A constitution is a set of laws on how a country is governed. Though in Spain we have a written Constitution, this is not like that for all countries in the civilized world. Thus Great Britain, Canada, New Zealand or Israel do not have such fixed, written constitutions.
Let's try to understand the process followed in a country with an unwritten constitution to ensure that the law is upheld.
The British Constitution is unwritten in one single document, unlike the constitution in America or the proposed European Constitution, and as such, is referred to as an uncodified constitution in the sense that there is no single document that can be classed as Britain's constitution. The British Constitution can be found in a variety of documents:
Acts of Parliament
Works of authority
A key element to understand these uncodified constitutions is the definition of convention as an accepted way in which things are done. They are not written down in law but tend to be old, established practices – the way they have always been done. Though these conventions are not set in legal stone, their very existence over the years has invariably lead to the smooth operation of government. For example, it is a convention that the queen will accept the legislation passed by the government, or it is accepted that a departmental minister will resign if he/she loses the confidence of the House of Commons (i.e. within their own party). Conventions can be changed, as they have no legal status. But they tend to be tolerated as they allow the system to work.
Because it can be modified by an ordinary act of Parliament , the British constitution is often termed flexible. This enables Britain to react quickly to any constitutional emergency. But, on the other hand, this means it requires a considerable amount of study and probably a degree in politics or law to fully understand how Britain is governed.
As you can see, even in matters that you may have considered basic to a democratic system, we are not all the same.