Law is a system of rules created and enforced through social or governmental institutions to regulate behavior. Its precise definition is a matter of ongoing debate, though it has often been described as a science and as the art of justice. Law may be made by a collective legislature through statutes, decrees and regulations, by the executive branch through orders and regulations, or by judges through precedent, normally in common law jurisdictions. Private individuals can also create legal rights and responsibilities through contracts and other documents, such as wills, trusts and letters of attorney.

The laws of a nation serve many purposes, including establishing standards, maintaining order, resolving disputes and protecting liberties and rights. Some nations have more extensive, complex and detailed legal systems than others. A legal system can serve its citizens best when it is designed with their needs in mind, while avoiding the potential for oppression or discrimination against minorities.

Laws in a nation are generally categorised into criminal and civil. Criminal laws are enacted to punish people who have committed offences against the state or its citizens, while civil laws cover disputes between individuals, such as family and property law. A country may also have special laws covering specific fields, such as aviation law, labour law and medical jurisprudence.

In a “common law” legal system, decisions by courts are recognised as legally binding on future judges in the same court, and are based on a principle of stare decisis. In contrast, in a “civil law” system, legislative statutes and administrative regulations are given more weight than court decisions.

The legal system is a complex, diverse and often confusing field. Oxford Reference offers a range of articles that provide clear, concise and straightforward explanations and answers to key questions about law. Our articles are written by expert authors and include tables, charts, chronologies and links to further reading. They explore the major issues, concepts, processes and organisation of law at all levels, from legal dictionary entries to in-depth encyclopedic articles on specific areas of law such as international law and family law. Our articles are also designed to support research at every stage, from students studying for exams to experienced professionals and practitioners. They are written in plain English and are clearly structured with headings and subheadings for each main area of law. They also refer to relevant legislation where appropriate.