Law is a body of rules that people agree to follow, with consequences for those who disobey them. It is a major factor in politics, economics, history and society. For examples of the law shaping human interactions see censorship; crime and punishment; and social restrictions. It also has a powerful effect on the economy, as laws are used by businesses to determine their financial risk. The legal profession is concerned with the study of the law, and the practice of it; see legal profession and legal education.
The law is a complex topic, and definitions vary widely. John Austin’s utilitarian definition states that “law is the aggregate of commands, backed by the threat of sanctions, given by a sovereign to his subjects as his political superiors.” Other philosophers, such as Jean-Jacques Rousseau and Thomas Aquinas, define law in terms of natural morality.
In common law systems, judicial decisions are considered part of the law on equal footing with legislative statutes and executive regulations. This allows for a doctrine called stare decisis, which means that the decision of a higher court binds lower courts in similar cases.
Civil law includes fields such as family law, which deals with marriage and divorce, property ownership rights, and child custody; corporate law, which concerns how a business is run; criminal law, which deals with preventing crimes, and punishing those who commit them; and constitutional law, which relates to the constitution of nation-states and the separation of powers between different branches of government. There is also international law, which deals with the rights of people who live outside the borders of a particular country.