Law is a system of rules that control human behavior in a society. It is based on principles of justice and fairness that are applied impartially. Law also establishes the status and rights of individuals. Law can be formal and written, such as statutes or regulations, or informal and unwritten, such as custom, tradition or social norms. Law can be enforced by courts, police, or other government agencies. Law can also be private, such as contracts or arbitration agreements.
The precise definition of law is a long-standing subject of debate. Hans Kelsen, for example, proposed the “pure theory” of law, which states that law is a “normative science,” but a more common interpretation is that law is simply the set of rules that must be followed by members of society to ensure justice and peace.
A large variety of legal systems exist in the world, from ancient and medieval law to modern criminal and civil legislation. The concept of law is largely dependent on political circumstances and is highly variable from nation to nation. In general, laws are based on principles of equity and fairness, which are applied in different ways depending upon the culture and history of a given nation. In some nations, laws are based on religion; for example, Jewish and Islamic law are derived from scriptures that provide guidance through detailed systems of interpretation, Qiyas (reasoning by analogy), Ijma (consensus), and precedent.
In most cases, laws are made by the legislative branch of the government through statutes, and in some cases, they are imposed by the executive branch through decrees or regulations. In other cases, law is created by judges through precedent, and in still others, law is based on religious or cultural traditions. The structure of a nation’s governing body, and the extent to which it exercises discretion over the lives of its citizens, is also an important factor in the creation of law.
The scope of law is vast and varied, with laws regulating everything from the minimum amount of capital that banks must hold to a specific way of dressing in public. Other laws are more narrowly focused, such as a prohibition on the manufacture of weapons or a requirement that all public utilities be provided by private companies bound by certain levels of social responsibility.
In some fields, like aviation and railroads, the federal government has established a comprehensive set of laws that preempt state law, while in other cases, such as family law or antitrust, a small number of federal statutes interact with a much larger body of state law. The laws of a particular country also vary greatly by the nature and extent of its economic activity.