Law is the system of rules created and enforced by a society to regulate human behavior. Its precise definition has long been a matter of debate, but has traditionally included both the set of commands issued by a government (see statutory law) and the set of customary policies recognized as binding in a legal system (see common law). The study of law is called jurisprudence.

The laws of a society can be created by a legislature, resulting in statutes; by the executive, resulting in decrees and regulations; or by judges in a court of law, resulting in case law. Private individuals may also create legally binding contracts, which are enforceable under contract law. Laws can be federal, which arise from the Constitution, or state, which are derived from the state’s constitution or a body of statutory law enacted by the legislature.

Some legal systems are based on the principles of a religion, such as Islamic law or Jewish law. Other legal systems are based on a mixture of secular and religious ideas, such as the Hindu or Buddhist legal traditions, or on the English common law system. Some legal systems are influenced by European countries, such as France or Germany, while others have been influenced by Eastern cultures, such as China or Japan.

Among the most important elements of law are rules about property ownership, inheritance, taxation and civil rights. Some laws protect freedoms, such as free speech, a free press and the right to privacy. Other laws regulate the economy, such as banking regulation, which sets minimum standards for how much capital banks must hold and rules about best practice for investment; or public utility regulation, which deals with the provision of utilities like electricity, gas and water. In modern times, some people have pushed for the expansion of the law to cover sexual harassment, environmental pollution and global warming, although many others are worried about how far the power of the state can be extended in this way without creating an authoritarian regime.

The rule of law reflects the balance between these concerns. In a democracy, the law must provide a safe and secure environment for all its citizens. This is achieved by the existence of a judicial system, a free press and a range of checks on the exercise of state power. The rule of law also requires that laws are enforceable, understandable and fair to all, regardless of social class.