Constitutional Conventions

Constitutional conventions are non-legal rules that regulate the conduct of constitutional actors. Unlike laws, conventions are not enforceable by courts. They are, however, politically binding and are generally regarded as obligatory by those to whom they apply. The uncodified UK constitution relies heavily on conventions to govern relationships between institutions, filling gaps left by statute and common law and ensuring that constitutional practice operates according to democratic norms. Without conventions, the constitution would be unable to function effectively, as many of the most important constitutional relationships are governed by convention rather than law.

Characteristics of Conventions

Conventions arise from practice and acquiescence. They evolve over time and may be modified or abandoned as constitutional practice changes. Sir Ivor Jennings identified three criteria for a convention to exist: precedents showing the practice, a belief by actors that they are bound by it, and a constitutional reason for the rule. Conventions typically govern the exercise of prerogative powers, the operation of Cabinet government, and the relationship between the House of Commons and the House of Lords. Unlike laws, conventions are not enforced by courts, but they are no less important to the functioning of the constitution. A government that violated a convention would face severe political consequences, including loss of confidence, ministerial resignations, and public criticism. Conventions are fluid and can change as constitutional practice develops. For example, the convention that the monarch appoints the Prime Minister has evolved to require the appointment of the person most likely to command the confidence of the House of Commons.

Key Conventions

Several conventions are central to British constitutional practice. The monarch must grant Royal Assent to bills passed by both Houses of Parliament—this convention dates from 1708 and has not been refused in modern times. The Sewel convention provides that the UK Parliament will not normally legislate on devolved matters without the consent of the relevant devolved legislature. This convention has been given statutory recognition in section 28 of the Scotland Act 2016 and equivalent provisions for Wales. Individual ministerial responsibility requires ministers to account for their departments’ actions to Parliament and to resign in cases of serious departmental failure. Collective Cabinet responsibility requires ministers to support government policy publicly or resign, ensuring that the government presents a united front. The Salisbury-Addison convention holds that the House of Lords will not oppose government bills that implement manifesto commitments, respecting the elected government’s mandate. The Ponsonby rule, now codified, requires treaties to be laid before Parliament before ratification.

Legal Status and Enforcement

Courts take notice of conventions but will not enforce them. In Attorney General v Jonathan Cape Ltd (1976), the court declined to enforce collective Cabinet responsibility as a legal obligation, though it recognised the convention’s existence and acknowledged that publication of Cabinet documents could be restrained where the public interest in confidentiality outweighed the public interest in disclosure. In R (Miller) v Secretary of State for Exiting the European Union (2017), the Supreme Court recognised the Sewel convention as an important constitutional principle but held that it was not enforceable by courts. The Court stated that the enforcement of conventions belongs to the political realm rather than the legal, and that judges have no jurisdiction to determine whether a convention has been breached or what consequences should follow. This case illustrates the distinctive nature of conventions: they are cognisable by law but not justiciable. Judges may refer to conventions in their reasoning but will not create legal remedies for their breach.

Codification and Reform

Some conventions have been codified in legislation. The Fixed-term Parliaments Act 2011 (now repealed and replaced by the Dissolution and Calling of Parliament Act 2022) placed the convention on dissolution on a statutory footing, though the experience demonstrated that codification can create unforeseen problems. The Cabinet Manual (2011) provides a written guide to the conventions of government, though it does not have legal force and is not binding. The House of Commons Public Administration and Constitutional Affairs Committee has periodically recommended further codification of conventions. The partial codification of conventions raises questions about whether conventional rules lose their character when reduced to writing. Some scholars argue that codification transforms the nature of the rule, converting a political obligation into a legal one. Others contend that conventions can be codified without losing their essential character, provided the codification is not accompanied by legal enforcement mechanisms. The debate reflects deeper questions about the relationship between law and politics in the constitution.

Conventions in the Modern Constitution

Conventions continue to play a vital role in the constitution. The prerogative power to dissolve Parliament, now governed by the Dissolution and Calling of Parliament Act 2022, traditionally operated by convention. The appointment of the Prime Minister is governed by convention: the monarch appoints the person most likely to command the confidence of the House of Commons. In hung parliament situations, conventions about coalition formation and the incumbent Prime Minister’s right to remain in office become particularly important. The conventions of ministerial responsibility have evolved to reflect the modern reality of collective Cabinet government and the dominance of the Prime Minister. These conventions, and many others, ensure that constitutional practice conforms to democratic principles without requiring formal legal rules. The flexibility of conventions is both a strength and a weakness of the uncodified constitution, allowing adaptation to changing circumstances but also creating uncertainty about the precise content of constitutional requirements.