I. Sources of the Common Law
A. Court Decisions
The principal source of positive law in the common law system is customary law. The common law system has some analogies to French medieval law: trial by jury, the binding nature of precedent. B. Statutes and treaties
Statutes and treaties are the other source of law in the anglo-saxon world. However to be enforced even statutes and treaties must be ultimately interpreted by judges. Statutes are however controlling; that is a statutory law can replace the customary (common) law. In the hierarchy of norms, the statute is the 'highest' norm. Then treaties.
Then the common law.
1. Stare Decisis
The doctrine of stare decisis states that legal decisions are binding and shall not be reversed. "The decision stands." That is, once a court has entered its judgment upon an issue, it shall not reverse itself. This is in fact the foundation of legality in the common law system - and is one of the principal differences between common and civil law. 2. Argument By Inductive Analogy
In the civil law, the principal method of argument is by deduction from general principals or from statutes toward particular cases. Further there is no doctrine of stare decisis. In the common law however the principle method of analysis is induction and analogy. Induction is reasoning from particular cases toward general principles. Analogy is argument from similarity. Thus the majority of common law reasoning consists in demonstrating the similarities or differences between a case which has been decided and the case at bar (=the case before the court). Why make such analogies? Because of the doctrine of stare decisis. If the court made a certain decision in the past, and if the facts of this case are sufficiently similar to the facts of the previous case, then the decision of the previous case must be applied to this case. 3. Res Judicata
Res judicata is a doctrine similar to stare decisis. Res...