The term “federal case law” describes the body of U.S. law that is made up of judicial opinions and decisions related to national law. In the United States, the legal system is based on both black letter, or statutory, law and case law, which is court interpretation and application of the same. Laws are further divided into federal laws, which apply uniformly to the nation, and state laws, which apply only within discreet state borders. Federal case law is decided in any of the nation’s numerous federal courthouses. Once decided, it is binding and holds precedent in all federal courts throughout the country.
United States law is based on the common law system of England. Under this system, the legislature and elected officials set the law, but it is up to the people to interpret and apply it. This application comes in the form of judicial opinion. When a case goes to trial, the presiding judge must hear the parties’ arguments, consider the evidence, and then decide how the statutory law should apply. The judge memorializes the ultimate decision in an official court opinion, which becomes a part of the ever-changing body of case law.
Most opinions contain far more than just a decision, however. Judges typically also take time to outline their reasoning, and to explain in detail just why they made the choices they did. When more than one judge weighed in on the opinion, as is often the case in courts of appeals, each judge will get a chance to write an individual review of the ultimate decision, including any points of dissent, if applicable. If the deciding court was a state court, that opinion and all additional judicial thoughts becomes state case law. In a federal court setting, it becomes federal case law.
Case law is very important to the functioning of the legal system. Most of the time, opinions are written only after considering the case law already in existence that touches on the same or similar laws. Case law at both the state and federal level builds upon itself according to a system of precedents. Once an opinion enters into the case law, it becomes precedential for all lower courts. Federal precedent means that a federal court must, in the course of deciding a specific legal issue, take into account and defer to the reasoning of any existing case law that is on point. Identifying judicial error is one of the only ways to refute precedence.
Federal and state case law are very similar, but they generally do not overlap. Much of this is owing to the functional differences between state and federal law. The federal court system exists entirely independently of the state law system. Each system maintains its own courthouses, judges, and means of appeal and ascension. Federal law matters are simply not addressed in state courts.
State case law is not typically influential in federal court proceedings. The inverse, however, is not true: federal case law can, in certain circumstances, be persuasive in state law trials and appeals. Most of the time, federal case law concerns matters of national law like constitutional rights or civil liberties that have been incorporated into state laws in some form. If a case involves an area of law that is addressed in both state and federal statutes, federal case law that is on-point can be used to sway the state-level court.