The American legal system relies heavily on court precedent in formal adjudications, and the decisions of certain courts are especially important when it comes to resolving disputes. In a civil law system, however, courts rely more on codes that lay down the rules of decision for particular disputes. When judges deviate from these codes, their decision is often irrelevant to subsequent decisions. Common law also has many differences from civil law, including the application of statutory and constitutional law.
The extent of the binding effect of judicial decisions depends on the court. Federal courts are divided into three tiers, with United States District Courts (trial level courts), the United States Court of Appeals (first-level court), and the Supreme Court. Each level has its own rules for reviewing decisions. In addition to these, each tier has its own set of rules and precedents.
The common law is crucial to understanding most important areas of U.S. law. While the basic laws of contract, torts, and property are governed by statute, there are no laws that expressly override the common law. While certain states recognize both types of law, common law is the basis for a large number of U.S. legal decisions. These cases have shaped the legal system in the United States and other Commonwealth countries.
The common law system has a long history of parallel authority between courts and legislatures. This parallel authority dates back to the 12th century and enables courts to “legislate from the bench.” Article III of the U.S. Constitution recognizes “judicial power.”