Simple overview:
Common law, often referred to as "judge-made-law", requires judges to use their discretion in making judgments. It is used when no appropriate statute law exists. A judges' decision may set a precedent, which must then be followed by all lower courts when the facts of the case are similar
In civil law countries, legislation is seen as the primary source of law. By default, courts thus base their judgments on the provisions of codes and statutes, from which solutions in particular cases are to be derived. Courts thus have to reason extensively on the basis of general rules and principles of the code, often drawing analogies from statutory provisions to fill lacunae and to achieve coherence. By contrast, in the common law system, cases are the primary source of law, while statutes are only seen as incursions into the common law and thus interpreted narrowly.
The main difference that is usually drawn between the two systems is that common law draws abstract rules from specific cases, whereas civil law starts out with abstract rules, which judges must then apply to the various cases before them.
An example:
- You steal a loaf of bread.
Civil law: The set of rules say stealing is against the law, and propose "standard sanctions". The judge use this to rule you can't steal of loaf of bread, and use the standard sanctions as a base to decide the penalty you will get in this particular case.
Common law: Some years ago, someone stole an egg. Stealing a loaf of bread is simular to stealing an egg. The judge uses the precedent ruling about the theft of the egg to decide what shall be done for bread.