A system of rules that regulates human behaviour and is enforced by a controlling authority, often through sanctions. Law shapes politics, economics, history and society in a variety of ways and also mediates relations between people.

Different legal systems use different methods to create laws. For example, countries such as the United States employ a common law system where judges determine whether people who are charged with crimes are guilty or not based on evidence presented in court. In contrast, countries such as Japan use a civil law system in which legislative statutes provide a framework for how judges should decide cases. Both kinds of systems rely on the principle of precedent, or stare decisis (Latin for ‘to stand by decisions’), which means that earlier rulings and decisions are binding on future courts and judges if they relate to similar issues.

Law can be divided into various categories based on the kind of issue it concerns, such as contract law, property law, employment law or family law. For instance, contract law involves the regulations for agreements to exchange goods or services, while property law relates to people’s rights and duties toward their tangible possessions, such as land, buildings or cars. Employment law focuses on labour relations between employees and employers, while legal theory and procedure involve the rules that govern how cases are investigated and decided upon in court.

It is not easy to give a clear definition of Law because there are many different ideas about what it is and how it should be created. Hans Kelsen proposed a ‘pure theory of law’ which stated that the law does not seek to describe what must occur, but defines certain rules that individuals must abide by.