When William the Conqueror gained the English throne in 1066, he established a strong central government and began, among other things, to standardise the law. Representatives of the king were sent out to the countryside to check local administration, and were given the job of adjudicating in local disputes, according to local law.
When these ‘itinerant justices’ returned to Westminister, they were able to discuss the various customs of different parts of the country and, by a process of sifting, reject unreasonable ones and accept those that seemed rational, to form a consistent body of rules. During this process – which went on for around two centuries – the principle of stare decisis (‘let the decision stand’) grew up. Whenever a new problem of law came to be decided, the decision formed a rule to be followed in all similar cases, making the law more predictable.
The result of all this was that by about 1250, a ‘common law’ had been produced, that ruled the whole country, would be applied consistently and could be used to predict what the courts might decide in a particular case. It contained many of what are now basic points of English law – the fact that murder is a crime, for example.
The principles behind this ‘common law’ are still used today in creating case law (which is in fact often known as common law). From the basic idea of stare decisis, hierarchy of precedent grew up, in line with the hierarchy of the modern court...