Law is a set of rules that are enforced by social or governmental institutions to regulate behavior and provide justice. Law has many functions, but the principal ones are establishing standards, maintaining order, resolving disputes and protecting liberties and rights. Its precise nature is a matter of long-standing debate, with some philosophers holding that it consists of a collection of social norms that are morally or ethically binding on people and others. Other scholars view law as the product of a collective decision making process, with a system of enforceable rights and punishments that is developed through history. Legal systems vary greatly from one place to another, and some governments are able to better serve the principal purposes of law than others.

Throughout history, the coercive nature of law has given rise to many fierce controversies over its status as a normative domain. Early utilitarian philosophers, such as Jeremy Bentham and John Austin, maintained that the central characteristic of law is its power to impose its practical demands by the threat of sanctions. By contrast, 20th century legal positivists like H.L.A. Hart and Joseph Raz argued that the coercive aspect of law is neither essential nor pivotal to its role as a normative institution.

The law may govern a variety of aspects of society, from individual rights and liberties to the structure of governments and international treaties. For example, property law establishes people’s rights and duties toward tangible property, such as houses or cars. Contract law defines the terms of agreements between two or more parties, and includes everything from buying a bus ticket to trading options on the stock market. Criminal law deals with offences against the state, such as homicide or fraud. Environmental law, administrative law and constitutional law are all parts of the law.

Many areas of the law are governed by both state and federal jurisdictions. States typically have more authority over local issues, such as traffic violations and municipal planning, while the federal government has greater powers over national matters such as the military, money (including taxes), foreign affairs, tariffs, patents and copyrights, and mail. The United States Code is a complete codification of federal laws, with each section arranged by subject matter and published every six years.

In bicameral legislatures, such as the Senate and House of Representatives in the United States, each chamber has to approve a bill before it can become a law. The executive branch can refuse to sign a bill, in which case it is returned to the legislature with a message explaining why, called a “veto”. Laws can also be amended through the legislative process by passing new bills or amending existing ones. In addition, there are various specialized fields of the law, such as administrative law (the rules that govern how government agencies operate), criminal procedure, civil procedure, family law and evidence law. The study of law is considered a highly respected profession, and those with degrees in law are often well-paid and in high demand.