Law is the system of rules and procedures governing a community for establishing and maintaining order, resolving disputes and protecting liberties and rights. It is the foundation of many professions, including journalism, politics, government, business and the arts. There are many branches of law, including contracts; criminal law; family law; labour law; property law; and constitutional law.

Law shapes politics, economics, history and society in a variety of ways. For example, contract law regulates agreements between people, determining their duties and expectations, the measure of damages in case of breach and how to resolve disputes. Property law defines people’s rights and duties toward tangible property, such as land or a house. Criminal law sets out the punishments for crimes and other wrongdoing.

The law is complex from a methodological point of view. It is normative (telling people what they ought to do or not do) rather than descriptive or causal, like empirical science (such as the laws of gravity) or even social sciences (such as a law of supply and demand in economics). In addition, it cannot be tested by direct observation. Instead, it is derived from a series of authoritative statements, whether in the form of judicial decisions or scholarly opinions.

Some nations have a civil law system, in which the sources recognised as authoritative are statutes adopted through the legislative process and regulations issued by executive branch officials. Other countries have a common law system, in which the authority is judge-made precedent and the “doctrine of stare decisis”.

A central theme of modern legal theory is that of the rule of law, which requires that all citizens are subject to the law and that the law is publicly available and consistently applied by authorities who are accountable and impartial. In a democracy, this includes elected leaders and the judiciary. In autocracies and dictatorships, the rule of law is more prone to deterioration when it has insufficient corrective mechanisms.

There are many factors that influence the effectiveness of a country’s legal system, including the strength and stability of its political structure, its constitutional framework, its laws, and its institutions. For more on these topics, see constitution; judicial system; law and society; legal education; and the relationship between law and the economy. For the law’s relationship to social issues, see human rights; land reform; and legal ethics. The legal system of a nation reflects the culture and historical background of its inhabitants. For example, Islamic Shari’ah law governs much of the world’s Muslim populations. It is a mixture of religious scripture and a secular jurisprudence. It is an example of both the law of nations and the natural jurisprudence that is inherent in all cultures. The concept of the law has been influenced by ideas from religion and philosophy as well as secular anthropology and sociology. It is considered to be one of the most important human achievements, and there are many articles and books on the topic of law.