Law is the system of rules governing the conduct of people and their relationships to one another. It has four principal functions: establishing standards, maintaining order, resolving disputes and protecting liberties and rights.
A wide variety of laws exist to serve each of these functions. For example, contract law regulates agreements to exchange goods or services; property law defines people’s rights and duties toward tangible possessions, such as houses, cars and money; and criminal law defines offenses against a state, such as murder, robbery and homicide. Laws may be enacted by a legislature, resulting in statutes; enforced by the executive, resulting in decrees and regulations; or established by judges through precedent, resulting in judicial decisions. Private individuals can also create legally binding contracts and arbitration agreements.
The precise nature of law is a subject of debate. Some philosophers, such as Jeremy Bentham and John Austin, have argued that the essence of law is the aggregate set of commands, backed by threat of sanctions from a sovereign to which his subjects are accustomed to obedience. Other philosophers, such as Jean Jacques Rousseau and Thomas Aquinas, have argued that law reflects innate principles of right and wrong. The legal concept of natural law arose in ancient Greek philosophy and later re-entered Western culture through the writings of Aquinas.
Legal systems vary widely among nations and within countries, reflecting the diverse cultural backgrounds of the populations they serve. Some laws are derived from religious precepts, such as Jewish Halakha and Islamic Sharia, which have been further elaborated through interpretive methods such as Qiyas (reasoning by analogy) and Ijma (consensus). Other legal traditions reflect a blend of secular and religious concepts.
In most nation-states, the authority to make and enforce laws is vested in elected officials, whose power to do so is dependent on the popular support of their policies. However, in many societies the ability of individuals to challenge existing political-legal authority is a fundamental element of democracy and civil society. Rebellions against the existing regime are common throughout history, and the aspiration for greater democratization and rights for citizens is a recurring theme in politics and in the legal field.
The legal process of establishing, interpreting and resolving disputes is a complex and time-consuming endeavor. The study of law encompasses a wide range of issues, including the role and scope of justice, the limits of state power, the role of the judiciary, the foundations of legal knowledge and the relationship between law and other disciplines. A number of specialized fields exist, such as international law, criminal law and the law of war.