Law is a set of rules that social or governmental institutions create and enforce to ensure a peaceful society, and impose sanctions on those who break them. The precise nature of law is a subject of debate and numerous books have been written on the subject, with different ideas about its exact meaning, purpose and method.
Law covers a vast number of areas, from contracts to property to criminal law. The study of law is a source for scholarly inquiry into legal history, philosophy, economic analysis and sociology.
The broad scope of law reflects the complex way people live together in modern societies. In the United States, contract law relates to everything from purchasing a bus ticket to trading options on the derivatives market, while property law governs how people own and use tangible possessions like homes, cars and computers, as well as intangible assets such as bank accounts and shares of stock. Criminal law deals with the activities of criminals, and the legal system establishes punishment guidelines that are based on the seriousness of crimes.
Many countries have different systems of law, depending on their history and culture. In “common law” systems, judicial decisions are given equal weight with legislative statutes and regulations, and judges adhere to the doctrine of precedent (the principle that similar cases should reach similar results) when deciding future cases. In civil law systems, the principle of precedent is less binding.
Religions provide another source of law, with Jewish Halakhah and Islamic Sharia providing guidelines through the process of ijtihad (reasoning by analogy), qiyas (contextual application) and ijma (consensus). These traditions are often viewed as immutable by human interpretation and elaboration, but can also be overturned by religious authority.
In the field of business, corporate law encompasses issues related to ownership, control and structure of companies. Commercial law covers complex contract law, such as insurance and bills of exchange, and the laws governing sales (which stem from the medieval Lex Mercatoria).
The law of war, military command and policing also fall under the umbrella term of law, as do social restrictions such as censorship and crime. These areas of law require specialized knowledge and skills that are not necessarily taught in law schools.