Law is the system of rules that a particular country or community recognizes as regulating the actions of its members. It consists of both statutes (written laws) and common law, which are decisions of judges that have become legally binding because they have been consistently upheld over time. The study of law encompasses a wide range of topics, from specific areas of the law such as criminal or family law to legal systems and history and general theories of law and ethics.
Whether a nation’s government is democratic, authoritarian, or somewhere in between, its laws serve to (1) keep peace and the status quo, (2) preserve individual rights against majorities and minorities, (3) provide social justice and orderly change, and (4) promote economic well-being. Some governments do a better job of these functions than others, though the precise reasons why vary widely from nation to nation.
A legal system may be based on the written or unwritten constitution of a country, and the rights it contains; on the principles of equity, fairness, and impartiality; on the notion of natural justice as formulated by Aristotle and other ancient philosophers; on the Bible and other religious texts; or on a combination of these and other traditions. A key aspect of a functioning legal system is the principle of accountability, which requires that both public and private actors are held to account by both the laws they create and the courts that enforce them.
Most societies have a number of different laws that govern all aspects of life and human behavior, including contracts, property, criminal, employment, environmental, constitutional, and international laws. These laws may be created by legislative bodies, resulting in statutes; by the executive, via decrees and regulations; or established by judges through precedent, known as case law. In addition, many nations have treaties that dictate the rights and obligations of their citizens with other countries.
Contract law regulates agreements to exchange goods, services or anything else of value, from buying a bus ticket to trading options on a derivatives market. Property law establishes people’s rights and duties toward tangible property, both real estate – land or buildings – and personal property, movable objects such as computers and cars, or intangible assets like bank accounts and shares of stock. Criminal law defines what constitutes a crime, including the actus reus (the action) and the mens rea (the mind involved in the act), which are often defined by statute and require proof beyond a reasonable doubt.
Environmental law focuses on the protection and preservation of the environment, while constitutional law addresses the limits to government power and the role of courts in interpreting and upholding the constitution. Employment law covers issues ranging from hiring and firing to workplace discrimination and safety. Immigration and nationality law deal with the right to live and work in a country, acquire or lose citizenship, and the problem of stateless individuals. And a variety of other legal fields, from canon law to biolaw, explore the intersections of science and the law.