Sources of the Constitution

These are laws, passed by the UK Parliament, which have a constitutional effect.

Examples:

• Human Rights Act 1998 brought the ECHR into UK law.
• Scotland Act 1998 transferred considerable power to a Scottish Parliament. 
• Freedom of Information Act 2000 gave considerable public access to official documents and information.

These are rules that are not legally enforcable but which are considered binding and so are virtually laws.

Examples:

• The Salisbury Convention is a rule that the House of Lords cannot obstruct a proposal that was contained in the governing party's last election manifesto. 
• Collective cabinet responsbility states that members of the government should always defend all government policies.

Similar to conventions, these are unwritten laws, but unlike conventions, they can be enforced by the courts.

Examples:

• The use of prerogative powers by the prime minister results from common law. This means the prime minister has a range of powers, transferred from the monarchy, but not sanctioned by Parliament. 
• Many individual rights and freedoms are established by common law.

The UK has signed a number of treaties, mostly concerning the transfer of power and sovereignty from the UK to the EU.

Examples:

• The Maastricht Treaty of 1992 and Lisbon (Reform) Treaty of 2007 both transferred power from the UK to the EU.

These are the writings of constitutional experts which describe constitutional practice. They have so much authority that they have become part of the constitution.

Examples:

• The rule of law as described by 19th century constitutional expert, A.V. Dicey, establishes the principle of equality under the law.
• The 2010 O'Donnell Rules were written by the Cabinet Secretary, Gus O'Donnell, as a guide to how to form a government with a hung parliament. 

These are customs and practices that have grown up over a long period of time. They are not legal, but tend to persist.

Examples:

• The annual Queen's Speech is how the government's annual legislative programme is announced.
• Parliamentary procedures are largely traditional.