Law is a system of rules and regulations established by a community and enforced by its government. It can be written or unwritten, formal or informal, and it may have a religious, political or social basis. Law shapes politics, economics and history in many ways and also acts as a mediator between individuals.

It is not easy to give a precise definition of law, as the concept varies from one society to another and across time. But a broad and basic view would be that the law is the set of rules that the state establishes to govern its people in a way that ensures peace, safety and prosperity. The law defines and limits the activities of a community and regulates relationships between citizens, among nations and between states. It governs the use of force in war and other disputes, sets out rights, duties and responsibilities in civil and criminal proceedings, establishes property ownership and explains how to settle disputes.

The law reflects the values and customs of the society that creates it. It is based on principles that are codified in statutes, treaties and constitutions or developed through judicial decisions. It can be influenced by cultural traditions and social pressures, political theories, avowed or unconscious prejudices of judges, and even the personal preferences of lawyers and other members of the legal profession.

Most laws are created through a legislative process in which ideas for new legislation are put forward in the form of bills, often identified by their initials: H.R. (House of Representatives), or S. (Senate). If the bill is backed by a majority of the House of Representatives or the Senate, it becomes law. It is important to note that the law can change at any time, and even a law that has been in place for a long time can be amended or repealed.

Judges have a particularly important role in shaping the law. Their opinions in particular cases are considered to be law, and they have a much greater influence than the legislative process. The history of the development of the law in Britain illustrates this. For example, it was once common practice for litigants to petition the King for an order against a trespasser who had invaded their property. This was known as ‘common law’ and was in contrast with the prevailing law of equity that was administered by the Lord Chancellor, in the courts of chancery.

The development of law has always reflected human experience and felt necessities, as well as a host of philosophical ideas about right and wrong. The evolution of the law can be seen in areas as diverse as tort law (accidents and wrongful death), family law, employment law, tax law, biolaw and competition law. It is impossible to understand a country without understanding its law. The Cambridge Dictionary of Law is a comprehensive, up-to-date reference for all aspects of law and its historical development. It includes thousands of concise definitions, and in-depth, specialist encyclopedic entries.