Law is a system of rules enforced by an authority, often a sovereign state, to regulate conduct and settle disputes. It serves four primary purposes: establishing standards, maintaining order, resolving disputes and protecting liberties and rights. Law can be created and enforced by a legislative body through statutes; by the executive branch through decrees and regulations; or by courts through judicial precedent (also known as case law). The precise definition of law varies widely depending on context and culture, with varying views about what constitutes legality, justice and morality.
Law encompasses a large number of specific areas, and the overlapping boundaries between different types of law give rise to a variety of systems of law. For example, contract law regulates agreements to exchange goods or services, and property law defines people’s rights and duties toward tangible and intangible property such as land, houses, cars and shares of stock. Criminal law deals with the punishment of crime, and environmental law establishes protections for natural processes such as climate change.
The United States employs a common law system, in which judges’ decisions are legally binding on future cases in the same jurisdiction, while countries like Japan use a civil law system, in which laws are written by legislators and codified in legal statutes. These two law systems are distinguished by their traditions and processes for interpreting and applying laws. Nevertheless, there has been considerable cross-fertilization of ideas between them. Today, a majority of the world’s population lives in common law jurisdictions or mixed systems that combine common law with civil law.