Constitutions are designed to set out the rules and regulations within which governments operate.

They establish the composition, powers and functions of the institutions of the state, regulate the relations between these institutions, and enshrine the legal rights and duties of the citizenry.

An important distinction can be drawn between codified and uncodified constitution

Codified constitutions are largely written, centered around a single document incorporating key constitutional provisions that are binding on all political institutions.

They are usually 'entrenched', enjoying the protection of a higher or supreme court, and can only be repealed or amended by special provisions, beyond the ordinary legislative process.

Examples of codified constitutions include the American Constitution of 1878, or the German Basic Law of 1949. Indeed, most constitutions are written and codified.

The United Kingdom is rare among liberal democracies in not having a codified constitution of this kind.

Unwritten constitution

The UK constitution is often described as an 'unwritten constitution', but it is best described as 'partly written and wholly uncodified' (Budge et al, 1998).

It is derived from a number of sources. Its principal source is statute law, i.e., laws passed by the UK Parliament.

Statute law is particularly important for determining the powers and scope of government, and the conduct of elections.

Examples include the Act of Union of 1707, which united Scotland with England and Wales, the various Representation of the People Acts, which extended the right to vote, and the European Communities Act of 1972, which took the UK into the European Community.

An array of conventions, or unwritten understandings and customs, also surround the rules of constitutional behavior. Although not supported by law, these are considered to be binding.

For example, it is a convention that the monarch sign Acts of Parliament passed by both Houses, and that the government should resign after losing a vote of 'no confidence'.

Constitutional authority is also derived from common law, that is, the legal principles and 'precedents' established by judicial decisions.

As a source of constitutional authority, common law has largely been replaced by statute law, but it remains important in the sphere of civil liberties, and in fundamental constitutional principles, such as the Royal Prerogative and parliamentary sovereignty.

Royal role

A historic feature of the UK constitution, the Royal Prerogative gives the Crown (the monarch) special powers, including the power to declare war, to make treaties, to pardon criminals, and to dissolve Parliament.

Today the role of the monarch in such matters is largely ceremonial, but the Royal Prerogative gives considerable powers to government ministers acting on the Queen's behalf.

The single most important principle of the UK constitution is that of parliamentary sovereignty.

Under this principle, Parliament can make or unmake any law on any subject whatsoever. No one Parliament is bound by the decisions of its predecessors, nor can it bind its successors.

There is no higher body, such as a supreme court, that constrains the legal authority of Parliament.

However, parliamentary sovereignty is now directly challenged by the UK's membership of the European Union.

EU membership necessitates the 'pooling' of sovereignty over areas where the member states have agreed to act together.

All laws passed at the European level are considered legally superior to domestic law, and are ultimately protected by a higher constitutional court, the European Court of Justice.

Should European Community law and UK law conflict, EC law will prevail.

© Nicola McEwen 2004
Lecturer in Politics
University of Edinburgh