The unwritten sources of the UK constitution are the royal prerogative and conventions. The royal prerogative stems from the powers which used to be exercised exclusively by the monarch and which are now exercised by the ministers on the Queens behalf. The best known examples of the royal prerogative are the power to declare war, control over the appointment of ministers and the right to dissolve Parliament. The legal nature of conventions is somewhat different, they are non-legal norms which should be obeyed by those to whom they apply; although conventions cannot be enforced by the courts they are usually respected. On the basis of the above it is possible argue that a large part of the British constitution has been codified in writing. Nevertheless, due to lack of a separate document called 'constitution' existence of written documents is often disregarded and the UK constitution is said to be unwritten.
The unwritten character of the UK constitution, or rather the existence of unwritten rules, has serious legal implications. The first point to note is that Parliament can pass and revoke the law as it sees fit. Until recently the British constitution did not guarantee any rights; although the Bill of Rights Act was enacted as early as 1688 it dealt exclusively with issues related to Parliament and Crown. This meant that, in theory, Parliament could pass any legislation it considered appropriate even if it infringed rights of UK citizens. Prior to the enactment of the Human Rights Act 1998 the only limitation on the Parliamentary sovereignty in cases involving human rights violations would have been the rule of law.
Its effectiveness, however, would have been questionable if the courts, wanting to avoid interference with Parliamentary decisions, refused to enforce it. This should be juxtaposed with countries which have written constitutions and a clearly defined aim of safeguarding rights of ordinary citizens by means of specially drafted provisions.