Precedent comes from what is called the common law. The common law is one of the main sources of law in England and the USA. The common law developed after the year 1066. When the whole of England developed the same body of laws instead of each area having its own local laws-that is why it is called common. The common law covers both criminal and civil court decisions.
As judges decisions were written down, often described as 'recorded',in law reports that were common to the whole country, the idea of precedent developed. This means that when a judge decides the result of a particular case he or she must pay attention to the principles of law that come from an earlier case dealing with the same or similar points. In this way, a statement of law can become binding upon later judges and can become the law for everyone to follow. When does a particular decision, or pronouncement, by a judge become binding upon later judges? There are two important deciding factors.