and non-citizens in Canada. Its contents are an amalgamation of various codified acts, treaties between the Crown and Indigenous Peoples (both historical and modern), uncodified traditions and conventions. Canada is one of the oldest constitutional monarchies in the world.

The Constitution of Canada comprises core written documents and provisions that are constitutionally entrenched, take precedence over all other laws and place substantive limits on government action; these include the Constitution Act, 1867 (formerly the British North America Act, 1867) and the Canadian Charter of Rights and Freedoms. The Constitution Act, 1867 provides for a constitution "similar in principle" to the largely unwritten constitution of the United Kingdom, recognizes Canada as a constitutional monarchy and federal state, and outlines the legal foundations of Canadian federalism.

The legal system of Australia has multiple forms. It includes a written constitution, unwritten constitutional conventions, statutes, regulations, and the judicially determined common law system. Its legal institutions and traditions are substantially derived from that of the English legal system, which superseded Indigenous Australian customary law during colonisation. Australia is a common-law jurisdiction, its court system having originated in the common law system of English law. The country's common law is the same across the states and territories.

The Australian Constitution sets out a federal system of government. There exists a national legislature, with a power to pass laws of overriding force on a number of express topics. The states are separate jurisdictions with their own system of courts and parliaments, and are vested with plenary power. Some Australian territories such as the Northern Territory and the Australian Capital Territory have been granted a regional legislature by the Commonwealth.

Advice is a formal instruction given by one constitutional officer of state to another that, in many parliamentary systems, is usually binding. For example, heads of state (such as constitutional monarchs) often only act on the advice of the head of government (such as the prime minister) or other ministers. Common examples of advice include the appointment of ministers, the use of executive powers, the calling of elections and the request to deliver formal statements, such as a speech from the throne.

Depending on the state, the duty to accept advice may or may not be legally enforceable. For example, advice is generally not legally enforceable under most countries that follow the Westminster system. Nevertheless, the convention that ministerial advice is always accepted is so strong that in ordinary circumstances, refusal to do so would almost certainly provoke a constitutional crisis, or, at minimum, the removal of the head of state. By contrast, Japan's head of state (the Emperor) is obliged by the constitution to appoint the prime minister designated by the parliament (Diet).

The Constitution of the Republic of Singapore is the supreme law of Singapore. A written constitution, the text which took effect on 9 August 1965 is derived from the Constitution of the State of Singapore 1963, provisions of the Federal Constitution of Malaysia made applicable to Singapore by the Republic of Singapore Independence Act 1965 (No. 9 of 1965, 1985 Rev. Ed.), and the Republic of Singapore Independence Act itself. The text of the Constitution is one of the legally binding sources of constitutional law in Singapore, the others being judicial interpretations of the Constitution, and certain other statutes. Non-binding sources are influences on constitutional law such as soft law, constitutional conventions, and public international law.

In the exercise of its original jurisdiction – that is, its power to hear cases for the first time – the High Court carries out two types of judicial review: judicial review of legislation, and judicial review of administrative acts. Although in a 1980 case the Privy Council held that the fundamental liberties in Part IV of the Constitution should be interpreted generously, Singapore courts usually adopt a philosophy of deference to Parliament and a strong presumption of constitutional validity, which has led to fundamental liberties being construed narrowly in certain cases. The courts also generally adopt a purposive approach, favouring interpretations that promote the purpose or object underlying constitutional provisions.

Cabinet collective responsibility, also known as collective ministerial responsibility, is a constitutional convention in parliamentary systems and a cornerstone of the Westminster system of government, that members of the cabinet must publicly support all governmental decisions made in Cabinet, even if they do not privately agree with them. This support includes voting for the government in the legislature. This convention formed in the 19th century in the United Kingdom. Some political parties, most commonly communist, apply a similar convention of democratic centralism to their central committee.

If a member of the Cabinet wishes to openly object to a Cabinet decision then they are obliged to resign from their position in the Cabinet.