Law is a system of rules created by the state to ensure people can live in harmony with each other and with nature. The rules are enforceable by mechanisms that may impose sanctions on those who break them. For example, the state might penalize individuals who drive too fast or businesses that evade taxes.
Legal systems vary between countries, with the US using a system called common law and many European nations employing civil law systems. In a common law legal system, decisions by judges are recognized as law on an equal footing with legislative statutes and executive regulations. The collection of these decisions is called case law. Civil law systems use codes that explicitly specify how judges should rule in particular cases.
The study of law encompasses a wide range of subjects from ancient criminal justice systems, such as coroners’ courts, to modern police forces and judicial systems that use electronic reports. It also explores the relationship between the law and society. For example, laws can restrict freedom of expression and freedom of religion. See censorship; crime and punishment; and police for more details. The study of law is also informed by questions of philosophy, with articles on legal ethics and jurisprudence.