A key difference between common law and civil law is in the nature of contracts. In civil law countries, a contract is based on provisions of the law rather than on custom. While the decisions of judges in common law countries are always final, they can still be appealed. In the United States, for example, a case may be heard by a network of state and federal courts. The federal Supreme Court has the final say, but the last court ruling stands as the verdict. It can also serve as precedent for future cases.
Common law systems are based on a set of precedents. Unlike a code of laws, common law is richer in detail. These precedents are a result of practical problems. It is in touch with everyday life and is not arbitrary. However, it is sometimes inflexible, resulting in illogical rulings. Ultimately, a common law rule depends on the context, judge, and society in which it is applied.
In general, common law systems don’t have much oversight for the lawmaking authorities in the judicial branch. Judiciary decisions can be overruled, but it can take a long time. And in a common law system, the decisions of judges are based on evidence and tradition, which is rarely predictable. A good judge may make a good decision, but he may not have been fair. A bad decision could lead to a long delay.