Law is a comprehensive system of rules and principles usually arranged in codes, which governs people’s relations with each other and the world around them. It has four principal purposes: establishing standards, maintaining order, resolving disputes, and protecting liberties and rights. It is applied by public and private actors, including governments, corporations and citizens. Law shapes politics, economics, history and society in many ways. Its study is an important part of legal education and research, as well as of philosophical inquiry and social analysis.
Law consists of many different types of legal texts, such as constitutions, statutes, treaties and case law. Statutory texts, such as criminal laws, are legislative acts that establish the rights and obligations of government agencies and individuals. Case law consists of prior court decisions that are judge-made and which guide how other laws (such as statutes) should be applied to particular situations. Both statutes and case law are used by judges when they make their decisions in a lawsuit.
Some case law is binding precedent, meaning that a previous decision must be followed unless there are compelling reasons or significantly different facts or issues. Other case law is non-binding and may be merely influential. Judges are obligated to follow the decisions of appellate courts that can review their cases, and all federal and state courts are bound by the decisions of the Supreme Court of the United States.
Other important areas of law include administrative law, which includes regulations concerning air travel, banking, the environment, health and safety, immigration, patents, telecommunications and taxation. Commercial law covers complex contract law, such as the law of agency, insurance, bills of exchange and insolvency. Property law covers ownership of land and personal possessions, such as computers and cars. The law of succession, or family law, deals with marriage and divorce.
Law is also concerned with the relationships between nations, peoples and cultures. It encompasses international law, which addresses the rights and responsibilities of nations with respect to each other, as well as domestic law, which addresses matters between individual citizens. The study of law is a major field in international relations, political science and history.