Law is the system of rules a particular country or community recognizes as regulating the actions of its members. It is a large and complex field that encompasses many topics, including contract law, criminal law, environmental law, family law, property law, intellectual property, administrative law and constitutional law. Law is an academic discipline, a social science, and a profession. The practice of law is regulated by governments and independent governing bodies. Lawyers must pass a qualifying examination, be admitted to a bar or bar association and complete a legal education program.

The purpose of the law is to establish standards, maintain order, resolve disputes and protect liberties and rights. It does so in a variety of ways, such as defining terms used in contracts and other agreements (commercial law), determining responsibilities and rights toward tangible goods or services (property law) and providing guidance on how to treat people in the course of a trial or other legal proceeding (legal ethics).

Even in well-ordered societies disagreements between individuals arise. The law provides a way to resolve these conflicts without violence, such as by deciding who owns a piece of land. It also ensures that public officials, such as police officers and government workers, are held accountable to the law.

A person who is accused of a crime can challenge the evidence presented in court by filing a motion to dismiss or to quash the complaint. A judge can then review the evidence and decide whether to dismiss the charge or allow a trial to proceed. The process of challenging the evidence or a decision by a judge is called an appeal.

There are two main types of laws: common law and civil law. In countries with a common law system, judges’ decisions in previous cases that have similar facts and laws determine how a current case should be decided. This is known as the “doctrine of precedent” or stare decisis. In contrast, civil law systems typically have legislative statutes that set out detailed rules for determining how a case should be decided.