Law is a system of rules that governs the behavior of people within a society. These rules are created by a controlling authority, and they can be enforced by that authority through the imposition of sanctions, or penalties. Law is a complex concept, and there are many different theories of it. Some of these theories differ in the ways they define law, and others focus on its various functions. The main purposes of law are establishing standards, maintaining order, resolving disputes, and protecting liberties and rights. Law also serves to encourage social change by ensuring that minorities are not oppressed by majorities, and it can protect individuals from the abuses of power exercised by governments.
Different countries have different systems of law, and some use different terms to describe their legal systems. The United States, for example, employs a common law system that relies on judicial decisions rather than legislative statutes. Decisions made by judges in cases that have been brought before courts are collected into books called case law, and these judgments form the basis for future decisions. In contrast, countries such as Japan employ a civil law system in which laws are written out in detailed codes. Civil law courts typically have less discretion in their interpretation of the code than common law courts do in deciding individual cases.
Other branches of law include criminal, family, and employment law. Criminal law involves the prosecution of people who have committed crimes, and the determination of their guilt or innocence based on evidence presented to a jury. Family law focuses on the relationship between parents and children, and includes issues such as adoption and divorce. Employment law relates to the relationship between workers and employers, including the right to unionize. This branch of law also addresses issues such as minimum wage and worker safety.
Commercial law, which includes such areas as the law of trusts, insurance law, contracts, and bills of exchange, traces its roots back to the medieval Lex Mercatoria. Other legal fields such as environmental law and constitutional law are based on international conventions that have been agreed upon by different nations.
The definition of law is a highly contested topic, and different writers have produced numerous books with their own ideas about what it should be. Some of these books focus on the history of law, while others concentrate on specific branches of the subject. A comprehensive reference on legal topics, Oxford Reference offers expert-level entries covering the main terms, concepts, processes, and organization of law. Our collection includes legal dictionaries, encyclopedias, and case law, as well as major debates in legal theory.