The law is an institution that shapes politics, economics, history and society in many ways. Its principal purposes are establishing standards, maintaining order, resolving disputes and protecting liberties and rights. Law may be viewed as a social construct (as a result of human action) or as a natural phenomenon (such as the laws of gravity).

The study of the legal system is known as jurisprudence. The process of determining the right course of action to take in a legal case is called litigation. The participants in a lawsuit are known as litigants, and the judge and lawyers who represent them are called attorneys. The judicial branch of government is responsible for making and applying the laws. It is also the source of legal interpretation, which is essential to interpreting laws and regulations that are vague or unclear.

A specialized area of law is space law, which deals with the rights and duties people have toward objects in outer space and in Earth orbit. Another specialty is criminal law, which covers the rules and punishments for committing crimes. Civil law encompasses the rights and duties of people in relation to each other and their possessions, such as contract law, property law and tort law. In most modern nations, these areas of law are governed by a legislative statute or the constitution, with decisions made by judges, often called barristers or barristeres.

In common law systems, judicial decisions are explicitly acknowledged as “law” on equal footing with the statutes passed by legislatures and the rules created by regulatory agencies. This principle is known as stare decisis. Decisions from higher courts are binding on lower courts, and bind future judges as well.

Other sources of “law” include the acts of a monarch or sovereign, or codes of conduct written by professional bodies. Religious law, such as Sharia in Islamic countries, still plays a role in some societies.

The concept of law is complex from a methodological point of view. It includes normative statements that tell us how people ought to behave, and prescriptive statements that tell us what they must do or not do: the law of self-preservation, for example. Holmes’s ontological definition of law describes how these laws emerge from human action: the act of participating in a social world shaped by each participant’s individual narrative and a codified community narrative that tells everyone their stories will be treated equally. As the participants’ experiences flow, their probability estimates are updated and the law evolves anew. Holmes viewed this fluid process as law’s essence. He believed that the law is “what you know to be true, when you know it to be true.” This article was originally published in December 2017 and has been updated. The author wishes to thank Dr. David Leighton for his assistance with this article.