Law is a set of rules that are enforced by social or governmental institutions to regulate behavior. Its precise definition is a topic of longstanding debate. Law may be enacted by a legislature, resulting in statutes; by an executive, resulting in decrees and regulations; or by judges, through precedent and the “doctrine of stare decisis” (Latin for “to stand by decisions”), in common law jurisdictions. Private individuals may also create legal contracts and arbitration agreements that establish binding rules, as well.

A central issue is how law relates to morality. John Austin, an early utilitarian theorist, defined law as “commands, backed by threat of sanction, from a superior to men, as his political subjects”. This view was challenged by philosophers such as Jean-Jacques Rousseau and Thomas Aquinas, who argued that laws reflect moral precepts, but that they may be modified by changing circumstances.

Modern law is an extremely complex subject with numerous specialties and areas of study, including criminal law, international law, property law, contract law, constitutional law, and administrative law. It has a broad range of practical applications, from regulating financial transactions to ensuring human rights and environmental protection. Its societal applications include the protection of individuals and communities from harm, the resolution of disputes, and the allocation of resources.

The development of modern laws is a dynamic process that is constantly being revised in response to new social and economic needs, as well as changing technologies. For example, computer programs are being used for drafting legal documents, and the Internet is providing access to a wide variety of legal information and services.

In the United States, the term law is often used to refer to a country’s system of laws, rather than individual statutes or legal cases. This is because the U.S. is one of many countries that employ a common law system, which relies on the precedent of past court decisions to decide future cases. In contrast, some countries use a civil law system, which is based on judicial rulings and legislative statutes.

Legal scholars and practitioners are concerned with the application of law to a wide variety of topics, including social justice, human rights, global governance, and environmental justice. These concerns are reflected in the articles on these topics in this encyclopedia. Articles focusing on the legal profession, legal education, and legal ethics are available as well. For more on the relationship of law to politics, see constitutional law; ideology; political party; and political systems. For more on the importance of law to society, see public law; civil rights; and societal change. The history of the law is also covered in articles on law reform; and legal anthropology.