Law is a system of rules created and enforced through social or governmental institutions to regulate behavior. Laws shape politics, history, economics and society in many ways. They can serve four principal purposes: establishing standards, maintaining order, resolving disputes and protecting liberties and rights.
The precise definition of law is a matter of debate, with the field of legal study broadly divided into a number of schools of thought. The most common theories of law focus on its origins and functions, including a broad set of assumptions and philosophies that form the foundation of most legal systems in the world today.
One common theory of law, developed by the sociologist John Erskine, defines it as “a command of a sovereign containing a common rule of life for his subjects and obliging them to obedience.” Another, elaborated by Hans Kelson, defines it as a hierarchy of norms in which every norm derives its validity from the superior norm (known as the grundnorm). Finally, H.L.A. Hart argues that law is the combination of primary rules of obligations and secondary rules of recognition.
Law shapes and guides a wide range of social activities, including commerce, labour, property, religion and the family. It also governs the treatment of animals, the environment and national security. Law is a central aspect of government and a major part of any modern democracy. Laws are generally created and enforced by democratically elected governing bodies, often with oversight by a judiciary.
There are many different laws in existence, with some based on religious beliefs and others on scientific principles. Most countries have a mix of legal traditions, with most having a civil law tradition, which originated in ancient Roman times, and a common law tradition, which evolved from precedent established by judges.
Laws can be created by a legislature, which results in statutes, or by the executive through decrees and regulations. Laws can also be established by courts through caselaw, a method that allows the legal system to evolve and adapt as the needs of society change.
The subject of law covers virtually all aspects of human life, and the subjects within law intertwine and overlap. Some examples include employment law, which regulates the relationship between employee and employer, and labour law, which governs trade unions, industrial action and the right to strike. Environmental law, which deals with the regulation of the production and use of natural resources like energy, water, oil and gas, is a particularly important field. In addition, laws relating to health and safety, the environment and crime are important in most jurisdictions. Lastly, there are laws concerning family, immigration and nationality, and the treatment of foreigners and stateless individuals.