Law is a system of rules governing the actions of individuals and groups within a society. A legal system may consist of a constitutional document or written statutes, or it may rely on custom and practice in place of formally written code. The term ‘law’ is also used to refer to the practice of a particular profession or the body of knowledge that lawyers possess.

Legal systems are designed to ensure a peaceful society by creating standards of behaviour and enforcing them through mechanisms such as police, courts and punishments. The primary function of law is to promote social cohesion by ensuring that people follow the same rules and are treated equally. It also protects individuals from unfair treatment and provides a framework for making contracts and conducting business.

Law is not universally applicable, and the extent to which it is observed varies between nations. For example, in the United States, laws are made by the federal government and enforced by state governments. In some countries, political power is concentrated in one or more ethnic or religious groups which can control the creation and enforcement of law. In some places, the military and bureaucracy have a great deal of authority over everyday lives, and this raises issues for accountability that did not exist in the days of Locke or Montesquieu.

The legal system is a complex area of study and there are many fields of law. For instance, criminal law concerns the punishment of crimes and offences; family law relates to marriage and divorce; labour law is concerned with tripartite industrial relationships between worker, employer and trade union, and the regulation of collective bargaining; constitutional law is the basis for the legal system in many countries; torts and contracts concern the rights and wrongs that arise in everyday life; and evidence law concerns which materials are admissible in court for building cases.

A well-developed knowledge of law is vital for a civilised society. It allows us to make informed decisions, plan for the future and develop a sense of justice and fairness. A stable and transparent legal system protects against anarchy and the Hobbesian war of all against all, while ensuring that human rights are respected, and that contracts and property are protected.

A good understanding of the rules of the legal system is essential for politicians, civil servants and all public officials. In addition, all government officers must take oaths to uphold the constitution and not act illegally. The Supreme Court of the United States requires all its judges to swear an oath to ‘preserve, protect and defend the Constitution of the United States against all enemies, foreign and domestic’. The rule of law should be protected by all governments, so that everyone is subject to the same laws and is equal before the law. This includes avoiding corruption and upholding the right to freedom of speech and assembly. The rule of law should be enforceable by an independent judiciary, and by open and accountable democratic processes.