Law is a set of rules that are created and enforced by social or governmental institutions to regulate behavior. Its precise definition is a matter of longstanding debate. It has been variously described as a science and as the art of justice. It is characterized by its connection with sanctions and by the fact that it can be derived from a hierarchy of norms.
The legal system varies from nation to nation. Different legal cultures develop different sets of laws that reflect their particular culture and history, although some of the basic features are universal to all systems. These include the principle that laws must be publicly promulgated, equally enforced and independently adjudicated; the principles of separation of powers, participation in decision-making and legal certainty.
From an ontological perspective, law can be defined as the fact that a person or group assigns true or false values to mathematically undecidable propositions (that is, probabilistic). This probability estimate is continuously revised and thus the system of laws is dynamic. This process is called experience and is the basis of Holmes’s definition of law as a flowing process.
Laws govern a wide range of topics, including immigration and citizenship; family, property and criminal law; the rights of children; contracts and commercial transactions; and the protection of the environment. In addition, the law shapes politics, economics, history and society in many other ways. For example, law influences the formation of political institutions, such as government and military, and the distribution of power.