Law is a body of rules created and enforced by social or governmental institutions to regulate behavior. Its precise definition is a subject of ongoing debate. Law may be enacted by groups of legislators, resulting in statutes; by the executive, through decrees and regulations; or by courts through precedent (common law jurisdictions). In addition to state-enforced laws, private individuals can create legally binding contracts. The study of law includes research into legal history and philosophy, as well as the more technical aspects of a specific jurisdiction’s legal system.

The principal purposes of law are to establish standards, maintain order, resolve disputes and protect liberty and rights. A nation ruled by an authoritarian government may, for example, keep the peace and maintain the status quo, but it can oppress minorities or political opponents. In contrast, a republic governed by the rule of law can provide freedom and opportunity for all citizens.

Legal systems vary greatly among nations, reflecting cultural traditions and historical experience. For example, Hindu and Islamic laws formerly prevailed in India until they were supplanted by common law when that country became a part of the British Empire. In contrast, western European countries derived their civil law from Roman law, while eastern Asian countries have developed a distinctively oriental legal tradition.

A key question in the theory of law is how much a legal system should reflect morality. Utilitarian philosopher Jeremy Bentham argued that law consists of “commands, backed by the threat of sanctions, from a sovereign to whom people have a habit of obedience”. In opposition, natural lawyers such as Jean-Jacques Rousseau argued that law reflects an innately moral and unchanging set of laws that exist in nature.

The practical application of law involves a complex process. For example, a court has to ascertain the facts of a case and examine any existing laws and cases. Judges then apply the principles, analogies and statements made by other judges to decide how they should rule on the particular facts before them. In this way the judges form a decision that constitutes the law for that case.

The scope of law is vast and varied, encompassing virtually any activity that requires a sanction from the state. Examples include criminal, tax and social security laws; business, property, intellectual property and environmental regulations; and employment and family laws. For more specialized fields, see: