The Salisbury Convention

Conventions are the key unwritten element within the constitution: being non-legal, they often lack clear and unambiguous definition. For example, there is a convention that the government will either resign or call a general election if defeated on a major bill by the House of Commons; but there is debate about what constitutes a‘major’ bill.And, anyway, there would be no legal consequences if the government simply ignored this rule. So why are conventions upheld? The answer is that they are upheld by practical political circumstances; in short, they make politics ‘workable’. The convention that the Royal Assent is always granted is upheld by the monarch’s desire not to challenge the ‘democratic will’ of Parliament, an act that would bring the future of the monarchy into question. Once established, constitutional conventions often assume historical authority, as they come to be based on custom and precedent. Examples of major constitutional conventions include:

• The exercise of Crown powers. The powers of the Royal Prerogative are, in the main, exercised by the prime minister and other ministers, not by the monarch. These powers include the power to appoint, reshuffle and sack ministers, to dissolve and recall Parliament, and to ratify international treaties (although, in the future, many of these powers will be subject to parliamentary consultation).

• The appointment of the prime minister. The monarch appoints as prime minister the leader of the largest party in the House of Commons, or, in the case of a ‘hung’ Parliament, the politician who is likely to command the confidence of the House of Commons.

Individual ministerial responsibility . This broadly defines the relationship between ministers and their departments, and it defines grounds on which ministers should resign

. • Collective ministerial responsibility . This defines the relationship between ministers and the cabinet, and between the government as a whole and Parliament; it determines, amongst other things, that the government should resign or call a general election if it loses the ‘confidence’ of the House of Commons.

• Use of referendums to approve major constitutional changes. This has gradually been established since the (failed) devolution referendums of 1979, although it is unclear which reforms it should apply to; referendums were not called over the Human Rights Act or fixed-term Parliaments, for example.

• Parliament consulted prior to the UK going to war. This has been accepted since Gordon Brown in 2007 announced that in future the UK would never declare war without Parliament having debated the issue beforehand.

The Sewel convention is an arrangement that regulates the relationship between the UK Parliament and the national assemblies of Scotland, Wales and Northern Ireland. It requires specific consent to be given from the devolved governments for any UK-wide legislation that encroaches on devolved matters, particularly health, legal and policing matters. If consent is refused, the UK Parliament can — and usually does — still pass the legislation, but reflecting ever-growing hostility, the three devolved governments now refuse this consent on multiple occasions each year, prompting calls for a full codification of the UK’s constitutional arrangements.