Law is the set of rules and customs enforced by social or governmental institutions in order to regulate behavior. Societal viewpoints on the definition of law reflect on issues of rationality, justice, morality and order. From a judicial perspective, the word law can refer to a policy, statute, guideline or rule.

In the United States, federal law is enacted by Congress through a legislative process resulting in statutes; by executive order or decree, resulting in regulations; or by judges, resulting in precedent. Judges’ interpretations of the meaning of laws carry the force of law through the principle of stare decisis. In addition, the Constitution gives the President authority to create treaties and international agreements. Traditionally, federal law focused on areas where the Constitution expressly granted the government power, such as the military, money, foreign affairs (especially international treaties), and tariffs. But since the start of the 20th century, broad interpretations of the Commerce and Spending Clauses have allowed the expansion of federal law into areas like aviation, telecommunications, railroads, pharmaceuticals, intellectual property, antitrust and trademarks.

A legal system’s purpose is to establish standards, maintain order, resolve disputes and protect liberties and rights. A legal system can accomplish these goals through coercion, persuasion or a combination of both. Coercion relates to the use of violence or other methods of physical force against individuals or groups, while persuasion is the logical opposite, involving the use of reason and rhetoric.

Law can be divided into several branches, ranging from family law to corporate governance and jurisprudence. Contract law, essential in commercial partnerships, outlines agreements and exchanges of goods and services between entities, while civil rights laws deal with the protection of an individual’s private and public interests. Criminal laws deal with societally unacceptable conduct and punish violators through fines, imprisonment or other means.

Many scholars study the nature of law and its evolution through historical or comparative analysis, using primary or secondary sources. In this type of research, historians or sociologists may look at the development of a particular law, while jurisprudents use case studies to analyze a specific legal situation. Legal practitioners also write articles to describe and explain new developments in a field of law. These articles can be published in professional journals, academic articles or in newspapers. Some of these legal articles are scholarly in nature, while others are more general and accessible to the lay reader. Legal articles are also available in audio and video format.